Author: Jim Collins

Dart: Crashing a Satellite Into an Asteroid for Planet Defense
What is the DART mission? Here is everything there is to know about it. Thousands upon thousands of asteroids speed through space with many of them routinely passing within Earth’s orbit. A regional or perhaps worldwide disaster could be triggered if one of them were to arrive on a collision track with Earth. With its DART mission, NASA is exploring whether or not this may be avoided; for the first time, humankind will seek to alter an asteroid’s course by use of a ram probe.
- DART successfully crashed into the asteroid Dimorphos
What could be done if an asteroid is headed in the direction of Earth? According to NASA, a more effective defense would be to use an unmanned spacecraft to deflect the asteroid. On September 26, 2022, NASA’s DART mission will put this kinetic deflector approach to the test.
How do you avoid an asteroid collision?
The risk is real: Earth has been bombarded by space debris several times during its existence. The impact of the 6.2-mile (10-kilometer) wide Chicxulub asteroid 66 million years ago terminated the Cretaceous epoch and wiped out the dinosaurs, while other impacts have created worldwide disasters and monumental mass extinctions. The Tunguska event of 1908 and the Chelyabinsk meteor explosion in February 2013 proved, however, that even tiny fragments may wreak devastating harm.
About 25,000 asteroids, each about 500 feet (150 meters) in size, orbit in the neighborhood of the Earth and often pass through the Earth’s orbit. Although many incidents still go unreported.
It’s just a matter of time
Small chunks up to 3.3 feet (1 meter) in size continue to impact Earth practically daily but are burned up in the atmosphere before reaching the surface. Asteroids up to 1,000 feet (300 meters) in size are expected to strike every few thousand years, and asteroids the size of the Chelyabinsk meteor are seen on average once every 50 years. They are big enough to obliterate a whole city of millions. It’s not a matter of if, but rather when, the next major impact on Earth will occur.
What could be done if an oncoming asteroid is noticed in time? Whether humanity still has time to adopt countermeasures for an approaching asteroid depends on the size of the asteroid and the time left before the impact. When the threat is known decades in advance, the “gentle” “Gravity Tractor” defense could be all that’s needed: Using the gravitational pull of a large probe brought in close proximity to the asteroid, you can divert the asteroid off an Earth collision trajectory.
The kinetic deflector
A spacecraft smashes the asteroid and attempts to divert it off its crash route in an asteroid defense via a kinetic deflector. (Image: INASA/Johns Hopkins University APL)
But in reality, it is more probable that the asteroid will go undetected until it is too late. Because many possible Earth-orbiting asteroids are hard to spot in advance due to their dimness and their orbital distance to the Sun. The 330-foot (100-meter) asteroid called “2019 OK,” for example, was only discovered 12 hours before its closest approach in 2019. Thankfully, it was passing Earth at a distance of barely one-fifth that of the moon. After that point, no amount of protective measures will be able to prevent an impact.
However, there is still hope for an asteroid deflection if an asteroid on a crash track is discovered months or perhaps years in advance. The kinetic deflector approach is generally thought to be the best in such a scenario. As part of the strategy, the heaviest feasible spacecraft is sent in the direction of the asteroid to smash it at a specific angle. If the collision happens early enough, the force of the impact can deviate the fragment off its trajectory, and a deviation of only a few millimeters or a modest slowing is enough to prevent a collision with Earth.
But there is more to it
However, such a deflection is notoriously difficult in reality. The asteroid probe has to make a perfectly timed and hard collision with the asteroid. Too much of an off-angle impact will just alter the asteroid’s spin and not its course. The deflecting impact will be insufficient if the momentum is too low. This method requires the most precise data available regarding the asteroid’s course, spin, and size in order to precisely plan the collision.
If the asteroid is porous, most of the impactor’s energy might be absorbed instead of dissipated. The spacecraft’s collision might cause the asteroid to fracture if it is fragile or made of debris that is only weakly held together. Multiple, potentially catastrophic chunks can still head toward Earth in this case.
Given these challenges, NASA is conducting its first practical tests of kinetic deflection, called the DART Project, as a means of asteroid deflection, serving as a kind of “dress rehearsal” for the real deal.
Target object of the DART
A double asteroid as the impactor
Dimorphos’ new orbit after the collision of the DART satellite. The LICIACube will track the collision and broadcast pictures of the impact back to Earth. (Image: NASA/DART)
This is no easy feat since the whole collision must take place millions of miles from Earth to redirect an asteroid off its crash course with Earth. However, if the asteroid is so far away, the scientists may not be able to determine its exact nature, rotation, or mass before sending out the defensive probe since it will be beyond the precision of current Earth-based telescopes.
The selection of the test asteroid for DART
With the “Double Asteroid Redirection Test,” or DART, NASA is exploring the limits of an asteroid defense mission’s success and the hazards it faces. If an asteroid were to be headed toward Earth, a kinetic deflector, like the one shown by DART, would be the only way to stop it. DART’s mission is to change an asteroid’s orbit, so it can not collide with Earth.
The primary stipulation for the DART is that the experiment must not endanger Earth in any way. Even after an unsuccessful deflection, the target asteroid must follow a course that moves it as far away from Earth as feasible. However, in order to accurately assess the ramming’s effects, the candidate asteroid must be rather near. Thus, it has to be visible with large telescopes.
Didymos and its moon Dimorphos
Size comparisons of DART, Dimorphos, and Didymos. (Image: NASA/Johns Hopkins University APL)
The 1996-discovered twin asteroid Didymos satisfies these requirements for the DART mission. Didymos, the 2560-foot (780-meter) asteroid, and Dimorphos, its moon, measure around 525 feet (160 meters) in diameter. Because of their eccentric orbits, they both swing from the furthest distance from the Sun outside of Mars’ orbit to the closest distance to the Sun within Earth’s orbit. Accordingly, both are circling the Earth and are part of the class of asteroids that, although not immediately dangerous, may one day approach Earth.
This is also why the DART mission isn’t actually aimed at the asteroid Didymos itself. Because there’s too much of a chance that the asteroid may be redirected in such a manner that it would eventually crash on Earth. The moon of the asteroid Dimorphos (Greek for “two forms”) is the actual target of the DART. Due to the stability of its orbit around Didymos, any deviation will only alter the minor-planet moon’s path relative to Didymos.
Observing Dimorphos with transits
When Dimorphos passes in front of his parent asteroid Didymos, the change in brightness allows scientists to calculate its orbital period. (Image: NASA/Johns Hopkins University APL)
While in orbit around Didymos, the asteroid moon also travels directly in front of it. Due to this predictable transit, astronomers have been able to estimate Dimorphos’ orbit and size using just Earth-based telescopes. This tiny moon takes 11 hours and 55 minutes to complete one orbit around its parent asteroid. During this time, the distance between them stays at just approximately 0.73 miles (1.18 kilometers).
The DART mission’s before-and-after planning requires a high level of foreknowledge about the asteroid system. Dimorphos’ orbit around its parent asteroid may be significantly altered if the DART probe collides with the moon at just the proper location and velocity. This deflection, at least in the model predictions, is expected to become apparent during the transit phase. As a result of the impact made by DART on the smaller asteroid in the Didymos system, its orbital period will be altered by at least 73 seconds.
The Didymos-Dimorphos binary asteroids will be within observing distance of Earth at the time of the DART’s collision on September 26, 2022, at a distance of just around 6.85 million miles (11 million kilometers).
Almost indistinguishable from the actual threat
However, there is a second reason why the Didymos system is well suited as a test case for the DART: its two components are illustrative of prospective asteroid impactors on Earth’s course. Dimorphos, with a diameter of around 540 feet (165 meters), is huge enough to cause widespread destruction in the case of an impact on Earth. While its size is comparable to that of probable next-catastrophic-impact asteroids, it is not one of them.
The composition of the target asteroid of the DART mission is also quite similar to that of the asteroids that are flying close to Earth. Didymos’s composition matches that of an “L/LL chondrite” meteorite class according to the analysis of its visible and near-infrared spectra. And this is the composition of most meteorites that strike Earth. The experimental findings of the DART collision will be used for a wide variety of planetary defense research.
Order of events of the DART mission
Specifications of the DART spacecraft
The DART probe places itself at the ideal impact point by autonomously navigating its course. (Image: NASA/Johns Hopkins University APL)
The DART spacecraft has been traveling toward the asteroid Dimorphos since it was launched on November 24, 2021. The asteroid moon Dimorphos will be rammed by the spacecraft on September 26, 2022, at 23:14 UTC, in an attempt to knock it out of orbit. This will be the first-ever test of a technology designed to protect Earth from asteroids. The DART mission is outfitted with various high-tech enhancements that allow this to happen.
The impactor probe used in the DART mission seems plain at first glance: The dimensions of its hull are 3.9 by 4.3 feet (1.2 by 1.3 meters), making it about the size of a soda machine. During the roughly 10-month approach, the DART probe has been powered by two solar panels, each of which is a good 26 feet (8 meters) in length. An experimental ion drive generates thrust by electrostatically accelerating and ejecting xenon ions in a magnetic field. DART has 12 hydrazine-fueled classical maneuvering thrusters for course corrections and fine-tuning of the final approach to Dimorphos.
DART’s autonomous target acquisition and approach
The DART spacecraft from two perspectives. (NASA)
The DART probe has a navigation system that is considerably sophisticated. This is due to DART’s ability to fine-tune its trajectory on its own. The data from the DRACO camera, a tiny telescope with a focal length of around 8.3 inches (21 cm), and a high-resolution digital image sensor are placed on DART for this purpose. High-resolution photos captured by the camera will reveal the precise location and shape of Didymos and Dimorphos.
The spacecraft’s autonomous navigation system records these photos with location and attitude data. About 4 hours before the crash with Dimorphos, at a distance of 56,000 miles (90,000 kilometers) from the target, this SMART Nav system will assume complete control of the DART probe. The navigation system will initially perform an evaluation of the data in order to pinpoint the precise locations of Didymos and its moon Dimorphos using custom algorithms. An hour before impact, Dimorphos will appear as a small 1.5-pixel light point.
The navigation system will then be able to make autonomous decisions about whether or not trajectory modifications are required, and the DART probe’s correction jets will receive new commands. When there are only 930 miles (1,500 kilometers) left between Dimorphos and DART, the asteroid in DRACO images will be around 22 pixels in size and it will be too late for DART to make any changes at this point. When DART is around 460 miles (740 kilometers) away from the target, it will be on a collision track with Dimorphos in two minutes. The probe will now just cover the rest of the distance.
The impact
The DART probe will crash on the surface of Dimorphos at a speed of around 14,000 miles (22,000 kilometers) per hour. DART weighs only 1,260 pounds (570 kilos), whereas the asteroid moon Dimorphos is predicted to weigh over 11 billion pounds (5 billion kilograms). Therefore their collision is more like a bug landing on an elephant. The impact’s relatively small impulse might not seem like it would accomplish anything.
This, however, is not true. The 540 feet (165-meter) rock will receive a little push from the high velocity of the DART collision. In addition to blasting between ten thousand and a hundred thousand pounds of debris into space, the impact will also create a hole in the asteroid’s surface. The force exerted on Dimorphos will be greater than that of the hit alone because of the rebound of this ejection. The combination of this amplified ramming action and the collision is enough to cause a little shift in the asteroid moon’s kinetic energy and knock it off of its orbit.
After DART crashed onto Dimorphos, the spacecraft will be destroyed but the scientific investigation will only be getting started.
Consequences of the DART Impact Event
What will happen to the massive Dimorphos-moon once the tiny DART spacecraft crashes into it? Will the massive asteroid be able to be steered out of orbit by kinetic deflection? How did scientists successfully predict the collision characteristics of the DART-Dimorphos event essential for a deflection?
LICIACube as the direct observer
The Italian Space Agency constructed LICIACube for the impact between DART and Dimorphos to send the collision images to Earth. (Image: (NASA/Johns Hopkins APL/Ed Whitman)
The LICIACube mini-satellite will report back the first data on the DART’s impact results and its effects on Dimorphos’s surface. This mini-satellite will ride behind the DART probe before it collides with the Didymos double asteroid, and its mission is to check out the impact area. Self-propelled with its maneuvering thrusters, it’s programmed to move into an observation point 15 days before the collision, which has already been initiated on September 11th.
LICIACube stands for Light Italian CubeSat for Imaging Asteroids. And the observations and documentation from this courageous little reporter will provide insights scientists couldn’t gain any other way. Using two optical cameras, LICIACube will capture the moment the DART spacecraft crashes on the surface of Dimorphos. Three minutes after the impact, LICIACube will adjust its course to fly near the DART’s crash location.
Images of the crater, the ejected material, and the type of debris of the DART impact are to be provided by this mini-probe. These photographs, together with the last close-ups captured by DART’s DRACO camera before the collision, will provide crucial details regarding the Dimorphos’ make-up, nature, and reaction.
A view of the Dimorphos orbit
Around the same time of the collision, a dozen or more very powerful telescopes on Earth will be aiming toward the Didymos system. The pair of asteroids are 6.85 million miles (11 million kilometers) away from Earth and are only a tiny speck of light even with the best telescopes. But we will be able to see from Earth the periodic variations in brightness of this light, which are set off by the transit of the moon Dimorphos in front of its parent asteroid.
A little shift in transit timing would indicate that the DART probe’s collision deflected the asteroid moon. Astronomers may roughly infer the strength of Dimorphos’ kinetic momentum and the extent to which its trajectory shifted in magnitude to find out whether the asteroid was successfully deflected and the DART mission was a success.
The essentials for the “genuine deal”
The events of DART’s mission definitely won’t be the basis for a Hollywood blockbuster, but the future of Earth’s safety is equally at stake. The ultimate goal of the DART mission is to demonstrate that human beings can deflect an approaching asteroid. If a similar-sized rock is ever found on a collision path with Earth, the knowledge and expertise gained from the DART test in the Didymos system will be invaluable.
Where to watch DART’s collision live
On Monday, September 26, at 4:14 p.m. PT / 7:14 p.m. ET, the spacecraft DART will crash with Dimorphos. Live coverage will start on NASA’s YouTube channel, and the NASA TV at 3 p.m. PT / 6 p.m. ET.
You can also see DART’s position live in the official NASA webpage.
Aftermath of DART
HERA, a spacecraft bound towards the Didymos system
This deflection mission won’t be completed right away despite the DART spacecraft’s collision with the asteroid moon Dimorphos and subsequent studies of the immediate repercussions.
HERA, a European spacecraft, will be launched in 2024 toward the Didymos system and arrive in 2026. For the first time, it will use on-site scientific instrumentation to explore the effects of this kinetic deflection. The HERA spacecraft will scan Dimorphos’s surface topography to an accuracy of within 33 feet (10 meters) using its LIDAR measuring system, camera, and mid-infrared scanner in order to examine the impact crater and any other changes to the surface that may have resulted from the collision.
More crucially, HERA will finally provide us with more accurate information on how far the DART probe steered away from its intended target. The rotation, mass, and orbit of Dimorphos and Didymos will be directly measured, unlike with terrestrial observatories. One way HERA will achieve this is by pointing its laser towards the parent asteroid and picking up the minute wobble caused by the small moon’s gravity. Additionally, HERA will do many near flybys of Dimorphos, transmitting data back to Earth each time. Scientists on the ground will be able to determine whether the asteroid moon’s gravity has altered the signals and, if so, by how much.
Milani: What are Didymos and Dimorphos made of?
The asteroids’ surface will be mapped by the CubeSat Milani, which will also examine the expelled dust. (Image: ESA/Science Office)
However, HERA isn’t traveling alone; it’s accompanied by two smaller satellites (CubeSats) that carry their own sets of equipment and will take readings that supplement those taken by HERA. The Milani minisatellite will use a hyperspectral camera and spectrometer to determine the elemental make-up of Dimorphos and Didymos.
This will also enable scientists to compare the composition of its surface to that of known meteorites and minerals, such as that of the DART crater and its ejecta. Milani also has an onboard analyzer calibrated to detect dust particles between 200 and 400 microinches (5 to 10 micrometers) in diameter. Scientists can use it to learn more about Dimorphos’ composition by studying the dust thrown up by the collision.
Juventas: First radar view into the interior of an asteroid
For the first time, radar will be used by the CubeSat Juventas to illuminate an asteroid’s interior. (Image: ESA/Science Office)
HERA’s companion CubeSat, Juventas, will be investigating the asteroids’ composition and dynamics up close. It is equipped with a miniature replica of the radar sensor used by ESA’s Rosetta comet mission to survey 67P/Churyumov–Gerasimenko, making it the smallest radar system ever sent into orbit. The Juventas radar system will carry out the same task at Didymos and Dimorphos. To do this, it will set up 4 radar antennas, each measuring 5 feet (1.5 meters) in length, and radiating radar waves with circular polarization. The incoming and outgoing signals from Dimorphos’ interior will be recorded and decoded simultaneously.
In order to get accurate readings, the tiny radar satellite Juventas will fly within 1.85 miles (3 kilometers) of Dimorphos at a slow enough speed to get high-resolution data despite the radar’s low power. The radar scan of an asteroid by Juventas will be the first of its kind which will greatly expand the understanding of asteroids. The reason for this mission is that the outside of an asteroid does not actually portray its interior accurately.
Determining whether Dimorphos is made of solid, compact rock or a loosely formed “pile of debris” will be crucial for future asteroid defense. This data, together with measurements of the DART deflection experiment will aid scientists in improving and adjusting the models and calculations used to plan such defensive operations to protect Earth from asteroids in the future.
September 24, 2022
An Explanation for Saturn’s Rings: A Lost Moon, Chrysalis
Saturn’s rings and current wobble in its rotating axis may have their origins in a “lost” moon. The research claims that Saturn’s hypothetical moon Chrysalis was broken apart by Saturn’s gravity when it went out of orbit around the planet 160 million years ago. This altered the planet’s axial tilt, which in turn disrupted Neptune’s resonance and produced sufficient debris to create the rings. It’s possible that this is also the reason Saturn’s rings are not that old.
No other planet in the solar system has such a large and intricate ring system as Saturn. Recent measurements imply that the thick bands of frozen pieces only formed around 100 million years ago, rather than simultaneously with Saturn.
Saturn’s rings are at a different location when it is in opposition to Earth because of the tilt and precession of Saturn’s axis (Credit: Mosesofmason/CC-by-sa 3.0).
It’s a puzzle why the axis is tilted
The rings and axis of rotation of Saturn are inclined 26.7 degrees with respect to the plane of its orbit around the Sun, giving it a somewhat powerful tilt. The known formation mechanisms in the protoplanetary disk or early collisions on the planet are insufficient to account for such a great inclination. Numerous hypotheses have been put forward, but none of them are very compelling.
There’s a suggestion that Saturn’s axial tilt is due to gravitational interactions with Neptune. As a result, Saturn’s axis wobbles nearly in time with Neptune’s orbital period, which may be indicative of a resonance effect.
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Scientists have assumed that Saturn’s rotational axis became as large as it is now due to a gravitational interaction between the planet and one of its moons.
