Video: Liftoff of Atlas 5 on space station cargo mission

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.

Two astronauts floated outside the International Space Station Thursday and installed two new cameras on the front of the lab complex that will provide views of commercial crew ships during final approach and docking. The spacewalkers also replaced a faulty high-definition camera and closed a door that was jammed open on an external instrument.

Hardware for two air-dropped Pegasus XL launchers previously purchased by Stratolaunch, a space launch company founded by the late billionaire Paul Allen, are now back under Northrop Grumman control and for sale to NASA, the Air Force, or commercial satellite operators, industry officials said.