A United Launch Alliance Atlas 5 rocket with the Air Force’s Advanced Extremely High Frequency-1 (AEHF-1) satellite launches from the Space Launch Complex-41 launch pad of Cape Canaveral Air Force Station at 7:07 a.m. EDT on Aug. 14, 2010.
Credit: ULA/Pat Corkery [Full Story]
The U.S. Air Force is gaining ground in its attempt to save an advanced new military communications satellite after a crippling malfunction left it without a working main engine.
The Advanced Extremely High Frequency 1 satellite launched successfully Aug. 14, but suffered a main engine breakdown a day laterwhile trying to perform maneuvers to raise its altitude in orbit.
The 13,420-pound (6,100-kg) spacecraft is the first of three to be provided to the Air Force under a nearly $6.5 billion contract with satellite builder Lockheed Martin, Air Force officials have said.
A series of smaller maneuvers using the satellite's smaller hydrazine thrusters have successfully raised it ?to an intermediate orbit.
"The current status for the first five burns for the parking orbit has all been nominal and the satellite is performing as expected," said Dave Madden, Military Satellite Communications Systems Wing program director at the Air Force's Space and Missile Systems Center.
Madden told SPACE.com Tuesday that these thrusters are working at 100 percent efficiency.
Dead engine in space
The small thruster maneuvers came after attempts to fire the AEHF 1 satellite's stricken main Liquid Apogee Engine failed. The satellite's hydrazine thrusters deliver 5 pounds (2.3 kg) of thrust, compared with the main engine's 100 pounds (45 kg).
"We believe the LAE is unusable, and at this point we have no plans to fire that engine again," Madden told reporters last week.
Lockheed Martin engineers are ?working with the Air Force to devise a strategy to save the spacecraft's mission using these smaller engines and a third set ofelectric ion thrusters that run on xenon gas.
Officials estimate it will take the satellite 10 months to a year to reach its intended orbit 22,300 miles (35,900 km) over the Earth's equator using just the smaller thrusters. Originally, the move was expected to take 90 days.
Avoiding space debris
The satellite must move to a higher orbit to complete its full mission, and also to avoid the hazardous bits of debris that tend to crowd the lower altitude it is currently in.
The satellite already escaped at least one close call with a piece of space junk, Madden said.
"We have to watch out for other particles because we?re in such a low orbit," he added. "And so we actually fired our 5-pound thrusters to do a collision avoidance maneuver."
Despite the challenges, Madden said he was "extremely confident" the spacecraft would be able to reach its intended orbit.
"I am confident this next step has acceptable risk that is anchored in sound testing, analysis and independent review, providing the best chance at maximizing final overall mission capability," Madden said in an e-mail.
The AEHF-1 spacecraft is the first in a network of satellites designed to serve as a vital communications link between military commanders and troops, as well as with the White House. The AEHF system, with its large data capacity and fast processing rates, is intended to replace the aging Milstar satellites.
Before any more satellites in the series are launched though, the Air Force wants to figure out what went wrong on this one.
"Understanding root cause is essential before moving forward with AEHF SV-2 launch plans," Madden said.
That second vehicle was originally slated to launch in February 2011, but now its liftoff will probably be pushed back to make sure it won't experience the same problems as its predecessor.
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