Video: Soyuz MS-01 leaves the space station for landing

Astronauts Randy Bresnik and Mark Vande Hei headed outside the International Space Station Thursday on a spacewalk to replace one end of the lab’s Canadian-built robotic arm, a changeout that engineers say will restore the device to full capability.

Nearly a decade in the making, NASA and SpaceX have set May 27 as the target launch date for the first crewed space mission to launch into orbit from U.S. soil since the retirement of the space shuttle in 2011.

Set to resume a brisk pace of launch activity after a nearly six-week respite, SpaceX test-fired its next Falcon 9 rocket Thursday at NASA’s Kennedy Space Center in Florida ahead of a planned liftoff Monday with several tons of experiments and supplies for the International Space Station.