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AEHF To Reach Intermediate Orbit In Weeks
Over the next few weeks, the U.S. Air Force plans to use one of two thruster systems still functioning on a protected military communications satellite built by Lockheed Martin to reach an intermediate orbit after failure of a liquid apogee engine on the spacecraft.
The Aug. 14 launch of the Atlas V carrying the first Advanced Extremely High Frequency (AEHF) satellite, estimated to cost more than $2 billion, toward geosynchronous orbit was nominal. But the spacecraft’s liquid apogee engine (LAE) failed prematurely, and this system has been rendered useless for the 22,000-mi. journey into its proper orbit (Aerospace DAILY, Aug. 27).
Engineers at the Air Force Space and Missile Systems Center — which oversees AEHF procurement — Lockheed Martin and The Aerospace Corp. are “assessing a modification to the original orbit-raising strategy that would use the other two healthy propulsion systems” on the satellite, according to the Air Force’s Military Satellite Communication Office. These are the reaction engine assembly (REA) and Hall Current Thruster (HCT) electric propulsion systems.
The REA, which will be used to raise the satellite into the intermediate orbit, is not as powerful as the LAE, “so the operation is anticipated to take longer than the original orbit-raising plan,” the Milsatcom officials say. “This activity to move to the intermediate orbit should be accomplished in the next few weeks.”
Once that orbit is reached, the Milsatcom officials say they will then head to GEO. They declined to say how, specifically. “It is going to take longer to get AEHF-1 to GEO, but it will get there,” one Air Force official says. “The final plan will have to use a combination of the smaller 5- and 0.2-lb. thrusters in conjunction with the Hall Current Thrusters to reach GEO.”
The alternate propulsion strategy, however, will require tapping into the satellite’s hydrazine tanks for fuel; this is on the spacecraft for station-keeping. “We’re still examining the net fuel required for this [journey to GEO], the time required and the steps to get there,” the Air Force official says. “But in the end, we expect a nominal mission duration,” meaning the operation should not significantly lessen the useful life.
Once Air Force officials determine the root cause of the LAE failure on the first AEHF, the “implication to other satellites with similar propulsion systems will be analyzed and addressed,” the Milsatcom officials say. The AEHF core is built from Lockheed Martin’s A2100 satellite design, as will be the upcoming GPS III.
Lockheed Martin First Advanced EHF Satellite Encapsulated
The first Advanced Extremely High Frequency (AEHF) military communications satellite was encapsulated into the fairing in preparation for a mid-August liftoff aboard an Atlas V rocket from Cape Canaveral Air Force Station, Fla.
Designed and built by Lockheed Martin Space Systems, Sunnyvale, Calif., the AEHF will deliver survivable, protected, secure links to U.S. national leaders, air, land and sea forces, providing rapid, global coverage for the nation’s strategic forces, the Air Force’s space warning assets and operationally deployed military forces. The AEHF constellation will also serve international partners including Canada, the Netherlands and the United Kingdom.
One AEHF satellite will provide greater total capacity that the entire Milstar constellation. Individual user data rates will be five times improved. The higher data rates will permit transmission of tactical military communication such as real-time video, battlefield maps and targeting data.
The AEHF team is led by the U.S. Air Force Military Satellite Communications Systems Wing 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 and system manager, with Northrop Grumman Aerospace Systems, Redondo Beach, Calif., as the payload provider.
Headquartered in Bethesda, Md., Lockheed Martin is a global security company that employs about 136,000 people worldwide and is principally engaged in the research, design, development, manufacture, integration and sustainment of advanced technology systems, products and services. The Corporation’s 2009 sales from continuing operations were $44.5 billion.
LockMart delivers first USAF advanced EHF Satellite
Lockheed Martin has delivered the first satellite in the Advanced Extremely High Frequency (AEHF) program to Cape Canaveral Air Force Station, Fla., where it will be prepared for a July 30 liftoff aboard an Atlas V launch vehicle. The AEHF system will provide the U.S. military and national leaders with global, protected, high capacity and secure communications.
The AEHF system is the successor to the five-satellite Milstar constellation and will provide significantly improved global, highly secure, protected, survivable communications for all warfighters serving U.S. national security. The governments of Canada, The Netherlands, and the United Kingdom participate in the AEHF program as international partners and will have access to the communications capability of AEHF.
A single AEHF satellite will provide greater total capacity than the entire Milstar constellation currently on-orbit. Individual user data rates can be up to five times higher than Milstar’s highest speed. The faster data rates will permit transmission of tactical military communications, such as high-quality real-time video and quick access to battlefield maps and targeting data.
The second AEHF spacecraft (SV-2) has completed Final Integrated System Test which verified all spacecraft interfaces, demonstrated full functionality and evaluated satellite performance and is now preparing for Intersegment testing to ensure the spacecraft is ready for flight.
The third AEHF satellite, SV-3, has completed acoustic testing, one of several critical environmental tests that validate the overall satellite design, quality of workmanship and survivability during space vehicle launching and on-orbit operations. SV-2 and SV-3 are on track for launch readiness in 2011.
The AEHF team is led by the U.S. Air Force Military Satellite Communications Systems Wing 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 and system manager, with Northrop Grumman Aerospace Systems, Redondo Beach, Calif., as the payload provider.
“Assured communications for our military services is absolutely essential wherever they may be deployed,” said Stuart Linsky, vice president, Satellite Communications, for Northrop Grumman. “Capabilities provided by AEHF will give more warfighters access to the protected communications they need.”
Lockheed Martin is currently under contract to provide three AEHF satellites and the Mission Control Segment. The program has begun advanced procurement of long-lead components for a fourth AEHF satellite.