The mission was by no means perfect; after all, the Japanese lunar lander SLIM was off-balance from the start. But at least the probe from the Japanese space agency JAXA accomplished something that only four other nations had achieved before: a (somewhat) gentle landing on the Moon.
Although the lander did not stand upright on the Earth’s satellite as planned and suffered from energy shortages, it survived several lunar nights and was later able to re-establish contact with the ground station on Earth. However, the project has now definitively ended: JAXA has declared the SLIM mission over after nearly eight months.
No More Communication
Communication with the probe has not been possible since last week, the agency announced on Monday on the online service X. “We have concluded that there is no prospect of successfully restoring communication with SLIM.
SLIM stands for “Smart Lander for Investigating Moon.” With the landing of the 2.40-meter by 1.70-meter probe on the Earth’s satellite, Japan became the fifth nation to land on the Moon, following the USA, the Soviet Union, China, and India, in early January. Two earlier Japanese lunar missions in 2022 and April 2023 had failed.
[Press Release] Conclusion of Lunar Activities of the Smart Lander for Investigating Moon (SLIM)#JAXAhttps://t.co/eO9xtP1zis
— JAXA(Japan Aerospace Exploration Agency) (@JAXA_en) August 26, 2024
Longer Than Expected
“SLIM continued to transmit information on its status and the surrounding environment for a much longer period than expected,” explained the space agency JAXA. The probe had landed on its side during its Moon landing, causing its solar panels to face west instead of upwards as planned. As a result, the device initially received only a little sunlight and consequently little power. Nevertheless, SLIM managed to transmit images of the lunar surface back to Earth.
The mission’s goal was to reach rock at the lander’s site in the Shioli crater that is usually buried deep beneath the lunar surface. This rock could provide clues about potential water occurrences on the Moon.
About 60,000 years ago, a mega-scale underwater landslide occurred off the coast of Morocco—the longest worldwide. It dragged about 162 cubic kilometers of mud and debris, more than 2,000 kilometers, into the Atlantic. The surprising thing, however, is that this underwater avalanche started very small and only grew to about a hundred times its volume during its course, as researchers report in Science Advances. Such rapid growth is not known from any other terrestrial landslide.
Mud and debris avalanches don’t just occur on land; there are also massive landslides underwater. Earthquakes, gas hydrates, or turbulence in submarine canyons can cause large sediment masses to slide off, especially on continental slopes, with catastrophic consequences. For instance, the Storegga Slide about 8,100 years ago caused large parts of the ice age Doggerland in the North Sea to sink. The previously longest underwater landslide was an avalanche that originated from the mouth of the Congo in 2020 and raced 1,100 kilometers into the Atlantic.
But how do such submarine landslides become mega-avalanches? For snow avalanches or landslides, it’s known how they develop and how much their volume can grow from beginning to end. For underwater landslides, however, this information has been lacking until now.
Underwater Landslide on a Megascale
Now, for the first time, researchers have managed to reconstruct the growth of an underwater landslide in one of the world’s largest submarine canyons. The Agadir Canyon begins off the coast of Morocco and is 450 kilometers long and 30 kilometers wide. The gorge, deeply cut into the African continental slope, extends to a depth of 1,200 meters into the Atlantic. Geological studies have shown that large landslides have repeatedly occurred in this canyon.
One of the last and largest events of this kind was the so-called “Bed 5” landslide almost 60,000 years ago. “This suspension flow comprised about 162 cubic kilometers of sediment and covered the extraordinary distance of more than 2,000 kilometers,” report Christoph Böttner from the University of Kiel and his colleagues. To clarify where and how this underwater avalanche originated and how it developed, they analyzed more than 300 sediment cores from the Agadir Canyon and its surroundings and mapped the entire submarine canyon using sonar.
Favored by Bud, Speed, and Giant Canyon
The analysis revealed the gigantic extent of the Agadir landslide: It formed an avalanche about 200 meters high that raced into the depths at breakneck speed, dragging everything around it. “This landslide was the height of a skyscraper and raced down the slope at more than 65 kilometers per hour,” reports co-author Christopher Stevenson from the University of Liverpool.
