OCO Launch Mishap Had Four Possible Causes

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WASHINGTON — NASA’s investigation into the botched launch of the agency’s Orbiting Carbon Observatory (OCO) Feb. 24 narrowed down to four the possible causes of the mishap, in which the fairing on the Taurus XL rocket used to launch the $209 million mission failed to separate.

After a predawn liftoff from Vandenberg Air Force Base in California, OCO’s Taurus XL launcher raced toward orbit, dropping its first stages as planned. The rocket should have jettisoned its clamshell-like payload fairing about three minutes into the flight, but that did not happen. The still-shrouded satellite continued its climb, reaching an apogee of 615 kilometers — some 27 kilometers short of its intended orbit — before falling back toward Earth and breaking up over the Pacific Ocean near Antarctica.

With no physical evidence available, NASA’s OCO Mishap Investigation Board relied on hardware testing, engineering analysis and simulation to recreate the launch mishap.

A summary of the investigation report released July 17 identifies four potential causes that could have resulted in the fairing not separating:

  •   A failure of the frangible joint, an explosive device that provides instantaneous separation of flight vehicle structures while maintaining confinement of explosive debris;
  •   A failure in the electrical subsystem used to initiate ordnance devices that trigger fairing separation;
  •   A failure in the pneumatic system that supplies pressure to thrusters that separate the fairing;
  •   A cord snagged on a frangible joint side rail nut plate.

The report makes a number of procedural recommendations to prevent future problems with any of the four suspect hardware components.

NASA, meanwhile, plans to order some type of OCO replacement mission this year. Both OCO and its Taurus XL launcher were built by Dulles, Va.-based Orbital Sciences Corp.

OCO was equipped with a single instrument, a suite of spectrometers designed to make precise measurements of atmospheric carbon dioxide.