Advanced EHF Military Communications Satellite, USA

Lockheed Martin Space Systems, Hughes Space and Communications and TRW have formed a National Team to build the Department of Defense's (DOD) next generation of highly secure communication satellites known as the Advanced Extremely High Frequency system.

The Advanced EHF programme provides the follow-on capability to the Milstar satellite programme. It provides the basis for the next generation military communications satellite system, for survivable, jam-resistant, worldwide, secure, communications for the strategic and tactical warfighter. The system replenishes the Milstar constellation in the EHF band.

MILSATCOM SATELLITE PROGRAMME

The MILSATCOM Programme Office, located at the Space and Missile Systems Centre, Los Angeles Air Force Base, California, will manage the Advanced EHF contract and is the lead agency for ensuring the secure communications capabilities of this system are made available to the warfighter.

The Advanced EHF Programme is the follow-on to the DOD’s Milstar highly secure communication satellite programme, which currently has two Milstar I spacecraft in orbit. Formation of the new team accelerated development of the new system by 18 months. The earlier deployment of Advanced EHF will help bridge the gap in military communication coverage caused by the loss of the third Milstar satellite, launched in 1999.

Under the National Team contract, the production phase of the programme is scheduled to begin in April 2001, with the first of five satellites to be launched late in 2004. The estimated contract value of the Advanced EHF programme is $2.5 billion. Earlier deployment of the system will help the military by putting vital tactical capabilities into the hands of US armed forces sooner, increasing both communications capacity and coverage.

EXTREMELY HIGH FREQUENCY SATELLITE CONSTELLATION

The fully operational Advanced EHF constellation will consist of four crosslinked satellites, providing coverage of the Earth from 65° north latitude to 65° south. These satellites will provide more data throughput capability and coverage flexibility to regional and global military operations than ever before. The fifth satellite built could be used as a spare or launched to provide additional capability to the envisioned constellation.

According to Lockheed Martin Space, Advanced EHF will benefit from the team's combined leadership in related military and commercial technologies to reduce satellite size and cost while significantly boosting performance and reduced programme risks.

SATELLITE SYSTEMS INTEGRATION

Lockheed Martin will contribute its systems integration, ground systems and satellite expertise to the project. TRW will design and produce the satellites' digital processing subsystem, which controls all onboard switching and processing of messages. TRW will also provide the satellites' nulling antenna subsystem, which prevents adversaries from jamming signals to and from the satellite, and the inter-satellite crosslinks with support from Hughes for the crosslink reflectors. The crosslink subsystem enables Advanced EHF satellites to send messages directly to each other, without the need for a ground station.

PAYLOAD, ELECTRONICS AND ANTENNAS

Hughes will lead the payload effort and will be responsible for payload integration, as well as production of RF electronics and phased array antennas. According to the company, Hughes’ commercial and government programme experience in payload system integration, RF electronics and phased array antennas will ensure the warfighter receives a state-of-the-art system in the shortest possible time.

The higher data rates permit transmission of tactical military communications such as real-time video, battlefield maps and targeting data. To accomplish this, Advanced EHF adds new higher data rate modes to the low data rate and medium data rate modes of Milstar II satellites. The higher data rate modes will provide data rates up to 8.2 million bits of data per second to future Advanced EHF Army terminals. Each Advanced EHF satellite employs more than 50 communications channels via multiple, simultaneous downlinks. For global communications, the Advanced EHF system uses inter-satellite crosslinks, eliminating the need to route messages via terrestrial systems

CONTRACTORS

On the new National Team, Lockheed Martin will serve as overall system integrator and prime contractor, issuing subcontracts to both Hughes and TRW. The roles and responsibilities of each team member will take advantage of their strengths in building highly secure military communications satellites.