“In the end, it covered an area larger than Great Britain under more than a meter of sand and mud.” The erosion traces are detectable over an area of about 4,473 square kilometers along the entire length of the canyon.
The enormous force and range of the underwater avalanche were made possible by a combination of several features. For one, the sediment slid off at a particularly high speed, giving the avalanche corresponding momentum.
For another, the seabed in this area consisted of fine, clayey mud. “The addition of mud increases the range and transport capacity even for coarser particles,” the researchers explain. This is because the fine particles remain suspended for a long time but simultaneously promote the cohesion of the suspension flow.
“Ultimately, the Bed 5 event was only limited by the cross-section of the canyon,” Böttner and his team explain. “Because this is exceptionally large, the landslide could become a catastrophic, massive event.”
Surprisingly Small Trigger
But where and how did this mega-landslide originate? Böttner and his colleagues were also able to clarify this. According to their findings, the trigger must lie in the southern part of the canyon tributaries—deeply incised, branched flow beds above the beginning of the gorge. There, the entire seabed could have detached in a closed layer up to 30 meters thick. According to the researchers, this large-scale but shallow slope failure could also explain why no clear traces are visible there.
The surprising thing, however, is that the trigger of the massive Bed 5 landslide was relatively small—it comprised only about 1.5 cubic kilometers. This means that the underwater avalanche must have drastically increased in volume from its beginning to its end. “This means that this landslide grew at least 100 times its original size,” report Böttner and his team.
Such an increase in volume is orders of magnitude greater than that of debris or snow avalanches on land.
Increased Risk for Coasts and Marine Infrastructure
According to the research team, the drastic increase in volume of this submarine landslide is not an isolated case: “We assume that this is a specific behavior of underwater avalanches,” says Böttner. “We have already seen similarly extreme growth in smaller landslides elsewhere.” However, the fact that even the largest events of this kind can have relatively small triggers is a new insight.
“Before this study, we thought that large submarine avalanches only originated from correspondingly large slope failures,” says senior author Sebastian Krastel from the University of Kiel. “Now we know that they can start small and then grow into extremely strong and extensive events.”
For a long time, astronomers have suspected: There must also be intermediate-mass black holes. But reliable observations have not been successful until now. Now, an international research team led by Maximilian Häberle from the Max Planck Institute for Astronomy in Heidelberg has presented the best evidence yet for exactly such a black hole.
In the archive data of the Hubble Space Telescope, the team detected seven stars moving at extremely high speeds in the center of the globular cluster Omega Centauri. Only the gravitational pull of a black hole could explain the movement of the stars, the researchers write in the journal “Nature.” From their data, they conclude: The black hole at the center of Omega Centauri has 8,200 times the mass of our sun.
The newly described black hole is, considering the vastness of space, close to Earth. It is about 18,000 lightyears away, explains co-author Nadine Neumayer. This makes it the closest known example of a massive black hole. The supermassive black hole at the center of our galaxy, the Milky Way, is at a distance of about 27,000 lightyears.
Search for Racing Stars
To find new black holes, astronomers had repeatedly searched for such racing stars, unsuccessfully until now. Häberle set out to search again. To calibrate his instruments, he used previously unutilized data from the Hubble telescope, which had repeatedly photographed Omega Centauri. In total, Häberle had access to 500 archive images spanning a period of 20 years. In these images, the researcher meticulously measured the movement of approximately 150,000 stars.
In the end, Häberle not only created the most comprehensive catalog of stellar movements in Omega Centauri to date but also identified seven stars moving at high speeds. At this speed, Häberle believes, the stars should fly out of the star cluster. Only the gravitational pull of a black hole with 8,200 times the solar mass can hold the stars in place, his calculations show.
Detecting a black hole with such a mass is of great importance for astronomers. Until now, sky researchers only knew of two types of black holes. So-called stellar black holes with up to 150 solar masses are formed when large stars have exhausted their nuclear energy supply and collapse helplessly.
And then there are the supermassive black holes at the centers of galaxies with millions or even billions of times the mass of the sun.
