The Parker Solar Probe, launched on August 12, 2018, is the fastest man-made object in space. It travels at 393,000 km/h (244,000 mph), fast enough to cover the distance between Paris and Tokyo in 1 minute and 30 seconds. However, the speed of probes is far from constant: they are accelerated when passing over planets, using their gravitational assistance. Space probes also have to escape other gravitational disturbances, especially when approaching the Sun.
In fact, it requires more energy to place a probe in orbit around Mercury than to reach Pluto! The duration of the journey also depends on the distance, which varies for planets with elliptical orbits. Here are the records set so far and the theoretical travel times at the speed of light (if we ever manage to achieve it…).
Mercury
- Average distance from Earth: 91.69 million kilometers
- Space probe: BepiColombo
- Launch date: October 19, 2018
- Arrival date (orbital insertion): December 5, 2025 (forecast)
- Travel duration: 2,604 days, or 7 years, 1 month, and 17 days (forecast)
- Theoretical travel time (speed of light): 5 minutes 6 seconds
Venus
- Average distance from Earth: 41.40 million kilometers
- Space probe: Venus Express
- Launch date: November 9, 2005
- Arrival date (orbital insertion): April 11, 2006
- Travel duration: 153 days, or 5 months and 2 days
- Theoretical travel time (speed of light): 2 minutes 18 seconds
Mars
- Average distance from Earth: 78.34 million kilometers
- Space probe: InSight
- Launch date: May 5, 2018
- Arrival date (landing): November 26, 2018
- Travel duration: 205 days, or 6 months and 21 days
- Theoretical travel time (speed of light): 4 minutes 22 seconds
Jupiter
- Average distance from Earth: 628.73 million kilometers
- Space probe: Juno
- Launch date: August 5, 2011
- Arrival date (orbital insertion): July 5, 2016
- Travel duration: 1,796 days, or 4 years and 11 months
- Theoretical travel time (speed of light): 34 minutes 57 seconds
Saturn
- Average distance from Earth: 1,275 million kilometers
- Space probe: Cassini-Huygens
- Launch date: October 15, 1997
- Arrival date (orbital insertion): July 1, 2004
- Travel duration: 2,451 days, or 6 years, 8 months, and 17 days
- Theoretical travel time (speed of light): 1 hour 10 minutes 53 seconds
Uranus
- Average distance from Earth: 2,723.95 million kilometers
- Space probe: Voyager 2
- Launch date: August 20, 1977
- Arrival date (flyby): January 24, 1986
- Travel duration: 3,079 days, or 8 years, 5 months, and 4 days
- Theoretical travel time (speed of light): 2 hours 31 minutes 26 seconds
Neptune
- Average distance from Earth: 4,351.40 million kilometers
- Space probe: Voyager 2
- Launch date: August 20, 1977
- Arrival date (flyby): August 25, 1989
- Travel duration: 4,388 days, or 12 years and 5 days
- Theoretical travel time (speed of light): 4 hours 1 minute 55 seconds
