A United Launch Alliance (ULA) operated Atlas V rocket carried mystery payload NRO L-35 into orbit for the National Reconnaissance Office (NRO). The launch took place at 0319 GMT on 13 December from the Vandenberg launch site in Calfornia. This mission used the 541 configuration of the Atlas V rocket which includes a 5-meter diameter payload fairing along with four Aerojet Rocketdyne solid rocket motors.
The Atlas rocket for this mission was powered by the RD AMROSS RD-180 engine and the Centaur upper stage was powered for the first time by the Aerojet Rocketdyne RL10C-1 engine which replaces the A-4 version previously carried. The RL10C-1 is actually refurbished and improved Delta IV RL-10B-2.
Mystery surrounds the payload. Given that it was sent into an egg shaped Molniya style (37748 x 2101 km x 62.9 degree according to amateur observations) orbit, analysts speculate that the NRO L-35 spacecraft is a version of the “Trumpet” Electronic Intelligence (ELINT) series. The spacecraft is also believed to carry an SBIRS HEO Early Warning payload aboard.