United Launch Alliance (ULA) will launch the NROL-42 mission onboard its Atlas V 541 rocket today at 10:30 p.m. PDT from Space Launch Complex 3 at Vandenberg Air Force Base in California.
NROL-42 is a classified mission for the United States National Reconnaissance Office (NRO) reportedly for Electronic intelligence (ELINT) operations.
The launch was delayed two days due to the requirement to change out a battery on the booster.
For this mission, Atlas V will fly in its 541 configuration with a five-meter payload fairing, four Aerojet Rocketdyne AJ-60A solid rocket motors and a single-engine Centaur upper stage. This is the second-most-powerful version of the rocket. This suggests the NROL-42 payload is fairly heavy, targeting a high orbit, or both.
NROL-42 will be the 25th mission that ULA has launched for the NRO since the company was founded in 2006.
This launch will be ULA’s sixth of 2017 and 121st overall. This mission will mark the 73rd Atlas V launch since its inaugural launch on Aug. 21, 2002.