To the limits of resonance
However, the angular momentum of Saturn is a vital quantity in determining whether or not the resonance theory is right. It affects how readily a planet may be knocked off of its orbit by natural or man-made disturbances.
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Neptune may be responsible for Saturn’s asymmetrical rotation if the angular momentum is too high. A decreased angular momentum, however, renders the whole situation implausible, necessitating the search for an alternative theory.
Jack Wisdom, Burkhard Militzer, and coworkers have recalculated Saturn’s angular momentum using a combination of observed data from NASA’s Cassini mission and theoretical considerations. Their finding was unexpected: the two planets do not resonate with one another. Regardless of the model assumptions or rotation period, the system is close to the resonance area but always outside of it. Their findings indicate a variation of about 1%.
Planetary scientists draw the conclusion from this that Saturn and Neptune were in resonance for an extended period of time. Nonetheless, this bond has obviously been compromised during the previous 200 million years.
Why is the moon Chrysalis missing?
But how exactly? The researchers used a model to replicate Saturn’s moon’s and its neighbors’ evolution to find out. Initially, they investigated whether the resonance break may have been caused by a shift in the orbits of Saturn’s moons. Although Titan, Saturn’s largest moon, has migrated further from the planet over time, this was not enough to disrupt the resonance between Saturn and Neptune.
If Saturn had a second moon in the past and subsequently lost it, the system could have been able to break free of resonance.
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It’s possible that this missing moon was swept away by a gravitational storm, or that it approached Saturn too closely and was shattered by the planet’s tidal forces. Each of these factors might disrupt the synchronization of Neptune’s orbit with Saturn’s axis.
Ejected from orbit
Based on their models, Wisdom’s team is able to piece together the following scenario: The new moon, Chrysalis, weighed nearly as much as Saturn’s third biggest moon, Iapetus. In theory, Chrysalis should be around 910 miles (1,470 kilometers) in circumference. Chrysalis’s orbit was predicted to lie between Titan and Iapetus, where it would have remained stable for a considerable amount of time. But then Titan started to move further and farther away from Earth.
The moon Chrysalis got into an unstable orbit due to this event sometime between 100 and 200 million years ago. In some simulation runs, this factor led to the moon being expelled from the system. The moon was ripped apart by Saturn’s tidal forces because it passed too near to the planet on previous orbits. Saturn would have lost resonance in either scenario.
Newly-formed ring explanation
Moreover, the rings were formed as fragments of the moon continued to circle Saturn. Their theory also explains the young age of Saturn’s rings, which has long been a mystery. Those icy rings might be what’s left behind from when Saturn had a huge ice moon. If the mythical moon Chrysalis existed and was eventually destroyed, it would account for a number of anomalies in Saturn’s system.
This explanatory mechanism for both Saturn’s proximity to a precessional resonance with Neptune and for its young rings seems quite plausible. Yet Wisdom and his colleagues acknowledge that further testing of the scenario is now necessary.
September 17, 2022
BlueWalker 3: Huge satellite to be the second brightest object in the sky
On Saturday, September 10th, the enormous satellite named BlueWalker 3 was launched, and today it was put into orbit. When its antenna is fully extended, BlueWalker 3 has the potential to far outshine the constellations that are visible in the night sky and to become the second brightest object in the sky after the Moon. BlueWalker 3 will be used to test a new kind of satellite Internet.
693 square feet behemoth
Credit: Nokia / AST SpaceMobile
AST SpaceMobile, a mobile communications company based in Texas, reportedly launched a massive satellite into Earth orbit over the weekend and gave it the name “BlueWalker 3.” Astronomers have expressed their displeasure with this incident in multiple sources. When the satellite’s antenna array, which is 693 square feet (64 square meters) in size, is fully extended, the reflected illumination from the satellite has the potential to match the brightest stars, completely obscuring the night sky—with the exception of the Moon, of course.
At dusk, the BlueWalker satellite will be just as visible as the brilliant star Vega, according to an astronomer who was quoted in the technology magazine Gizmodo. Her argument was that astronomical observations would be affected by the introduction of future communications satellites like the large BlueWalker 3.
Aim of the project
BlueWalker 3’s Falcon 9 launch.
The “BlueWalker” spacecraft was successfully delivered to a low Earth orbit by a “Falcon 9” rocket that was built by SpaceX and launched from Florida on Saturday. Along with the new satellite, SpaceX launched dozens of its own Starlink satellites. There, the U.S. company AST SpaceMobile plans to conduct a test to determine how successfully mobile Internet can be delivered to mobile devices from space.
AST SpaceMobile is “building the first and only space-based cellular broadband network to be accessible by standard smartphones.” BlueWalker 3 is the biggest commercial communications satellite ever launched into low-Earth orbit. Its true brightness will only be seen once it has been fully unfolded.
As part of the project “BlueBirds”, those satellites are intended to pair seamlessly with regular cellphones to provide a high-speed Internet connection. Compared to Apple’s demonstration of the technology only last week and SpaceX’s plans with T-Mobile, this new system has substantially more capacity than just making satellite emergency calls. They both want to provide a means of contact in case of an emergency when regular mobile phone service is unavailable but their connections won’t be fast enough for video conversations or web browsing, unlike the aim of Internet satellites like BlueBirds.
There are plans for 100 giant satellites
That’s how large the satellites will be one day. (Image: AST SpaceMobile)
If everything goes according to plan during the test phase, the company plans to put 100 more giant satellites into orbit before the end of 2024 in order to establish a global data network. The satellites are referred to as “BlueBirds,” and it is anticipated that they will have a size that will allow them to reflect the same quantity of light as “BlueWalker 3.”
Whether or not it will flicker or shine steadily is still unknown at this point. AST SpaceMobile still intends to launch satellites that are twice as large. As of right now, no international laws prohibit this, and very bright objects are not prohibited anywhere around the globe.
Already, astronomers all over the world are becoming concerned about the ever-increasing levels of light pollution in the sky.
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Elon Musk’s private space company, SpaceX, has ambitious plans to blanket the entire planet with high-speed Internet service by deploying 42,000 satellites into low Earth orbit. The company has requested clearance to operate tens of thousands of satellites, but they have only been granted permission to operate 12,000 so far.
There are plenty of companies besides SpaceX and AST SpaceMobile that have aspirations of putting hundreds of satellites into orbit. The emerging Internet service providers planning to operate out of space are competing head-to-head with companies such as OneWeb and Amazon.
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The construction of a vast network is also seen by China as having strategic value.
September 13, 2022
What Is Time? And How Can It Be best Defined?
September 7, 2022
Space Race: A 20th-Century Competition Between the Cold War Rivals
In the early 20th century, the Wright brothers were thinking of conquering the sky, and Russian schoolteacher Konstantin Tsiolkovsky was trying to conquer space. His pioneering calculations published in 1903 proved the possibility of space travel. He even proposed the fuel that powers many modern rockets today, such as liquid hydrogen and liquid oxygen. All these developments became the fuel for the space race.
How Did the Space Race Start?
Robert H. Goddard launched his first rocket in 1926. In 1937, he designed a more advanced one.
Moon emphasis: It was an American pioneer who first imagined the flight to the Moon. Robert H. Goddard launched his first rocket in 1926. In 1937, he designed a more advanced one.
In the same period, New England physics teacher Robert Goddard published a book named A Method of Reaching Extreme Altitudes in 1919. He took care not to reveal his main purpose; the “extreme altitude” in his mind was actually the Moon, and he was ridiculed for this idea. The first test rocket launched by Goddard in 1926 flew 165 feet (55 m) and fell into his aunt’s garden, where she grew cabbage.
Dr. Wernher von Braun’s V2 rocket targeted London in 1944.
The Rocket Man: Dr. Wernher von Braun was on duty in Germany’s World War II rocket program. His V2 rocket targeted London in 1944.
Meanwhile, another stargazer named Hermann Oberth in Germany was on the job. His work, Die Rakete zu den Planetenräumen (The Rocket into Interplanetary Space), published in 1923, formed the basis for the world’s longest-range rocket, the “V2 which Germany used in the Second World War. The V2 was developed by German engineer Wernher Von Braun, who later became America’s most important rocket scientist after the war.
What Did Apollo Achieve?
The Soviet Union had so far dominated the intercontinental ballistic missile system field, with heavy missiles superior to those produced by the US in size and power. The most important contribution of the American Apollo Program was in this field. However, scientifically, the Moon trip was not worth the effort. Astronauts did seismology studies and radiation experiments and brought 379 pounds (172 kg) of rock, but they could do very little that robots couldn’t.
However, the technology developed for this program has benefited satellites around the world. As a result, there has been a huge improvement in astronomy, communications, weather forecasts, and other unmanned space missions. In fact, less than one in every 30 space flights was manned. The most dramatic of the space flights were the Russian landing on Venus in 1975, the US landing on Mars in 1976, and Voyager passing near Jupiter in 1979.
In pictures sent from the Moon, the Earth appeared like a small, beautiful sphere in the dark and star-filled space, a sphere that is our planet.
How Did Russia React?
Allies in Orbit: Following the developments in building a space station, American Thomas Stafford and Russian Aleksey Leonov shake hands at the Apollo-Soyuz docking in 1975. In 1986, Russia launched the MIR space station.
Although there was no publicly declared promise of the Russian government that the Moon would be reached, evidence points to a hidden Moon landing program created by Russians. In the late 1960s, Russian scientists were testing the G-1, a giant rocket 40 percent stronger than the US Saturn rocket. With this rocket exploding on the test ramp in 1969, the Soviets fell behind America in the Space Race.
The Russians began to focus more on space stations. In April 1967, the first manned Soyuz satellite was launched; it was intended to dock with another satellite to form the first space station. However, Soyuz 2 was never launched, and Soyuz 1 was torn apart while entering the atmosphere. Soyuz 4 and 5 successfully connected in 1969 and created a living environment half the size of Apollo.
In 1971, the first Salyut space station hosted three astronauts for more than three weeks; but when returning to the atmosphere, a malfunction caused the pressure to drop suddenly, and all three astronauts died. By 1978, more than 50 Soyuz and Salyut missions and an American-Russian joint project were completed. The age of the space race was over, but a new page was about to be turned.
The Future of Humanity in Space
The techniques used in the Apollo Program are unlikely to be reused. These methods were surprisingly extravagant. 98 percent of the weight of the Saturn rocket was the fuel stored in its first three sections. All three of these sections were separated from the spacecraft before it left the Earth’s orbit.
On the return journey, the Lunar Module was abandoned early and only the Command Module returned to Earth. This was like starting the ocean voyage with a transatlantic cruise, then abandoning most of the ship to the sea after leaving the port, continuing the voyage in a lifeboat, and leaving it to swim ashore on a lifebuoy.
The Space Shuttle, a more efficient spacecraft with reusable fuel tanks and an atmosphere reentry vehicle capable of placing satellites in orbit at a lower cost, was later adopted by the United States. The Soviet Union focused on the construction of space laboratories that are sent into orbit and are able to make an astronaut live in space for six months or more.
One day, these technologies could enable people to initially live in Earth’s orbit and then in the depths of space. It may be possible to build city-size space colonies that can produce their own food and obtain their minerals from small planets. Sunlight can also serve as a power source.
Theorists believe that through these types of orbital colonies, humanity can establish substantial settlements in space. Unless special scientific research is in question, no group will spend their energy coming out of one pit just to fall into another. Whether mankind can reach the stars may remain a matter of speculation forever. The space travel of Pioneer 10 and 11 probes is currently underway, but even if they travel in the right direction, it will take 80,000 years to reach the nearest star.
However, a big leap was made in space exploration during the last century. Some scientists believe that a new breakthrough will take place in the next century, when humans will form colonies in the galaxy.
Timeline of the Space Race
In 1975, the first manned spacecraft of two nations met in space, Soyuz and Apollo.
In the 1950s, the technology had advanced enough to allow mankind to realize its dream of reaching the Moon, and thus, the space race had begun.
- 1957: The USSR launches Sputnik 1.
- 1958: US Explorer 1 launches.
- 1959: An unmanned space probe of the USSR, Luna, hits the Moon.
- 1961: Soviet citizen Yuri Gagarin becomes the first person to travel into space. (He would die in a plane crash in 1968.)
- 1961: Astronaut Alan Shepard becomes the first American to go to space.
- 1961: USSR cosmonaut Gherman Titov spends a day in Earth orbit.
- 1962: John Glenn, the first American to orbit the Earth, makes three turns around the planet.
- 1963: Valentina Tereshkova of the USSR becomes the first woman to go to space.
- 1964: The USSR makes its first three-manned space flight. The US space probe Ranger 7 hits the Moon.
- 1965: USSR’s Alexei Leonov makes the first space flight that lasts ten minutes.
- 1966: Luna 9 of the USSR makes its first soft landing on the Moon. The US Surveyor 1 makes a soft landing. The US Lunar Orbiter begins to map the Moon from its orbit.
- 1967: The USSR interlocks two unmanned satellites returning from their orbits.
- 1967: An accident occurs during a countdown and three American astronauts die.
- 1969: The first human reaches the moon with the Eagle module of the Apollo 11 mission, United States.
- 1970: Luna 17 of the USSR leaves the automated lunar traveler on the Moon’s surface.
September 6, 2022
The First Moon Landing (1969): Man’s Journey to the Moon
“One small step for man, one giant leap for mankind.” Armstrong’s famous Moon landing quote were the final point of the race to reach the Moon, which began 12 years ago when Russia placed the first satellite orbiting the Earth. In 1961, President Kennedy promised his country that the first person who would step on the Moon would be sent at the end of the 1960s. The National Aeronautics and Space Administration (NASA) embarked on an enormous and complex project under the code name Apollo in 1962, worth $25 billion and involving 400,000 people. In 1968, Frank Borman, Jim Lovell, and Bill Anders were out of the world’s gravitational pull and became the first humans to orbit around the Moon with Apollo 8. Five months before the end of the decade, Apollo 11 was ready to launch in July 1969.
The Launch Vehicle Saturn V
The Apollo 11 Saturn V rocket launch vehicle lifts-off with astronauts Neil A. Armstrong, Michael Collins and Edwin E. Aldrin, Jr., at 9:32 a.m. EDT July 16, 1969, from Kennedy Space Center’s Launch Complex Pad 39A. Image: NASA.
The launch vehicle Saturn V, which weighed around 6,600,000 lb (3,000 metric tons) and was 360 ft (110 m) long, consumed 600,000 gallons (2,300,000 liters) of fuel in the first 2.5 minutes of the flight. This vehicle was installed on the world’s largest indoor platform at a height of 500 ft (152 m) and transported to the launch pad with the world’s largest vehicle with a payload capacity of 310,000 lb (140 metric tons).
The 95,000 lb (43 metric tons) spaceship at the top of the rocket had three sections: the service module, the command module, and the lunar module. The service module provided propulsion for the spaceship during the three-day lunar journey. The service and the command modules were planned to remain in orbit while approaching the Moon, and the 31,000-lb (14 metric tons) weighted Lunar module would perform the landing.
On the Verge of a Disaster
The man’s journey to the Moon and return to Earth was not trouble-free. American astronauts Neil Armstrong and Edwin “Buzz” Aldrin were on the verge of a disaster on July 20, 1969, while heading toward the Moon. The bug-shaped, bulky lunar module Eagle carried them and left its orbit to find a soft surface suitable for landing. But when they approached the surface of the Moon by 690 ft (210 m), they realized how low they were and how difficult it was to distinguish the reference craters that had previously been spotted with the help of Apollo 10.
The first steps: The second man who set foot on the Moon, Aldrin, realizes the man’s most impossible dream: Walking on another planet. Aldrin’s helmet shows the reflection of Neil Armstrong, the mission’s commander and the first man to set foot on the Moon. Image: NASA
Armstrong began to operate the module manually and slow down the vehicle’s descent. First, it descended to 300 ft (90 m) and then to 200 ft (60 m). Eagle grazed the dusty and pocky-looking soft landing surface named “The Sea of Tranquility,” which was the planned site. About 4 miles (6.5 km) away, Armstrong reported what he saw below: Spooky ground with VW Beetle-sized rocks. It would be suicide to get down here.
While Armstrong was speeding the vehicle safely over the rocks, a terrible concern arose at the Mission Control Center in Houston. Only 60 seconds of fuel remained in the landing tank; either Armstrong would find a place to land at this time, or Aldrin would have to end the mission by putting the take-off tank into action. The Eagle descended to a height of 40 ft (12 m), then 30 ft (9 m). Without the ability to lift upward, the engine that would provide this elevation could crash on the ground.
The surface is like a fine powder. It has a soft beauty all its own, like some desert in the United States.
Neil Armstrong
But everything went smoothly, and the Mission Control Unit heard Armstrong’s voice amid static rustling; “Houston, Tranquility base here. The Eagle has landed.“
The rise of the Earth from the Moon’s surface: Apollo 11’s astronauts were the first people to watch the earth rise from the horizon of the Moon. While the command module continues to orbit around the Moon, the lunar module has made the risky landing on the surface of the planet filled with craters. Image: National Air and Space Museum.
Using the last drops of landing engine fuel, Armstrong lowered the module to the Moon’s surface. Aldrin was still waiting, ready to fire the launching engine and end the mission in case the dusty surface of the Moon could not bear the weight of the module or the module appeared to be damaged.
Perfect Touchdown
The launch on July 16 was broadcast live from the Kennedy Space Center and the Houston Mission Control Center. Six hours after the landing on the Moon, Armstrong went down the ladder in his bright space suit. As he stepped onto the dusty surface and bounced off due to the low gravity, he declared the famous words that reflect the idealism of this particular space mission, “One small step for man, one giant leap for mankind.” During the 13 hours they spent on the Moon’s surface, Armstrong and Aldrin collected rock fragments, made experiments, and then prepared to take off.
Safe landing: At the end of their space mission that marked a new era, the Apollo 11 astronauts landed in the Pacific waters and left the command module with a rubber boat. Image: NASA/Public Domain.
This was a tense moment; they could not survive if the engines failed. Everything went according to plan; the lunar module’s legs were used as the launch pad, and they fired the ascent engine. The module reunited with the main module, in which Michael Collins awaited them. The crew fired the service module engine to begin the return to the Earth.
After entering the Earth’s atmosphere, the command module slowed down due to air friction and landed in the Pacific Ocean with the help of a parachute. After the landing on July 24, the crew was happy to swing on a sea on the Earth inside the spacecraft, which turned into a lifeboat. Then the astronauts were rescued and kept isolated for 17 days, in case they or the cargo they brought from the Moon would carry an unknown Moon germ and spread to the whole world. After the “Danger Has Passed” sign, they were all ready for the delayed welcome.
With his “one giant leap for mankind,” astronaut Neil Armstrong was the first person to set foot on the Moon more than 50 years ago, on July 20, 1969. Thus, the Apollo 11 Moon landing was a watershed moment in the history of human space exploration. This was the first time that humanity had entered an alien celestial body.
During the superpower conflict known as the “Cold War,” the Soviet Union was the United States’ primary adversary, therefore, the American Moon landing was a major victory. What was once hailed as a scientific and political achievement is mostly forgotten now. After receiving frequent human visits beginning in the early 1970s, the Moon fell out of human sight and has since been circling the Earth in beautiful isolation.
