MUOS-5 finally reaches operational orbit, Navy says

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WASHINGTON — The U.S. Navy announced that its MUOS-5 satellite has finally reached operational orbit following a problem with the main propulsion system in June.

“We are happy to announce today that MUOS-5 has reached its operational orbit, and has successfully deployed its arrays and antennas,” said a statement from Steve Davis, a spokesman for the Space and Naval Warfare Systems Command. “The satellite has begun its on-orbit testing in preparation for acceptance by the Navy and handover for operational use.”

The fifth MUOS satellite – which stands for Mobile User Objective System – launched June 24 and was expected to reach a geosynchronous orbit 35,000 kilometers above Hawaii by July 3, according to the Navy.

But the main orbit-raising propulsion system failed during the maneuvers, leaving the Lockheed Martin Space Systems-built satellite stuck in limbo in a “stable intermediate orbit.” Launch operators weren’t too concerned about the orbit degrading; yet the satellite wasn’t at an optimal position for use.

Davis said MUOS operators performed a series of 26 orbit-raising burns over six weeks using thrusters intended for station keeping and relocation. The new orbit — which MUOS-5 reached Oct. 22 —  is slightly less circular and more inclined than the original intended orbit. However, the Navy does not expect operations of the satellite’s onboard communications systems to be affected by the change.

Any effects from the new orbit, Davis said, have been mitigated through ground and waveform software changes.

“Subject to results of normal satellite testing currently in progress, the satellite is expected to fully perform its mission in its current orbital location,” he said. “The satellite will not be relocated to another orbital location.”

The fifth satellite in the constellation was designed to be a backup, and Navy officials said the problems did not affect operation of the MUOS network of UHF communication systems and ground stations.