The Environmental Verification Experiment for the Explorer Platform (EVEEP) is an on-orbit contamination verification experiment that will fly as a secondary payload with the Extreme Ultraviolet Explorer (EUVE) mission aboard an Explorer Platform (EP). The EP includes a Multi-mission Modular Spacecraft (MMS) with a Platform Equipment Deck (PED) to accommodate mission unique payloads. The EUVE will be the first payload to fly on an EP. The EP/EUVE will be launched aboard a Delta II in May 1992. The current contamination control engineering approach for extremely sensitive instruments onboard spacecraft like EUVE is to restrict the view factors between the instrument apertures and the spacecraft, control vent locations, and reduce out-gassing to levels that allow end-of-life requirements to be met. This design approach relies heavily on the ability of current molecular mass transport computer programs to predict the fraction of the spacecraft's molecular out-gassing mass which is scattered off itself or the ambient atmosphere and condensed back onto the sensitive surfaces. These analytical programs have never been verified on orbit. Due to the uncertainty of their predictions, more margin than may be necessary is being incorporated into the design, which translates into significant additional expense. Although a few contamination experiments have been flown for other reasons, little is known of the host vehicle's out-gassing rates or vent paths during these experiments. This makes it impossible to use the flight data for model verification. Ground tests are not suitable because it is impossible to simulate the orbital velocities and the long mean free paths of these molecules. The EVEEP is designed to be an important step in providing the needed on-orbit verification.
Environmental Verification Experiment for the Explorer Platform Prelaunch Mission Operation Report
1992
12 pages
Report
Keine Angabe
Englisch
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