“Luna” vs. “Apollo”
Cold War in Space
For the United States, the Moon landing was not only a much-needed triumph in a fierce war, but also a huge stride for humanity and a historic milestone in space travel. In 1961, then-U.S. President John F. Kennedy issued a challenge to the archrival Soviet Union by declaring that an American would be the first to set foot on the Moon within the decade.
According to Kennedy in his 1961 address, no space endeavor would create a larger effect on all humanity and be more important in the long-term conquest of space. It was not lost on either Soviet President Khrushchev or his American equivalents, Eisenhower, John F. Kennedy, Lyndon Johnson, or Richard Nixon, how monumental a symbolic gesture this would be. The race was on to determine who would be the dominant space power for their nation.
An Advantage for the Soviet Union
In 1957, the Soviet Union beat the United States to the launch of the first artificial satellite when they sent up Sputnik. Thus, the race to “conquer space” was officially underway. American leaders could not sit back and watch this Soviet victory for political reasons alone. It was crucial that they beat the Soviet Union to the next space step, the Moon landing, to prove their scientific and technological supremacy and military power.
Both the United States and the Soviet Union attempted to place unmanned space probes into lunar orbit towards the end of the 1950s, but practically all of them failed on their way there or sailed past the Moon entirely. The United States sent the Pioneer probe, while the Soviet Union sent the Luna probe. The American “Ranger” series, which was launched in 1961, was similarly a flop until 1964, when “The Ranger 7” spacecraft successfully reached the Moon and sent back more than 4,000 pictures of the lunar surface.
The Soviet Union, too, overcame its poor luck and started reporting victories again a year later. In 1966, the landing capsule of their probe “Luna 9” successfully touched down on the lunar surface, and in 2008, their probe “Zond 3” successfully orbited the Moon and produced the first photos from the far side of the Moon.
The US Is Making Up Ground
Apollo 11 crew Neil Armstrong (left), Edwin “Buzz” Aldrin (right) and Michael Collins
The human flight phase of the Moon race started while the unmanned probes were still busily mapping the lunar surface. In 1967, however, the United States encountered a catastrophe at the very outset of their Apollo program. Virgil Grissom, Edward White, and Roger Chaffee perished when the control module of the Apollo 1 spacecraft caught fire during a launch pad rehearsal.
After this disaster, all launch preparations were placed on hold, and the lunar program faced an early collapse danger. However, in October 1968, an Apollo was launched once more for dress rehearsals in Earth orbit after major changes were made to the main module of the Apollo series.
During this time period, the Soviet Union’s primary focus was still on lunar research using robotic rovers. At the end of 1968, the United States accomplished the first manned lunar orbit with the Apollo 8 spacecraft, making its crew the first people to travel beyond Earth orbit.
On July 20, 1969, Apollo 11 astronaut Neil Armstrong said, “The Eagle has landed,” effectively ending the race to conquer the Moon. With this “great leap for mankind,” the United States not only won the race, but was also guaranteed a massively positive media echo at a crucial time in terms of both foreign and domestic policy. The Vietnam War, racial tensions, and other social issues seemed to fade into the background for a time. In its place, “Our Man in the Moon” became the talk of the nation and sparked a newfound sense of togetherness in the United States.
The Timeline of the First Moon Landing
July 16, 1969; 9:32 a.m. EDT: The launching
Apollo 11 and its Saturn V launch vehicle lifted off from Launch Pad 39A at Cape Kennedy Base in Florida on the morning of July 16, beginning one of the most historic journeys in space history.
Aldrin reflected on his time in space, saying, “Even though Earth didn’t seem to have changed much since my first journey, I still couldn’t tear my gaze away from it. Mentally, I knew I was finally leaving; emotionally, I was still unable to get my head around it.” The third stage of the Saturn launch rocket propels the three astronauts out of Earth orbit and onto a new trajectory for the Moon at speeds approaching 40,000 kilometers per hour after they have completed one and a half orbits of the planet.
At 2:49 p.m.: Everything goes according to plan
Separating the Eagle Lander from Saturn, turning it around, and connecting it to the Apollo command capsule were the tasks that must be completed while the spaceship is traveling away from Earth.
“Performing this move was essential to the overall flying strategy. Failure of the separation and docking technique would have required us to return to Earth,” NASA astronaut Buzz Aldrin elaborates. “We wore our spacesuits the whole time to shield us in the event of a collision or damage to our capsule,” the crew said. Everything goes according to plan, and the “double being” (the command capsule and the “Eagle”) resume their flight toward the Moon with the nose of the capsule attached to the “Eagle’s” top.
There wasn’t a whole lot to report on days two and three in space. On day three, Armstrong and Aldrin tested out the lander by entering it themselves.
July 19: Soon after Apollo 11 vanishes from view
The gyrating motion of the space capsule is complete, and it swings around. The astronauts had their first glimpse of the Moon during the mission. “These new developments are quite exciting. The Moon I’ve seen in the sky my whole life, a flat yellow disk, has become a breathtaking sphere.” Collins adds, “All of a sudden, it’s so real that I feel like I can touch it; its globe protrudes toward us.”
Armstrong relays the following message to the ground station: “Seeing the Moon in all its splendor is a remarkable sight. Two-thirds of our window is taken up by it. That one sight just about paid for the whole vacation.”
Soon after Apollo 11 vanishes from view behind the Moon, another critical move is required: the astronauts must momentarily activate the thrusters to slow their travel to the point where they may be trapped by the Moon’s gravitational field. They have also had their first close-up view of the spot where they plan to land.
July 20, 9:37 a.m.: The Lander’s first descent
The Apollo 11 spacecraft makes its last lunar orbit after a second-course correction; Michael Collins stays in the “Columbia,” while Buzz Aldrin and Neil Armstrong go onto the lander. To his two coworkers, he said, “You cats take it easy on the surface.”
Armstrong and Aldrin initiate the Lander’s first descent after the “Eagle” separates from the command capsule. N. Armstrong says “The Eagle has wings!” Michael Collins and the Command Module emerge from the Moon’s shadow a few minutes later, allowing them to report back to Earth on the first successful stride toward the surface.
The First Moon Landing
Apollo 11 landing site in the panorama.
July 20 – The landing area is in view
The two astronauts on board the “Eagle” were still able to view the original landing spot, which was in the midst of a crater the size of a soccer field and littered with stones, while the computer-controlled landing approach continued. So, Armstrong takes the helm and moves the lander to a more favorable location manually. Meanwhile, Aldrin keeps giving him support in velocity and altitude.
Armstrong: “Due to the amount of dust we kicked up during the latter stages of the landing approach, we were concerned that we might lose a clear picture of our location and altitude. We knew that a misstep at this stage might have serious consequences.” The ground crew maintains a low profile but listens intently to Aldrin’s updates on the spacecraft’s altitude as the landing approach’s fuel runs short.
First Moon landing: July 20, 1969, 12:50 p.m. EDT
When the lander’s four legs strike the ground, the indication light lights on, and Armstrong shuts off the rockets. Armstrong calls the ground station at 4:17 p.m., local time, to report: “Houston, Tranquility Base here. The Eagle has landed.” The lander’s fuel supply was down to its last 30 seconds upon touchdown.
A short time later, Aldrin claims that he was gazing outside the Eagle and saw: “The landscape surrounding us seems to be composed of rocks of every imaginable shape, edge, and chunk size. The terrain is practically devoid of color, ranging from an almost white powdery gray to deeper, ash-like tones.”
One small step for a man
The two astronauts have everything set up in the lander for re-entry before they take any “small steps” or anything like that. Having completed this, Armstrong proposed to the ground station that they commence the “extravehicular activity” (the first steps on the Moon) sooner than originally scheduled.
Squeezing through the airlock, Armstrong cautiously descends the lander’s nine-step ladder toward the Moon’s surface. On July 20 at 10:56 p.m., Earth time, history was made as Neil Armstrong stepped onto the Moon. A human person has landed on the surface of another planet for the first time in history. “That’s one small step for a man, one giant leap for mankind,” said Armstrong.
The first minutes on the Moon
Armstrong takes his first steps on the Moon after a brief survey of his new surroundings. Each stride becomes a kangaroo-like jump when gravity is just one-sixth of what it is on Earth. Armstrong said, “I haven’t seen any issues, and getting about is even simpler than it was in our practice sims.”
Experts have previously cautioned that the Moon’s strange atmosphere and gravity may pose serious challenges for humans before the mission ever began. But obviously, this wasn’t the situation. Armstrong: “Within minutes of touching down on the Moon, we had adjusted to the light gravity with ease. We really liked it more than both regular Earth gravity and total weightlessness.”
As Armstrong noted in the logbook, “The topography is powdery and fine, and it adheres to the soles and sides of my shoes like chalk. This high-quality fabric shows every one of my designs.” Armstrong’s thick, carefully insulated “lunar boots” left the first human footprints on the Moon, and since the Moon has no atmosphere, these boots should have survived nearly completely intact.
Aldrin follows Buzz off of the lander a mere fifteen minutes later. Aldrin: “As I broke the surface, I felt a mixture of joy and apprehension. In typical tourist fashion, Neil started shooting photographs of me as I arrived.”
The first of three experiments was begun by the two astronauts as anticipated. In this scene, Aldrin drives a telescoping rod into the ground, to which he has connected a makeshift bag made of aluminum foil. Its purpose is to collect particles from the solar wind and send them back to Earth for further study.
American flag on the Moon
Aldrin: “Eventually, Armstrong proposed erecting the flag. The apparently easy endeavor almost led to complete failure despite our best efforts. Training in public relations seems to be as important as training in any other field.” The flagpole wouldn’t go deep enough into the lunar dirt, and the bracket meant to keep it flat wouldn’t extend far enough, too.
“It took a lot of work, but we managed to achieve a condition of near-balance. On the other hand, I could see the flag crashing to the ground in front of the cameras with millions of people watching.” As the lander lifted off for its return trip, the flag did indeed fall, but not in front of the camera.
While Aldrin was busy installing two devices—a seismograph to record earthquakes, volcanic eruptions, and other signals of geologic activity, and a laser reflector to make an even more precise measurement of the Earth-Moon distance—Armstrong gathered samples of lunar rocks.
Leaving the Moon
Armstrong and Aldrin returned to the “Eagle” lunar module after spending barely 2.5 hours outdoors. Everything has been finished, including unloading the experiments and taking photos. According to Aldrin, “We felt like little kids in a candy shop. So many plans, so little time.”
The two astronauts are to sleep after removing their spacesuits in preparation for liftoff. Aldrin: “We weren’t able to get much sleep since we were still far too stimulated and because it was fairly chilly.”
The “Eagle” lander leaves the lunar surface at 1:54 p.m., after 21 hours on the Moon, to meet up with the “Columbia” command capsule. Michael Collins spent the whole mission alone in lunar orbit. During each orbit around the Moon, the Columbia was out of communication range for 47 minutes, and a comment from the ground station was recorded, saying something along the lines of, “Since Adam, probably no human being has ever experienced such complete loneliness and isolation as Michael Collins did.”
The exposed film, an aluminum bag with samples of the solar wind, and 20.81 kilos of lunar dust and boulders all departed the Moon with the crew. The U.S. flag, laser reflector, seismograph, and lander descending stairs, all with commemorative plaques, were left behind: “Here men from the planet Earth first set foot upon the Moon July 1969, A.D. We came in peace for all mankind.”
No problems arise on the return. The Apollo spacecraft splashes down in the Pacific at 12:54 p.m. on July 24, 1969, around 24 kilometers from the U.S.S. Hornett, which is tasked with retrieving it. A diver releases the escape hatch and provides the three “lunar travelers” with isolation suits; once on board the Hornett, they are brought to a mobile quarantine container where they will spend the next three days.
The total time spent traveling to and from the Moon was 195 hours, 18 minutes, and 35 seconds.
What Did the Apollo Missions Discover?
Though it was no longer thought that the Moon was made of green cheese, as was still held in the Middle Ages, its geology and history of development were still completely unknown until the Apollo missions. The only way we came any closer to understanding the Moon was through the experiments left by astronauts and the samples of Moon rock carried back to Earth.
In any case, the Apollo astronauts’ photographs and experiences promptly put to rest at least one of the “popular ideas” of the time: that the Moon was populated. None of the samples indicated any fossil or recent evidence that the Earth’s satellite could have ever supported any type of life, including the “man on the Moon.”
However, one of the most crucial findings of the Apollo period was that the Moon had a very similar structure to the Earth. Clearly, it shares Earth’s adventurous past, with the surface rocks being melted several times, expelled by volcanoes, and squeezed by meteorite strikes. The stratigraphy of Earth’s satellite is similar to that of Earth, with a solid crust, a partly liquid asthenosphere, and perhaps an iron core.
A common origin for both celestial entities was deduced from the findings of Apollo drilling samples and seismographic investigations. In many places on the Moon, you may still see evidence of the early processes and events that shaped its present-day appearance. Due to erosion, these artifacts are no longer accessible on Earth, making the Moon an essential “archive” for the early history of our solar system.
The lunar surface also stores information on variations in solar radiation. Without an atmosphere to shield it, the surface rock (known as regolith) remained unprotected from the electromagnetic solar wind for millions of years, allowing it to accumulate isotopes and elements from the sun.
Thirty years after the Apollo missions returned samples from the Moon, scientists in 60 labs across the globe are still studying them. Researchers in their third generation are hard at work deciphering the Moon’s last secrets with the assistance of tools their predecessors in the 1970s could only have dreamed of.
History of the Apollo Program
With Apollo 1 in 1967, the United States launched the Apollo program, which concluded with Apollo 17 in 1972. Thirty astronauts embarked on a total of twelve spaceflights. Apollo 8’s first human spaceflight and Apollo 11’s successful first Moon landing were the program’s crowning achievements.
Apollo 1 (January 27, 1967)
Crew: Virgil (Gus) Grissom, Edward White, Roger Chaffee
A tragedy struck the Apollo program just before the launch of the first human spacecraft in the Apollo series. Apollo 1’s three-person crew perished when a fire broke out on the launch pad and quickly spread to the spacecraft. Launches of the next Apollo spacecraft were originally postponed after this incident while investigators figured out what caused the fire.
Apollo 7 (11 – 22 October 1968)
Crew: Walter Schirra, Donn Eisele, Walter Cunningham
Apollo 4 through 6 were uncrewed test missions for the Saturn launch vehicles, and the next manned flight, Apollo 7, was given the name Apollo. Apollo 7, a practice run for the next mission, did not include a lunar lander since testing could only be done in Earth orbit. The test proved the core Apollo components were spaceworthy, putting to rest concerns that had arisen in the wake of the Apollo 1 mishap.
Apollo 8 (21 – 27 December 1968)
Crew: Frank Borman, James Lovell, William Anders
Humans first left Earth orbit with the Apollo 8 crew. Even though the spacecraft was supposed to conduct yet another test in Earth orbit, the urgent need to beat the Soviet Union in the space race sent it instead to the Moon. On the morning of December 24th, Apollo 8 achieved lunar orbit and spent the next 20 hours circling the Moon. Without a lander on board, the astronauts in the command capsule captured the first images of Earth rising over the Moon. Apollo 8’s voyage to the Moon and back successfully demonstrated that it was feasible to do so with the technology available at the time.
Apollo 9 (3 – 13 March 1969)
Crew: James McDivitt, David Scott, Russel Schweickart
The Lunar Module was first tested in orbit during Apollo 9. The crew spent 10 days in Earth orbit practicing every operation (save the landing) involving the launch vehicle, command capsule, and lander. Scott and Schweickart went on an autonomous spacewalk so that Schweickart could try out his new spacesuit. Furthermore, they were the first Apollo crew to give their vessels official titles.
Apollo 10 (18 – 26 May 1969)
Crew: Thomas Stafford, John Young, Eugene Cernan
The “Snoopy” lander came within 15 kilometers of the lunar surface during the practice landing. The Apollo 10 crew followed the same identical procedures as the Apollo 11 crew, right down to the landing. During Apollo 11, Stafford and Cernan flew over the Sea of Tranquility in the Lander while Young remained in lunar orbit with the Command Module. There was another “first” that Apollo 10 brought to the table: the first-ever live color TV transmission.
Apollo 11 (July 16–24, 1969)
Crew: Neil Armstrong, Michael Collins, Edwin “Buzz” Aldrin
On July 20 at 4:17 p.m. Eastern Standard Time, Apollo 11 touched down on the Moon as scheduled. Six hours after Armstrong’s “great leap for humanity,” Aldrin followed suit, and the two of them spent the next two and a half hours gathering samples, planting flags, and taking photos. They spent a total of 21 hours on the Moon before heading back to the orbiting command module “Columbia.”
Apollo 12 (14 – 24 November 1969)
Crew: Charles Conrad, Richard Gordon, Alan Bean
The second Moon landing, which took place in the Sea of Storms, was an exemplary feat of accuracy and aiming. With its almost fully automated landing approach, the lander came within 180 meters of the Surveyor 3 probe, which had been sent to the Moon over two and a half years before. The two astronauts gathered further rock samples and placed instruments to monitor the seismicity, solar wind, and magnetic field of the Moon, before bringing sections of the probe back to Earth for study. During this time, multispectral photographs of the Earth were captured in orbit by the Yankee Clipper command capsule.
Apollo 13 (11 – 17 April 1970)
Crew: James Lovell, Fred Heise, John Swigert
With the help of the film starring Tom Hanks, “Houston, we have a problem,” the Apollo 13 mission has become one of the most well-known near-catastrophes in space history. An oxygen tank on the service module burst almost 300,000 kilometers from Earth, nearly incapacitating the Apollo command spacecraft. Only by returning to Earth after circling the Moon could the astronauts hope to escape. The three passengers were trapped in the cramped and freezing landing shuttle for four days before finally making it to Earth.
Apollo 14 (31 January – 9 February 1971)
Crew: Alan Shepard, Stuart Roosa, Edgar Mitchell
Shepard and Mitchell used a “lunar rickshaw” to bring samples back to the lander after their two lunar walks after landing in the Fra Mauro area, the landing location originally planned for Apollo 13. When the two astronauts “got lost” and couldn’t find their way back, they had to call off another sampling mission. Quarantine was observed for the last group of lunar explorers, the Apollo 14 crew.
Apollo 15 (26 July – 7 August 1971)
Crew: David Scott, James Irwin, Alfred Worden
The first usage of a “lunar rover” occurred on the Moon during the first prolonged mission landing. Scott and Irwin drove their lunar rover for 27 kilometers, during which they gathered several artifacts, including the now-famous “Genesis Rock.” Worden completed the first spacewalk between Earth and the Moon on the return trip to Earth.
Apollo 16 (16 – 27 April 1972)
Crew: John Young, Thomas Mattingly, Charles Duke
The main thrusters on board “Orion” almost failed upon landing due to a technical issue. After that happened, Duke and Young spent three days exploring the area around the Descartes Highlands. They found that the area that looked like a volcano wasn’t really a volcano. The biggest piece of Moon rock ever brought back was one of the samples they carried with them.
Apollo 17 (December 7 –19, 1972)
Crew: Eugene Cernan, Ronald Evans, Harrison “Jack” Schmitt
Geologist and astronaut Harrison Schmitt was the Moon’s last human visitor and its first scientist. More lunar samples were gathered by Schmitt and Cernan, and they drove the Moon vehicle about 34 kilometers into the Taurus-Littrow Valley. When they left, they also left a plaque that read: “The first human lunar expedition concluded here. It’s December of 1972. Thank you for the serenity that you brought with you. May it permeate the world.”
September 6, 2022

