United Launch Alliance will deliver to orbit NROL-42 to orbit on Friday, September 22, 2017. Classified payload will be operated and controlled by National Reconnaissance Office intelligence satellite.
Launch is planned for 05:38 UTC from SLC-3E launch pad at Vandenberg Air Force base in California. Payload will be satellite collecting radio signals from Molniya orbit for American intelligence. It will be delivered to orbit by Atlas V 541. It is most refined version of the rocket, long for 62 m with mass of 522 t. It is supported by four SRB boosters joined with Common Booster Core with single RD-180 engine. Payload will be covered by 5 m wide, short fairing delivered by Centaur upper stage with single RL10C-1 engine.
Classified payload will be probably satellite equipped with SBIRS-HEO-3 sensor. Spacecraft will be probably next generation Trumpet class satellite and will replace on Molniya orbit one of older satellites which are reaching end of operational life.