Astronauts set to return to Earth after nearly a year in space

After 340 days on board the International Space Station, astronaut Scott Kelly and cosmonaut Mikhail Kornienko are scheduled to return home March 1. Tuesday’s departure will mark the end of a stint in orbit about twice as long as a typical visit to the space station.

Kelly and Kornienko left Earth on March 27, 2015, for an expedition designed to study the physical and psychological challenges that future astronauts will have to endure on trips to far-flung locales such as Mars. Back on Earth, Kelly’s identical twin brother, Mark, is serving as an experimental control so researchers can compare how space changes a person with the same genetic makeup.

A year is a long time, but it’s not the longest sojourn to low Earth orbit. That honor goes to cosmonaut Valeri Polyakov, who stayed on space station Mir for nearly 438 days in 1994 and 1995.

No word yet on whether the gorilla suit that Mark recently sent his brother is staying behind.