posted January 31, 2013
On Thursday morning, Jan. 10, MILSATCOM Systems Director James Liau delivered a detailed, 40-minute presentation at the corporation on the current state of the Advanced Extremely High Frequency (AEHF) program.
The early portion of the talk dealt with the technical anomaly that hampered the first AEHF satellite (AEHF-1) shortly after its launch on Aug. 14, 2010.
Liau explained that a restriction in the satellite’s oxidizer line was found to have contributed primarily to the failure of its liquid apogee engine, with the result that the satellite ended up in a low-earth orbit a few hundred miles above Earth while it needed to be in a geo-stationary orbit more than 20,000 miles above the planet.
As the satellite’s bi-propellant thruster system remained inactive, a team consisting of employees from Aerospace, the Air Force, and Lockheed Martin devised and executed a 14-month rescue operation of AEHF-1 utilizing its hydrazine system and its Hall Current Thruster electric propulsion system. Liau gave an in-depth explanation of the rescue program and concluded that the anomaly was most likely caused by obstructions in AEHF-1’s propulsion manifold.
The second portion of Liau’s presentation focused upon the rigorous testing of AEHF-2 and AEHF-3 in the wake of AEHF-1’s difficult path to orbit. Since the obstruction most likely happened during a rework of AEHF-1, the exonerative tests of AEHF-2 and AEHF-3 focused upon areas where similar repairs were performed.
After a series of in-depth tests and a pedigree review, the two satellites were both cleared for flight. AEHF-2 was launched on May 4, 2012 and is now on orbit. Further tests and analysis have been, and continue to be, carried out on orbit as well as on the ground to accumulate critical data about the satellites’ respective HCT systems for the benefit of future AEHF satellites.
Liau concluded with a status update for AEHF-4, listing the satellite’s proposed technical upgrades and its completed components — which include the U-frame and payload wing structures. At the end of his talk, Liau responded to a number of specific questions about the AEHF program from the audience.