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Milstar
Milstar
Milstar
Credit: USAF
American military communications satellite. Milstar was a series of advanced US military communications satellites designed to provide global jam-resistant communications for military users.

AKA: Military Strategic and Tactical Relay System. Status: Operational 1994. First Launch: 1994-02-07. Last Launch: 2003-04-08. Number: 6 . Gross mass: 4,500 kg (9,900 lb). Height: 12.00 m (39.00 ft).

The Milstar system consisted of four Block 2 satellites in low-inclination, geosynchronous orbits. The operational system accommodated direct links to numerous, highly mobile Milstar ground terminals installed on vehicles, ships, submarines and aircraft. The first two Block 1 spacecraft, launched in 1995, were eventually replaced by the Block 2 Milstar 3 through 6, which were launched beginning in 1999. The full Block 2 constellation allowed as many as 10,000 users to access the system at any given time.

The spacecraft was 3-axis stabilized, with two large solar arrays. The second spacecraft (F2) carried 398 kg of ballast to replace a classified payload which was removed. The Block 1 satellites had costly nuclear hardness and survivability features which were not included in the four Block 2 satellites. Two crosslink dish antennas located at opposite ends of each spacecraft connected all four Block 2 satellites to form a secure constellation controlled from a single fixed or mobile control station. Crosslink operations were performed at or near frequencies that were absorbed by Earth's atmosphere, preventing detection by Earth-based ground stations. The satellite and ground station designs also incorporated advanced signal processing/encryption technologies to deny access of downlinked signals to unauthorized users.

The Low data rate (LDR) EHF payload was built by TRW and had 192 channels with rates between 75 and 2400 bps. Block 2 spacecraft carried the LDR in addition to a Medium Data Rate (MDR) payload built by Hughes. The MDR provided rates of 4800 bps to 1.544 Mbps per channel. The MDR payload also included two nulling spot antennas that could identify and pinpoint the location of a jammer and electronically isolate its signal, allowing Milstar users to operate normally and at full capacity with no loss in signal quality or speed, despite any attempt by hostile forces to jam or intercept its signal.

The Defense Department's Milstar, distinguished itself as the first of its kind in several groundbreaking advancements: the first satellite system to allow all branches of the U.S. Armed Services to communicate with one another on the same secure network; the first to operate at extremely high frequencies; and the first to provide satellite-to-satellite communications. Milstar's "switchboard-in-the sky" operational concept was considered revolutionary because the satellites handled all processing and traffic management chores without ground station relays, greatly enhancing data security and jam resistance.

Lockheed Missiles and Space, as prime contractor and systems integrator, led a team responsible for designing, building and launching the system. Two Milstar satellites were launched in 1994 and 1995 aboard Titan IV-Centaur boosters built by Lockheed Martin Astronautics. Software updates to the satellite memory increased Milstar's flexibility and operation.


More at: Milstar.

Subtopics

Milstar-1 1, 2 (Milstar 1, 2) Null

Milstar-2 1, 2, 3, 4 (Milstar 3, 4, 5, 6) Null

Family: Communications, Geosynchronous orbit, Military communications sat. Country: USA. Launch Vehicles: Titan, Titan 4, Titan 4B, Titan 401A/Centaur, Titan 401B/Centaur. Launch Sites: Cape Canaveral, Cape Canaveral LC40. Agency: USAF, Hughes, TRW, Lockheed. Bibliography: 2, 296, 552, 554, 6, 6710, 12837, 12838.
Photo Gallery

USA 99USA 99
Credit: Manufacturer Image


USA 164USA 164
Credit: Manufacturer Image



1994 February 7 - . 21:47 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC40. LV Family: Titan. Launch Vehicle: Titan 401A/Centaur.
1995 November 6 - . 05:15 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC40. LV Family: Titan. Launch Vehicle: Titan 401A/Centaur.
1999 April 30 - . 16:30 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC40. LV Family: Titan. Launch Vehicle: Titan 401B/Centaur. FAILURE: Centaur software programming error.. Failed Stage: U.
2001 February 27 - . 21:20 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC40. Launch Pad: SLC40. LV Family: Titan. Launch Vehicle: Titan 401B/Centaur.
2002 January 16 - . 00:30 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC40. Launch Pad: SLC40. LV Family: Titan. Launch Vehicle: Titan 401B/Centaur.
2003 April 8 - . 13:43 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC40. Launch Pad: SLC40. LV Family: Titan. Launch Vehicle: Titan 401B/Centaur.

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