United Launch Alliance (ULA) and the U. S. Air Force are poised to launch the second Advanced Extreme High Frequency (AEHF) communications satellite from Cape Canaveral May 3 on board an Atlas V rocket.
In a solid demonstration that the U. S. space program is far from dead, four days after the Atlas V lifts off from Launch Complex 41, SpaceX plans to launch a large Falcon 9 rocket from nearby Complex 40 carrying a Dragon spacecraft full of supplies for the first commercial unmanned resupply mission to the ISS.
The AEHF satellite for the Atlas mission is valued at more than $1 billion and has a design life of 14 years extending to the year 2026.
In addition to providing top secret communications capabilities to all branches of the U. S. military especially Special Forces Command, Strategic Command and critical civilian agencies like the CIA, the new AEHF spacecraft will also serve the highly classified needs of the British, Canadian and Dutch military.
Launch of the Atlas V is planned to occur at 2:46 p.m. EDT at the start of a 2 hr. launch window that will close at 4:46 p.m. EDT.
The initial 45th Space Wing launch forecast calls for a 60% chance of favorable weather, with the 40% risk of unfavorable weather on both May 3 and 4 due to cumulus clouds and anvil clouds.
The 204 ft. Atlas V 531 will liftoff on about 1.7 million lb. thrust from its Russian Energomash RD-180 engine and three Aerojet solid rocket boosters.
The 13,600 lb. Lockheed Martin /Northrop Grumman satellite will use high speed frequency-hopping and powerful anti-jam countermeasures to relay top secret, highly encrypted messages, images and video between top commanders, including the President, and to forces in the field.
The system will consist of four spacecraft in geostationary orbits, one of which was launched in August 2010. The Air Force says the AEHF program value including overruns and delays is somewhat over $6 billion but the General Accounting Office says the true cost of the AEHF program is more like $10 billion.
The 531 version of the Atlas V uses a 5 meter diameter launch shroud and a single engine Centaur upper stage.
The Atlas V will place the spacecraft into a 31,070 x 140 mi. super synchronous transfer orbit. 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 slip into geosynchronous orbit at about 22,236 mi. above the equator.
The spacecraft uses a Lockheed Martin A2100 satellite bus with solar arrays spanning 89 ft.
In addition to the solar arrays, the satellite must also deploy two critical structures carrying multiple phased array and traditional antennas capable of forming nearly 200 spot beams on a single hemisphere between 65 deg. north and south latitude.
AEHF 2, as with the first spacecraft, will be parked on the equator at a secret location. With both AEHF 1 and 2 aloft, it is likely that one would be positioned at about 60-70 East longitude where it could provide secure communications to U. S. and allied forces throughout the Middle East.
The Advanced EHF spacecraft will provide three data rate options; a new channel providing up to 8.192 Mbit/s per user, and the previous Milstar Low Data Rate services of 75 – 2400 bits per second and Milstar Medium Data Rate services at 4.8 kbit/s – 1.544 Mbit/s.
The AEHF system also brings several new capabilities to the field:
- Improved adaptive antennas to cancel out the impact of enemy emitters designed to disrupt US warfighter communications.
- New narrowband services to allow Special Operations Forces and other “disadvantaged users” efficient access to communications.
- “Virtual satellite” control to enable war fighters to positively manage the communications resources necessary for successful engagement.
- Greatly enhanced security improvements to block theft of cryptographic information.
The 8.1 Mbit/s data rate is more than 150 times faster than the 56 kilobit-per-second modems of today’s personal computers. Each Advanced EHF satellite employs more than 50 communications channels via multiple, simultaneous downlinks. For global communications, the Advanced EHF system uses inter-satellite crosslinks, eliminating the need to route messages via terrestrial systems. The AEHF program is to replace the Milstar satellites.
According to Kevin Bilger, Lockheed Martin’s vice president and general manager of Global Communications Systems , “One AEHF satellite will provide greater total capacity than the entire 5 satellite Milstar constellation currently on-orbit.”
