Tuesday night, at 11:27 p.m. Eastern U.S. time (or Wednesday at 04:27 UTC if you prefer), Cmdr. Scott Kelly and Mikhail Kornienko will return to their home planet.
Kelly is an American astronaut, and Kornienko a Russian cosmonaut. They’ve been on board the International Space Station since March 28, when they started a mission scheduled to last 340 days, very close to a full year—twice the usual length of a NASA ISS Expedition. The purpose is to study the effect of living in microgravity for long durations, in part as preparation for a mission to Mars.
On Monday, Kelly, who was in command of the station, handed over the keys (metaphorically) to American astronaut Tim Kopra, who has been on board ISS since Dec. 15, 2015. That will happen at 20:10 UTC (15:10 Eastern). For the next hour or so the space travelers will say their goodbyes, then Kelly, Kornienko, and fellow cosmonaut Sergei Volkov will stuff themselves into their Soyuz TMA-18M capsule. Undocking is scheduled for 01:05 UTC (Tuesday evening at 20:05 for U.S. folks, Wednesday morning for points east), perform a deorbit burn at 03:34 UTC, and touch down in Kazakhstan at 04:27 UTC (23:27 Eastern).
When they do so, Kelly and Kornienko will have completed the fourth longest space flight in human history.
I’ll be watching, especially after touchdown; a year in space will leave Kelly and Kornienko very weak, with bone calcium loss and muscular atrophy. How they react when they are helped out of the capsule should be pretty interesting, and quite honestly emotionally uplifting. Seeing astronauts smiling and joyous after that bumpy ride and months spent on orbit is really something to behold.
And the landing is not soft. Here’s a video describing just how rough it is:
Kelly holds the record for an American astronaut with most time logged in space, a record he broke in October. When he lands he’ll have more than 500 days in space under his belt. FYI, the longest duration spent continuously in space is 400 days, and longest accumulated time is a staggering (literally) 879 days!
This mission is pretty cool. If you want to learn more I suggest reading NASA’s 10 Things to Know About Scott Kelly’s Year in Space, and a highly detailed article about it at AmericaSpace.
In October, NASA put together a nice tribute video to Kelly as well:
Also, over the past 340 days, Kelly has been taking phenomenal photographs of our planet from his 400 kilometer high perch.* You can find those on Instagram and Twitter. You can also look through every single one of his photos in high resolution at Windows on Earth, and even vote on which ones you like best!
Safe journey to everyone involved!
*Correction, March 2, 2016: I originally misstated that the height of the space station was 500 kilometers.