A view of the SpaceX Dragon cargo ship moments after its release from the International Space Station's robot arm Saturday.The spacecraft, loaded with 3,276 pounds of equipment and experiment samples, splashed down in the Pacific Ocean west of Baja California five-and-a-half hours later. Alexander Gerst/NASA

A commercial cargo ship loaded with some 3,276 pounds of equipment and experiment samples, believed to include mice that were on board as part of a muscle atrophy study, returned to Earth Saturday to close out a five-week visit to the International Space Station.

Astronaut Reid Wiseman, operating the station's robot arm, detached the solar-powered Dragon spacecraft from the forward Harmony module around 8 a.m. EDT (GMT-4), maneuvered it into position and released it to open space at 9:57 a.m.

SpaceX flight controllers at the company's Hawthorne, Calif., plant then uplinked commands to fire the spacecraft's braking rockets at 2:43 p.m., putting the capsule on course for a fiery plunge back into the atmosphere.

The Dragon's re-entry systems apparently worked normally, parachutes deployed and the cargo ship splashed down in the Pacific Ocean 265 miles west of Baja California at 3:38 p.m.

Recovery crews standing by aboard a ship in the landing zone planned to haul the spacecraft back to Long Beach, Calif., where time-critical research samples will be offloaded and turned over to NASA.

The capsule then will be shipped to SpaceX's McGregor, Texas, facility where the rest of the cargo, including computer gear, spacewalk equipment and other hardware, will be removed.

This was SpaceX's fourth station resupply flight under a $1.6 billion contract with NASA that calls for 12 missions to deliver some 44,000 pounds of cargo to the International Space Station.

The Dragon departure sets the stage for the undocking of a Russian Progress cargo ship from the Pirs module at 1:39 a.m. Monday. Unlike the Dragon capsule -- the only station resupply craft capable of carrying cargo back to Earth -- the Progress will burn up in the atmosphere later in the day.

Orbital Sciences plans to follow the Progress and Dragon departures with launch of a commercial Cygnus cargo craft from Wallops Island, Va., on Monday at 6:45 p.m. Making the company's third operational resupply flight, the Cygnus is expected to be captured by the station's robot arm and berthed at the Harmony port just vacated by the Dragon spacecraft on Sunday, Nov. 2.

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SpaceX cargo ship returns to Earth after station visit