Prepare, calibrate and fly a programmable low-energy particle detection instrument on board the SCATHA satellite

This report summarizes the progress made on the preparation of the SC-9 plasma particle instrument for flight on the SCATHA space vehicle. The history of this project is long and complicated. Originally UCSD proposed to fly an ATS-5 flight spare instrument with suitable refurbishment and calibration. Then several agencies became involved with the problems of spacecraft charging. By the time the concept of SCATHA was established, the prototype instrument of the ATS-6 plasma instrument was available. This instrument is a vastly improved version of what had been flown on ATS-5. It detects particles over a much wider energy range and features sensing heads which rotate in two perpendicular directions. A major problem with either instrument is that they were built to interface to a specific spacecraft which had a considerably different configuration from SCATHA. This necessitated the construction of an interface box which not only prepares the telemetry signals, but does such things as accumulate the output signals (on ATS-6 accumulation and log compression were spacecraft functions). This in turn required the design and construction of a totally new ground support equipment.