al., 2004). Analogous sentiments are echoed in the most recent version of the Bioastronautics Roadmap (NASA, 2005), which states that “actual risks must be operationally based, not research based.” Flight personnel identified four high-priority items:

1. Medical care diagnosis and treatment

2. Radiation exposure

3. Behavioral health and performance

4. Neurovestibular functionality

Bone loss was considered a lesser, but still important, item. The difference between this highest-priority list and preceding ones is that flight personnel place higher value on the ability of an astronaut to pilot a spacecraft during nominal and/or contingency operations. At the same time, they expressed the belief that successful countermeasures for musculoskeletal deconditioning are imminent.

An excellent example of the different values applied to the BR comes from the results of a consensus workshop held in May 2004 in Houston. Representatives of the Astronaut Office, Space Medicine Office, and the Bioastronautics Science Management Team (BSMT) met to review the BR and assess its suitability for reducing the risk of human space travel to Mars. Participants were asked to rate their concern about the subset of BR human risks, the need for future research in each area, and modifications to any of the risk set. Figure 3.1 summarizes data supplied to the committee.

Although the median “worriness” rating for the high risk category in the BR exceeded that of the medium risk category (median values 6.0 vs. 2.5; p = 0.015), the considerable overlap of “worriness” scores among the high, medium, and low risk BR categories (dark, medium and light gray dots, respectively in Figure 3-1) suggests that different heuristics to evaluate risk for human space exploration operate within NASA. Those communities most directly affected by the risk of a human space flight to Mars (i.e., astronauts and flight physicians) did not share all concerns raised by the disciplinary experts responsible for developing the BR, and in several cases felt that some risks did not belong in the Bioastronautics Roadmap (i.e., “worriness” score of 0).