Tonight, three astronauts onboard the International Space Station will load into a Russian Soyuz capsule, beginning their nearly seven-hour journey back home to Earth. The returning crew is an international bunch, including NASA astronaut Tim Kopra, British astronaut Tim Peake of the European Space Agency, and Russian cosmonaut Yuri Malenchenko. The trio will board the Soyuz after 10:15PM ET and then undock from the ISS around 1:52AM ET.
The astronauts are finishing up a 186-day stay in space
After that, the Soyuz will remain in orbit until about 4:21AM ET. That’s when the vehicle ignites its engines, taking the Soyuz out of Earth’s orbit. This "deorbit burn" initiates the spacecraft’s descent through the atmosphere, eventually reaching a speed of 755 feet per second. A series of four parachutes help to slow the Soyuz down from that insane speed to a rate of just 24 feet per second. That’s still pretty fast for a landing though, which is why a set of thrusters fire underneath the Soyuz just before it reaches the surface, helping to slow the vehicle even more so that it can touch down safely. Landing is supposed to occur around 5:15AM ET.
Tonight’s returning astronauts are finishing up a 186-day stay in space, after launching to the ISS in December 2015. Notable among them is Peake — the first British astronaut registered with the ESA to go to space — who has certainly made a name for himself while onboard the station. On April 24th, Peake ran the London marathon in space, and if that wasn’t impressive enough, he did it in record time. He finished the race in three hours and 35 minutes, beating out the last space marathon runner, Sunita "Suni" Williams, who ran the Boston marathon on the ISS in four hours and 24 minutes. He’s also clearly had fun up there, making this cute video about how to get dizzy in space. (Spoiler: you can’t.)
Once Peake and his fellow crew members leave the station tonight, Expedition 48 begins on the ISS. The remaining astronauts — NASA astronaut Jeff Williams and Russian cosmonauts Oleg Skripochka and Alexey Ovchinin — will be by themselves for three weeks until the next crew arrives aboard a Soyuz on July 6th. That expedition will finally bring a woman to the ISS — NASA astronaut Kate Rubins. The station has been purely male-dominated since ESA astronaut Samantha Cristoforetti left in June 2015.
Correction June 17th, 11:45AM ET: A previous version of this article misstated the speed of the Soyuz's descent. It's 755 feet per second, not miles per second, and the text has been updated.