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USA 99, the first of the six Milstar geostationary communications spacecraft, was launched from Cape Canaveral by a Titan 4 rocket. Milstar is a series of advanced US military communications satellites designed to provide global jam-resistant communications for military users. The Milstar system, when completed, will consist of four Block 2 satellites in low inclination, geosynchronous orbits. The operational system will accomodate direct links to numerous, highly mobile Milstar ground terminals installed on vehicles, ships, submarines and aircraft. The first two Block 1 spacecraft, launched in 1994 and 1995, will eventually be replaced by the Block 2 Milstar 3 through 6, which are scheduled for launch beginning in 1999. When the full Block 2 constellation is deployed, as many as 10,000 users will be able to access the system at any given time.

The spacecraft is 3-axis stabilized with two large solar arrays. It has costly nuclear hardness and survivability features which will not be included in the four Block 2 satellites. Crosslink operations were performed at or near frequencies that are absorbed by Earth's atmosphere, preventing detection by Earth-based ground stations. The satellite and ground station designs also incorporate advanced signal processing/encryption technologies to deny access of downlinked signals to unauthorized users.

Alternate Names

  • USA 99
  • 22988
  • Milstar 1-01

Facts in Brief

Launch Date: 1994-02-07
Launch Vehicle: Titan IV
Launch Site: Cape Canaveral, United States
Mass: 4500 kg

Funding Agency

  • Department of Defense-Department of the Air Force (United States)


  • Communications
  • Surveillance and Other Military

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office

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