Snapshots from Atlas 5 launch

The mobile service tower retracts from the Atlas 5 rocket, revealing the 197-foot-tall vehicle for liftoff from Vandenberg Air Force Base, California, carrying the classified NROL-42 national security payload for the U.S. government.

A logistics-delivery vessel for the International Space Station, launched and operated privately by commercial companies on behalf of NASA, is scheduled to arrive at the lab complex Saturday at 6:05 a.m. EDT (1005 GMT).

This photo gallery shows the U.S. Navy’s Mobile User Objective System communications satellite No. 4 being encapsulated in the United Launch Alliance Atlas 5 rocket’s payload fairing for the planned Aug. 31 liftoff.