Members of a White House-appointed committee tasked with reassessing NASA’s human spaceflight plans voiced disagreement Oct. 8 about how safety should be factored into the group’s forthcoming ranking of space exploration options in the post-shuttle era.

The panel, led by former Lockheed Martin chief Norm Augustine, held a public teleconference in which panelist Bohdan “Bo” Bejmuk argued in favor of ranking the five options according to vehicle safety. Bejmuk said the metric would give NASA’s planned Ares 1 rocket a leg up versus other launch vehicle options laid out by the panel in an interim report released in September. The panel’s final report is expected in mid-October.

Fellow panelist Wanda Austin, president and chief executive of Los Angeles-based Aerospace Corp., said the safety of each option had been scored according to mission destination — low Earth orbit, the Moon or beyond — rather than the hardware used to get there.

“Part of the challenge we have is for vehicles that have not flown,” such as Ares 1, Austin said. “Trying to make a safety assessment is, in the area of risk, probably a difficult thing for us to do.”

Augustine agreed, saying Bejmuk’s proposed eleventh-hour change would be “very inconsistent with how we’ve rated everything else” in terms of safety. Augustine suggested including language in the panel’s final report stating that launch vehicles based on simple, solid-rocket boosters, including Ares 1, are safer than those based on liquid engines.

Bejmuk said he could live with the change, but added that “participation of a simpler rocket should be a positive from the point of view of mission safety. I’m not sure our rating system recognizes that.”