The losses of the space shuttles Challenger in 1986 and Columbia in 2003 dramatically illustrated the risks involved in the human exploration of space, and provide starkly instructive case studies in the ethics of science and technology.

A central mission of the National Aeronautics and Space Administration (NASA) is human exploration of space. Given this legitimate political commitment to human space exploration, the space shuttle program is ethically and politically acceptable insofar as the agency in charge, NASA, promotes careful and honest examination of the human risks and, in reaching the compromises unavoidable in balancing safety against performance, involves those most subject to the risks and those making the political commitment.

The careful, honest examination of risk cannot be done once; it must continue as flight experience accumulates. In balancing safety and performance the shuttle's design both represents NASA's understanding...