Military satellite's rise to final orbit delayed by thruster shutdown

The Air Force and Lockheed Martin Corp. plan to raise the orbit of a recently launched military communications satellite without the aid of its primary thrusters, which shut down prematurely, according to the Air Force.

The liquid apogee engine system, or LAE, is one of three propulsion systems on the first satellite launched by the Advanced Extremely High Frequency program, which intends to provide highly secure communications channels even during nuclear war.

The AEHF program is expected to cost $6.5 billion to build and operate the first three spacecraft.

The satellite called AEHF-1 launched flawlessly at 7:07 a.m. Aug. 14 from Cape Canaveral Air Force station atop a United Launch Alliance Atlas V rocket, and separated within an hour.

Last Friday, the Air Force's Space and Missile Systems Center announced a delay in plans to raise the spacecraft to a geosynchronous orbit more than 22,000 miles above the planet while assessing a concern that arose during the early orbit-raising process.

Now, AEHF teams are working on a strategy that would use the two healthy propulsion systems to complete the orbit raising, according to a spokesperson at the Air Force's Military Satellite Communications Wing.

Those systems are called the reaction engine assembly, or REA, and Hall Current Thruster electric propulsion system, or HCT.

Managers plan to use the reaction engine assembly system to raise the AEHF-1 satellite to an intermediate orbit, a process that takes longer because the engines are less powerful than the liquid apogee system. It could be accomplished within a few weeks, according to an Air Force spokesman.

Then the electronic propulsion system would complete the job as planned.

The Air Force says the satellite is safe and all subsystems are stable.

The root cause of the engine failure is under investigation, and it's not yet clear if the issue could delay future program launches. The next was planned as soon as the first quarter of next year.

Image: Artist's rendering of an AEHF spacecraft. Courtesy: U.S. Air Force.