MILNET: Satellites - MILSTAR Military Communications System

Datasheet Drawing (184K)
A Constellation (126K)
Color Structure Drawing (350K)

The MILSTAR system was one of the first military grade secure communications systems implemented making use of EHF (Extra-High Frequency) signals. The first 2 units are currently in service, with a total of 2 more to be launched to complete the constellation.

It is thought that the satellites most likely carry frequency hopping gear and is pretty obvious that there are different levels of encryption being used on the signals processed. However, it is not clear if any decoding is being used by the satellites themselves, over and above that used on the control channels.

Locations of MILSTAR (and the follow on) satellites is not published, however, like any other communications satellite, it is pretty easy to find them by monitoring military surface contacts and scanning the heavens in real time for the objects relaying information which are in line of sight.

According to Air Force Magazine 1, the satellites are 52 ft (antenna array), and have a 108 foot solar arrayed when deployed. The estimated weight is 10,000 lbs, and the magazine reports the orbit as being geosynchronous with an inclination at 5 degrees, and are three axis stabilized.

The magazine also reports that the satellites have a lifetime prediction of 10 years.

1 Air Force Magazine, Air Force Almanac 1997, pg 148.

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