These supermassive black holes are presumed to have formed through the merger of smaller black holes with a few thousand solar masses. Some of those intermediate-mass black holes should still exist in the cosmos today. Indeed, sky researchers have come across a whole series of candidates for such objects in smaller galaxies and globular clusters. But direct evidence was lacking until now: the movement of stars in such distant objects is simply too difficult to observe.
Galaxy Swallowed by the Milky Way
This is where Omega Centauri comes into play: With ten million stars, it is the largest globular cluster in the Milky Way. Even the naked eye can spot it in the southern sky. Omega Centauri is probably the former central region of a small galaxy that collided with the Milky Way billions of years ago, losing its outer regions in the process.
The idea was that if this collision happened, Omega Centauri should still contain an intermediate-mass black hole that was once present in the center of the small galaxy. The globular cluster’s proximity to Earth allows us to observe the movement of stars there.
The stars now detected by Häberle and his team confirm this consideration. However, the Hubble images only show the movement of the stars in the sky and not the movement towards or away from us. The researchers now want to measure the radial movement of the seven racing stars with the James Webb Space Telescope and thus eliminate any last doubts about the existence of the black hole in Omega Centauri.
According to a new study, the active ingredient semaglutide in the coveted weight loss injection Wegovy and the diabetes medication Ozempic from Novo Nordisk may be linked to a dangerous eye disease. After analyzing data from over 16,800 patients at a large eye clinic in Boston, an international team of researchers concluded that people taking semaglutide have a four-fold increased risk of non-arteritic anterior ischemic optic neuropathy (nAION).
This eye condition results in sudden unilateral loss of vision due to a circulatory disorder of the optic nerve.
Diabetics have an increased risk for this disease. According to the study published in the journal “JAMA Ophthalmology,” among the patients, there were 710 people with type 2 diabetes and 979 people with overweight or obesity who were treated with either semaglutide or another medication. During the three-year observation period, the risk of a nAION diagnosis for diabetics taking semaglutide was 8.9 percent, compared to a risk of 1.8 percent when using other antidiabetic drugs.
For overweight and obese individuals in the semaglutide group, the risk was 6.7 percent, compared to 0.8 percent in the group taking other weight-reduction medications.
The scientists emphasized that this does not prove that semaglutide is the reason for this increased risk. However, further investigation of the connection is necessary. Medical professor Graham McGeown from Queen’s University in Belfast explained that while the study had a high quality level, the study authors themselves had pointed out important weaknesses.
Cause and Effect Unclear
The data doesn’t disclose the rationale behind administering the medications. A factor could be that those treated with semaglutide had previously been more severely ill with diabetes than the other subjects. Additionally, there are doubts about how representative the group of patients is for the US population. The semaglutide group was, on average, older than the others. This could explain the NAION risk, and people of African American descent are also considered disproportionately at risk.
Larger studies would need to verify the connection. “Given the rapid increase in the use of semaglutide and its potential approval for a range of problems other than obesity and type 2 diabetes, this question deserves further investigation,” McGeown stated.
Semaglutide belongs to the class of so-called GLP-1 agonists, which lower blood sugar levels and reduce appetite. Ozempic and Wegovy helped the Danish pharmaceutical manufacturer Novo Nordisk achieve record sales and become Europe’s most valuable publicly listed company. Novo stated that patient safety is the company’s highest priority. “We take all reports of adverse events associated with the use of our medicines very seriously.” Overall, however, the published data are not sufficient to establish a causal relationship between the use of GLP-agonists and nAION. There are also important methodological limitations to the study that must be considered when interpreting the results.
nAION occurs in about two to ten cases per 100,000 people, making it the second most common cause of blindness due to optic nerve damage. A previous study had already shown that semaglutide can worsen diabetic retinopathy, a disease of the retina. Therefore, specialists recommend an eye examination before and during semaglutide use.
While performing a detailed simulation of the formation of a supermassive black hole, researchers discovered that magnetic fields play a much more important role than previously thought. While it was believed that the accretion disk was relatively flat, the influence of the magnetic field would make it rather puffy and rough.
