On September 2, 2015, United Launch Alliance (ULA) conducted successful launch of Atlas V 551 launch vehicle with the US Navy’s fourth Mobile User Objective System (MUOS-4) satellite, built by Lockheed Martin, from Space Launch Complex-41 at Cape Canaveral Air Force Station, Florida.
MUOS-4 mission marked the 56th Atlas V flight since the vehicle's inaugural launch in August 2002 and the sixth launch of its 551 configuration. Previous missions launched on Atlas V 551 include three MUOS missions, as well as the New Horizons mission to Pluto and the Juno mission to Jupiter.
MUOS-4 satellite is the latest addition to an advanced network of orbiting satellites and relay ground stations that is revolutionizing secure, tactical UHF communications for mobile military forces and connecting military users almost anywhere around the globe. The next generation of narrowband communications, MUOS continues support for the legacy UHF satellite system, but once fully operational, will provide users with 10 times more communications capacity over the legacy system. Some new MUOS features include:
- MUOS network users will be able to talk direct, text and transfer mission data amongst any other MUOS users around the world beyond line-of-sight. Previously UHF satellite system users could 'talk' as long as they are under the coverage of the same satellite.
- The MUOS advanced waveform allows improved connectivity in stressed environments including urban canyons, mountains, jungle, weather and scintillation.
- MUOS extends UHF communications further into polar regions, surpassing its original 65 degree latitude north/south requirement, reaching as far as 89.5 degrees latitude north – about 30 miles from the pole – during testing.
- Once MUOS is declared operational, the number of MUOS users is expected to grow rapidly. Already, more than 55,000 currently fielded radio terminals can be upgraded to be MUOS-compatible, with many of them requiring just a software upgrade.
- MUOS-4 joins the MUOS-1, MUOS-2 and MUOS-3 satellites already on orbit and all required ground stations. MUOS-5, an orbital spare satellite, is expected to launch in 2016. MUOS full operational capability is expected in 2017.
As we mentioned, the mission has utilized Atlas V launcher in 551 configuration, where the first digit '5' means a 5-meter-diameter payload fairing, second digit '5' stands for five solid boosters at the first stage, powered by two Russian-made RD-180 engines, and '1' is for a single Aerojet Rocketdyne RL10A engine that powers Centaur upper stage.MUOS-4 mission was also 99th successful launch for United Launch Alliance, joint venture of Boeing and Lockheed Martin, established in December 2006. The next, anniversary mission is scheduled for early October, when Atlas V 421 is to deploy Mexsat-2 (Morelos-3) telecommunications satellite into a geostationary orbit.