<title>Results of STS-51 orbiter crew compartment contamination generation and extravehicular activity (EVA) payload bay transfer experiment</title>

Abstract

Results of STS-5 1 orbiter crew compartment contamination generationand EVA payload bay transfer experimentPatricia A. HansenSwales and Associates, Inc.Beltsville, Maryland 20705Randy J. HedgelandNASA/Goddard Space Flight CenterGreenbelt, Maiyland 20771Carl R. MaagT & M EngineeringGlendora, California 91740Calvin H. SeamanNASA/Johnson Space CenterHouston, Texas 77058ABSTRACTContamination witness plates were flown on STS-51 as part of a NASA Extravehicular Activity (EVA) Flight Test Experimentto quantify and identify particulate contamination generated in the Orbiter crew compartment which has the potential tocontaminate the Extravehicular Mobility Units (EMUs) and transfer from the EMUs to mission critical hardware during EVAs.Particles, larger than 100 microns, were found on both witness plates, indicating transfer from the EMUs during EVAs. Formissions such as the Hubble Space Telescope First Servicing Mission, where contamination critical optical elements wereexposed during EVAs, the potential for particulate transfer from the crew compartment to these optical elements and theHubble Space Telescope was evaluated.Key Words: Extravehicular Activity, particulate contamination, Orbiter crew compartment contamination, Hubble SpaceTelescope, First Servicing MissionINTRODUCTIONSuccessful on-orbit servicing of the Hubble Space Telescope (HST) was conducted during five Extravehicular Activities(EVAs) of the STS-61 mission, December 2-13, 1993. The most contamination critical EVAs involved exchanging twoscientific instruments (SIs) with corrected optics for the first generation instruments, the Wide Field Planetary Camera II(WFPC II) with the WFPC I and the Corrective Optics Space Telescope Axial Replacement (COSTAR) with the High SpeedPhotometer. The COSTAR resides in the HST Aft Shroud (AS) and required that the EVA crew enter the AS during thechangeout to secure cables and insert the SI. This was the first time an astronaut would enter a working Observatory andconcerns were raised whether exposure of the EVA Crew to the AS would unacceptably degrade the AS cleanliness levels.During the evaluation it was found that the Crew Aids and Tools (CATs) and Extravehicular Mobility Units (EMUs) had thegreatest exposure to contamination within the Orbiter crew compartment. No data existed to determine if crew compartmentcontamination degrades the cleanliness level of the EMUs during standard EVA missions. Degradation of the EMUscleanliness level was a concern if the subsequent exposure to the AS would cause unacceptable contamination of the AS orSIs. While exposure to the Orbiter crew compartment may be insignificant for most payloads, more than 150 of the HST FirstServicing Mission (FSM) CATs were exposed to the crew compartment. The collective surface area of these CATs was largeand could possibly carry a great deal of contamination into the PLB and subsequently into the HST AS during the EVAs. Asimple experiment was devised to determine if contamination generated in the crew compartment is indeed transferred to the2 /SPIE Vol. 2261