The second U.S. Air Force Advanced Extreme High Frequency (AEHF) communications spacecraft was successfully launched into a super synchronous transfer orbit May 4 atop a United Launch Alliance (ULA) Atlas V 531 rocket.
Liftoff of the 197 ft. tall 2.7 million lb. thrust vehicle from Launch Complex 41 at Cape Canaveral Air Force Station occurred at 2:42 p.m. EDT.
“The 13,600 lb. satellite cost $1.7 billion”, said USAF Capt. John Francis, the AEHF project lead in charge of Operations and Sustainment. This makes it one of the most expensive military spacecraft ever launched from Cape Canaveral. The first AEHF spacecraft launched in August 2010 also cost $1.7 billion.
“The AEHF satellite series is the most sophisticated military communications system ever built and it will be a integral part of our national space security architecture,” said Steve Tatum, Lockheed-Martin’s Communications Director.
“We’re extremely pleased and excited with today’s launch,” said USAF Capt. Francis. “We have a big AEHF-2 team and it all culminated today,” he said. It’s kind of like the Super Bowl – and we just scored the winning touchdown.”
One AEHF satellite will provide greater total capacity than the entire 5 satellite Milstar constellation currently on-orbit. In addition it is backward compatible with all five operational Milstars, meaning that the total U. S. network capable of relaying the most secret traffic now stands at 7 spacecraft, Tatum said.
The Atlas V flew in its 531 vehicle configuration with a five-meter fairing and three Aerojet solid rocket boosters.
Its single engine Centaur upper stage powered by a Pratt & Whitney liquid oxygen/hydrogen RL-10 flew a 2 burn profile to release the spacecraft in about a 31,070 x 140 mi. super synchronous transfer orbit 51 min. after liftoff from Launch Complex 41.
The AEHF-2 was released over the equator, high above the Indian Ocean southeast of Diego Garcia where USAF antennas monitored the milestone.
Trajectory analysts have determined that instead of raising perigee as in traditional transfer orbits, it is more efficient for AEHF-2 to later both lower apogee and raise perigee to eventually slip into geosynchronous orbit at about 22,236 mi. above the equator.
It was during this process that the first AEHF-1 satellite, launched on an Atlas V in August, 2010, ran into serious trouble when its large maneuvering engine failed to fire. Investigators later determined that a satellite propellant line was likely blocked, possibly by a piece of cloth left behind during cleaning. The AEHF-1 spacecraft finally reached its assigned geosynchronous position by ascending using small attitude control thrusters and tiny Hall thrusters similar to electric propulsion hardware.
There will be four initial AEHF spacecraft to carry the nation’s most highly secret communications, one over each hemisphere and a fourth in orbit spare. But USAF is also actively seeking funding for a fifth and sixth spacecraft.
With two AEHF now aloft individual user data rates will be increased five-fold, permitting transmission of tactical military communications, such as real-time video, battlefield maps and targeting data. In addition to its tactical mission, AEHF also provides the critical survivable, protected, and endurable communications links to national leaders including presidential conferencing in all levels of conflict.
“AEHF is integral to our national security space architecture, providing significantly improved protected communications capabilities for both tactical and strategic users,” said Kevin Bilger, Lockheed Martin’s vice president and general manager of Global Communications Systems.
The AEHF team includes the U.S. Air Force Military Satellite Communications Systems Directorate at the Space and Missile Systems Center, Los Angeles Air Force Base, Calif. Lockheed Martin Space Systems Company, Sunnyvale, Calif., is the AEHF prime contractor, space and ground segments provider as well as system integrator, with Northrop Grumman Aerospace Systems, Redondo Beach, Calif., as the payload provider.
In addition to the nearly 7 ton AEHF, the Atlas V also launched a small CubeSat spacecraft developed with the assistance of Lockheed Martin and about 50 students enrolled in Florida’s Merritt Island High School (MIHS) da Vinci Academy of Aerospace Technology and CubeSat program.
Merritt Island is a large island on which the Atlas V’s Launch Complex 41 is positioned as well as the two Kennedy Space Center Launch Complex 39 pads originally built for the Apollo Saturn V, then also used for the Space Shuttle.
“The students’ nano-satellite will communicate with a California Polytechnic State University satellite to assist commercial companies with the balance needed to protect against launch vibrations and additional costs resulting from over-design,” Lockheed Martin said.
Lockheed Martin has had an ongoing mentor relationship with MIHS since 2009, serving as da Vinci Academy of Aerospace Technology advisory team members and student mentors to encourage the study of Science, Technology, Engineering and Mathematics.
The launch was originally scheduled for May 3 but was scrubbed about 10 min. prior to launch due to lack of helium flow used for temperature control from the ground support equipment to the Centaur Interstage Adapter compartment on the launch vehicle. The ULA launch commentator indicated that Atlas V launch controllers believed that the problem was caused by human error when a valve had been incorrectly positioned before the countdown.
Another reason for the scrub was radio interference picked up southeast of Launch Complex 41 in the 421-427 Mhz range by a 45th Space Wing Frequency Control truck. These highly specialized vehicles are positioned at various locations during a countdown to ensure no spurious radio interference affects the launch vehicle or Range Safety destruct links during ascent.
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