Photos: Atlas 5 powers away with NROL-61 payload

Follow the key events of the Falcon 9 rocket’s ascent to orbit with the third set of 10 next-generation satellites for Iridium’s voice and data relay fleet.

SpaceX has pushed back the liftoff of a Bulgarian television broadcast satellite on the company’s second previously-flown Falcon 9 rocket until at least Friday, giving ground crews time to replace a valve on the launcher inside a hangar at its Florida launch pad.

The next Delta 4-Heavy rocket was raised vertical Friday at Cape Canaveral, signaling the start of a comprehensive series of pre-flight tests before liftoff next year with a top secret U.S. government spy satellite.