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Milstar Satellite Communications System

MILSTAR satellite system history spotlight graphic, U.S. Air Force graphic

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Milstar provides the President, Secretary of Defense and the U.S. armed forces with assured, survivable satellite communications (SATCOM) with low probability of interception and detection. Designed to overcome enemy jamming and nuclear effects, Milstar is the most robust and reliable SATCOM system currently employed by the Department of Defense (DoD).

The objective of the Milstar program was to create a global, secure, nuclear-survivable, space-based communication system (considered a top national priority during the Reagan Administration in the 1980s). Milstar was designed to perform all communication processing and network routing onboard, thus eliminating the need for vulnerable land-based relay stations and reducing the chances of communications being intercepted on the ground.

There are five operational Milstar satellites. The first two satellites (Milstar I) carry a low data rate (LDR) payload. The LDR payload can transmit 75 to 2,400 bps of data over 192 channels in the extremely high frequency (EHF) range. Encryption technology and satellite-to-satellite crosslinks provide secure communications, data exchange and global coverage. The other three satellites (Milstar II) carry both LDR and medium data rate (MDR) payloads. The MDR payload can transmit 4,800 bps to 1.544 Mbps of data over 32 channels. The higher data rates provide the user the ability to transmit large amounts of data in a short period of time. These 5 satellites, continuous 24-hour LDR and MDR coverage to the warfighter between 65 degrees north and 65 degrees south latitude.  The follow-on to Milstar, Advanced EHF consisting of 5 satellites, is fully backward compatible with Milstar and will form an integrated constellation of satellites.

A key feature of the Milstar system is the use of interoperable terminals by the warfighters of the U.S. Armed Forces. For example, sea-based terminals can be used to upload data in real time onto cruise missiles carried aboard submarines and guided missile destroyers. Land-based terminals provide communications and data exchange for the mobile, ground-based warfighter.  Primary command and control of the Milstar constellation is accomplished through a highly survivable mission control segment with both fixed and mobile control stations. A secondary method of command and control uses the Command and Control System-Consolidated (CCS-C) and the Air Force Satellite Control Network (AFSCN). This integrated system provides backup command and control through S-band links for both Milstar and the Advanced EHF satellite systems. 

General Characteristics
Primary function: survivable and protected communications
Primary contractor: Lockheed Martin
Payload: LDR, MDR, and UHF
Antennas: LDR: Earth Coverage (uplink & downlink), Agile Beams (5 uplink, 1 downlink), Spot Beams (2 narrow, 1 wide), MDR: 2 Nulling, 6 Distributed User Coverage Area
Capability: LDR: 75 bps - 2.4 kps / MDR: 4.8 kps1.544 Mbps

Flight 1 - Feb 7, 94
Flight 2 - Nov 7, 95
Flight 3 - Feb 27, 01
Flight 5 - Jan 15, 02
Flight 6 - Apr 8, 03

Advanced EHF
Space Vehicle 1 - Aug 14, 10
Space Vehicle 2 - May 4, 12
Space Vehicle 3 - Sep 18, 13
Space Vehicle 4 - TBD
Space Vehicle 5 - TBD

(Current as of November 2015)

Point of Contact: Air Force Space Command Public Affairs Office; 150 Vandenberg St., Suite 1105; Peterson AFB, Colo., 80914-4500;
DSN 692-3731 or (719) 554-3731


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