Cygnus completes first ISS resupply mission

A commercial spacecraft operated by U.S. space company Orbital Sciences Corp. left the International Space Station (ISS) on Tuesday morning, completing its first official cargo resupply mission to the orbiting lab, U.S. space agency NASA said. Cygnus, which delivered almost a ton-and-a-half of supplies for scientific experiments in January, was released by astronauts aboard the station using the station's robotic arm at 6:41 a.m. EDT (1141 GMT), NASA said. At the time of release, the ISS was orbiting about 260 miles (about 418 km) over the southern Atlantic Ocean off the southeast coast of Argentina and Uruguay. Cygnus, now loaded with trash, is expected to fire its engines twice in a maneuver that will enable it to slip out of orbit for a destructive entry into Earth's atmosphere on Wednesday. Finally, the spacecraft will burn up over the Pacific Ocean later Wednesday afternoon, said NASA. Cygnus was launched atop the Antares rocket, also built by Orbital Sciences, on Jan. 9 from NASA's launch range at the Wallops Flight Facility in eastern Virginia, and arrived at the complex three days later. Under a 1.9-billion-U.S. dollar contract with NASA, Orbital Sciences will still need to fly at least seven cargo missions to the ISS by late 2016. Cygnus's departure will clear the way for the arrival of California-based SpaceX's third commercial cargo mission using the Dragon spacecraft, which is set to launch from Cape Canaveral Air Force Station in Florida on March 16, NASA said. Orbital Sciences and SpaceX are the only two commercial spaceflight companies selected by NASA to fly unmanned cargo delivery missions to the ISS.