posted 01-23-2009 10:00 AM               

The space industry is approaching a fateful six-day period that has become an annual time of reflection and rededication, as it honors the memory of the three great space tragedies in our history: Apollo 1 (Jan. 27, 1967), Challenger (Jan. 28, 1986) and Columbia (Feb. 1, 2003).

These anniversaries serve as reminders that the price we sometimes pay for extending our reach beyond our earthly grasp can be high. For that reason, it is imperative that we base decisions about how to proceed with our nation's agenda in space on the right arguments.

There is an ongoing discussion among the aerospace and political community regarding the risks of flying the space shuttle beyond its current retirement date of 2010. Those who oppose it often cite aging and safety concerns. Too often, these arguments have been based on somewhat scary probability figures that, by themselves, are wholly inadequate to determine how much longer the shuttle should fly.

...after 126 flights, the demonstrated reliability of the space shuttle is 98.4 percent. Other than the Russian Soyuz (98.2 percent), the demonstrated reliability of systems currently being considered for human spaceflight is zero, since those systems have not yet flown.

Ultimately, there is no way to eliminate risk in spaceflight. At best we can try to understand and manage it to an acceptable level. The risk of flying the shuttle has been successfully managed in 98.4 percent of the missions. The continuous efforts to improve the safety and reliability have resulted in a robust system that is, in many ways, safer each time it flies.