How Do Scientists Weigh a Planet or Star?

We simply put ourselves and all sorts of other things on the scales to determine their weight. The mass of a planet is not quite so easy to determine. Over time, people have developed highly diverse types of scales—there are spring scales, beam scales, inclination scales, and many more. However, the basic principle is the same for all of them: Scales measure the weight force acting on the body lying on them. Since this weight force is proportional to the mass and the constant of proportionality is known—it is the acceleration due to gravity on the earth—the mass can be calculated from the weight force. Conveniently, most scales do not show the weight force in the unit of Newton but rather the mass in pounds or kilograms.

However, the acceleration due to gravity varies minimally from place to place. This is because it depends not only on the gravitational pull of the Earth but also on the centrifugal force acting at the respective location due to the Earth’s rotation. In addition, the planet is not an exact sphere but is slightly flattened. And the Earth’s surface is not smooth but has all kinds of unevenness with mountains and valleys. All this means that the gravitational acceleration is not the same everywhere. But in everyday life, these differences do not play a significant role since they are only in the per-mille range.

In addition to scales, another method used to determine masses is measurement by volume, like with a measuring cup. If the density of a substance is known, the mass is simply the volume multiplied by the density. There are different measuring cups for different substances that are adapted to their respective densities. While both measuring methods work well for all kinds of living beings and objects on earth, they are not suitable to weigh the planets and other celestial bodies in space.

Newton and His Law of Gravity

But physics also offers a solution here. The basis of weighing a planet or star is the law of gravitation discovered by Isaac Newton: It is the force of attraction that two masses exert on each other. According to Newton, the force is proportional to the two masses and inversely proportional to the square of the distance between the two masses. For example, if one of the masses is doubled – regardless of which one – the force of attraction is also doubled. If, on the other hand, you double the distance, the attractive force drops not only to half but to a quarter of the original value.

With this law, Newton successfully described the motion of the planets in the solar system in 1687. And it was also used to explain the law of free fall described by Galileo Galilei. The acceleration due to gravity is proportional to the mass of the Earth and inversely proportional to the square of the Earth’s radius. Since the size of the earth was already well known at Newton’s time, this gave Newton a possibility to determine the initially unknown constant of proportionality in his law of gravitation. But for this, he needed – also unknown by then – the mass of the earth.

Finding the Mass of Earth

In General Relativity, the bending of space-time by mass is what causes the force of gravity. (Image: Ligo/T. Pil) — In General Relativity, the bending of space-time by mass is what causes the force of gravity. (Image: T. PYLE/CALTECH/MIT/LIGO LAB)

To obtain the value in question, Newton first estimated the average density of our planet – based on the density of a rock. Since the radius and thus the volume of the earth was known, the estimated value for the density could be used to calculate the mass of the earth. The average density should be about five times greater than that of water, thus, Newton calculated the mass of Earth about 5.5 × 10²⁴ kilograms. Considering the rather rough estimate, this is not a bad result: According to today’s measurements, Earth’s mass is 5.972 × 10²⁴ kilograms. Newton was thus able to approximate the magnitude of the constant of proportionality in the law of gravitation.

A more precise determination of these gravitational constants was not possible until 1797 when the British natural scientist Henry Cavendish developed a “gravitational balance”. The gravitational attraction between small bodies could now be measured directly for the first time. The masses of the bodies were known and so the experiment allowed to calculate the proportionality constant in the law of gravitation from the measured gravitational attraction. The more exact value for the gravitational constant and the much more easily measurable gravitational acceleration now make it possible to determine the mass of the Earth with far greater accuracy than by volume. Earth was the first planet that scientists could weigh using Newton’s law of gravity.

Measuring the Weight of the Solar System

More than 99 percent of the solar system's mass is found in the sun. — More than 99 percent of the solar system’s mass is found in the sun.

The solar mass is the standard unit of mass in the astronomical community. The Sun’s mass is equal to 1.9890 x 10³⁰ kg, or around 333,000 Earths. More than 99 percent of the solar system’s mass is found in the sun.

Almost three decades before Cavendish’s experiment, researchers had already succeeded in scaling our solar system. Before that, the ratios between different distances in the solar system were known, but not absolute distances. Knowledge of both the absolute distances of celestial bodies and the gravitational constant finally enabled astronomers to weigh other planets as well. For if one disregards other forces – which play only a very minor role in celestial mechanics – gravity alone determines the orbit of a celestial body.

A common method for determining the masses of a planet is by determining the orbits of its moons or by passing space probes. Mass creates gravity, and the planet’s gravitational pull in turn determines the orbit of any object moving around the planet, in terms of size and orbital period.

This relationship can be illustrated using the example of a moon orbiting a planet. The gravitational pull of the planet that is keeping the moon in orbit can be calculated with the help of Newton’s law of gravity. The gravitational force acts here as a so-called centripetal force since it forces the moon into a circular orbit. This makes it possible to determine the mass of the planet solely from the orbital radius and orbital period of the moon. Astronomers have been able to weigh all the planets in the solar system by using this method except Mercury and Venus – which have no moons. This technique allows to find the mass of many celestial bodies, even including space probes.

Weighing the Exoplanet (Extrasolar) Planets

Astronomers must proceed somewhat differently if they want to weigh planets near other stars. Consider a planet and star that do orbit around their common center of gravity. This causes the star to periodically move toward and away from us. The motion is minimal, but it leaves traces in its light spectrum – caused by the so-called Doppler effect. The characteristic signatures of this light spectrum tell a lot about the star. And since the greater the planet’s mass (a bigger gravitational force), the more a star moves, scientists can use this method to determine the planet’s mass.

For this, however, not only the distance of the system must be known but also the type of star and thus its mass. However, both quantities are usually easy to determine in astronomy. Nevertheless, scientists usually get only a minimal value for the mass. Because as long as they do not know the orientation of the planet’s orbit in space, the actual distance between the star and its companion cannot be precisely quantified. This orientation could be better known only if the planet regularly passes in front of its star from Earth.

The Weight of Various Celestial Objects

Name	Mass	Type
Sun	(1.989 × 10³⁰ kg)	star
Jupiter	(1.899 × 10²⁷ kg)	5th planet
Earth	(5.9742 × 10²⁴ kg)	3rd planet
Mars	(6.4185 × 10²³ kg)	4th planet
TON 618	66 billion solar masses	black hole
Milky Way	64 billion solar masses	galaxy
Ganymede	(1.482 × 10²³ kg)	satellite of Jupiter
Pluto	(1.305 × 10²² kg)	dwarf planet
Ceres	(9.5 × 10²⁰ kg)	dwarf planet

Sources:

How Do We Weigh Planets? | NASA Space Place – NASA Science for Kids. (2020, June 1). How Do We Weigh Planets? | NASA Space Place – NASA Science for Kids.
How do scientists measure or calculate the weight of a planet? (n.d.). Scientific American.

