Astronaut Scott Kelly, in good spirits and looking surprisingly fit after a record 340 days in space, said Wednesday he could have stayed up longer if necessary, giving him confidence future astronauts will be up to the challenge of even longer flights to Mars and beyond.

Flying by hand, Russian cosmonaut Alexander Skvortsov undocked his Soyuz space capsule from the International Space Station late Sunday (U.S. time) and maneuvered the ship to a new parking spot on the million-pound research complex, clearing the way for the arrival of a new Soyuz spacecraft Monday night after aborting its first approach.

India’s first dedicated astronomical observatory lifted off at 0430 GMT (12:30 a.m. EDT) Monday aboard a Polar Satellite Launch Vehicle, riding into a 400-mile-high orbit to begin a five-year mission studying the births and deaths of stars.