Encyclopedia Astronautica
Program 437

America's second operational anti-satellite system, launched on sub-orbital trajectories by Thor LV-2D's operated by the US Air Force from Johnson Atoll in the Pacific. Operational 1964-1970.

Program 437 was America's second operational anti-satellite system. It was launched on sub-orbital trajectories by Thor LV-2D's operated by the U.S. Air Force from Johnson Atoll. Perhaps not coincidentally, Thor had been used for space nuclear tests from the same launch site in the early 1960's. These tests that inadvertently led to discovery of the extreme damage to electronics that could be caused by EMP (electromagnetic pulse) from a high altitude nuclear detonation. The Program 437 Thor could hit satellites up to 700 km altitude using a Mk. 49 nuclear warhead with an 8 km kill radius. The first flight was February 1964, and the system was declared operational in June 1964. The system had a two week reaction time - the missiles and warheads were stored in kits at Vandenberg and had to be deployed to the atoll.

The limitations of a nuclear-tipped ASAT system were apparent - using nuclear warheads just to get a satellite would be destabilizing in a non-nuclear war scenario. Furthermore the EMP effect could damage a large number of your own satellites. The Program 437 system was put 'on standby' in 1970 and canceled in 1972 when a hurricane damaged the guidance computers on the atoll beyond economic repair.

In 1965-1966 four Program 437 Thors were launched with 'Alternate Payloads' for satellite inspection. This was evidently an elaboration of the system to allow visual verification of the target before destroying it. These flights may have been related to the late 1960's Program 922, a non-nuclear version of Thor with infrared homing and a high explosive warhead.

The SALT-1 Treaty of May 1972 prohibited 'interference with national means of verification' which meant that ASAT's were not allowed, by treaty, to attack Russian spy satellites. While this did not explicitly prohibit development of ASAT's, further development would be met by Soviet protests and opposition by certain political groups in the US.

After the loss of Program 437 capability, the USAF moved on to air-launched conventional warhead ASAT's, first with project SPIKE for launch from an F-106, culminating in the F-15 ASAT missile of the 1980's.

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Associated Countries
See also
Associated Launch Vehicles
  • Delta American orbital launch vehicle. The Delta launch vehicle was America's longest-lived, most reliable, and lowest-cost space launch vehicle. Delta began as Thor, a crash December 1955 program to produce an intermediate range ballistic missile using existing components, which flew thirteen months after go-ahead. Fifteen months after that, a space launch version flew, using an existing upper stage. The addition of solid rocket boosters allowed the Thor core and Able/Delta upper stages to be stretched. Costs were kept down by using first and second-stage rocket engines surplus to the Apollo program in the 1970's. Continuous introduction of new 'existing' technology over the years resulted in an incredible evolution - the payload into a geosynchronous transfer orbit increasing from 68 kg in 1962 to 3810 kg by 2002. Delta survived innumerable attempts to kill the program and replace it with 'more rationale' alternatives. By 2008 nearly 1,000 boosters had flown over a fifty-year career, and cancellation was again announced. More...

Associated Manufacturers and Agencies
  • USAF American agency overseeing development of rockets and spacecraft. United States Air Force, USA. More...
  • Douglas American manufacturer of rockets, spacecraft, and rocket engines. Boeing Huntington Beach, Huntington Beach, CA, USA. More...

  • Federation of American Scientists Web Site, Web Address when accessed: here.
  • Peebles, Curtis, Battle for Space, Bookthrift, 1987.

Program 437 Chronology

1964 June - . LV Family: Delta. Launch Vehicle: Thor. LV Configuration: Thor LV-2D.
  • Program 437 ASAT declared operational. - . Nation: USA. Spacecraft: Program 437. Summary: The system had a two week reaction time - the missiles and nuclear warheads were stored in kits at Vandenberg and had to be deployed to the Johnson Atoll launch site..

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