The AEHF (Advanced Extreme High Frequency Satellite), a.k.a. AWS (Advanced Wideband Satellite), program is the next generation of highly secure, high capacity, survivable communications to the U.S. warfighters during all levels of conflict, and will become the protected backbone of the Department of Defense's military satellite communications architecture.
The AEHF system will be integrated into the legacy Milstar (Military Strategic & Tactical Relay) constellation, and will be backward compatible with Milstar's low data rate (LDR) and medium data rate (MDR) capabilities, while providing extreme 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 originally planned for April 2008. The first launch was delayed until 2010. They cost approximately $580 million per satellite.
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 extreme data rates (XDR) and larger capacity at substantially less cost than the Milstar system.
AEHF satellites feature following 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
Up to six satellites were planned, but in late 2004 it was decided, to end the AEHF program after the third satellite in favour of introducing the next generation T-Sat earlier. Problems with the T-Sat program led to procurement of two more AEHFs instead. Later a sixth was added.
AEHF 1 was launched in August 2010. After launch, the apogee propulsion system developed problems and the orbit was raised over a longer period using the attitude control engines and the Hall Current Thruster electric propulsion system consisting of four XR-5 5 kW Hall thrusters.
