A commercial spacecraft operated by U.S. space company Orbital Sciences Corp. left the International Space Station (ISS) on Friday morning, completing its second official cargo resupply mission to the orbiting lab, U.S. space agency NASA said.
The Cygnus spacecraft, which delivered 3,300 pounds (about 1.5 tons) of cargo and laboratory supplies in July, was released by astronauts aboard the ISS using the station's robotic arm at 6:40 a.m. EDT (1040 GMT), NASA said.
Cygnus, now loaded with trash, is expected to fire its engines twice in a maneuver that will enable the spacecraft to slip out of orbit for a destructive entry into Earth's atmosphere on Sunday morning.
Finally, the spacecraft will burn up over the Pacific Ocean, the space agency said.
The six astronauts aboard the ISS will try to document Cygnus' reentry as part of an engineering excise to study the mechanics of the breakup of a space vehicle.
Cygnus was launched atop the Antares rocket, also built by Orbital Sciences, on July 13 from NASA's launch range at the Wallops Flight Facility in eastern Virginia, and arrived at the ISS three days later.
Under a 1.9-billion-U.S.-dollar deal with NASA, Orbital will use Antares and Cygnus to deliver up to 44,000 pounds (20 tons) of cargo to the ISS over eight missions through late 2016. Its first mission was launched in January.
Orbital said its third cargo mission has been scheduled for October with another three resupply launches being planned for 2015.
Besides Orbital, NASA has also signed a deal with another private company, SpaceX, to supply cargo to the ISS.