Live coverage: Soyuz blasts off on third mission for O3b

NASA said Thursday that rookie astronaut Serena Auñón-Chancellor will replace Jeanette Epps on an expedition set for launch to the International Space Station in June.

SpaceX’s first Falcon Heavy launch for the U.S. Air Force took a major step closer to liftoff with a hold-down engine firing Wednesday night at launch pad 39A at NASA’s Kennedy Space Center in Florida. Liftoff with a cluster of experimental satellites and weather monitoring craft is set for June 24.

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.