Orbital Sciences Cygnus cargo ship reached the International Space Station on Sunday, the second commercial spacecraft to fly to the orbital outpost.

Cygnus’ 7 a.m. EDT arrival came a week later than originally planned, delayed first by a software glitch and then by the higher priority docking of a Russian Soyuz capsule with three new station crewmembers.

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Orbital is one of two firms hired by NASA to restore a U.S. supply line to the station following the retirement of the space shuttles in 2011. Rival Space Exploration Technologies, which started work about 18 months before Orbital, already has made a test flight and two cargo runs to the station, a project of 15 nations.

SpaceX, as the company is called, is taking a bit of a hiatus as it prepares to test a beefed up version of its Falcon 9 rocket. Launch is expected between noon and 2 p.m. EDT on Sunday from a new complex at Vandenberg Air Force Base in California.

Orbital’s Cygnus capsule blasted off aboard an Antares rocket from Wallops Island, Va., on Sept. 18. The spacecraft, which is on a demonstration flight, is expected to remain docked at the station for about a month.

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Unlike SpaceX’s Dragon spacecraft, Cygnus is not designed to return to Earth. Instead, once it leaves the station, the capsule — like the Russian, European and Japanese cargo ships that also service the outpost — will burn up as it re-enters the atmosphere.

After loitering in orbit for four days to allow the Soyuz to dock, Cygnus flew itself to the station and parked about 39 feet away so astronauts operating the station’s 58-foot long robotic crane could lasso the capsule and prepare it for berthing.

“That’s a long time coming, looks great,” astronaut Catherine Coleman, from NASA’s Mission Control in Houston, radioed to the crew as Luca Parmitano and Karen Nyberg plucked Cygnus from orbit.

The station crew is expected to open Cygnus’ hatch on Monday.

Image: Cygnus is grappled by the space station’s robotic arm. Credit: NASA TV