AEHF-2 (USA 235)

Spacecraft n°:

US spacecraft n°:

Launch data: Designation  38254 / 12019A Launch date  04 May 2012 - 18:42 UT Launch site  CC, SLC-41 Launch vehicle  Atlas-V(531) (AV-031) Mission  Military: Communications Earth orbit on May 4.86: Perigee / Apogee  175 x 50098 km Eccentricity  0.792 Inclination  20.71 deg Period  927.98 min

Description:

• 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.
• 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 might lead to procurement of two more AEHFs instead.
• AEHF 1 was launched in August 2010. After launch, the apogee propulsion system developed problems and the orbit will be raised over a longer period using the attitude control engines and the Hall Current Thruster electric propulsion system.

Mission details:

• Atlas V flight AV-031 was launched from Cape Canaveral on May 4, 2012 into a 185 x 901 km x 27.5 deg parking orbit and then a 225 x 50031 km x 20.6 deg transfer orbit. It deployed the 6200 kg AEHF SV-2 satellite. The US Air Force Advanced EHF communications satellite provides strategic military communications at EHF frequencies and is based on the Lockheed Martin/Sunnyvale A2100 spacecraft bus with a Japanese IHI BT-4 apogee thruster and an electric propulsion system.
• The AV-031 Centaur stage vented its remaining propellant; an initial set of orbital data implying deorbit seems to have been incorrect. Orbit on May 5 is reported to be 88 x 50406 km x 20.4 deg, with first perigee pass around 1040 UTC on May 5.