Photos: Atlas 5 rolls out for launch

NASA has selected SpaceX and United Launch Alliance to deliver to orbit a joint U.S.-European oceanography mission and the next land imaging satellite in the Landsat series on Falcon 9 and Atlas 5 rockets.

A hold-down test-firing of a Falcon 9 rocket Friday at Cape Canaveral marked a major step in preparations for SpaceX’s 13th mission of the year, scheduled for liftoff Monday with a commercial communications satellite.

Watch the briefing to learn what is aboard the Orbital ATK Cygnus OA-6 resupply freighter launching to the International Space Station on March 22 aboard a United Launch Alliance Atlas-5 rocket.