Abstract:

The International Space Station (ISS) has been operating in space for over 14 years and permanently crewed for over 12 years. Throughout this time, the ISS Program has implemented and continually improved its risk management process. This ISS risk management process identifies risks that may exist and alternatives for mitigation if the risks are significant. Risk management has provided input that has been essential to the program management decision making process. Risks can be reduced, mitigated or accepted and are prioritized to ensure program resources are used as efficiently as possible. The ISS risk management process has increased the probability of success of the ISS mission objectives and overall crew safety.
This paper presents two case studies on how the ISS risk management process has been used to address specific areas of risk. The first case describes how the ISS Program has analyzed and mitigated the risk of Micrometeoroid Orbital Debris (MMOD) strikes to pressurized modules. MMOD has been a major safety concern since the beginning of the program. The second case study describes the risk assessment of Visiting Vehicle (VV) collisions. There has been a significant increase in the number of visiting vehicle flights to the ISS since the retirement of the Space Shuttle Program. This has caused an elevated cumulative risk of collision when considering the frequency of vehicle traffic to the ISS.