Estimating the Public Safety Risk of New Capsule Re-Entry Systems

摘要

Commercial developers are entering a domain that had traditionally been that of the government via NASA: launching human crew into space and returning them safely to Earth. The crew is envisioned to comprise astronauts in the near term, and members of the public at large in the mid to long term. Both NASA and the FAA will have to address the risks to the human crew and develop processes by which they decide what risks are acceptable and what methods are adequate to estimate those risks. But even before human crew gets on-board, demonstration missions can pose safety risks to the general public. The FAA has a long history of assessing and regulating general public safety risks posed by the launch of vehicles into space and the potential for launch vehicle failures leading to falling debris. As commercial companies develop and test their crewed launch systems, the FAA role is expanding to assess and regulate the risk posed by the corresponding re-entry vehicles. This paper reviews a practical method to estimate the general public safety risk posed by a new re-entry system using a capsule design. The paper shows how a general risk estimate can be derived before first launch, and discusses the factors to take into account to update it for subsequent launches. Accent is placed on ways to avoid common risk quantification pitfalls and strive for accuracy over precision. The authors hope that the practical pointers in the paper can be of use not only to those needing to estimate similar risks, but also to those developing the processes and methods needed to support the commercial development of human spaceflight.