The fourth in a Lockheed Martin-built, five-ship fleet for a next-generation, narrowband tactical military satellite communications system has been encapsulated in its 5.4-meter (17.7-foot), bullet-like payload fairing for an early morning nighttime liftoff atop a 206-foot-tall United Launch Alliance (ULA) Atlas-V rocket from Cape Canaveral Air Force Station later this month.
The U.S. Navy’s 7.5-ton Mobile User Objective System-4 (MUOS-4) arrived in Florida on June 28 onboard a C-5 Galaxy transport aircraft via Lockheed’s Sunnyvale, Calif., facility and nearby Moffett Federal Airfield, courtesy of the 60th Air Mobility Wing at Travis Air Force Base.
“Delivery of this fourth satellite for the U.S. Navy completes the initial MUOS constellation and provides near-global coverage for the network,” said Iris Bombelyn, vice president of Narrowband Communications at Lockheed Martin. “For our mobile forces, that means for the first time they will be able to have secure, high-fidelity voice conversations, networked team calls and data exchange, including video, with anyone around the world connected with a MUOS terminal.”
Launch is currently scheduled for Aug. 31 during a window from 4:07 a.m. EDT to 8:07 a.m. EDT.
MUOS operates like a “smart phone cell tower in the sky,” supporting a worldwide, multi-Service population of users in the UHF band, providing increased communications capabilities to smaller terminals while still supporting interoperability with legacy terminals. The new military SATCOM system will, for the first time, give MUOS Wideband Code Division Multiple Access technology users beyond-line-of-sight capability to transmit and receive voice and data using an Internet Protocol-based system, giving users greater mobility, higher data rates, and improved operational availability.
MUOS gives military users more communications capability over existing systems, including simultaneous voice, video, and data—similar to the capabilities experienced today with smart phones and providing users with 10 times more communications capacity.
MUOS-4 has been undergoing final testing and preparations for flight at Astrotech Space Operations in Titusville, Fla., since arriving on the Sunshine State’s “Space Coast,” and now the time has come to transport the enormous flight-ready military satellite to nearby Space Launch Complex-41 (SLC-41) to meet its Atlas-V rocket, which will fly in its most powerful “heavyweight” variant (551 configuration) to deliver the enormous 15,000-pound MUOS-4 to a 22,000-mile-high geosynchronous orbit.
In simple terms, that means the rocket will need the added power of five strap-on solid rocket boosters (supplied by Aerojet Rocketdyne) to get MUOS-4 into space, something that the rocket has only done previously on five of its 55 flights over the last 13 years since the vehicle’s inaugural launch.
Three of those flights were the first three MUOS satellites. The other two were both NASA spacecraft to worlds in the outer Solar System: New Horizons to Pluto in 2006 and JUNO to Jupiter in 2011.
The MUOS satellites represent the heaviest payloads ever to be launched by ULA’s Atlas-V.
The satellite will make its way to the launch pad this weekend, at which point it will then be hoisted vertical and integrated on top of ULA’s workhorse Atlas-V for final integrated testing and closeout preparations for launch. The rocket will then be rolled out from its Vertical Integration Facility (VIF) to the launch pad on Aug. 28.
Although a total of five MUOS satellites will make up the MUOS fleet, only four will actually be required to put the whole system into action; the fifth and final MUOS to launch in 2016 will instead serve as an on-orbit spare, should any of the first four lose their capabilities.
Original plans called for the first MUOS to launch by 2010, but budgetary adjustments made in response to the Iraq war led to a two-year delay. MUOS-1 launched on Feb. 24, 2012, followed by MUOS-2 on July 19, 2013, and MUOS-3 on Jan. 20, 2015. In the time since they have demonstrated new capabilities, especially in the Arctic, an area previously beyond the coverage of UHF satellites and growing in interest for transportation and natural resources exploration above 65 degrees north latitude. In the past year MUOS successfully connected users near the Arctic poles during independent testing by Lockheed Martin, and during the U.S. Navy’s 2014 Ice Exercise (ICEX) and the U.S. Coast Guard’s Arctic Shield 2014.
The MUOS satellites seek to offer global satellite communications narrowband (64 kbits/sec and lower) connectivity for use by U.S. and allied forces, with an ultra-high frequency range from 300 MHz-3 GHz. When fully functional, it will replace the legacy UHF Follow-On (UFO) satellite network—the first of which was launched back in March 1993—before the latter system reaches the end of its operational service. MUOS will provide new capabilities and enhanced mobility, access, capacity, and quality of service, with particular emphasis upon mobile users, such as aerial and maritime platforms, ground vehicles, and dismounted soldiers.
By operating in the UHF frequency band, which is lower than that used by conventional cellular networks, MUOS will provide U.S. and allied warfighters with the tactical ability to communicate in “disadvantaged” environments, including heavily forested areas where higher-frequency signals would be otherwise impaired. Even troops in buildings with no satellite access are expected to see an increase in communications capability.
The infrastructure to both fly the MUOS satellites and control access of a user’s communications is managed from the ground. Operationally, information flows to the satellites via UHF WCDMA links, and the satellites then relay the information to one of four ground sites located in Hawaii, Virginia, Italy, and Australia via a Ka-band feederlink. These facilities identify the destination of the communications and route the information to the appropriate ground site for Ka-band uplink to the satellite and UHF WCDMA downlink to the correct users. MUOS will also provide users access to select Defense Information System Network voice and data services.
The MUOS network is expected to be operational by the end of 2015, and all four required MUOS ground stations are complete. According to Lockheed, over 55,000 currently fielded radio terminals can be upgraded to be MUOS-compatible, with many of them requiring just a software upgrade.
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