"This will be Orbital ATK’s fifth operational mission to the ISS for NASA under the Commercial Resupply Services contract, and the first Cygnus to conduct scientific experiments onboard the spacecraft," the release explained.
The Cygnus spacecraft will be launched atop an Atlas V rocket, carrying approximately 3,600 kilograms of cargo to astronauts aboard the ISS, along with several small satellites that will be deployed directly from Cygnus, according to the release.
The two-stage Atlas V rocket uses a Russian-made RD-180 booster powered by kerosene and liquid oxygen for its first stage, the release noted. The second stage consists of a US-built RL-10 engine that burns liquid hydrogen and liquid oxygen.
The US Air Force is developing a US-made substitute for the Russian RD-180 booster, which it hopes to deploy by 2019.
