SpaceX cargo ship departs station for Pacific splashdown

Space station astronauts unbolted a commercial cargo ship early Thursday, used the lab's robot arm to pull it away and released it into open space to set the stage for re-entry and splashdown off the Baja California peninsula to close out a successful test flight and set the stage for the start of routine cargo delivery missions later this year.

With the space station's Canadian-built robot arm locked onto the Dragon cargo craft, four gangs of motorized bolts holding the capsule in place were driven out, releasing the spacecraft from Harmony's Earth-facing port at 4:07 a.m. EDT

Flight engineer Joseph Acaba, operating the robot arm from a computer work station inside the lab's multi-window cupola compartment, pulled the Dragon capsule away, moving it to a pre-determined release point well away from station structure.

One orbit later, Acaba and flight engineer Donald Pettit released the spacecraft, opening snares in the arm's latching end effector at 5:49 a.m. as the space station sailed 250 miles above the southern Indian Ocean. SpaceX flight controllers in Hawthorne, Calif., working in concert with NASA's flight control team at the Johnson Space Center in Houston, then monitored three quick rocket firings to begin Dragon's departure and eventual descent to Earth.

Within 11 minutes or so, the capsule was outside a pre-defined safety zone around the space station and SpaceX assumed full responsibility for the remainder of the mission.

"The departure sequence is fairly quick, it's a three-burn series, two small burns then one big burn," said NASA Flight Director Holly Ridings. "The Dragon will head away from the space station outside the integrated space and that'll be the end of our integrated activity with the SpaceX/Dragon team. That process is 10 or 11 minutes after the release time."

"So again, very quick, very different from rendezvous day when we spent a lot of time in integrated space. The Dragon will head on out and be on its own in terms of the Dragon team controlling and managing the rest of the activities through the day."

Once outside the safety zone, the SpaceX team planned to close a protective door over navigation sensors and the grapple fixture used by the robot arm.

"We'll be closing that up, performing some checkouts and then performing our large re-entry burn, which till take about 10 minutes," said SpaceX mission director John Couluris. "And with that, about five-and-a-half hours after release from the arm, we should be in the water."