to develop a Scout-launched target vehicle for ASAT experiments. NASA advised the U.S. Air Force on how to conduct the ASAT test to avoid producing long-lived debris. However, congressional restrictions on ASAT tests intervened.
In order to complete an ASAT test before an expected Congressional ban took effect (as it did in October 1985), the DoD chose to use the existing Solwind astrophysics satellite as a target.
NASA worked with the DoD to monitor the effects of the tests using two orbital debris telescopes and a reentry radar deployed to Alaska.
NASA assumed the torn metal would be bright. Surprisingly, the Solwind pieces turned out to appear so dark as to be almost undetectable. Only two pieces were seen. NASA Scientists theorized that the unexpected Solwind darkening was due to carbonization of organic compounds in the target satellite; that is, when the kinetic energy of the projectile became heat energy on impact, the plastics inside Solwind vaporized and condensed on the metal pieces as soot.
NASA used U.S. Air Force infrared telescopes to show that the pieces were warm with heat absorbed from the Sun. This added weight to the contention that they were dark with soot and not reflective. The pieces decayed quickly from orbit, implying a large area-to-mass ratio. According to NASA, as of January 1998, 8 of 285 trackable pieces remained in orbit.
The Solwind test had three important results:
- It raised the possibility that the objects optical systems were detecting were large and dark, not small and bright as was generally assumed. This had implications for the calibration of optical and radar orbital debris detection systems.
- The test also created a baseline event for researchers seeking a characteristic signature of a hypervelocity collision in space.
- Awareness was raised about the orbital debris problem.
In the end, the Solwind ASAT test had few consequences for the planned U.S. space station as station completion was pushed beyond the mid-1990s. The record-high level of solar activity during the 1989–1991 solar maximum heated and expanded the atmosphere more than anticipated in 1985, accelerating Solwind debris decay.
|1||21 January 1984||Missile successfully tested without miniature vehicle|
|2||13 November 1984||Missile failed when MHV was directed at a star.|
|3||13 September 1985||Missile successfully destroys the satellite P78-1 Solwind|
|4||22 August 1986||Missile successfully tested when MHV was directed at a star.|
|5||29 September 1986||Missile successfully tested when MHV was directed at a star.|
Fifteen ASM-135 ASAT missiles were produced and five missiles were flight tested.
Operational history[edit | edit source]
The United States Air Force intended to modify 20 F-15A fighters from the 318th Fighter Interceptor Squadron based at McChord Air Force Base in Washington and the 48th Fighter-Interceptor Squadron based at Langley Air Force Base in Virginia for the anti-satellite mission. Both squadrons had airframes modified to support the ASM-135 by the time the project was cancelled in 1988.
The USAF had planned to deploy an operational force of 112 ASM-135 missiles.
The deployment of the ASM-135 was central to a policy debate in the United States over the strategic need for an anti-satellite weapon and the potential for anti-satellite weapon arms control with the Soviet Union. Starting in 1983, Congress placed various restrictions on the ASM-135 program, and in December 1985, banned testing the ASM-135 on targets in space. This decision was made only a day after the Air Force sent two target satellites into orbit for its next round of tests. The Air Force continued to test the ASAT system in 1986, but stayed within the limits of the ban by not engaging a space-borne target.
In the same year the deployment of the ASM-135 was estimated to cost $US5.3 billion up from the original $US500 million estimate. The USAF scaled back the ASM-135 program by two-thirds in attempt to control costs. The USAF also never strongly supported the program and proposed canceling the program in 1987. In 1988, the Reagan 