September 5, 2022

Supermoon: What Makes It Super and When Does It Occur?
The Earth’s satellite is supposed to appear unusually large in the sky at certain times of the year. And if you go outside – assuming the weather is good – and look at the Moon, you get truly amazed. The full Moon hovers majestically above the horizon. In its orbit around the Earth, the Moon comes particularly close to us several times a year. This promises a particularly large and bright full Moon in the night sky called ‘supermoon‘. But although this effect is hardly visible to the naked eye, the supermoon amazes many observers. In fact, the amazement is rather due to another effect: An optical illusion makes the Moon appear bigger near the horizon.
When the Moon Is Especially Close to Us
The distance between the Moon and the Earth varies by around 50,000 kilometers. When the Moon is at its closest point to the Earth, the perigee, a supermoon occurs. In the apogee, at which the maximum distance of more than 400,000 kilometers is achieved, a minimoon is observed.
But “supermoon” is neither a historically coined nor an astronomical or generally a scientific term. Rather, it was an astrologer, Richard Nolle, who first wrote in 1979 about a supermoon that was supposed to be responsible for earthquakes and volcanic eruptions – namely, whenever the Earth’s satellite is particularly close to the Earth at a full Moon or new Moon.
But even if Nolle’s considerations are not based on scientific principles – they cannot be completely dismissed. The tidal forces of the Moon and the sun not only lead to ebb and flow, but also to movements in the Earth’s crust.
If the sun, Earth, and Moon are almost in a straight line, the tidal forces of the sun and Moon add up and particularly strong spring tides occur. The high tides, often colloquially referred to as spring tides, are about 20 percent higher than ordinary high tides. In fact, strong earthquakes also occur more frequently in parallel with spring tides, as a team led by geologist Satoshi Ide showed in 2016 by analyzing more than 10,000 earthquakes.
However, since the Moon does not move in a circular but an elliptical orbit around the Earth, not all spring tides are the same. The distance of the Moon from Earth varies between 221.456 miles (356.400 km) and 252.711 miles (406.700 km). It is therefore quite obvious that the effects of the tides are stronger when the Moon is also close to the Earth during a spring tide. However, this influence is very small: On average, spring tides are only about two percent stronger when the Moon is close to the Earth. Accordingly, a connection between the supermoon and earthquakes has not yet been proven.
Bigger and Brighter
The right supermoon appears 14 percent larger and 30 percent brighter than the minimoon on the left.
Nevertheless, the term supermoon was recently taken up in the past years but is still different than originally meant by Nolle. Today, a supermoon does not refer to the alleged effects of earthquakes or volcanic eruptions any longer. Instead, it simply refers to a full Moon in a near-Earth position and the associated size and brightness of the Earth’s satellite in the night sky.
This is because when the Moon is close to Earth, its apparent diameter is up to 14 percent larger than that of a Moon far from Earth – a so-called minimoon. And with the larger area that the supermoon occupies in the night sky, the perceived brightness of the Earth’s satellite also increases. The Moon appears up to 30 percent brighter near the Earth than far away.
However, these are extreme values. The Moon’s orbit is by no means invariable but varies due to the gravitational forces of the sun and the major planets. The distance of the Moon from the Earth at perigee, the closest point to the Earth in the respective orbit, varies between 221,456 mi (356,400 km) and 230,155 mi (370,400 km).
Therefore, those theoretically possible extreme values occur only rarely. This raises the question of when a full Moon is considered a super full Moon. Nolle himself has changed his definition again and again over the decades – currently, he uses an arbitrarily chosen distance of less than 229,056 mi (368 630 km) at the full Moon as a limit.
Only a Near Full Moon Is Also a Supermoon
An illustration showing the Moon’s apogee and perigee positions. Numbers indicate the extreme values of the distance betWeen the two phases of the Moon: supermoon on the right and minimoon on the left. (Source: NASA (Earth) Gregory R. Revera (Moon))
There are two to four supermoons each year. After the first supermoon on May 16, the Earth’s satellite was 222,238 mi (357,658 km) away from the Earth for the second time on June 14, 2022. On the following full Moon on July 13, the Moon was even a tiny bit closer to the Earth and only one month after on August 11 there was the fourth (and last) supermoon of 2022 that occurred.
The November 14, 2016 supermoon was the closest recent supermoon since January 26, 1948, and will not be exceeded until November 25, 2034. The closest ever supermoon of the 21st century will be on December 6, 2052. Supermoons and complete lunar eclipses may occur together. The last time was May 2022; the next time will be October 2032.
A Worthwhile Observation?
So whether a particular full Moon is “super” or not is consequently debatable. Also the phenomenon “super moon” has no special scientific meaning. But isn’t it nevertheless worthwhile to have a look at the Earth’s satellite when it is particularly close to us? After all, the differences in apparent size and brightness are quite remarkable. However, the differences between a normal full Moon and a supermoon can hardly be seen with the naked eye in the night sky due to the lack of objects to compare them with. Thus, a supermoon standing high in the sky does not appear much different to the observer than any other full Moon.
Nevertheless, motivated by news of the supermoon, many people go outside in the evening hours and are amazed at the size of the Moon when they see it near the horizon shortly after it rises. The seemingly enormous size of the Moon on the horizon is due to a completely different phenomenon: An optical illusion makes the Moon appear larger near the horizon than when they are high in the sky. So this has nothing to do with the supermoon itself.
Sources:
- Phillips, Tony (May 2, 2012). “Perigee “Super Moon” On May 5–6″. NASA Science News. NASA.
- Espenak, Fred. “Full Moon at Perigee (Super Moon): 2001 to 2100”. astropixels.com.
- “What is a Supermoon? Facts vs. Fiction”. Sky & Telescope. November 8, 2016.
- “Super Full Worm Moon Lights Up the March Sky”. www.timeanddate.com.
- “Closest supermoon since 1948!”. EarthSky. November 12, 2016.
September 5, 2022
How Do Spacecraft Travel in Space?
On 1969, the first man landed on the Moon. Missions planned for the Moon landing required long preparatory works because getting from Earth to the Moon was not going to be in a straight line. During this time, the space agency not only developed the necessary technology for space flight but also had to find the best possible route to the Moon. This is because, unlike on Earth, the start and end points in space change their position relative to each other during the course of a journey. But everything is in constant motion: The Earth revolves around itself and orbits the sun. And the destination – in this case, the Moon – also revolves around the earth and, together with it, around the sun.
A Curved Trajectory
Couldn’t a rocket still simply fly from the Earth directly to the Moon? Physically, there is nothing to be said against it. But such a flight would require an extremely powerful engine and a lot of fuel. And so space scientists are trying to make the best possible use of the celestial bodies’ own motions and gravitational forces to save some energy.
This starts with the launch: Rockets are preferably launched into space near the equator and in the direction of the Earth’s rotation. This alone gives a rocket a speed of 1040 miles (1674 km) per hour. However, for a typical orbit around the Earth at an altitude of 185 mi (300 km), a spacecraft must reach a speed of 17.400 mi (28.000 km) per hour.
In order to get from an Earth orbit to a more distant one like the Moon – in the most energy-saving way possible, there are different ways. One is the so-called Hohmann orbit: This is an ellipse with the Earth at its focal point. The point closest to the Earth in this ellipse touches the original orbit around the Earth, and the point farthest from the Earth in the ellipse is in the desired orbit – the orbit of the Moon. Already in 1925, the German space pioneer Walter Hohmann described this transition between two orbits in his book “The Attainability of Heavenly Bodies”.
Hohmann orbit
To reach such an elliptical orbit leading to the moon, the spacecraft must be accelerated to a speed of about 24.850 mi (40,000 km) per hour. The thrusters must ignite at exactly the right moment so that the Hohmann orbit actually intersects with the moving Moon at the furthest point from Earth. This flight maneuver was both technically and computationally challenging in the 1950s and 1960s. Any smartphone today is a million times superior to the NASA computers used for the Apollo missions. And getting into orbit around the Moon or landing smoothly on the Moon requires following an even more complicated trajectory.
Why Do Space Rockets Not Go Straight Up?
Reaching orbital velocity, which is around 20 times the speed of sound, is the most challenging component of space travel. At first, rockets make a wide arc to get away from the takeoff site, and then they begin gaining horizontal velocity. Their precise trajectory is a careful balancing act between the forces of gravity, air resistance, and aerodynamic loading.
When a rocket points vertically upward, gravity acts in the other direction, slowing it down. To reduce this, rockets are launched at an angle immediately after leaving the launchpad.
In order to enter orbit, or a circular route of motion around the Earth, rockets must tilt to the side as they ascend into the sky. A gravity turn is a steering maneuver that makes advantage of the Earth’s gravity to assist save rocket fuel and lessen stress on the spaceship. To aid the spacecraft bend its course into orbit, the spacecraft is rotated until its heavier side is facing down.
Numerous Attempts Until the Landing
The Apollo astronauts’ journey to the Moon took three days and four hours. A short flight time is a decisive criterion for manned missions because it means less radiation exposure for space travelers. For unmanned probes, flight time plays a minor role. Flight routes that take months but cost little in terms of energy are also conceivable. Such orbits initially usually lead far out of the Earth-Moon system and make use of the gravitational pull of the Sun to finally head to the Moon.
Another major advantage of the space probes is that they approach the Moon at a relatively low velocity, which means that only minor corrections are required to enter an orbit around the space object.
There have been a total of 124 known attempts to fly to the moon. Of these, 55 failed in a variety of ways, from explosions on launch to unplanned crashes on the Moon. However, it is possible that some failed flights have not entered the official records. As part of NASA’s Apollo program, there were nine flights to the Moon and six successful Moon landings from 1968 to 1972 – a total of twelve people have walked on the Moon’s surface.
In numerous attempts, the space agencies slowly felt their way toward the moon: After several false starts, the Soviet probe Lunik 1 raced past the Moon on January 4, 1959 – at a distance of about 3730 mi (6000 km). On September 12, 1959, Lunik 2 was the first space probe to hit the Moon. The first soft landing on the Moon was made on February 3, 1966, by Luna 9, also a Soviet probe, and on April 3 of the same year, Luna 10 swung into orbit around the Moon for the first time. On December 24, 1968, Apollo 8 was the first manned spacecraft to reach the Moon, orbiting it a total of ten times within twenty hours. And just seven months later, NASA’s Apollo 11 was the first manned lunar landing.
September 4, 2022
Perseids: The Most Popular Meteor Shower
As every year, the mild summer evenings are favorable for prolonged observation of the sky, especially during the Perseids. It is certainly the most popular meteor shower visible from the northern hemisphere of the year. But what are perseids, what causes them and where are they coming from?
The Perseids are active from July to September each year and usually peak in mid-August. They are considered to be the “best” meteor shower of the year, as they are one of the most abundant – 50 to 100 meteors observed per hour on average in the sky. With very fast and bright meteors, Perseid meteors frequently leave long “trails” of light and color behind them as they pass through Earth’s atmosphere, allowing skywatchers to easily notice them.
Key Takeaways: Perseids
- The Perseid meteor shower is an annual celestial event that takes place from late July to mid-August. It stands out as one of the most renowned and reliably occurring meteor showers.
- These meteor showers stem from the remnants left behind by the Swift-Tuttle comet. As our planet traverses through this residue, the particles incinerate upon entry into our atmosphere, resulting in luminous streaks of light famously referred to as meteors or, colloquially, “shooting stars.”
- Typically, the Perseid meteor shower culminates in intensity around the period of August 11–13 each calendar year. During this span, onlookers can anticipate an augmented count of meteors adorning the heavens.
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- Perseid meteors frequently exhibit brilliance and rapid motion, leaving evanescent trails of light in their wake as they disintegrate. Certain meteors might even leave behind enduringly glowing trails, often termed “persistent trains.”
- For optimal Perseid meteor gazing, seek out a location distant from urban luminosity, providing an unobstructed and clear panorama of the firmament. The prime times for observation fall within the pre-dawn hours when the radiant point, the apparent source of the meteors, ascends higher in the sky.
- Emanating from a point in the constellation Perseus, these meteors are dubbed Perseids, signifying their celestial origin.
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This composite mostly contains Perseid meteors. They all seem to be streaking in the same direction. Image Credit: NASA/MEO.
A meteor is a space rock, or meteoroid, that enters the Earth’s atmosphere. As it falls toward Earth, the resistance – or drag – of the air on the rock makes it extremely hot. This bright trail is not actually the rock, but rather the hot air and glowing dust as the hot rock passes through the atmosphere and disintegrates.
Where Do Perseid Meteors Come From?
Meteors come from the remnants of comet particles and broken pieces of asteroids. As comets approach the sun, they see their ice evaporate and pulverize tiny pieces of rock, forming a cloud of small rocky particles. Each year, the Earth passes through these trails of debris, which collide with our atmosphere and disintegrate to create these fiery and colorful trails in the sky. The peak of a shooting star shower corresponds to the peak of meteor activity when the Earth passes through the densest part of the debris shower.
109P/Swift-Tuttle.
The space debris that interacts with our atmosphere to create the Perseids comes from comet 109P/Swift-Tuttle. It was discovered in 1862 by Lewis Swift and Horace Tuttle. Its nucleus measures 16 miles (26 kilometers) in diameter, nearly twice the size of the meteor that is supposed to have led to the disappearance of the dinosaurs, and four times faster: it goes around the Sun in 133 years. It was Giovanni Schiaparelli who realized, in 1865, that this comet was at the origin of the Perseids.
As the largest object in the solar system (except for the Moon) to pass repeatedly close to Earth, the movements of Comet Swift-Tuttle have been meticulously studied by scientists and have been predicted for many years. Its most recent “perihelion”—the point in its orbit where it comes closest to the Sun—was in 1992, and the next one will not occur until July 12, 2126.
The point in the sky from which the Perseids seem to originate—their radiant—is the constellation of Perseus, which gave the Perseids their name. Although the constellation the meteor shower is named after helps the observers determine which shower they are looking at on a given night, the Perseus constellation is not the source of the Perseid meteors.
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How to See the Perseid Meteor Showers?
Perseids.
While a shooting star often lasts only a fraction of a second in the sky (with an average speed of 30 mi/s or 50 km/s), it is best to watch a large portion of the sky for at least 30 minutes beforehand for the eye to get used to the darkness. This should be done preferably in “complete darkness” and toward the northeast, for the Perseids. No special equipment is required.
The Perseids are much more visible in the northern hemisphere, because no meteor is visible below about 30 degrees south latitude. The best time is during the hours before dawn when the sky is darkest. It is sometimes possible to see the Perseid meteors during the peak of activity as early as 10 p.m., but the best time for observation is at 3 a.m., according to NASA.
Nevertheless, this year, unlike last year, the Perseid observation will meet a major obstacle, the Moon. There will be a full Moon and it will illuminate the whole sky.
In addition to the Perseids, there are many more meteor showers to observe each year. The Southern Delta Aquariids, usually active between July and August, can be best seen from the southern tropics. These are generally small meteors and are difficult to observe.
There are also alpha Capricornids, active from July to August. What is remarkable about this shower is the number of bright meteors produced during its period of activity, which was observed on both sides of the equator.
Then, this year, we will have to wait for the Orionids, between September 26 and November 22, 2022, with a peak of activity on the night of October 20 to 21. They are quite visible, despite a low density of shooting stars (10 to 20 per hour). These meteors come from Halley’s Comet.
September 4, 2022
Why Do We Never See Black Holes in Pictures?
September 4, 2022
The Higgs Boson: Everything About the God Particle
Paul Dirac named these particles “bosons” to honor Satyendra Nath Bose, an Indian scientist who developed the idea with Albert Einstein. The discovery of the Higgs boson on July 4, 2012, marked a turning point in physics. With it, the fundamental component of the cosmos that gives everything its mass has been identified. But 10 years later, there are still many unresolved concerns regarding this special particle called the “god particle” and its impact on the foundations of our conception of the physical universe.
Our planet would likely not exist at all if it weren’t for the Higgs field and the Higgs boson that goes along with it. Several physicists, including Robert Brout, Francois Englert, and Peter Higgs, proposed this as early as 1964. The expected particle has now been discovered as of 2012. However, the Standard Model of particle physics still has a few significant holes. Additionally, the Higgs boson has in some ways generated more questions than it has resolved. So, what’s the next step?
What Makes the Higgs Boson Special?
The absence of mass would result in a cosmos devoid of atoms and other forms of ordinary matter. The fundamental constituents of matter stick together and interact with one another only because of the mass of the particles that make them up. But from whence does the mass of the constituent particles come? For a very long time, the Standard Model of particle physics—the foundation of our conception of the physical universe—did not provide a solution.
