Thursday, August 05, 2010

AEHF-1 Milsat may launch next week

According to an article on SpaceFlight now, the AEHF-1 Milsat is scheduled to launch next week, August 12, and will be tested at an on orbit geo location of 90 degrees west.

The advanced satellite that will be used for relying secure US military communications will be launched on an Atlas 5 (5-531 configuration) rocket from Cape Canaveral AS, Florida. Liftoff had been targeted for August 12 at 7:14 a.m. EDT, but the launch could be sliding a day or two.

This maiden AEHF bird should be ready, if all goes well, to enter service early next year from an orbital location dictated by the needs at that time, officials said.

"AEHF will provide tactical and strategic support to a wide variety of Army, Navy, Marine and Air Force users," said Col. Michael Sarchet, commander of the Protected Satellite Communications Group at the Space and Missile Systems Center.

The U.S. military purchased a series of AEHF satellites for launches in the coming years to replace the aging Milstar communications spacecraft that link the national leadership and warfighters. The Advanced EHF Program is the next generation of global, highly secure, survivable communications system within all services of the Department of Defense.

"AEHF is a very sophisticated satellite because it is built to provide the highest levels of protection for our nation's most critical users. Encryption, low probability of intercept and detection, jammer resistance and the ability to penetrate the electro-magnetic interference caused by nuclear weapons are essential features when communication can be of the highest priority," Sarchet said.

In Nov. 2001, the U.S. Air Force awarded Lockheed Martin Space Systems and Northrop Grumman Space Technology (Formerly TRW Space & Electronics) a $2.698 billion contract to begin the System Development and Demonstration (SDD) phase of the Advanced Extremely High Frequency (Advanced EHF) Program.

The SDD phase will deploy two Advance EHF satellites and the Advance EHF mission control segment. The new mission control segment will support both Milstar and AEHF. Lockheed Martin will serve as the developer of the ground segment, satellite bus provider, space vehicle integrator and overall systems integrator and prime contractor. This role builds on Lockheed Martin's successful experience on Milstar and DSCS. Northrop Grumman will provide the payload and associated components (digital processor and RF equipment).

The MILSATCOM Program Office, located at the Space and Missile Systems Center, Los Angeles Air Force Base, Calif., is the Advanced EHF contract manager and lead agency for ensuring the secure communications capabilities of this system are made available to the warfighter.

The Advanced EHF Program is the follow-on to the DoD's Milstar highly secure communication satellite program, which currently has a four-satellite operational constellation. The last Milstar satellite was successfully launched in April 2003.

As envisioned by the Pentagon, the fully operational Advanced EHF constellation will consist of four crosslinked satellites providing coverage of the Earth from 65 degrees north latitude to 65 degrees south. These satellites will provide more data throughput capability and coverage flexibility to regional and global military operations than ever before. A fifth satellite built could be used as a spare or launched to provide additional capability to the envisioned constellation.

Advanced EHF satellites will provide 10 times greater total capacity and offer channel data rates six times higher than that of Milstar II communications satellites. The higher data rates permit transmission of tactical military communications such as real-time video, battlefield maps and targeting data.

To accomplish this, Advanced EHF adds new higher data rate modes to the low data rate and medium data rate modes of Milstar II satellites. The higher data rate modes will provide data rates up to 8.2 million bits of data per second (Mbps) to future Advanced EHF Army terminals. That 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.

U.S. Air Force Fact Sheet
Advanced Extremely High Frequency (AEHF) System


The Advanced Extremely High Frequency (AEHF) System is a joint service satellite communications system that will provide survivable, global, secure, protected, and jam-resistant communications for high-priority military ground, sea and air assets. Advanced EHF will allow the National Security Council and Unified Combatant Commanders to control their tactical and strategic forces at all levels of conflict through general nuclear war and supports the attainment of information superiority.


The AEHF System is the follow-on to the Milstar system, augmenting and improving on the capabilities of Milstar, and expanding the MILSATCOM architecture. AEHF will provide connectivity across the spectrum of mission areas, including land, air and naval warfare; special operations; strategic nuclear operations; strategic defense; theater missile defense; and space operations and intelligence.


Part of the MCSW's Protected SATCOM Group, the system consists of four satellites in geosynchronous earth orbit (GEO) that provides 10 times the throughput of the 1990s-era Milstar satellites with a substantial increase in coverage for users. First launch in late 2010, AEHF will provide continuous 24-hour coverage between 65 degrees north and 65 degrees south latitude. The AEHF system is composed of three segments: space (the satellites), ground (mission control and associated communications links) and terminals (the users). The segments will provide communications in a specified set of data rates from 75 bps to approximately 8 Mbps. The space segment consists of a cross-linked constellation of three satellites. The mission control segment controls satellites on orbit, monitors satellite health and provides communications system planning and monitoring. This segment is highly survivable, with both fixed and mobile control stations. System uplinks and crosslinks will operate in the extremely high frequency (EHF) range and downlinks in the super high frequency (SHF) range. The terminal segment includes fixed and ground mobile terminals, ship and submarine terminals, and airborne terminals used by all of the Services and international partners (Canada, Netherlands and UK). MCSW is responsible for acquisition of the space and ground segments as well as the Air Force terminal segments. The Army and Navy will acquire their own terminals.

General Characteristics

Primary Function: Near-worldwide, secure, survivable satellite communications
Primary Contractor: Lockheed Martin Space Systems Company
Payload: Onboard signal processing, crossbanded EHF/SHF communications
Antennas: 2 SHF Downlink Phased Arrays, 2 Crosslinks, 2 Uplink/Downlink Nulling Antennas, 1 Uplink EHF Phased Array, 6 Uplink/Downlink Gimbaled Dish Antenna, 1 Each Uplink/downlink earth coverage horns
Capability: Data rates from 75 bps to approximately 8 Mbps