Scott Kelly shares spectacular ‘spacewalk selfie’

NASA says, by that time, he will have tallied 522 total days in space over four separate missions.

Between them, Kornienko and Kelly share the record for longest single stay on the global Space Station.

Cosmonaut Valeri Polyakov spent 437 consecutive days aboard the Russian Space Station Mir starting in 1994, and Gennady Padalka returned to Earth in September after spending 879 days among the stars over the course of five missions.

“Some astronauts on long-duration space flights have had a degradation in their vision that is concerning”.

Today, Scott Kelly breaks NASA’s record for longest single spaceflight of an American astronaut, surpassing the previous record of 215 days held by Michael Lopez-Alegria.

The 51-year-old astronaut started his year-long journey back in March 2015. Kelly, along with his identical twin brother Mark, are part of the NASA Twins Study, which aims to observe the effects of zero gravity on Kelly’s brain and body and then compare it to the records of his twin brother Mark, who was a former USA astronaut. The study will have 10 experiments in 4 areas: human physiology, behavioral health, microbiology and molecular.

As part of a yearlong series of films about the mission, TIME’s A Year in Space Director Shaul Schwarz spoke with Kelly from NASA’s Johnson Space Center in Houston on Thursday about the spacewalk, breaking the record and missing home.

Just yesterday Kelly broke another record of maximum number of consecutive days spent by an U.S. astronaut in space. Kelly is now on a one-year mission, scheduled to return to Earth in March 2016. On November 2, the ISS crew celebrate the 15 year of continuous presence of humans in space aboard the ISS.