The Weak Nuclear Force
Additionally, there is a difficulty with the bosons, which serve as the basic forces’ carriers. According to theory, they should not have any mass, unlike fermions that create matter, such as quarks and electrons. Photons and gluons are also examples of carrier particles of electromagnetic and strong nuclear forces. They have no mass. Photons may thus travel at the speed of light without encountering any obstacles.
The weak nuclear force, however, does not work with the plan: On the one hand, it contains two carrier particles, the W and Z bosons, instead of one. And these bosons, on the other hand, have a mass. This explains the weak nuclear force’s limited range and how it works in radioactive decay. However, for many years, it was unknown how and why only these exchange particles, but not the others, acquire mass.
The Scalar Field
Could particles have mass due to a field that permeates the whole universe? (Image: CERN)
Further light was shed on the issue only in the early 1960s, when numerous theoretical physicists, including Peter Higgs in Great Britain and Robert Brout and Francois Englert in Belgium, started looking for a solution. They independently concluded that the issue may be resolved by an unseen field that permeates the whole cosmos. Some of the constituent particles may interact with this scalar field in quantum interactions, modifying their characteristics. So, they can only move by using energy, and because of this, they have mass.
The Brout-Englert-Higgs mechanism is often compared to a cocktail party by the British physicist David Miller. A throng of other guests swiftly congregates around a significant celebrity as soon as it enters the room. Due to the crowd, the celebrity is unable to travel very far—much like a particle with a large mass that can only be propelled with a lot of energy.
Asymmetrical Effect
The Brout-Englert-Higgs mechanism also explains the fact that not all carrier particles have mass: The Higgs field has an asymmetry; it does not interact with all bosons uniformly. The carrier particles of these forces, photons, and gluons, remain massless since they are neutral regard to electrodynamics and quantum chromodynamics. However, the field has a kind of braking effect on all other particles and gives them mass.
This is comparable to how fur has its hair growing in one direction: a particle, like a photon, feels no resistance and maintains its masslessness if it flows along the Higgs field’s “hairline.” On the other hand, when a particle goes against the flow, more energy is needed, and the particle accumulates mass. This holds for all fermions that may form matter, as well as for the W and Z bosons of the weak nuclear force.
The Higgs Field
That makes up the theory. But how can you back it up? The Higgs boson enters the picture here. Because if such a scalar field exists, it is capable of condensing at certain locations. The Higgs field may also appear as a particle at these locations, just as a photon is both a wave and a particle. “What else can be keeping the agreement between the Standard Model and the data just as good as it is? If there is not a Higgs boson, the theory does not make sense at all.” Peter Higgs said in 2004.
Even then, the physicist was sure that this missing component of the Standard Model’s puzzle would soon be discovered. The Higgs boson was sought after.
How Was the Higgs Boson Discovered?
One of the LHC’s all-purpose detectors is the ATLAS detector. The Higgs boson was discovered for the first time by ATLAS and the CMS detector.
The Higgs boson was ultimately discovered in 2012 after almost 50 years of worldwide investigation by scientists. But why was it so challenging to find this missing Standard Model particle?
The issue was that the theory did not predict the characteristic that was essential for the experimental finding of the Higgs boson. These theories predict that this particle should just have mass and not spin or charge. But it was unknown how big this mass was. Only 18 megaelectronvolts to 800 gigaelectronvolts were within the range that could be used. The energy required to accelerate a particle is indicated in electron volts. This also applies to an elementary particle’s mass.
This has the following implications for the search for a particle: If you know the mass, you also know the energies at which you must fire particles at each other to generate the particle you are seeking in a collision. But when it came to the Higgs boson, researchers were stumbling about in the dark, and, on top of that, particle accelerators could only produce collision energy up to a certain point. Since these tests had previously shown that the Higgs boson would likely need to be heavier than 114 gigaelectronvolts, this was not entirely surprising.
Locating a Needle in a Haystack
The quest for the Higgs boson received a significant boost in 2008 with the start of operation of the Large Hadron Collider (LHC) at the CERN research facility close to Geneva. Because the finest circumstances for eventually discovering the sought-after particle were provided by this biggest particle accelerator in the world’s high-energy proton collisions. If the universe took the shape of the Higgs mechanism predicted by the Standard Model, there was no way to hide once the LHC got going.
The Higgs boson, however, decays back into the matter in less than a trillionth of a second and is only produced in around one out of a billion proton collisions. As a result, it cannot be directly viewed or quantified. Only the decay products it leaves behind may be used to identify it. Sadly, they are made of elementary particles like pairs of photons, muons, or Z-bosons, which are also released when the other collision products break down.
Therefore, finding the Higgs boson’s signature among all of these millions of particles is more like seeking out a specific haystack than it is like hunting for the fabled needle. The seemingly impossible procedure was made feasible by carefully analyzing which decay products, based on known mechanisms, the detectors should find, and then examining if there are deviations from this anticipated curve in a mass and energy range. If the Higgs boson was involved, there would be a little extra of the things that happen when it breaks down.
Unevenness in the Curve
Simulation of a particle collision that results in the production of the Higgs boson. (Image: CMS/Lucas Taylor)
The same thing was seen at the LHC, at not only one but two of the big detectors: On July 4, 2012, representatives from the ATLAS and CMS consortia made their long-awaited announcement in front of the world’s media: the distinct signature of the Higgs boson has been found independently at both detectors. This could be found by looking for a “hump” in the decay product curve that is caused by the photon pairs or Z bosons that are made when the Higgs decays.
More than five standard deviations of significance were attained for both outcomes, which equates to a likelihood of nearly 3.5 million to one that the results are not just coincidental. The data from ATLAS and CMS satisfied the criteria for the official discovery of a particle with this value. Their findings indicated that this particle likewise required a mass of around 125 gigaelectronvolts. This matched the exact mass range in which the Higgs boson was thought to be present based on past searches.
Breakthrough in Physics
The Higgs boson, the last piece of the Standard Model’s jigsaw, was discovered after decades of research. Its discovery proved both the existence of a cosmic scalar field that provides mass and the Brout-Englert-Higgs mechanism, which was proposed more than 50 years ago.
For scientists throughout the globe, the discovery of the Higgs boson constituted a significant turning point. Peter Higgs and Francois Englert were awarded the 2013 Nobel Prize in Physics for their work. The hundreds of experimental physicists at CERN who participated in the search, and the theorists who had already passed away, were left empty-handed since the Nobel Prize may only be shared by a maximum of three live individuals.
The Particles Next to the Higgs Boson
The Standard Model of particle physics places a significant emphasis on the Higgs boson. (© CERN / Daniel Dominguez)
The Higgs boson is the cornerstone of the Standard Model, so everything that is discovered about this particle is important to the basic rules of physics. One of the most important questions about the Higgs boson’s interactions after its discovery was: Does the Higgs couple with other particles in the manner predicted by theory? Its discovery involves interactions with photons, W bosons, and Z bosons in each of the decays that were investigated. But the Higgs would also need to interact specifically with quarks and leptons if it is the “mass-giver” particle we are seeking. The latter include the heavier “siblings” of the electron, the muon and tau lepton.
The Higgs boson’s decay into bottom quarks and tau leptons allowed researchers at the LHC to discover the first of these interactions in 2016. This demonstrated that the Higgs truly interacts with matter particles as well as the fundamental force’s carrier particles. It took a little longer to find the Higgs boson’s most frequent decay: this preferred decay of the Higgs into two bottom quarks should occur 58 percent of the time.
But amid the “haystack” of many particles created by proton collisions in the particle accelerator, it was impossible to identify this decay phase. The evidence was finally available in 2018, when the ATLAS detector and the CMS detector at the LHC both produced data that demonstrated the Higgs boson’s decay into two bottom quarks with a significance of more than five sigmas.
A Strong Competition
Particle traces of a ttH event, or the interaction of a top quark and the Higgs boson. (Image: CERN)
The Higgs boson should have the greatest coupling to the top quark, the particle that makes up the bulk of matter, according to the theory; only then does it get its huge mass. If true, certain proton collisions at the LHC should result in the production of a Higgs boson, together with a top quark and an anti-top quark.
However, this so-called ttH production method is exceedingly uncommon; just 1 percent of the Higgs bosons are formed together with top quarks. The only way to identify top quarks is via the decay products they leave behind since they are not stable. As a result, it took until 2018 for the measurements at the LHC to be of sufficient relevance. This was the first time that this mechanism had been empirically proven. The scientists had now witnessed all of the Higgs boson’s interactions with third-generation heavy quarks and leptons, as well as all of the significant ways that the particle was produced.
From the “Higgs Portal” to Dark Matter
However, interactions between undiscovered elementary particles and those specified by the theory might be much more intriguing: The Higgs boson, unlike other particles in the Standard Model, has no charge nor spin and may therefore interact with neutral particles, including types of bosons that have not yet been identified. Many scientists believe that such a neutral particle might be the long-sought dark matter particle.
We also refer to this potential as the Higgs portal. This makes the Higgs a terrific instrument for the quest for dark matter. Some Higgs decay products appear to be missing from some bosons in the LHC could be one way to find these “dark” interactions. When neutral “dark bosons” that cannot be identified by detectors are produced during the process, they either escape unnoticed or cause an imbalance in the known decay patterns.
Physicists at CERN may have discovered some early proof of recognizable divergences thus far. But they have a long way to go before they can find them or pinpoint exactly what they are. During the third run of the LHC, which has started, they are hoping for better data and higher Higgs production.
The Higgs Field’s Hidden Properties
The sombero or champagne bottle model of the Higgs field. (Image credit: ©Gonis /
CC-by-SA 3.0)
The Standard Model of Physics now has a substantial hole that the Higgs boson has filled. But even though it has been found, there are still many questions about it, not the least of which is what the Higgs field and its particles are made of. The Higgs boson is often presented as the particle that completes the Standard Model but in practice, it brings up a ton of new issues.
Spontaneous Symmetry
One of them addresses the history and characteristics of the Higgs field. The Higgs boson is the first and only scalar particle among the basic forces of existence. The Higgs field, in contrast to other forces, has no preferred direction and is consistent even when reflected. The theory states that this field was produced immediately after the Big Bang, long before atoms were ever thought of.
Initially, the Higgs field’s scalar values averaged zero everywhere. Nothing and no one had mass as a consequence. The Higgs field, however, experienced a spontaneous symmetry breach only a few fractions of a second after the Big Bang, adopting a new configuration whose values, on average, amount to an energy of around 246 gigaelectronvolts. It started to affect other fields and particles, giving some of them mass. The counterintuitive aspect of this is that although the physical world is not symmetrical, the equations defining this field are nonetheless symmetrical.
Physicists also use the sombrero (the Mexican hat) or champagne bottle models to explain this spontaneous symmetry breakdown of the Higgs field: The scalar field looks like the curving sombrero or champagne bottle’s upturned bottom. The field’s design allows for complete symmetry, such that everything would balance on the middle elevation if a pencil were placed there. However, in practice, the pencil topples over relatively rapidly and falls in one direction, breaking the symmetry—at least for the pencil—even while the field’s form remains unchanged.
Beyond the Hat’s Brim
The issue with this scenario is that it is not yet apparent if or how the Higgs field can be accurately characterized by the Sombrero model and how it continues once past the brim of the hat. Is it possible that there is a chasm beyond it where the field might take on even lower values than in the valley of the “hat brim”? The field would only be metastable at that point and may shift into a brand-new, lower energy state. The Higgs field would be stable if the values of the “hat brim” kept expanding outward.
The so-called triple gauge boson couplings—a characteristic that represents the interaction of the Higgs boson with its own peers—is one method of providing an answer to this query. According to the theory, the Higgs particle may be the only one in the Standard Model to interact with itself. In the particle accelerator, some Higgs bosons would have to decay into two more Higgs bosons if this were the case.
The frequency and energy at which this triple-coupling happens, if it does exist, will be crucial in determining whether the Higgs field behaves as predicted by the Standard Model or if there is an opportunity for “new physics” in the form of undiscovered particles or forces. Scientists aim to have more and better data in the third run of the LHC, which started on July 5th, 2022. The ATLAS team at the LHC has already started hunting for the decay products of such triple boson production.
Divisibility of the Higgs
And the ATLAS collaboration’s researchers are presently looking into yet another query about the Higgs boson: Does the Higgs boson even have a substructure or is it a true, indivisible fundamental particle like photons, quarks, and gluons? This is predicted by several theories of physical processes beyond the Standard Model. These models suggest that the Higgs could more closely resemble the pion, a particle made up of an up quark and an anti-down quark that mediates the bonding between protons and neutrons in the atomic nucleus.
The production of unusual “vector-like” quarks would be a sign of such a substructure of the Higgs boson. The first analyses of the collision data from the LHC were presented by physicists with the ATLAS collaboration in 2021. But as of now, these findings show that the Higgs boson operates as predicted by the Standard Model, proving that it is a real elementary particle.
But the study of the Higgs boson and its quirks has only just started. Because if we can detect the properties of the Higgs, then it will address some of the hottest concerns in physics.
Future for the Lhc and the Higgs Boson
Future Circular Collider (FCC) collisions with energies of up to 100 teraelectronvolts will be possible. (Image credit: CERN)
The Higgs boson’s discovery was a significant achievement in physics. However, significant advances in particle physics have not been made since, and many important topics remain unresolved. It has taken a while for physicists to finally see the abundance of new particles and scientific advances they had hoped for, particularly from the second run of the LHC and the discovery of the Higgs boson. For now, the LHC has mostly discovered the Higgs boson and the Higgs field it carries.
But in reality, there are still a lot of issues that physics has to address. Because there are still significant gaps in the Standard Model, even with some ambiguities clarified by the Higgs boson. For instance, Albert Einstein attempted to provide a true explanation of how the fourth basic force, gravity, relates to the other fundamental forces, but he was unsuccessful. It is also unknown whether gravity contains a carrier particle similar to those found in the other fundamental forces.
It is also unclear why, immediately after the Big Bang, the universe did not collapse once again. Because at that time, equal and oppositely huge amounts of matter and antimatter should have been created, and they would have destroyed one another. Yet, it is clear that the great annihilation did not occur since we would not be here now. Because of this, scientists believe that there must have been a small distinction between the properties or behaviors of particles and their antimatter counterparts. But thus far, searching for it has been fruitless.
Dark Energy and Dark Matter
Additionally, dark energy and dark matter—two components whose existence is still entirely unknown—constitute about 95 percent of our universe. The expansion of our universe is being driven by dark energy. Astronomers and physicists are still unsure of how it does this and why cosmic expansion is speeding up.
Dark matter is almost as enigmatic but a bit more researched. According to what we know about it, it must exist practically everywhere in the universe, including our solar system and the halo of the Milky Way. The velocity and form of galaxy clusters and galaxies are influenced by their existence. However, dark matter’s nature is likewise unknown since gravity is essentially its only mode of interaction with regular matter. It is still unclear what kinds of particles dark matter is made of and if a boson like the Higgs may be responsible.
Some basic issues concerning behavior and characteristics in the field of particle physics remain unanswered. One is the supersymmetry theory, which states that every known particle should have an additional, heavier, unnamed partner. However, there has been no sign of these hypothetical particles in the data as of yet. The proponents of this theory had anticipated a glut of such supersymmetry particles even from the initial runtimes of the LHC.
Scientists are still debating whether neutrinos exist in a fourth, sterile form in the case of these “ghost particles.” There are still some unresolved contradictions in the electroweak interaction, which results from the coupling of the electromagnetic and weak basic forces. People look to the Higgs boson and how it decays for more information, especially in this area.