The gravitational force of a black hole attracts matter, which first orbits around it and forms an accretion disk. Intense radiation from this disk enables the imaging of black holes, with the first indirect image appearing in 2019. However, the way these disks of matter form and behave remains partly misunderstood.
Gaps in Simulation Scales
To analyze complex cosmological processes in depth, physicists usually resort to computer simulations. This type of simulation is generally based on parametric data governing the environment of these objects, such as equations of gravitational processes and molecular interactions within the surrounding matter.
For example, if a gas cluster becomes dense enough due to gravitational collapse, computers deduce that a star forms. However, “if you just think that gravity pulls everything together and then the accumulated gas forms a star and stars accumulate, you’re completely wrong,” explains theoretical astrophysicist Philip Hopkins in a blog post from the California Institute of Technology (Caltech).
Indeed, many processes influence stellar environments. Stars, for example, can emit radiation fluxes that can “blow away” surrounding gas and matter, altering their chemistry. Computers must therefore take these processes into account as they regulate the number of stars that can form within a galaxy.
On the other hand, the physical parameters to include are different when it comes to larger scales.
The behavior of atoms and molecules in galaxies, for example, is extremely important. However, for accretion disks, molecular chemistry can be negligibly integrated into simulations (or even ignored), as the environment is too hot for atoms and molecules to exist. Accretion disks are thus composed of ionized plasma.
However, to simulate all the physical processes occurring within a black hole’s accretion disk, all scales must be taken into account.
However, “some codes contained the physics needed to solve the small-scale part of the problem and others contained the physics needed to solve the larger part, but nothing allowed to do both,” says Hopkins.
To fill these gaps, Hopkins and his colleagues imagined and developed a new type of simulation combining both scales for the first time. The project was born from a collaboration between the Feedback in Realistic Environments (FIRE) simulation program, which focuses on large cosmological scales (such as galactic collisions), and STARFORGE, dedicated to smaller scales (such as individual stars). Their results are detailed in The Open Journal of Astrophysics.
Puffy Accretion Disks
The Caltech team used a technique known as “superzoom” to perform the simulation, which targeted a supermassive black hole. They notably developed a computer program called GIZMO that adapts the FIRE program to make it compatible with STARFORGE, and vice versa. “We designed it in a very modular way, so that you can turn on and off any piece of physics for a given problem while making sure they’re all compatible with each other,” explains Hopkins.
For this type of object, the resolution obtained is 1000 times higher than the previous simulation record.
Hopkins’ technique allowed modeling the accretion disk of a supermassive black hole about 10 million times the mass of the Sun in the early Universe. The simulation shows a process where a stream of matter is torn from a protostellar cloud and begins to swirl around the black hole. The algorithm allows for observing in detail each step of the gas’s journey towards the edge of the black hole.
The team was surprised to find that magnetic fields play a much more important role than previously thought in the formation of the accretion disk. Physicists initially assumed that thermal pressure (the pressure variation caused by the temperature change of the gas in the accretion disk) prevented them from collapsing under the influence of the black hole’s gravitational force, while the influence of the magnetic field would be minor. This would give a flattened appearance to the accretion disk.
However, the new simulation shows that the pressure exerted by the magnetic field is 10,000 times greater than the thermal pressure, which causes the disk to puff up. “Our theories told us that disks should be flat like pancakes,” explains Hopkins. “But we knew this wasn’t true, because astronomical observations reveal that disks are actually puffy and velvety, more like a cake.”
These results could have important implications for predictions about their mass, density, thickness, the speed at which matter moves within them, and even their geometry. The GIZMO program also paves the way for other simulations where scale differences are lacking, such as galaxy mergers and the formation of the first stars in the Universe, the team suggests.
Curious individuals who have recently discovered a passion for space sometimes wonder about the different terms used to refer to those who travel there. There is a plethora of words constructed around the suffix “-naut,” derived from the ancient Greek word ναύτης (navigator), but with distinct prefixes. These prefixes are generally related to nationality, but with a few subtle differences. Here’s a lexicon to clarify these terms.
