Video: Change of command aboard International Space Station

SpaceX is targeting launches March 6 and March 11 for its next two missions after swapping an upper stage for its next Falcon 9 rocket with another stage already being readied for liftoff at Cape Canaveral.

Astronauts Peggy Whitson and Jack Fischer put on spacesuits Friday and headed outside the International Space Station for several repair and maintenance tasks, but the duo only completed part of their originally planned work after a leaky cooling umbilical delayed the start of their spacewalk.

In the final hours of a 340-day mission, Scott Kelly and Mikhail Kornienko said goodbye to their crewmates and closed the hatch to the International Space Station on Tuesday, heading for a parachute-assisted touchdown in Kazakhstan a few hours later.