Photos: Gantry rolled back to reveal Atlas 5 rocket for launch

Riding a half-million pounds of thrust, a Minotaur 4 rocket fired off a launch pad in Virginia, surpassed the speed of sound in less than 20 seconds, and vaulted into orbit Wednesday with four classified payloads for the National Reconnaissance Office.

The United Launch Alliance Atlas 5 rocket with the NROL-52 spacecraft aboard moved to the launch pad this morning for liftoff Saturday to serve the national interest. Liftoff is scheduled for 3:31 a.m. EDT (0731 GMT).

The launch of five commercial Iridium message relay satellites and a pair of U.S.-German orbiting geophysics probes on a Falcon 9 rocket from California has been delayed three days to May 22, and a week-long schedule slip to May 31 is expected for the next SpaceX flight from Cape Canaveral with an SES communications payload.