Nuclear Detection¶
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Nuclear Detection
By all accounts, the Vela nuclear detonation detection satellite system has been one of America’s most successful military space programs ever. The reason for building the Vela system was to monitor compliance with the 1963 Limited Nuclear Test Ban Treaty. The total number of satellites built was 12 - six of the Vela Hotel design, and six of the Advanced Vela design. The Vela Hotel series was to detect nuclear explosions in space, while the Advanced Vela series was to detect not only nuclear explosions in space but also in the atmosphere. All spacecraft were launched in pairs, either on a Atlas-Agena or Titan III-C boosters, and placed in 63,000 to 70,000 mile orbits, well above the Van Allen radiation belts. The first pair was launched in 1963, three days after the Test Ban Treaty was signed, while the last pair was launched in April 1970. The last satellite to be shut down was Vehicle 9 in 1984, which had been launched in 1969. It had lasted 15 years. Vela started out as a small budget research program in 1959.
It ended 26 years later as a dramatically successful, cost-effective space system. In the 1970s, the nuclear detection mission was taken over by the Defense Support Program (DSP) system, and in the late 1980s, by the Navstar Global Positioning System (GPS) satellites. Some controversy still surrounds the Vela program when in the late 1970s, one of the satellites detected an atmospheric nuclear explosion allegedly in South Africa. Many scientific and policy experts at that time (during the Carter Administration) took pains to debunk the data as a false reading. However, in the mid-1990s, South Africa openly admitted they had conducted an atmospheric nuclear test at that time. The satellite was RIGHT!
Communications
Military communications has two very distinct requirements - one is strategic communications serving users who have medium to high rate data needs using large stationary ground terminals usually between fixed bases, and the other is tactical communications serving users who have low to medium data rates using small, mobile terminals. Military satellite communications during the 1970s included further development of strategic communications and initial development of tactical communications. The military took its fledging steps toward solving its strategic needs with the Initial Defense Communications Satellite Program or IDCSP in the 1960s. When IDCSP reached initial operational capability (IOC), the system was renamed the Defense Satellite Communications System I (DSCS I). Later in its use, DSCS I proved it also had tactical capability. In mid 1969, DoD gave the go-ahead to develop the next stage of strategic military communications, a satellite that would use the geosynchronous orbit (at 22,300 miles) called DSCS II. DSCS II would be larger, offer increased capability than DSCS I, and have a longer lifetime than its predecessor. The satellites were to be launched in pairs aboard a Titan III-C booster. Though once in orbit, these satellites performed well, their launch track record was spotty at best. The first pair was launched in 1971, but quickly experienced operational problems once in orbit. It took six months to overcome these problems and make the satellites usable. DSCS II underwent a major redesign based on the problems of the first launch, and a second pair were launched in 1973. A third pair of DSCS II satellites failed to reach orbit in 1975. The next set reached orbit in 1977, while the fifth pair again was a launch failure. A sixth set was launched in 1978, and the Air Force could now finally claim a full operational DSCS II constellation after seven years of trying with four operational, geosynchronous satellites and two on orbit spares. In 1973, the Air Force began designing the next generation communications satellite, DSCS III. It called for increased communications capacity, particularly for mobile terminal users, and for improved survivability. Though planning for DSCS III began in 1973, the first launch did not occur until 1982.
Developmental testing of tactical communications satellites began in the late 1960s with the launch of the Lincoln Experiment Satellites (LES) 5 and 6, and the Tactical Communications Satellite or TACSAT I. All three satellites operated at ultra and super high frequencies, and tested the feasibility of supporting small, mobile antenna users. In July 1970, initial operational capability was declared for tactical requirements using LES 6 and TACSAT I. However, it was the Navy who took the initiative to fully develop a complete operational system solely serving the tactical user, called Fleet Satellite Communications System or FLTSATCOM. This system was an outgrowth of the LES satellites and TACSAT I. Development of FLTSATCOM began in 1971, with five satellites launched between 1978 and 1981, with one failure due to damage during boost phase. Program management was totally under the control of the Navy, but the satellites were acquired by the Air Force through the Space and Missile Systems Organization at Los Angeles Air Force Base for the Navy.
There is one final communications customer, the nuclear capable forces. It was through these users that our nation’s strategic nuclear forces are controlled. These users required low data rates like tactical users, but needed high availability, worldwide coverage, and maximum survivability. Their needs were met with the space element of the Air Force Satellite Communications System (AFSATCOM). These transponders were placed on FLTSATCOM satellites and Satellite Data System (SDS) spacecraft.