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October 15, 2012

Engine Failure Lingers on CRS-1 Space Station Supply Mission

By Doug Mohney, Contributing Editor


NASA and SpaceX (News - Alert) have jointly formed a CRS-1 post-flight investigation board to determine what happened during an engine failure on the Falcon 9 rocket on the October 7 launch. While the primary payload/mission objective, the Dragon spacecraft, is now successfully docked at the International Space Station (ISS), the engine failure led to the effective loss of the secondary payload, an ORBCOMM (News - Alert) prototype satellite. 

Since Falcon 9 is the launch vehicle SpaceX will use for its commercial crew services offering, the engine-out is getting more than a once-over look.

During the evening launch of CRS-1, engine 1 of the Falcon 9's nine first stage engines registered a loss in pressure. The onboard flight computers shut the engine down and adjusted the burn time and trajectory of the remaining eight engines to make sure the Dragon spacecraft was put in a sufficient orbit to rendezvous with the space station. 

From the video taken of the flight, it appears that debris came away from the engine location once the engine was shut down. SpaceX attributes this to the shutdown of the engine at max aerodynamic pressure of the flight, with the forces on the engine cowling effectively crumpling it when thrust was cut off. 

The adjusted burn used slightly more fuel and oxygen to put Dragon into its targeted orbit, leaving the ORBCOMM OG2 prototype satellite at the mercy of NASA safety protocols to protect ISS. NASA had required a restart of the single engine upper stage only if there was a very high probability – over 99 percent – of fully completing a second burn to put OG-2 into its higher orbit.  

The Falcon 9 had enough fuel, but only enough liquid oxygen on board to provide a 95 percent likelihood of completing its burn.  

ORBCOMM OG2 was deployed in a much lower orbit, leaving the company with little choice but to deorbit it. The OG2 Engineering teams from ORBCOMM, Sierra Nevada and Boeing (News - Alert) were able to establish communications with the prototype satellite and able to verify a number of critical systems, including solar array and communications payload antenna deployments, along with satellite bus systems and the reprogrammable software radio.

All the verification tests haven't prevented ORBCOMM for filing an insurance claim on the OG2 as a total loss. The satellite was insured for $10 million, an amount that would "largely offset" the expected cost of the OG2 prototype satellite, associated launch services, and the launch insurance policy, according to an ORBCOMM statement.

Despite the failure to reach a proper orbit, ORBCOMM says it still has faith in SpaceX and plans to use the Falcon 9 to launch the full constellation of OG2 satellites in a pair of launches in mid-2013 and 2014. “We appreciate the complexity and work that SpaceX put into this launch,” stated Marc Eisenberg, ORBCOMM’s CEO. “SpaceX has been a supportive partner, and we are highly confident in their team and technology.”

Various space advocates are touting the engine-out incident as a success for SpaceX since the Falcon 9 did what it was designed to do – successfully put its primary payload into orbit even if one engine goes out. If its payload had been a manned crew, there would have been no need for a dramatic in-flight abort to separate a capsule away from the Falcon 9.

Advocates also hold that there's only one more Falcon 9 flight with SpaceX's Merlin 1C engine. Future flights will use the more powerful, redesigned Merlin 1D, with increased reliability via a simplified design, along with increased fatigue life, and increased chamber and nozzle thermal margins.




Edited by Braden Becker



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