Orbital ATK commenced delivery of cargo to the ISS under the NASA Commercial Resupply Services (CRS) contract in 2014.
The Antares launch system utilizes Orbital ATK's proven MACH avionics system and many management approaches, engineering standards, production and test processes common to Orbital ATK’s family of successful small-class Pegasus and Minotaur launch vehicles. The Antares design has been upgraded with newly-built RD-181 first stage engines to provide greater payload performance and increased reliability. The company is currently targeting a return to flight in 2016 with a total of 6 missions thru 2018 to fulfill the company’s CRS1 agreement with NASA to deliver supplies to the ISS. Orbital ATK recently was awarded the CRS2 contract which includes at least six missions starting in 2019.
The Antares 230 rocket carrying the S.S. Alan Poindexter Cygnus spacecraft rolled to the pad on Wednesday and is set for launch this coming Sunday, October 16th at 8:03 p.m. EDT
Spacex still has to get back to launching after their explosion. Orbital is thus critical for ISS service missions.
SOURCES- Orbital ATK