The US's first anti-satellite system was
Program 505, based at the
Kwajalein Missile Range, about halfway between Hawaii and the Philippine islands. This system became operational in 1962, based on the
Nike Zeus anti-ballistic missile that had been tested at that site. These missiles had been modified for greater range, but even with these modifications the system could only intercept satellites that flew very close to the base, with a maximum altitude around . A system with longer range was an obvious requirement. Program 437 was based on the much more powerful
PGM-17 Thor ballistic missile. It used Thor DSV-2E missiles armed with a
W49 or
W50 nuclear weapon, which would destroy or disable targets through
nuclear explosion or the resulting
electromagnetic pulse. Eight Thor DSV-2E missiles were launched between May 2, 1962, and November 1, 1962. Though the program would routinely run successful tests with unarmed Thor missiles, the only high altitude nuclear explosions were conducted through Operations
Argus,
Hardtack I, and
Dominic/
Fishbowl between 1958 and 1962. Operation Argus operated out of the South Atlantic, while Hardtack and Dominic conducted their high altitude tests from the Johnston Island facilities. "Tightrope" was part of "Fishbowl" but was a lower altitude detonation. Some results of these tests, Dominic's 1962
Starfish Prime test in particular, presented concerns throughout the program's existence. In addition to the widespread effects of the nuclear explosion's electromagnetic pulse, which inadvertently damaged many
satellites as well as land based electronics as far as away, a large amount of
charged particle radiation was released by the nuclear explosion. This radiation became trapped by the
Earth's magnetic field, creating artificial belts of radiation 100 to 1,000 times stronger than
background levels. The heightened levels of radiation eventually crippled one-third of all satellites in low orbit, while rendering seven others completely useless, including the first commercial
communication satellite ever,
Telstar. It was eventually concluded that the due to the wide radius of damage, wartime deployment of Program 437 would result in indiscriminate destruction of friendly and enemy satellites, potentially destabilizing or escalating otherwise non-nuclear conflicts. In addition to these problems, the
Soviets deployed numerous
military satellites, making specific targeting impractical or ineffective. Furthermore, the
United States Air Force had a limited supply of Thor missiles, and all military resources (especially financial) had become increasingly strained with the US involvement in the
Vietnam War. In October 1970, the
Department of Defense transferred Program 437 to standby status as an economic measure. Test launches were no longer run, and the weapons system would take fourteen to thirty days to intercept targets, requiring components stored at
Vandenberg Air Force Base to be
airlifted by a
C-124 Globemaster II to Johnston Island for deployment. These obstacles further degraded the weapon's suitability and effectiveness for war. Part of Program 437 was
437 Alternate Payload (AP) which was used for satellite inspection. Thor DSV-2J missiles were used for the 437 Alternate Payload program. Eighteen DSV-2J Thors were launched from the Atoll between February 14, 1964, and November 6, 1975.
Demise On 19 August 1972,
Hurricane Celeste destroyed most of the facilities and guidance
computers at Johnston. Though the systems were able to be restored by September 1972, unspecified damage caused them to fail on 8 December. The program became fully repaired and restored by 29 March 1973, and remained in standby status until the anti-satellite mission on the Johnston Island facilities were ceased on 10 August 1974. Program 437 was officially terminated on 6 March 1975 at the request of
NORAD, and on 1 April 1975 the
Department of Defense terminated funding for any anti-satellite programs or development. In January 1977, at the end of his term of office, then
President Gerald Ford issued a directive for the DoD to again enter research and development on an operational anti-satellite program. It was an order his successor, President
Jimmy Carter, followed through on, and anti-satellite technology has continued to be in some form of research or development since. ==Operations==