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Apollo-Soyuz Test Project

Apollo-Soyuz docking
Credit: NASA

* Mission Overview

The Apollo-Soyuz mission occurred in July, 1975. In addition to the manned mission objectives of international space cooperation, testing universal docking systems, etc., Apollo-Soyuz carried a number of scientific instruments.

* Instrumentation

The U.S. portion of the mission carried a proportional counter system sensitive to 0.18-0.28 and 0.6-10.0 keV X-rays. The total effective area was 0.1 m2, and there was a 4.5 degree FWHM circular field of view.

* Science

Results from this experiment included the discovery of soft X-ray emission from the supernova remnant MSH 14-63 and of rapid pulsations (0.716 s) from the binary SMC X-1. Due to the (comparatively) short duration of the Apollo-Soyuz mission, little other science of note was done with the proportional counter system. In addition, the detector had a moderately high background level that steadily increased through the duration of the mission until almost no X-ray sources were discernible. The cause of the background problems remains unknown.

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