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Overview of EVA PRA for TPS Repair for Hubble Space Telescope Servicing MissionFollowing the Columbia accident in 2003, NASA developed techniques to repair the Thermal Protection System (TPS) in the event of damage to the TPS as one of several actions to reduce the risk to future flights from ascent debris, micro-meteoroid and/or orbital debris (MMOD). Other actions to help reduce the risk include improved inspection techniques, reduced shedding of debris from the External Tank and ability to rescue the crew with a launch on need vehicle. For the Hubble Space Telescope (HST) Servicing Mission the crew rescue capability was limited by the inability to safe haven on the International Space Station (ISS), resulting in a greater reliance on the repair capability. Therefore it was desirable to have an idea of the risk associated with conducting a repair, where the repair would have to be conducted using an Extra-Vehicular Activity (EVA). Previously, focused analyses had been conducted to quantify the risk associated with certain aspects of an EVA, for example the EVA Mobility Unit (EMU) or Space Suit; however, the analyses were somewhat limited in scope. A complete integrated model of an EVA which could quantify the risk associated with all of the major components of an EVA had never been done before. It was desired to have a complete integrated model to be able to assess the risks associated with an EVA to support the Space Shuttle Program (SSP) in making risk informed decisions. In the case of the HST Servicing Mission, this model was developed to assess specifically the risks associated with performing a TPS repair EVA. This paper provides an overview of the model that was developed to support the HST mission in the event of TPS damage. The HST Servicing Mission was successfully completed on May 24th 2009 with no critical TPS damage; therefore the model was not required for real-time mission support. However, it laid the foundation upon which future EVA quantitative risk assessments could be based.
Document ID
20090033146
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Bigler, Mark
(NASA Johnson Space Center Houston, TX, United States)
Duncan, Gary
(Science Applications International Corp. Houston, TX, United States)
Roeschel, Eduardo
(Science Applications International Corp. Houston, TX, United States)
Canga, Michael
(Science Applications International Corp. Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2010
Subject Category
Space Transportation And Safety
Report/Patent Number
JSC-CN-18833
Meeting Information
Meeting: 10th International Probabilistic Safety Assessment and Management Conference
Location: Seattle, WA
Country: United States
Start Date: June 7, 2010
End Date: June 11, 2010
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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