The Solwind research satellite, which was providing useful scientific data until it was destroyed Sept. 13 in the first U.S. antisatellite test against a moving target, was originally scheduled to be fired at in the weapon's seventh test, a Defense Department official said yesterday.
That test would probably have come in 1987, when the satellite's solar research program was expected to be ending, according to scientists associated with the program.
Solwind was moved up for the first test because an instrumented target vehicle developed problems and Defense Secretary Caspar W. Weinberger wanted to go ahead "to show resolve," an Air Force official said at the time of the test.
Astrophysicists were surprised and angered that the satellite, which after six years was still providing unique images of activity in the sun's atmosphere, was used as the antisatellite target.
Yesterday, an Air Force spokesman said two experiments were operating when the Solwind was destroyed: a coronagraph run by the Naval Research Laboratory, which was providing a detailed record of solar activity, and a gamma ray spectrometer run by the Defense Advanced Projects Research Agency. There was no description released on the purpose of the gamma ray experiment, although it was considered the prime mission of the satellite.
Weinberger described the satellite as "burned out" on Wednesday, but yesterday an Air Force spokesman said the fact that the satellite was still sending signals back to Earth played a key role in its selection as a target.
"We had to have an active telemetry system to verify it had been hit," one official said. "A dead satellite would not have given us that."
The Solar Max satellite now in orbit provides some of the same type of imagery as Solwind, the official noted. That satellite is run by the National Aeronautics and Space Administration, not the Air Force as reported in yesterday's editions.