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Implementing Recommendations of the Columbia Accident Investigation Board - Development of on-Orbit RCC ThermographyOne of NASA s Space Shuttle Return-to-Flight (RTF) efforts has been to develop thermography for the on-orbit inspection of the Reinforced Carbon Carbon (RCC) portion of the Orbiter Wing Leading Edge (WLE). This paper addresses the capability of thermography to detect cracks in RCC by using in-plane thermal gradients that naturally occur on-orbit. Crack damage, which can result from launch debris impact, is a detection challenge for other on-orbit sensors under consideration for RTF, such as the Intensified Television Camera and Laser Dynamic Range Imager. We studied various cracks in RCC, both natural and simulated, along with material characteristics, such as emissivity uniformity, in steady-state thermography. Severity of crack, such as those likely and unlikely to cause burn through were tested, both in-air and in-vacuum, and the goal of this procedure was to assure crew and vehicle safety during re-entry by identification and quantification of a damage condition while on-orbit. Expected thermal conditions are presented in typical shuttle orbits, and the expected damage signatures for each scenario are presented. Finally, through statistical signal detection, our results show that even at very low in-plane thermal gradients, we are able to detect damage at or below the threshold for fatality in the most critical sections of the WLE, with a confidence exceeding 1 in 10,000 probability of false negative.
Document ID
20040171549
Acquisition Source
Headquarters
Document Type
Preprint (Draft being sent to journal)
Authors
Ottens, Brian
Parker, Brad
Stephen, Ryan
Date Acquired
August 22, 2013
Publication Date
January 1, 2005
Subject Category
Spacecraft Design, Testing And Performance
Meeting Information
Meeting: Thermosence XXVII
Location: Orlando, FL
Country: United States
Start Date: March 28, 2005
End Date: April 1, 2005
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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