Snapshots from Atlas 5 launch

A steel tube built as a stand-in for the core stage of NASA’s Space Launch System has arrived at the Kennedy Space Center for a series of rehearsals to hone the skills of technicians before the real rocket reaches the spaceport, an oft-delayed milestone that could still be a year or more away.

The gates to the Johnson Space Center have been closed to all but essential personnel as heavy rains from Tropical Storm Harvey inundate the Houston area. Flight controllers are on lock down at the Mission Control Center but continue to monitor the health of the International Space Station as usual.

United Launch Alliance will launch the USSF-106 mission as its first flight for the U.S. Space Force using a Vulcan rocket. The vehicle will carry two satellite missions onboard.