SpaceX Launches 3rd Station Delivery Mission for NASA

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WASHINGTON — After a series of delays, including one prompted by a glitch that forced the company to replace a faulty helium valve on the core stage of its Falcon 9 rocket, Space Exploration Technologies Corp. launched its third contracted cargo delivery mission to the international space station April 18.

SpaceX’s Dragon spacecraft, laden with more than 2 metric tons of cargo, is due to rendezvous with station April 20.

The mission is the third of 12 SpaceX owes NASA under a $1.6 billion Commercial Resupply Services contract signed in 2008.

While Dragon is berthed with station, where it was slated to stay for about a month, astronauts will perform a spacewalk to replace an external computer — a so-called External-2 Multiplexer/Demultiplexer — that failed April 11. The spacewalk is scheduled for April 23.

The failed computer controls, among other things, the positioning of the space station’s massive solar arrays. Those functions were passed to a backup computer after the April 11 failure.

One of the two astronauts tapped for repair duties will don the same spacesuit that nearly drowned Italian astronaut Luca Parmitano back in July, when his helmet filled with fluid. NASA has since determined that a clogged filter was the cause, and the spacesuit has undergone repairs to make it safe, according to Michael Suffredini, space station program manager at the Johnson Space Center in Houston.

The successful SpaceX launch means Orbital Sciences Corp., NASA’s other contract cargo-hauler, will wait until early June to launch its Antares rocket and Cygnus freighter to the station in what would be the second of a planned eight resupply flights. Orbital had been working toward a May 6 flight date, but only as a hedge against a prolonged delay of the SpaceX mission.

The next scheduled Falcon 9 launch will carry half a dozen data-messaging satellites for machine-to-machine data communications provider Orbcomm. That mission is now scheduled for mid- to late May, Orbcomm said on its website.