The fourth Mobile User Objective System (MUOS) satellite in the launch order is progressing in its final testing phase, having successfully cleared acoustic tests. This evaluation used powerful sound waves to simulate vibrations the satellite will experience during launch. Now the satellite moves on to thermal vacuum testing, which is the last step in its environmental trials.

"MUOS-4 is showing all the benefits of learning curve and process improvements that we have implemented over time. To date, we have seen a 74 percent reduction in non-conformance defects and a 45 percent reduction in labor hours over our first build," said Iris Bombelyn, vice president of Narrowband Communications at Lockheed Martin.

The MUOS satellite will complete environmental and final system checkouts in the coming months, readying for launch in summer 2015.

MUOS is a next-generation narrowband tactical satellite communications system designed to significantly improve ground communications for U.S. forces on the move.

MUOS will provide military users more communications capability over existing systems, including simultaneous voice, video and data similar to the capabilities experienced today with smart phones.

Lockheed Martin Space Systems, Sunnyvale, California, is the MUOS prime contractor and system integrator. The Navy's Program Executive Office for Space Systems and its Communications Satellite Program Office, San Diego, California, are responsible for the MUOS program.