The Russian Soyuz spacecraft carrying the Expedition 61 Flight Engineer Koch, Soyuz Commander Alexander Skvortsov of Roscosmos and Luca Parmitano of ESA (European Space Agency) reached Kazakhstan safely at 2.42 pm India time.
Koch in December set a new record for the longest single spaceflight by a woman, eclipsing the record of 288 days set by former NASA astronaut Peggy Whitson in 2016-17.
Her stay is just 12 days short of all-time US record set by Scott Kelly during his one-year mission in 2015-16.
“Having the opportunity to be up here for so long is truly an honour. Peggy is a heroine of mine and has also been kind enough to mentor me through the years, so it is a reminder to give back and to mentor when I get back,” Koch said in December.
Koch, who arrived at the space station on March 14, was expected to be on a typical six-month mission. NASA extended her stay, partly in a bid to collect more data about the effects of long-duration spaceflight.
Koch will have spanned 5,248 orbits of the Earth – a journey of 139 million miles, roughly the equivalent of 291 round trips to the Moon.
She conducted six spacewalks during her 11 months on orbit, spending 42 hours and 15 minutes outside the station and witnessed the arrival of a dozen visiting vehicles and the departure of another dozen.
“Earth is alive, and I have witnessed its power and beauty from a special vantage point 250 miles above the surface,” said Koch.
“Back on Earth I anticipate looking up and seeing the space station streak across the sky, wondering how my friends and colleagues are doing up there without me. For almost 20 years humans have continuously lived and worked in space and the mission continues,” she added.
At the time of undocking, Expedition 62 formally begins aboard the station, with NASA astronauts Jessica Meir and Morgan as flight engineers and Oleg Skripochka of Roscosmos as station commander.
They will remain on board the orbital outpost until early April, when NASA astronaut Chris Cassidy and Russian cosmonauts Nikolai Tikhonov and Andrei Babkin will launch to the station.