OM in the News: NASA’s “Failed Mission” Probabilities

NASA is working with Elon Musk’s SpaceX to redesign part of the fuel system for the company’s Falcon 9 rockets and then will demand at least 7 successful unmanned flights before allowing astronauts on board. With routine flights ferrying U.S. astronauts to the orbiting international space station slated to begin in fall of 2019, the agency has raised new questions about potential hazards and longstanding NASA safety standards, writes The Wall Street Journal (Jan.18, 2018). Ending current U.S. reliance on Russian capsules for crew transportation may “require decisions to accept a higher risk” on next-generation U.S. systems than anticipated, says NASA.

NASA’s statistical limit for a “failed mission” remains 1 in 55 launches, despite several years of intense development, NASA expenditures of about $5 billion and significant additional investment by the two companies bidding for contracts–Boeing and SpaceX. That limit applies to mission failures in which the vehicle doesn’t reach the space station but the crew uses emergency procedures to survive.

NASA’s statistical standard for crew fatalities is no greater than one in 270 flights, though neither Boeing nor SpaceX is on track to meet that precise mandatory benchmark. By contrast, the global airline industry has achieved fatal accident rates for jetliners of 1 crash for several million flights.

System reliability is an old, but crucial issue at NASA. During the long era of the Space Shuttle, which I was proud to be a part of, mission reliability was set at 98%. This meant a critical failure was anticipated every 50 flights. And indeed, the first Shuttle exploded on flight no. 25 (Challenger), and the 2nd loss on flight 113 (Columbia) . The Shuttle program ended with flight no. 135, as a 3rd crash was viewed as unsustainable.

Classroom discussion questions:

1. Is 1 in 55 (reliability = .982) acceptable? Why?
2. Why is NASA seeking this alternative to Russia’s Soyuz ferrying rockets?