GPS Satellite in Correct Orbit Despite Delta IV Malfunction

GPS Satellite in Correct Orbit Despite Delta IV Malfunction

United Launch Alliance (ULA) says that the Air Force GPS II-F3 satellite it launched on Thursday is in its correct orbit despite the fact that the second stage of ULA’s Delta IV rocket did not perform as planned.

ULA says it “observed an unexpected data signature” signalling reduced thrust from the RL10 engine on the second stage.  “The onboard inertial guidance and flight control systems compensated” for the reduced thrust, however, “and the Delta second stage delivered the satellite to the proper orbit.”

RL-10 manufacturer Pratt & Whitney Rocketdyne and ULA are investigating the problem. 

The next ULA launch also is for the Air Force, this time of the X-37B Orbital Test Vehicle (OTV) on an Atlas V rocket, which uses a different version of the RL-10.  ULA says, however, that the OTV mission will not be certified ready for launch until the issue with the GPS II-F3 launch is understood.  The OTV launch is currently scheduled for October 25.

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