AEHF SV-1 (USA 214)

Spacecraft n°:

US spacecraft n°:

Launch data: Designation  36868 / 10039A Launch date  14 Aug 2010 - 11:07 UT Launch site  CC, SLC-41 Launch vehicle  Atlas-V/531 (AV-19) Mission  Military: Communication Earth orbit on Aug 30.20: Perigee / Apogee  427 x 49975 km Eccentricity  0.785 Inclination  21.67 deg Period  930.83 min Earth orbit on Sep 21.10: Perigee / Apogee  4544 x 49975 km Eccentricity  0.675 Inclination  15.37 deg Period  1023.32 min Earth orbit on Nov 23.84: Perigee / Apogee  7030 x 50391 km Eccentricity  0.617 Inclination  12.67 deg Period  1090.22 min

Spacecraft data: Prime contractor  Lockheed Martin Space Systems Platform  A2100M Operator  US Air Force Mass at launch  6169 kg Dry Mass   kg Basic shape  Box + 2 panels Dimension (m)   Equipment   Solar array   Stabilization   Propulsion   DC power   Design lifetime  14 yrs

Credit: Lockheed Martin Space Systems

Mission details:

• The US Air Force's first Advanced EHF communications satellite was launched on Aug 14, 2010. AEHF 1 is a Lockheed Martin A2100M satellite with a launch mass of around 6200 kg. The AEHF constellation's SHF and EHF communications payloads will replace the Milstar satellite system launched in the 1990s.
• AEHF 1's Lockheed Martin/ULA Atlas V launch vehicle AV-019 was a model 531 variant with three strapon solid motors; the first burn of the Centaur upper stage reached a 167 x 1281 km x 27.8 deg orbit at 1121 UTC. Centaur restart at 1129 UTC pushed AEHF 1 into a 221 x 50179 km x 22.2 deg deployment orbit. Large burns with the liquid bipropellant apogee thruster was intended to raise the orbit initially followed by several months of burns from AEHF 1's Hall-thruster electric propulsion system. However, the bipropellant thruster cannot be operated and instead a series of small burns with a lower thrust monopropellant hydrazine engine, using the same hydrazine tank, will be needed.
• Many A2100 class satellites have used AMPAC's LEROS 1 engine, but AEHF 1 uses a different brand of apogee thruster, the BT-4 developed by Japan's IHI Aerospace. This thruster is also flown on Orbital's Star 2 satellites. Investigation has not yet revealed whether the fault is in the thruster itself or some other part of the propulsion system that interacts with the thruster.
• According to the SeeSat list, hobbyists have tracked AEHF following six hydrazine burns to date; on Sep 7, 2010 AEHF 1 was in a 1146 x 49994 km x 20.0 deg orbit; on Sep 20 it was in a 4546 x 49981 km x 15.4 deg orbit.
• Constellation of 3 plus 1; will replace the Milstar system. This satellite's main engine failed right after launch, stranding it in a transfer orbit. It may reach its GEO orbit by summer 2011.
• During late March to late April, 2011 the US Air Force's AEHF 1 communications satellite raised its orbital period from 23 hours to 25 hours, passing briefly through the geosynchronous range. AEHF 1 was launched in 2010 Aug to a supersynchronous transfer orbit of 249 x 50019 km x 22 deg; after failure of its main propulsion system, electric thrusters have been used to slowly raise the orbit to its current 22923 x 51539 km x 7.1 deg. Once the perigee has been raised to the 35780 km or so needed for geostationary orbit, the apogee will be lowered to match and the satellite will return to geosynchronicity.
• AEHF-1, took nearly 17 months to achieve its final intended orbit, after debris in an onboard fuel-line impeded the use of its main spacecraft engine. After some 500 firings of its small electrical maneuvering thrusters, the spacecraft team wound up performing one of the great satellite rescues to date, as AEHF-1 was declared ready to enter service as of January 2012.