Advanced Extremely High Frequency (AEHF) Program

In November 2001, the U.S. Air Force awarded Lockheed Martin Space Systems and Northrop Grumman Space Technology (Formerly TRW Space & Electronics) a $2.698 billion contract to begin the System Development and Demonstration (SDD) phase of the Advanced Extremely High Frequency (Advanced EHF) Program. The Advanced EHF Program is the next generation of global, highly secure, survivable communications system for Warfighters within all services of the Department of Defense.

The SDD phase will deploy two Advance EHF satellites and the Advance EHF mission control segment. The new mission control segment will support both Milstar and AEHF. Lockheed Martin will serve as the developer of the ground segment, satellite bus provider, space vehicle integrator and overall systems integrator and prime contractor. This role builds on Lockheed Martin’s successful experience on Milstar and DSCS. Northrop Grumman will provide the payload and associated components (digital processor and RF equipment).

The MILSATCOM Program Office, located at the Space and Missile Systems Center, Los Angeles Air Force Base, Calif., is the Advanced EHF contract manager and lead agency for ensuring the secure communications capabilities of this system are made available to the warfighter. The Advanced EHF Program is the follow-on to the DoD’s Milstar highly secure communication satellite program, which currently has a four-satellite operational constellation. The last Milstar satellite was successfully launched in April 2003. As envisioned by the Pentagon, the fully operational Advanced EHF constellation will consist of four crosslinked satellites providing coverage of the Earth from 65 degrees north latitude to 65 degrees south. These satellites will provide more data throughput capability and coverage flexibility to regional and global military operations than ever before. A fifth satellite built could be used as a spare or launched to provide additional capability to the envisioned constellation.

Advanced EHF satellites will provide 10 times greater total capacity and offer channel data rates six times higher than that of Milstar II communications satellites. 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 (Mbps) to future Advanced EHF Army terminals. That rate is more than 150 times faster than the 56 kilobit-per-second modems of today’s personal computers. 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.

AEHF Mission

The Advanced Extremely High Frequency (AEHF) System is a joint service satellite communications system that provides global, secure, protected, and jam resistant communications for high-priority military ground, sea, and air assets. The system consists of three satellites in geosynchronous earth orbit (GEO) that provide 10 to 100 times the capacity of the 1990s-era Milstar satellites. A constellation of three AEHF augmented by a Transformational Communications Satellite (TSAT) will provide continuous 24-hour coverage. Advanced EHF will allow the National Security Council and Unified Combatant Commanders to control their tactical and strategic forces at all levels of conflict through general nuclear war and support the attainment of information superiority. The AEHF System is a follow-on to the Milstar system, augmenting and improving on the capabilities of Milstar, and expanding the MILSATCOM architecture to enable Transformational Communications and Network-Centric Warfare. AEHF will provide connectivity across the spectrum of mission areas including land, air, and naval warfare; special operations; strategic nuclear operations; strategic defense; theater missile defense; and space operations and intelligence.

AEHF Description

The AEHF system is composed of three segments: space (the satellites), terminals (the users), and ground (mission control and associated communications links). The segments will provide communications in a specified set of data rates from 75 bps to approximately 8 Mbps. The space segment consists of a cross-linked constellation of three satellites. The mission control segment controls satellites on orbit, monitors satellite health and provides communication system planning and monitoring. This segment is highly survivable, with both fixed and mobile control stations. System uplinks and crosslinks will operate in the extremely high frequency (EHF) range and downlinks in the super high frequency (SHF) range. The terminal segment includes fixed and mobile ground terminals, ship and submarine terminals, and airborne terminals, including the Family of Advanced Beyond Line-of-Sight-Terminal (FAB-T), used by all of the Services and international partners (Canada, Netherlands and UK). The AEHF satellites will respond directly to service requests from operational commanders and user terminals, providing real-time point-to-point connectivity and network services on a priority basis. On-board signal processing will provide protection and ensure optimum resource utilization and system flexibility among the Armed Forces and other users who operate terminals on land, sea, and air. The AEHF system will be integrated into the legacy Milstar constellation, and will be backward compatible with Milstar’s low data rate (LDR) and medium data rate (MDR) capabilities, while providing extended data rates (XDR) and larger capacity at substantially less cost than the Milstar system. Each satellite will be launched on an Evolved Expendable Launch Vehicle (EELV) with the first launch planned for April 2008. The AEHF Satellite Communications System will augment and replace the Milstar constellation, improve DoD EHF capability, and enable Transformational Communications and Network-Centric Warfare. The MILSATCOM Systems Wing is responsible for the development, acquisition and sustainment of the AEHF Program.

General Characteristics

Primary function: Global, secure, survivable satellite communications

Primary contractor: Lockheed Martin Space Systems Company Satellite Bus: A2100 line

Weight: Approximately 14,500 lbs at launch, 9,000 lbs on-orbit

Orbit-Altitude: 22,300 Miles (geosynchronous)

Payload: Onboard signal processing, crossbanded EHF/SHF communications

Antennas: 2 SHF Downlink Phased Arrays, 2 Crosslinks, 2 Uplink/Downlink Nulling Antennas, 1 Uplink EHF Phased Array, 6 Uplink/Downlink Gimbaled Dish Antenna, 1 Each Uplink/Downlink earth coverage horns

Capability: Data rates from 75 bps to approximately 8 Mbps

Number of Terminals Supported: 6,000

Reconfigurations Time: Minutes

Launch Vehicle: Delta IV and Atlas V EELVs

Inventory: 3 satellites ordered

Unit Cost: Approximately $580 Million per satellite

Test equipment utilized for projects of this type includes spectrum analyzers, network analyzers and oscilloscopes.

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