Aerospace’s Characterization of the External Tank Foam Debris Risk Analyses Critical to Shuttle Return-to-Flight

Corporate Staff
posted November 30, 2012


Space shuttle Columbia disintegrated during re-entry on Feb. 1, 2003. Seven astronauts died, and the nation’s human spaceflight program was halted. Subsequent investigations revealed that the liberation of foam from the shuttle external tank had damaged the leading edge of the Columbia wing during ascent. NASA needed science-based analyses of this foam liberation to determine corrective action and to assure the NASA administrator and the American public that we could again safely transport humans into space. In early 2004, it became obvious that NASA and Boeing did not have a satisfactory approach to assess foam debris risk for future flights.

NASA Administrator Michael Griffin convened a debris summit in Houston to address the foam debris risk issue. During the summit, Administrator Griffin expressed his dissatisfaction with the current worst-case on worst-case approach to the determination of foam debris risk. Griffin outlined a Monte Carlo analysis approach needed for the accurate determination of foam debris risk. Such a tool would normally require three to six months to develop and refine before being operational.

Aerospace Actions:

In 2003, the Aerospace team led by John Brekke had been able to convince a skeptical NASA to allow Aerospace to work on a Monte Carlo approach to foam debris risk as a backup approach. Later that same day, the Aerospace Monte Carlo foam risk tool was presented to NASA. NASA adopted the approach, placing Aerospace on the critical path for the first shuttle Return-to-Flight launch (STS-114 launched on July 26, 2005) and every subsequent shuttle flight until the completion of the shuttle program in 2011. Aerospace foresight in developing a Monte Carlo approach to foam debris risk analysis saved NASA three to six months of schedule, with an estimated consequent cost savings of $1 to $2 billion dollars.

From this point, Aerospace had significant responsibility and accountability for the safe return to flight of the U.S. Human Spaceflight Program. There were considerable pressures to return to flight sooner rather than later. The Aerospace team demonstrated courage, dedication, and commitment to analyses-based recommendations as we developed the tools and processes that would allow NASA to understand and mitigate the foam liberation hazard. Aerospace was well aware that another shuttle loss would doom the program permanently and would cost additional lives. Yet the United States and its international partners were anxious for re-establishment of this critical ability to lift humans and supplies to low Earth orbit.

Value Added:

Summary. The Aerospace team provided critical foam debris risk analyses to NASA for the space shuttle. Without Aerospace’s contribution, NASA had no clear path for return to flight after the Columbia shuttle accident. Aerospace provided world-class, first-of-a-kind, critical support within the highest-stress environment conceivable: a critical national program involving human life. NASA could not have returned to flight when it did without Aerospace. This work exemplifies Aerospace mission assurance at its best.

Aerospace on the Critical Path for Safe Return to Flight for a Human Spaceflight Program. This work exceeded normal job responsibilities and expectations in every way. First, we were on the critical path for safe return to flight for a human spaceflight program — this fact alone exceeds normal expectations at Aerospace. Second, the president of the United States was involved, and partner nations were also involved in this program. The world was watching to see if NASA could determine the cause of the Columbia failure, implement corrective action, and safely re-establish the United States as the world’s premier spacefaring nation. Aerospace was central to NASA’s accomplishment of all these objectives. The sole determinant for return to flight was the foam liberation that caused the Columbia accident. Aerospace was the critical element for solving this perplexing problem. It is rare for Aerospace to be placed in such a high-visibility, high-exposure, and high-importance role.

Monte Carlo Foam Debris Analysis Tool Attains Shuttle Program Critical Math Model Status. Over the seven-year period following the Columbia accident, the Aerospace team of John Brekke, Randall Williams, Matthew Eby, and Brian Hardy consistently exceeded NASA’s expectations. It was an outstanding achievement when the Aerospace’s original Monte Carlo foam debris analysis tool was incorporated in as one of the shuttle program’s critical math models. NASA Associate Administrator Chris Scolese in a 2008 letter of commendation to Dr. Wanda Austin praised Aerospace for this accomplishment (“Aerospace’s foam debris Monte Carlo analysis tool has attained Critical Math Model status for the Shuttle Program. Additionally, your impact test results for small, high speed foam on tile is considered Category 1 level, the highest possible within the Shuttle Program. These achievements demonstrate a corporate commitment to NASA’s requirements.”) However, Aerospace did not curtail its support to NASA after this notable achievement. Aerospace continued to improve this analysis tool throughout the return-to-flight effort. The team supported the flight readiness reviews of all 22 successful missions following the Columbia accident. Aerospace provided high fidelity and refined analyses of the shuttle’s foam debris risk, which were remarkably complemented by the results of Aerospace’s NASA-certified test program that simulated high-speed foam projectile impacts on Orbiter tiles. Aerospace’s dedication to mission success and technical excellence served to improve NASA’s damage models well beyond the agency’s expectations.

Letter of Commendation. In a 2012 letter to Dr. Wanda Austin, Chris Scolese, NASA associate administrator, and William Gerstenmaier, NASA associate administrator for space operations, recognized the contributions of Aerospace saying: “These achievements demonstrated a corporate commitment to NASA’s goals. The analytical and empirical results generated by your team enabled the Shuttle community to put the foam debris issue in the proper perspective at each Flight Readiness Review, giving NASA confidence the risk had been appropriately characterized before each flight. NASA is very grateful to have mission partners such as The Aerospace Corporation and we appreciate your commitment to NASA’s record of mission success.”….“Your analyses and testing helped provide NASA Leadership needed confidence in continuing the fly-out of the Program.”