All of these occurrences could be caused by “new physics”—processes and particles that have not yet been discovered. However, this has so far been well disguised from the physics community’s view. Certain obvious discrepancies have been found by physicists at the LHC and other particle accelerators, such as in the magnetic moment of the muon or B meson decays. The main issues, however, still have not been resolved.
The third run of the LHC at CERN is now expected to provide at least some answers. Because it is significantly more potent, numerous collisions could at least confirm and aid in elucidating the oddities previously picked up in hints. The maximum 13.4 teraelectronvolts that the LHC can produce in proton collisions is insufficient to explain many of the phenomena that are currently unsolved. More energy and alternative techniques are needed.
“Future Circular Collider” (FCC)
Due to this, some follow-up initiatives using more potent and substantial particle accelerators are already being discussed. The “Physics Beyond Colliders” initiative at CERN is investigating the future of accelerator rings. A 100-kilometer acceleration ring is also being developed for the years after 2040. Electrons and positrons will first collide and operate as a “Higgs boson factory” in this “Future Circular Collider” (FCC). The Higgs products are simpler to study since they smash with less energy yet create fewer interfering particles.
Later, the FCC will host proton collisions with energies of up to 100 teraelectronvolts. In the shape of an electron and positron ring accelerator of comparable scale to the CEPC, China is likewise preparing to build its version of the Higgs factory. A linear accelerator has been discussed in Japan, but it is unclear if the government will contribute to its funding. Some physicists are placing their hopes in novel kinds of mini particle accelerators that accelerate electrons with the use of plasma lasers in addition to the massive, pricey facilities. Their energies are often modest, but they are cheap, portable, and might be utilized to specifically examine certain sub-aspects.
It is too soon to say which of these initiatives will be carried out and which will succeed. But it is evident that to find new physics outside of the Standard Model, we must use every tool at our disposal, including astrophysical data, modest experiments at lower energies, and massive high-energy particle accelerators.
Bibliography
1. Notes on Dirac’s lecture Developments in Atomic Theory, 1945
2. The Bose in the Boson. The New York Times.
3. Higgs boson: The poetry of subatomic particles. BBC News.
September 4, 2022
James Webb Space Telescope: Everything You Need to Know
The James Webb Space Telescope is an outstanding project; it is the biggest, most intricate, and most costly (10 billion USD) device that humanity has ever sent into space. This telescope is able to see more clearly and farther than any other space telescope thanks to its 269 square foot (25 square meter) mirror and extremely sensitive infrared optics. The launch of the James Webb Space Telescope on December 25, 2022, was one of the most challenging tasks ever carried out in space. Because the tennis court-sized sunshield and mirrors had to unfold from their compact transport configuration, which resembled a reverse origami. Also, more than 300 steps and mechanisms had to function with perfect precision.
The James Webb telescope traveled 930,000 mi (1.5 million km) away from Earth to get to its “workplace” after the launch. The new “eye in space” examines the atmospheres of neighboring exoplanets and hunts for indications of life while also looking back to the time of the first stars to provide novel insights into the cosmos.
Why is the James Webb Telescope special?
The Hubble Space Telescope has set the standard for expansive space vistas into far-off space and breathtaking photographs of cosmic events. Its photos have offered vital information for astronomical and astrophysical studies for more than 30 years. But as time goes on, the Hubble is becoming older, and failures are mounting. At least part of Hubble’s responsibilities has been taken over by the James Webb Space Telescope (JWST) which is bigger, sharper, and farther.
Greater, Sharper, and Farther
In many respects, JWST is bigger and more advanced than its more seasoned partner. In comparison to the Hubble, which is about the size of a truck, the JWST is a colossal 236 ft (22 m) long and 129 ft (12 meters) wide. What makes this telescope so precious, though, is its primary mirror, which is even more significant. Its 70 ft (6.50 m) diameter is about three times that of Hubble’s 26 ft (2.40 m) mirror. Such a big mirror was never sent into space. The Webb telescope weighs 6.5 metric tons or 14,300 lbs.
The Webb telescope has a lot more light output and resolution as a consequence. As shown by its “Legacy Field,” the Hubble telescope can still see bright objects 13.3 billion light-years away. On the other hand, the JWST is intended to explore older, further parts of space. Galaxies that formed up to 300 million years after the Big Bang are visible now.
It’s a Specialist
Comparison of the mirror sizes of the Spitzer, Hubble, and James Webb telescopes. (NASA)
However, since it “sees” a different region of the radiation spectrum than Hubble, the Webb telescope has a distinct perspective on the cosmos. In a way, the Hubble telescope is an all-arounder since its wave spectrum spans from ultraviolet to near-infrared. On the other hand, Webb is more of an expert in infrared: its spectrum spans the mid-infrared range, or 28.5 micrometers to 0.6 micrometers (1122 to 23.6 micro inch), the red zone of visible light that is just visible to humans.
This elevates Webb to the status of a Herschel or Spitzer-style infrared space telescope replacement. The universe has at least as many breathtaking things to offer in infrared as it does in visible light, as their photographs previously showed. The infrared cosmos was made accessible by the breakthrough of the Hubble and Spitzer space telescopes. These missions have now evolved into Webb, which combines Hubble’s sensitivity and resolution with Spitzer’s infrared vision.
Comparison of the observed spectrum from Hubble and James Webb. (NASA)
At the same wavelength, Webb’s 0.03 arc second resolution is a little bit sharper than Hubble’s 0.05 arc second. Because of how sensitive its infrared optics are, it is still possible to perceive a single bumblebee’s warmth on the Moon from Earth.
Utilizing the Icy Space
However, the Webb telescope’s very sensitive infrared optics pose additional difficulties. The mirrors and other optics of the JWST must be cooled to practically absolute zero to collect the feeble thermal radiation of the furthest celestial objects. This is the only method to stop the background noise from drowning out the delicate signals in the telescope’s thermal radiation.
As a result, the mirrors and optics of the telescope cannot become any warmer than minus 218 degrees Celsius (-360 Fahrenheit). While Spitzer and other infrared space telescopes have done this by actively cooling their optical components using helium, this is not feasible with the Webb telescope’s massive mirror. As a result, the JWST employs a different tactic: it allows space’s icy air to handle the cooling.
Why the Lagrange Point Instead of Earth’s Orbit?
With this orbit of L2, Webb keeps its location in relation to Earth while simultaneously keeping a safe distance from the Sun, Earth, and Moon’s intense lights. (Credit: WebbTelescope)
But this also implies that this space telescope cannot orbit the Earth as Hubble can. This is because the Earth emits heat and infrared radiation when seen from space, which would obstruct the observations. In addition, depending on where it is in orbit, the Sun also emits interference radiation. The JWST would need to either have an insulating cover all around, which is impractical due to the large mirror, or a moveable sunshield that would need to be adjusted continuously to entirely shield the optics from every ray of sunlight.
As a result, Lagrange Point 2 has been chosen as the James Webb telescope’s viewing location. This spot is facing away from the Sun and it is 1.5 million km (930,000 mi) from Earth. Space probes may orbit there in a stable manner without using a lot of energy thanks to the equilibrium of the gravitational forces between the Sun and the Earth. One shield is adequate to block the thermal radiation since the sunlight there always arrives from the same direction at the same time. JWST’s thermal shield is the size of a tennis court and is made up of five very thin insulating membranes for the job.
That is why the Webb telescope is neither the first nor the only one at Lagrange Point 2: the no longer operational Wilkinson Microwave Anisotropy Probe (WMAP) and Planck, which have studied the cosmic background radiation, orbit there. The European space telescope Gaia and the X-ray telescope eROSITA are both still operational at the Second Lagrange point (L2).
JWST’s Scientific Objectives
The primary use of infrared light by the James Webb Telescope is directly tied to the scientific objectives of its mission. This is because one of the JWST’s duties is to gaze back in time much farther than Hubble has been able to, to the moment when the very first galaxies were born. Scientists are conducting the first-ever study of galaxies from the immediate post-Big Bang period using Webb. This was not achievable with any other telescope up to JWST.
Since the Big Bang, the universe has been expanding, which causes the radiation that has been traveling to us for billions of years to similarly expand. As a consequence, the light spectrum of far-off galaxies and stars is changing from the UV or optical range to the longer-wavelength infrared – and it is exactly this range that the Webb telescope is studying with its big mirror and optical instruments.
Looking Back at the Bang
The James Webb telescope is intended to study the reionization period, when the first stars and galaxies were created. (Credit: © NASA/ESA, Joyce Kang (STScI))
The earliest galaxies that have been discovered so far were created just over 500 million years after the Big Bang. However, it is still unknown when the first galaxies started to form. According to certain theories, there should be at least 50 galaxies that predate Hubble’s observation, although fewer are predicted by others. The Webb telescope is revealing for the first time when and how the very earliest stars and galaxies were created. This also provides light on how certain galaxies and quasars have managed to become so massively large at such a young age.
The James Webb Space Telescope can also discern the light spectrum of distant stars and galaxies with great resolution due to its high light output and precise optics. Its mid- and near-infrared operating spectrographs, MIRI and NIRSpec, are responsible for achieving this. The latter may be utilized to allow targeted radiation just from certain areas of the image since it contains almost 250,000 micro apertures. Scientists just open the spectrograph’s micro apertures to examine the spectrum of hundreds of these young galaxies for the first time.
Dark Matter, Galaxies, and Stars
The view into the infrared, however, has another benefit: Many cosmic events are encircled by thick dust clouds. The dust blocks the vision, making it impossible to see the creation of new stars and planets in visible light. On the other hand, these clouds are penetrated by infrared radiation with longer wavelengths. Thus, the JWST for the first time sheds light on the earliest phases of star formation and eventually the early history of our solar system.
Examining certain galaxies close up that are in the Milky Way’s local vicinity is another effort. Most of these dwarf galaxies are very dim, making it challenging to examine them closely with conventional telescopes. The Webb telescope’s sharp “eyes,” on the other hand, can keep track of how these galaxies and their stars move.
This might provide insight into how these galaxies interact with one another and how their mergers result in bigger star clusters.
This is what the JWST’s analysis of the light spectrum of an exoplanet like Earth with an atmosphere reveals. (Credit: NASA)
Thanks to the JWST, astronomers are now getting more knowledgeable about the distribution of dark matter and its function in galaxy formation. The characteristics of dark matter determine how structures develop in the cosmos. The JWST just needs to provide additional details about them. This will also help to explain why certain dwarf galaxies seem to have essentially no dark matter.
A Perspective on Alien Worlds
The James Webb telescope has great promise for planetary researchers as well. It can examine the atmospheres of exoplanets for the first time and look for molecular indicators of alien life. The NIRISS instrument, a near-infrared spectrograph that blocks the primary star’s outshining light, was created especially for this use. This enables James Webb to detect and examine the planet’s much softer light. Near Infrared Camera (NIRCam) detects light from the earliest stars and galaxies.
Additionally, Webb’s optics are sufficiently sharp to provide the first images of neighboring exoplanets. Several Earth-like exoplanets in our immediate cosmic neighborhood, such as the seven Earth-sized planets in the TRAPPIST-1 system, which is just 40 light-years away, are among the telescope’s first targets. That’s because a few of these planets could be suitable for supporting life.
The Webb Telescope’s Mirrors
James Webb’s main mirror is made up of 18 hexagonal parts and is the most remarkable component of the space telescope. It has a diameter of 21 ft (6.50 m) and a surface area of 269 sq ft (25 sq m), which is more than five times that of the Hubble mirror. This tiny optical apparatus needed some cutting-edge technology to be sent into space. Its use in the infrared range poses additional technical difficulties.
The mirror’s beryllium surface as well as its wafer-thin gold coating had to be flawlessly polished. (Credit: Chris Gunn/NASA)
Weight is the first challenge for a space telescope with mirrors of this size since launch vehicle cargo is limited. All components must be as light as possible. The JWST would no longer be transportable if its mirrors were composed of glass with a metal coating, like those of the Hubble telescope. Because of this, NASA engineers decided to employ beryllium, a substance that has previously been used in supersonic planes and the space shuttle.
The Benefit of Beryllium
This alkaline earth metal is exceptionally stable despite being the second-lightest metal after lithium. Beryllium is very stiff compared to its bulk. Beryllium is hence even six times stiffer than steel. This honeycomb structure of millimeter-thick struts on the back of the mirror is enough to maintain the very thin mirror surface since it combines great strength and low weight.
Despite the JWST’s primary mirror being nearly three times bigger than the Hubble telescope’s, it weighs 1554 pounds (705 kilograms) instead of 1818 pounds (825 kilograms) due to the use of beryllium and the incredibly light design.
However, beryllium has another, arguably more significant benefit: it has very high thermal conductivity while also having a little reaction to temperature fluctuations. This is an essential characteristic of the mirrors’ curvature and almost nanometer-level alignment accuracy. At the low temperatures of space, beryllium maintains its stability across a broad range of temperatures, unlike other metals that expand when heated and contract again when cooled.
At these temperatures, beryllium is just amazing because even when the temperature changes, nothing moves at all. But beryllium can only be thermostable for a limited time at temperatures below minus 200 degrees C (-328 F). However, while the mirrors are being made in terrestrial temperatures, the alkaline earth metal also experiences a small amount of expansion. This required NASA engineers to calculate the mirror diameters to the nearest fractions of a micrometer, making them overly large on Earth but precisely the perfect size in space.
Careful Polishing
The first image of the Hubble Space Telescope around 30 years ago showed that even the finest material is useless if the optical surface does not have the proper shape and smoothness. The visuals were hazy back then due to a 0.16-inch (4 mm) difference in the mirror’s curvature. During a shuttle flight in 1993, spacewalking astronauts constructed and installed the new sensors and corrective optics on Hubble.
Polishing the beryllium segments of the JWST is also challenging since, unlike Hubble, it is located 932,000 mi (1.5 million km) away from Earth at Lagrange Point 2, making repair missions almost unfeasible. The most challenging and crucial technical step in the creation of the telescope was polishing the mirrors. The fact that the telescope’s mirror is made up of 18 segments that are polished independently yet must then properly complement one another further complicates issues.
The main mirror’s segments must be properly aligned to within one ten-thousandth of the thickness of a human hair for them to work as one big mirror. Each mirror has six actuators on the rear that allow for precise positioning in space. This adjustment, accurate to within ten nanometers, is only made once the mirror and the entire telescope optics have cooled down to the final working temperature of -220 to -243 degrees Celsius (-245 to -245 Fahrenheit).
Gold for the Best Light
The gold coating, however, is still a key component of the completed mirrors. This is because just this thin (about 100 nanometers) coating of precious metal makes it possible for the incoming infrared radiation to be nearly entirely reflected and focused on the secondary mirror. For this reason, the main mirror’s segments and the convex secondary mirror, which is located around 23 ft (7 m) above the primary mirror, both have gold coatings. This coating’s entire weight is just about 1.76 ounces or 50 grams, and a marble’s worth of gold might be contained inside it.
But how do you fit a sunshield the size of a tennis court and a telescope mirror the size of a 269 sq ft (25 sq m) payload capsule into a rocket? That was the precise issue that engineers working on the JWST mission had to address, and their solution was perhaps the most complex structure ever sent into space.
The Ariane 5 rocket’s payload capsule measures 15 ft (4.57 m) in diameter and 53.1 ft (16.19 m) in length internally. The major components of the space telescope had to be folded and dismantled like a sophisticated piece of origami in order for it to fit within this container, together with its enormous mirrors and protective shields. And everything that was so meticulously packaged on Earth must subsequently be unwrapped once again in space, automatically and at precisely the correct moment.
To do this, a vast army of levers, bolts, motors, gears, and wires was properly meshed. All the endeavors were in jeopardy if even one component failed. Space scientists always want to avoid in-orbit deployments at all costs. However, James Webb made it impossible to do that. Instead, the telescope had to carry out some of the most difficult tasks ever undertaken on an in-orbit deployment.
JWST’s Sunshield
JWST’s sunshield
Similar to a parachute jump, the first challenge was to find the ideal amount of folding. Numerous engineers spent years experimenting with different ways to fold and compress the 0.025 to 0.05 millimeter thick, gossamer membranes of the tennis court-sized sunshield so they wouldn’t rupture during the launch of the rocket or while it was being deployed. The five-layer heat shield was finally arranged in such a way that it wraps two sides of the telescope.
