1 Effectiveness of Accident Investigations of the Space Shuttle for Safety Improvement Taiki Matsumura 1 , Raphael T. Haftka 2 , and Nam H. Kim 3 University of Florida, Gainesville, FL, 32611 Accident investigation has been playing a crucial role for improving aviation safety by identifying unknown accident causes and leading to corrective actions. While the cost effectiveness of accident investigations for airliners has been studied, such studies are lacking for spacecraft. We study the cost effectiveness of the investigations of the Space Shuttle disasters. We find that for airliners we can ignore risks that were not involved in the accident, but for spacecraft this approximation is not accurate enough, and the effect of the corrective actions on the system failure probability must be accounted for. We evaluate the cost effectiveness of the Space Shuttle investigations by using the Department of Transportation guidelines for the value of saving lives in public transportation. According to the guidelines, the accident investigations of the Space Shuttle disasters are not cost effectives in terms saving lives. The cost effectiveness is also examined from the point of view of program sustainability (monetary value of the vehicle). We find that the Challenger case is substantially cost effective and the Columbia case is worth spending more than $100 million. I. Introduction he safety of airplanes and space vehicles have been improved alongside the evolution of design, manufacturing and maintenance [1, 2]. In addition, safety improvements triggered by accidents have been playing a crucial role. Investigation following an accident or incident identifies failure modes which were not recognized by designers and operators. Then safety recommendations are issued in order to prevent similar accidents in the future. Safety remedies following investigations consist not only of modifications of design and maintenance procedures but also of improvements in regulations and design philosophies, which make a significant contribution to risk reduction by being applied to entire communities. These are not limited to current fleets, but also to yet-to-developed vehicles in the future. For commercial aviation, there is an independent organization responsible for accident investigation, i.e., the National Transportation Safety Board (NTSB). The annual budget of NTSB for aviation safety is around $30 million [3]. The actual cost of an investigation is much higher than the NTSB cost (at least by a factor of four) when the cost of other agencies and private sector is taken into account [4]. In comparison, the space community often organizes an independent committee responsible for investigation in case of disaster (e.g., Columbia Accident Investigation Board (CAIB) for the Space Shuttle Columbia accident in 2003). The investigation reportedly costed more than $100 million. Thus, cost for accident investigation of a space vehicle is substantially higher than for an airplane accident. While the cost effectiveness of safety implementations after accidents is usually examined, e.g., FAA’s airworthiness directives, there are few studies on cost effectiveness of accident investigations in the open literature. Matsumura et al. [5] demonstrated the ease of estimating cost effectiveness of a single accident investigation for commercial airplanes. It was shown that two past accident investigations for commercial airplanes were considered cost effective according to the Department of Transportation (DOT) guideline for public transportation about monetary value of life saved ($6.2 million [6]). 1 Graduate student, Mechanical and Aerospace Engineering department, PO Box 116250, University of Florida, Gainesville, FL 32611, Student Member AIAA. 2 Distinguished professor, Mechanical and Aerospace Engineering department, PO Box 116250, University of Florida, Gainesville, FL 32611, Fellow AIAA. 3 Associate professor, Mechanical and Aerospace Engineering department, PO Box 116250, University of Florida, Gainesville, FL 32611, Associate Fellow AIAA T