ULA’s Atla5 rocket used for NASA’s Twin Radiation Belt Storm Probes (RBSP) payload. Photo: ULA

[Via Satellite 08-12-2015] Orbital ATK has purchased a second Atlas 5 mission from United Launch Alliance (ULA) to deliver cargo to the International Space Station (ISS) for NASA under its Commercial Resupply Services (CRS) contract. The mission will carry more cargo than previous Cygnus missions with the Antares rocket, and is scheduled for 2016.

Orbital ATK contracted an Atlas 5 mission from ULA in December 2014 following an October launch failure with the Antares rocket. The company is replacing the AJ-26 engines from Aerojet Rocketdyne with new RD-181 engines — a direct adaptation from the RD-191 used for Angara — from Russian supplier NPO Energomash.

The first Cygnus-Atlas 5 CRS mission, designated OA-4, is scheduled for December 2015 from Cape Canaveral, Fla., with 3,500 kg of pressurized cargo. All future Cygnus spacecraft for CRS missions feature an extended Pressurized Cargo Module (PCM) that allows it to deliver larger volumes than in the past.

“In 2016, we will carry out at least three more CRS missions: two (or possibly three) will be launched by Antares rockets, the first of which is on a path to be ready to launch early in the year, and one more will be launched aboard Atlas V to support NASA’s need for additional cargo,” Culbertson added. “We have not finalized the exact sequence of these missions yet, but the plan capitalizes on the flexibility of Cygnus to launch on either vehicle and provides better schedule assurance for our customer.”
Orbital ATK expects repairs of the Mid-Atlantic Regional Spaceport (MARS) Pad 0A launch facility at Wallops Island will conclude at the end of September. Resumption of CRS missions from Wallops Island is expected in early 2016.