The Cygnus spacecraft is an unmanned resupply spacecraft being developed by Orbital Sciences Corporation as part of NASA's Commercial Orbital Transportation Services (COTS) developmental program.
It is designed to transport supplies to the International Space Station (ISS) following the retirement of the American Space Shuttle in 2011. Since August 2000 unmanned ISS resupply missions have been regularly flown by Russian Progress spacecraft, as well as by the European Automated Transfer Vehicle, the Japanese H-II Transfer Vehicle, and the SpaceX Dragon. With the Cygnus spacecraft, NASA seeks to increase its partnerships with domestic commercial aviation and aeronautics industry.