SpaceX’s Dragon resupply craft reached the International Space Station early Sunday, permitting two NASA astronauts to successfully capture the capsule with the orbiting lab’s Canadian robot arm after some post launch difficulties.

SpaceX Dragon approaches the International Space Station for robot arm capture early Sunday. Photo Credit/ NASA TV

The grapple at 5:31 a.m., EST, came well ahead of schedule.

“That was a brilliant capture,” NASA’s Mission Control informed space station commander Kevin Ford and Tom Marshburn, the two astronauts assigned to carry out the grapple, as the two spacecraft orbited the Earth high above northern Ukraine.

NASA flight controllers than took over, steering the capsule and its cargo of science equipment, food, spare parts and other equipment to a berthing point on the station’s Harmony module.

Dragon will remain berthed until March 25.

During the docking period, the capsule will be reloaded with preserved medical and biomedical specimens and other equipment for a parachute descent to Earth.  SpaceX recovery ships will be stationed in the Pacific Ocean off the coast of Baja, Calif., to retrieve the Dragon so the science materials can be distributed to researchers involved in medical and materials experiments.

The SpaceX Dragon lifted off Friday atop a SpaceX Falcon 9 rocket from Cape Canaveral Air Force Station,Fla.After reaching orbit, however, the capsule’s flight control system detected an obstruction in the system that pressurizes the thrusters. The 18 thrusters, arranged on four capsule pods, raise the spacecraft’s altitude and provide attitude control.

The SpaceX flight control team in Hawthorne, Calif., overcame the difficulties late Friday, but the delays postponed Dragon’s arrival at the space station from early Saturday until early Sunday.

The mission is the second for SpaceX, which was awarded a $1.6 billion contract from NASA in late 2008 to fly at least a dozen re-supply missions to the space station.

NASA is fostering a second commercial space station delivery service with Orbital Sciences Corp.  Orbital Sciences is preparing a test flight of its Antares rocket with a mock up of the Cygnus supply capsule this spring.  The company anticipates its first cargo delivery flight this year.