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First milestone reached on AEHF 1's long road to orbit

Posted: September 5, 2010

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The U.S. Air Force has completed the initial phase of its multi-step, multi-month strategy to maneuver the new secure communications satellite into the proper orbit without the main engine operating.

United Launch Alliance's highlights film from liftoff

Satellite-tracking hobbyists report that the Advanced Extremely High Frequency 1 spacecraft has climbed into the intermediate orbit that project officials were targeting.

The craft spent the week performing four orbit raising burns using tiny steering thrusters to boost the low end of the satellite's highly elliptical orbit by more than 400 miles.

Controllers are employing the so-called Reaction Engine Assembly motors to save the satellite after its large Liquid Apogee Engine failed to work shortly after launch.

Air Force officials are confident AEHF 1 will achieve the intended geosynchronous orbit and have enough remaining fuel to function for its full 14-year mission. But getting the satellite boosted into the circular perch using thrusters instead of the main engine will take a half-year longer to accomplish.

The initial phase of the rescue plan wanted to get the satellite's perigee safely above the influences of atmospheric drag. The following numbers show that has occurred:

Orbit at start of rescue:
170 x 31,060 miles inclined 22.1 degrees to the equator

Orbit after Segment 1, Burn 1:
275 x 31,060 miles inclined 21.7 degrees

Orbit after Segment 1, Burn 2:
360 x 31,065 miles inclined 21.2 degrees

Orbit after Segment 1, Burn 3:
490 x 31,055 miles inclined 20.8 degrees

Orbit after Segment 1, Burn 4:
590 x 31,050 miles inclined 20.4 degrees

The next segment will "more than double" the orbit's low point with continued burns of the hydrazine-fueled thrusters, according to Dave Madden, Military Satellite Communications Systems Wing program director at the Air Force's Space and Missile Systems Center.

Later phases to reach a circular geosynchronous orbit 22,300 miles above the planet will use the Hall Current Thrusters of the satellite's xenon-fed electric propulsion system.

AEHF 1 should arrive at its destination by next June or July, officials predict.

To learn more about the rescue plan, see our earlier story.

Details about the main engine investigation and possible impacts to the AEHF 2 launch are posted here.

For more on the AEHF 1 satellite and its mission, see our story from launch day.