The protective layer rolled back first and made room to unfold the five layers of solar protection in space, stretch them, and bring them into the proper kite-shaped configuration. The membrane holding mechanism must then be released by 107 retaining clips acting in the proper order. The membranes are then gradually stretched over a system of 90 hauling cables.
The automated packing and unpacking operation was tested several times using scaled-down replicas of the sunshield before being applied to the actual object. The sequence has to be further refined since membrane cracks and damage happened multiple times. In the end, the deployment process of James Webb was sluggish yet precisely and orderly timed.
In vacuum chambers, weightlessness can be replicated, but space’s vacuum cannot. The team consequently tested the automated unfolding from several angles to at least change the gravity impact. However, there was no dress rehearsal while the telescope was suspended in space.
The Unfolding of the Mirror
The opening of the main mirror was equally important in the deployment of the James Webb Space Telescope. The telescope’s 18 hexagonal parts had to be joined and aligned to within a few hundred nanometers for the Webb to function properly. Two of the mirror’s edges, each made up of three segments, were folded in for transportation since the complete mirror, with a diameter of 21.3 ft (6.5 m) was too enormous to fit within the Ariane rocket. It was taking over three hours to unfold these “wings” again.
Similarly important was the structure’s unfolding, from which the 74-centimeter secondary mirror hung out. The three 25 ft (7.60 m) rods were folded up and laid parallel to the main mirror for transit. Then the secondary mirror had to move into the path of the light focused by the first mirror. Only after these first procedures can the mirrors’ delicate adjustment via the actuators on their backs start. When all 138 actuators function properly, the direction and curvature of each mirror can be controlled to provide an ideal image.
With 178 processes involved, the Webb observatory performed 50 crucial unfolding steps during its deployment. The Webb telescope deployment is by far the trickiest task any spacecraft has ever had to do. However, nothing about Webb is easy—and nothing has ever been done before.
How Did All Happen?
The Ariane payload capsule’s two-part shell is opened shortly after liftoff. (ESA)
Every time NASA rovers arrive on Mars, the difficult, multi-step deployment entails “seven minutes of anxiety.” However, people engaged with the James Webb telescope had to go through 29 days of anxiety all at once. The time required to fully deploy and position the space telescope’s major components was that amount of time.
Just a few minutes after launch, the crucial step started: The two halves of the payload capsule were jettisoned, and 28 minutes later, the telescope was freed from the Ariane 5 launch vehicle’s burned-out upper stage. From this point on, the Webb telescope had to navigate to Lagrange Point 2 on its own. It initially extended its solar sails to provide itself with energy before doing this. The base station’s communication antennae came up around two hours after launch.
Twelve hours after launch, the JWST completed its first crucial action: the propulsion jets activated, providing the telescope with the required power and guiding it in the appropriate direction for the journey to the Lagrange point. The Webb telescope entered lunar orbit in only two days, traveling far more quickly than the Apollo capsule from more than 50 years ago.
The Deployment Took Two Weeks
The first significant deployment started in three days: To provide the telescope with the required separation from the sunshield and the other “warm” areas of the observatory, the mounts for the sunshield first folded out. After that, the entire optical complex of the telescope lifted by around 6.5 ft (2 m). The sunshield’s five layers then progressively spread out over the course of the next seven days.
The mirror components took up the second week of the unfolding phase. The secondary mirror with its telescoping poles was set up on the tenth day, and the main mirror’s sides folded in on the twelfth. It was essential for these structures to be correctly activated at this time. The icing was a thing to watch out for as it must not develop on the optical components. Other than that, if the water vapor and other gases were to condense on the cool mirror surfaces, the probe’s still-warm components would be at the risk of outgassing (being subjected to the vacuum of space).
Calculate and Hope For the Best
The most dangerous and error-prone aspect of the operation was over after 29 days. Since there are no live cameras on the James Webb telescope to monitor its overall standing, the ground staff was unable to see the procedure if anything went wrong. But the numerous sensors that offer feedback everywhere throughout the intricate structure as to whether a component has been released, extended, engaged, or otherwise performed its role are the main sources of information on the James Webb.
The engineers have to come up with a workable solution if one of these sensors reports an error using the observatory’s onboard resources. For instance, the JWST could attempt to shake a trapped bolt, clamp, or cable free. The scientists jerk the whole spaceship back and forth to do that.
The James Webb Telescope carried out one more flying maneuver to complete the deployment phase and reach its orbit around Lagrange Point 2. Everything went as planned, and the biggest and most complicated space telescope ever launched into space was able to start operating. After that, scientists adjusted the mirrors, checked all the instruments, and calibrated them for many months before the scientific expedition began. The James Webb Space Telescope is answering the fundamental questions of where we came from and why life originated on Earth out of all places.
Bibliography
1. NASA JWST – “How big is Webb?“
2. “JWST Orbit”. JWST User Documentation.
3. “Will Webb be able to tell us more about the Big Bang?” – NASA JWST
September 4, 2022
TOI-1452 b Could Be the First Ocean Planet
September 4, 2022
What Is the Artemis Mission: Phases and Objectives
- NASA aims to return people to the Moon by 2025 under the “Artemis” program.
- “Artemis 1” is an unmanned mission in 2022 to test the Orion spacecraft and European Service Module.
- The Artemis program’s estimated cost is $93 billion, with each Artemis launch costing around $4 billion.
Returning to the moon is meant to mark the beginning of a new era for American space exploration. NASA hopes to return people to the Earth’s satellite by 2025. This puts “Mission Artemis” under a lot of strain, however. The launch vehicle, space capsule, and lunar module weren’t ready until recently, and there wasn’t enough money either. The new American lunar program, dubbed “Artemis” after Apollo’s twin sister, is a clear reference to the first trips that humans made to the moon. Additionally, there is a similarity between Artemis and Apollo just like when John F. Kennedy pledged a moon landing “before this decade is out.” In 2019, a U.S. president once again assigned NASA a specific deadline: American astronauts should return to the moon in five years.
Artemis 1 fly date is November 16, 2022 at 9:04 AM GMT+3.
The Return to the Moon
The idea of going back to the moon has been discussed for a very long time, and not just at NASA. The moon is once again proving to be a highly intriguing destination 50 years after the first moon landing. After all, it not only provides fresh supplies of raw minerals but also a strategically advantageous starting point for further missions to Mars and beyond.
But carrying out such plans is the issue. After being restricted to low Earth orbit for decades, human spaceflight is now starting to go farther out. This has represented a fresh start for NASA in many ways. Because the required technology and expertise were initially insufficient, despite all the technological advancements since the Apollo period. Since the final Apollo manned mission to the moon took place 47 years ago, the spacecraft, landing modules, and launch vehicles from that era are only useful as museum exhibits.
The twelve main space organizations in the world, including NASA and ESA, decided in 2013 to work together on a shared timeline called the Global Exploration Roadmap to have adequate time for the required new advances. Thus, human flights to Lagrange Point 2, 1 million miles (1.5 million km) away, or near-Earth asteroids were to begin by 2025. The return of people to the moon and the presumably slow building of a lunar outpost were only envisaged after that, until about 2030.
But then, in 2017, Donald Trump’s “Space Policy Directive-1” gave the US space programs a new focus, moving away from Earth surveillance and asteroids and toward a heavier emphasis on the Moon and Mars. Additionally, there was to be greater involvement by commercial suppliers. The objective was to land on the moon in 2028 and gradually build a lunar gateway, or space station, in lunar orbit.
This was unquestionably good news for the NASA departments and subcontractors working on the lunar mission since it implied more money for them. Since then, NASA’s effort in the lunar program has substantially increased. Tests of the Orion spacecraft and work on the new launch vehicle, the Space Launch System (SLS), have been accelerated.
Artemis 1: An Unmanned Moon Orbiter
Commercial companies will manage the Lunar Gateway’s construction and supply. ©NASA
Three main parts make up the Artemis mission: an unmanned test flight in 2022, an astronaut-led lunar orbit in 2024, and a lunar landing near the lunar south pole in 2025.
In September 2022, the first unmanned flight of the next lunar mission is planned to launch from Cape Canaveral. The main purpose of this mission is to test the Orion spacecraft and the attached European Service Module (ESM). The capsule is to house the astronauts, just as the Apollo missions did. The engine, power, and life support systems are provided by the service module. Two dummies outfitted with instruments in Artemis 1 stand in for the astronauts.
The Artemis 1 mission’s sequence is similar to the Apollo 8 mission’s flight plan from more than 50 years ago: The spacecraft sails to the moon, reaches lunar orbit, and spends a few days orbiting the Earth’s satellite. The capsule is then propelled out of lunar orbit and back toward Earth by the firing of its propulsion nozzles.
The main difference is that Artemis 1 will send the spacecraft further than any previous lunar mission, in a loop that extends some 40,000 miles (65,000 km) beyond the moon. The mission will also launch 13 CubeSat miniature satellites as a tiny extra service. Still, in theory, Artemis 1 doesn’t have to achieve anything that hasn’t previously been done.
Trying to Find A Launch Vehicle
The initial issue was finding a launch vehicle for the Artemis mission. As stated by NASA Administrator Jim Bridenstine in March 2019, NASA did not have a rocket that could launch Orion plus the European Service Module to the Moon in 2019. Since the Saturn V was retired, there hasn’t been a launch vehicle on the planet that can lift the weight of such a spacecraft not just into Earth’s orbit but also beyond.
NASA’s Space Launch System (SLS) was created especially for this use, but it took a while to determine if it would be ready in time. That’s because, as of 2019, only the various components of this launch vehicle—including the primary engines, which are manufactured from reused space shuttle engines—had been put through testing. Moreover, the intricate, 321-foot-tall (98-meter) colossus had never flown.
Two Steps to Reach the Moon
Artemis I 2022 mission profile by NASA.
Orion and its service module could also be sent to the moon on a commercial rocket. For the Artemis 1 mission, NASA had been debating between employing a Falcon Heavy from SpaceX or a Delta IV from Boeing. However, these rockets didn’t have the upper stage necessary to send this payload from Earth orbit. For that, a rocket’s upper stage would need to be blasted into orbit independently using a different launch vehicle before being attached to Orion. However, this operation had never been tried, and Orion was not equipped with the necessary docking module anyway.
Even if some of the commercial vehicles could function, none would enable NASA to accomplish Artemis Mission 1’s intended lunar orbit on time and within a set budget. This investigation has given NASA the go-ahead to keep using the SLS. Despite significant obstacles, the strategy was successful; the Space Launch System (SLS) is now ready, allowing Artemis 1 to launch with a two-year delay.
Artemis 2 and the Lunar Gateway: Astronauts on a Lunar Trajectory
Artemis II 2024 mission profile by NASA.
The return of human lunar missions is planned in the second stage of the Artemis program. In 2024, a human lunar orbit will be the focal point. Parallel to this, the initial parts of a lunar space station will be launched into lunar orbit. This Lunar Gateway will act as a staging area and base for future lunar landings. Gateway will be humanity’s first space station in lunar orbit.
Similar to its previous mission’s flight plan, Artemis 2 is manned. An SLS launch vehicle will place the service module and the four passengers aboard the Orion spacecraft into Earth orbit, where they will orbit the satellite a few times before receiving the thrust for their journey to the moon. However, unlike Artemis 1, the Artemis 2 mission will take a so-called free return trajectory rather than enter a lunar orbit. Without the need for extra braking or acceleration procedures, the spacecraft will be deflected by lunar gravity alone and restored to Earth’s trajectory throughout an eight-shaped loop.
There will be women and people of color on board the spaceship for the first time on a lunar mission. NASA wants to be clear that, unlike Apollo, the leaders of the future lunar missions are no longer all white men, as was the case with that mission’s name, Artemis.
However, there will be several flights to the Moon before the actual lunar landing; Artemis 2 is not the only one. There will be many unmanned cargo rocket trips to the Moon in addition to this initial human test mission. According to NASA, there may be seven or eight of these trips. That’s because it’s also necessary to test and bring to the moon the lunar cargo module and the first components of the lunar orbiting station.
The Utilization Module, a very compact housing, and the power and thruster modules are the initial components of the Lunar Gateway that need to be launched into orbit. The lunar orbiting station’s core is made up of these two modules, which will serve as the launching pad for people to reach the lunar surface in 2025.
The Artemis mission plan also specifies that the lunar lander, or lunar landing module, must initially be built in lunar orbit. Depending on whose business constructs it and how that company intends to handle the travel from the Lunar Gateway down to the lunar surface, this lander will have either two or three components. However, these transport missions won’t be carried out using NASA’s own SLS launch vehicle; instead, they will be given out to private companies.
It’s still obvious how constrained the schedule is. Less than five years remain for NASA and its subcontractors to develop, test, and launch the required space modules and components.
Artemis 3: The Landing
Artemis III 2025 mission profile by NASA.
The lunar landing in 2025 will mark the culmination of the Artemis program. Four people will be placed in lunar orbit by an Orion spacecraft if all goes according to plan. Some of the crew will stay in the primitive lunar space station, while the remainder will use a landing module that was already stationed there to descend to the lunar surface.
In essence, this concept isn’t much more than a rehash of the Apollo missions. That’s because the time frame has been compressed, leaving little of NASA’s initial, more ambitious intentions. For instance, instead of spending at least a week on the lunar surface, the Artemis 3 crew would likely just remain there for a few days, and the base in orbit is essentially just the Apollo spacecraft’s command module.
Landing on the Moon’s Far Side
Astronauts are anticipated to land at the South Pole–Aitken Basin at the lunar south pole. © NASA
The Artemis astronauts’ landing location is, at the very least, novel. The South Pole-Aitken Basin, a large, old impact depression on the far side of the moon, will be Artemis 3’s landing spot. Its side that faces away from Earth has mainly been undiscovered up to this point; neither spacecraft nor people have accessed it for decades. But the Chinese space probe Chang’e 4 made history in 2019 when it became the first artificial object to touch down at the lunar south pole.
The first human landing in this intriguing scientific field is anticipated by planetary scientists to provide some fresh revelations. The moon’s far side is dominated by plateaus made of very ancient crustal rock, as opposed to its near side’s huge expanses of basalt lava. The Aitken Basin is seeing a rise in lunar mantle rock, according to data from the Chinese Yutu rover. The first opportunity for scientists to get samples of this lunar rock will be via the Artemis mission.
Who Builds the New Lunar Lander?
The Artemis crew won’t be transported to their landing spot at the moon’s south pole by a NASA lander, in contrast to the Apollo missions. NASA is not able to handle everything on its own. Thus, the required modules have to be provided by commercial sources. The transportation service that will take the astronauts from the Lunar Gateway to the moon will be essentially something NASA would purchase.
NASA had originally chosen eleven American firms to create prototypes for the next lunar lander’s submodules in 2019. Five companies and concepts remained after the selection was completed in 2021. There will be two or three submodules in the lunar module. In the first, humans will be transferred from the Lunar Gateway to the low lunar orbit. A descent module will then assume control and continue the fall to the lunar surface, much like the Apollo missions. Only the capsule carrying the astronauts will return to lunar orbit.
Cost of the Artemis program: $93 Billion
NASA gets over 20 billion dollars annually from the US government. It must, however, utilize this money to fund a wide variety of space operations, from unmanned trips to Mars and other planets in the solar system to satellites in Earth orbit and contributions to the International Space Station (ISS). It appears there isn’t much left over for a human moon trip.
For a long time, NASA kept the expense of the Artemis program a secret. According to initial estimates, the overall cost of the moon landing, including the expenditures of the prelude missions, was to be between 20 and 30 billion US dollars. As a result, NASA had to expand its budget by an extra 6 to 8 billion dollars annually, which would represent a financial boost unheard of since the Apollo period.
But as of September 2022, the Artemis mission had already cost around $43 billion and NASA will end up spending a total of $93 billion on the Artemis program between 2012 and 2025. The overall price of the SLS rocket alone doubled to $20 billion from its initial planned amount of $10 billion. One Artemis launch costs around $4 billion to complete.
Sources:
1. NASA, Moon to Mars.
2. NBC News, NASA’s Artemis program will return astronauts to the moon and give us the first female moonwalker.
3. Space.com, NASA Has a Full Plate of Lunar Missions Before Astronauts Can Return to Moon.
4. NASA, Artemis Accords.
September 3, 2022