Photos: Atlas 5 powers NRO payload into the night

SpaceX test-fired the Falcon 9 rocket early Saturday ahead of launch with the next four astronauts heading to the International Space Station. The static fire test before sunrise Saturday in Florida was a major step toward liftoff Thursday.

Ziplines are used by thrill-seekers in adventures around the world, but now they are coming to the U.S. space program as the emergency escape system for personnel at Cape Canaveral’s Complex 41.

SpaceX’s second Falcon Heavy rocket is set for liftoff Thursday from NASA’s Kennedy Space Center in Florida, and the heavy-lift launcher will head on an easterly course over the Atlantic Ocean atop more than 5 million pounds of thrust.