Astronaut: The Generic Term
Eugene Cernan on the Moon during the Apollo 17 mission.
The most common term is undoubtedly “astronaut.” The prefix “astro-,” derived from the ancient Greek word ἄστρον, refers to stars. In principle, it refers to all humans who navigate among the stars and, by extension, in space, without any specific distinction.
Specifically, it is also a full-fledged professional title. The North American space agency, better known as NASA, officially awards it to anyone who joins its prestigious Astronaut Corps. This group currently comprises 41 astronauts based at the renowned Johnson Space Center in Texas.
Among the most well-known astronauts is the legendary Neil Armstrong, the first human to set foot on the Moon during the Apollo 11 mission in 1969. He is famously known for the phrase, “That’s one small step for a man, one giant leap for mankind.” He walked on the lunar surface alongside Edwin “Buzz” Aldrin, while Michael Collins remained in the command module.
The term “spationaut” is based on the Latin word “spatium,” which literally means “space.” It specifically refers to astronauts from Western Europe or, depending on the context, from France.
This is a rarer and mainly informal designation. Like its American counterpart, the European Space Agency also uses the term “astronaut” in its official documents. They are gathered in the European Astronaut Corps, established in Cologne in 1998 to unite European astronauts under one banner.
The European Astronaut Corps currently has six active members, including Italians Luca Parmitano and Samantha Cristoforetti, Germans Alexander Gerst and Mathias Maurer, Danish astronaut Andreas Mogensen, and notably, France’s own Thomas Pesquet. Thomas Pesquet holds the record as the European astronaut with the most time spent in space, totaling 396 days, 11 hours, and 34 minutes away from Earth.
Cosmonaut: A Russian Version Inherited from the Cold War
Yuri Gagarin.
This term is a direct transliteration of “космонавт,” derived from the ancient Greek word κόσμος, meaning “universe.” It specifically refers to astronauts affiliated with the Russian space agency, now known as Roscosmos.
This word entered public vocabulary during the Cold War, which pitted the Western bloc, centered around the United States, against the Eastern bloc represented by the Soviet Union. From the perspective of the United States, it was a way to distinguish its own astronauts, true national heroes, from their Russian counterparts, whom Americans did not wish to hold in the same regard.
This distinction lost its pejorative character at the end of the Cold War. Thankfully, because it was the cosmonauts who achieved humanity’s first feats in space. In 1961, Yuri Gagarin became the first human to journey into space aboard the Vostok 1 mission.
Beyond this particularly famous example, a cohort of cosmonauts ventured into space before Americans even set foot there. Among them are Gherman Titov, who orbited space at the tender age of 25, Alexei Leonov, the first to conduct a spacewalk, and Valentina Tereshkova, the first woman to leave Earth.
More recently, as more nations aspire to explore space, new terms have started to emerge, including “taikonauts,” who are astronauts affiliated with the Chinese space agency. The term is derived from the Mandarin “tàikōng” (太空), which literally means “space.
However, “taikonaut” is an informal term coined in the West and is not used in China. It is not well-received by some English-speaking Chinese audiences, as it is seen as drawing a parallel to the astronaut-cosmonaut divide during the Cold War, in a context where Chinese aerospace advances rapidly and diplomatic relations with the United States are tense.
Officially, Chinese astronauts are called “hángtiānyuán” (航天员), roughly translating to “celestial navigators.”
The most well-known among them is Yang Liwei, the first Chinese national in space. His mission was notably a solo flight, a rarity in the modern era. More recently, Jing Haipeng, Zhu Yangzhu, and Gui Haichao made history with their stay aboard the Tiangong, the new Chinese space station.
It is perhaps the least known term on this list because there has been only one true Indian citizen astronaut.
This distinction belongs to Rakesh Sharma, who went to space in 1984. At the time, ISRO had just launched its first satellites into orbit, and the institution was far from sending humans into space. Sharma’s mission was made possible through a collaboration with the Soviet space program.
However, this might change soon. The number of vyomanautes is expected to quadruple with the Gaganyaan program, through which ISRO plans to send three astronauts into orbit in 2025.
