Spaceflight Insider

MUOS-5 encounters anomaly while raising orbit


An artist’s rendering of a MUOS satellite in geostationary orbit. Image Credit: Lockheed Martin

An anomaly has temporarily halted the fifth Mobile User Objective System (MUOS-5) satellite from reaching its targeted geostationary orbit (GEO), according to a statement from the United States Navy. The announcement comes just two weeks after the craft was launched atop a United Launch Alliance (ULA) Atlas V rocket.

Photo Credit: Michael Deep / SpaceFlight Insider

An Atlas V propels MUOS-5 spaceward June 24. Photo Credit: Michael Deep / SpaceFlight Insider

MUOS-5 was launched on June 24 into a geostationary transfer orbit (GTO). Over the last couple of weeks, the vehicle’s onboard engines were tasked with circularizing the orbit over the course of some seven orbits, according to Spaceflight Now.

The raising of the spacecraft’s orbit was scheduled to be completed by July 3 for the satellite to enter its test location some 22,000 miles (35,000 kilometers) above Hawaii.

Due to the anomaly, the nature of which has yet to be announced, the orbit-increasing burns had to be temporarily halted.

“Nothing is more important to Lockheed Martin than mission success. We are working closely with our Navy customer to determine the cause of the anomaly,” Chip Eschenfelder, a spokesperson for Lockheed Martin told SpaceFlight Insider.

According to a July 8 press release, the Navy’s Program Executive Office for Space Systems has reconfigured the satellite from orbital transfer into a stabilized, safe intermediate orbit to allow for the MUOS team to evaluate the situation and determine options for proceeding.

As the spacecraft’s solar panels and mesh antennas have yet to be deployed and were expected to be so within nine days of launch, it is unclear how this delay will impact activation of those systems and how long the vehicle can remain in this temporary orbit.

This is the fifth satellite in the MUOS constellation, its primary function is that of an on-orbit spare. The other four satellites are positioned equidistant around Earth at GEO.

“[The] delay in reaching its test location will have no impact upon current legacy or Wideband Code Division Multiple Access [WCDMA] satellite communications operations,” the press release stated.

According to Spaceflight Now, hobbyist observers tracking the satellite have pinpointed the current orbit of MUOS-5 at 9,471 by 22,185 miles (15,242 by 35,703 kilometers) at an inclination of 9.8 degrees. The satellite has been there for about a week.

If the situation with MUOS-5’s orbit is rectified, the satellite will ultimately be circularized into an orbit of some 22,300 miles (35,900 kilometers) in altitude with an inclination of 5 degrees. After initial tests, the spacecraft will then be maneuvered to a position near where MUOS-4 is currently residing, over the Indian Ocean.

This is the final piece of the $7.7 billion mobile communications network for the U.S. Navy, which includes four ground stations. All five satellites have a projected lifespan of approximately 15 years. MUOS-1 was launched in February of 2012; MUOS-2 in July 2013; MUOS-3 in January 2015; and MUOS-4 in September 2015.

Those with MUOS terminals can connect with “smartphone-like” capabilities, which includes voice, text, video, and data transmission on a high-speed Internet Protocol-based system.

Each satellite in the MUOS constellation was built by Lockheed Martin and has a 14-meter-diameter reflecting mesh antenna. Additionally, all five are equipped with both WCDMA and UHF supporting hardware.

Video courtesy of SpaceFlight Insider


Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity. You can find him on twitter @TheSpaceWriter.

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