“Individual user data rates will be five times improved, providing transmission of tactical military communications, such as real-time video, battlefield maps and targeting data,” he said.
In addition to its tactical mission, AEHF also will provide the critical survivable, protected, and endurable communications to the National Command Authority, including Presidential conferencing in all levels of conflict.
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.
In a nuclear crisis, even if subjected to the affects of a nuclear strike , AEHF spacecraft are hardened to guarantee they can maintain communications from the National Command Authority, to forces in the field such as Boeing 707/ E-6B Mercury “TACAMO” (Take Charge And Move Out) aircraft that relay war orders received via AEHF satellite to ballistic missile submarines by conversion of the EHF messages to extremely low frequency communications transmitted at 200,000 watts hundreds of feet below the sea surface by the aircraft.
The Advanced EHF / ELF equipped Mercury aircraft based at Tinker AFB, Okla. carry two reel out trailing wire antennas, one a half mile long and the other 5 mi. long. The aircraft continually flies in a 30-50 deg. bank for up to 3 hr. at a time to make the antennas align as vertically as possible relative to sending communications to submarines that have also deployed long trailing wire antennas.
This scenario is exercised daily over the Atlantic and Pacific Oceans and possibly elsewhere for “Tactical Trident” operations where the subs are increasingly used to deploy Navy Seals on counter terrorism missions.
The totally white 707-300 aircraft with a satellite dome atop, unusual wingtip antennas and red cone trailing wire stabilizers on the belly and the base of the tail are frequent visitors to Patrick AFB, Fla. near Cape Canaveral.
Another Advanced EHF user will be the U. S Air Force B-2 Stealth Bomber which undertakes top secret tactical and strategic missions.
The first AEHF satellite was successfully launched from Cape Canaveral on an Atlas V on Aug. 14, 2010. The Atlas Centaur placed it precisely in the desired super synchronous transfer orbit.
When ground controllers tried to use the spacecraft’s Liquid Apogee Engine provided by AMPAC, a respected rocket engine company based in Niagara Falls, N. Y. , the engine failed to start. After extensive analysis it was decided to use Aerojet attitude control thrusters for 12 firings over 9 months to raise perigee by 2,900 mi. The 89 ft. solar arrays were then deployed and the rest of the maneuvers were performed by Hall thrusters, a form of tiny thrust electric propulsion. But it worked and AEHF 1 was rescued with its planned lifetime restored.
The AEHF 2 launch will have the same basic launch milestones and all Atlas V missions to transfer orbit. Those are:
–The mission begins with RD-180 engine ignition approximately 2.7 seconds before liftoff
–SRB ignition takes place at T+0.8 seconds after telemetry indication of healthy RD-180 startup.
–Liftoff occurs at T+1.1 seconds. Shortly after the vehicle clears the pad, it performs its pitch/yaw/roll maneuver.
–There are two dynamic pressure peaks during the flight. the first occurs at approximately 48 seconds and the second at approximately 58 seconds.
–The SRBs burn out at approximately 92 seconds. The first two SRBs are jettisoned 115 seconds into the flight the third is jettisoned at approximately 117 seconds.
–The payload faring jettison takes place at 214 seconds.
–Booster engine cutoff (BECO) occurs at approximately 258 seconds. Centaur separation occurs 6 seconds after BECO.
–Centaur main engine start (MES-1) occurs
16 seconds after BECO.
–Just before 14 minutes into the mission, the first Centaur main engine cutoff (MECO-1) occurs.
–At 22 minutes into the mission, Centaur reorients itself for its second main engine start (MES-2). The second Centaur engine burn lasts a little more than 5 minutes, followed by the second Centaur main engine cutoff (MECO-2).
–After MECO-2, Centaur reorients its attitude for spacecraft separation and begins a passive thermal control roll.
— AEHF-2 separates at 51 min. 11 sec. after liftoff.
