Prediction of Lunar- and Martian-Based Intra- and Site-to-Site Task Performance

BACKGROUND: This study aimed to investigate the feasibility of determining the physiological parameters associated with the ability to complete simulated exploration type tasks at metabolic rates which might be expected for lunar and Martian ambulation. METHODS: Running (V)over doto(2max) and gas exchange threshold (GET) were measured in 21 volunteers. Two simulated extravehicular activity field tests were completed in 1 G in regular athletic apparel at two intensities designed to elicit metabolic rates of similar to 20.0 and similar to 30.0 ml.kg(-1) . min(-1), which are similar to those previously reported for ambulation in simulated lunar- and Martian-based environments, respectively. RESULTS: All subjects were able to complete the field test at the lunar intensity, but 28% were unable to complete the field test at the Martian intensity (non-Finishers). During the Martian field test there were no differences in (V)over doto(2) between Finishers and non-Finishers, but the non-Finishers achieved a greater %(V)over doto(2max) compared to Finishers (78.4 +/- 4.6% vs. 64.9 +/- 9.6%). Logistic regression analysis revealed fitness thresholds for a predicted probability of 0.5, at which Finishing and non-Finishing are equally likely, and 0.75, at which an individual has a 75% chance of Finishing, to be a (V)over doto(2max) of 38.4 ml . kg(-1) min(-1) and 40.0 ml . kg(-1) . min(-1) or a GET of 20.1 ml . kg(-1) . min(-1) and 25.1 ml . kg(-1) . min(-1), respectively (chi(2) = 10.2). Logistic regression analysis also revealed that the expected %(V)over doto(2max) required to complete a field test could be used to successfully predict performance (chi(2) = 19.3). DISCUSSION: The results of the present investigation highlight the potential utility of (V)over doto(2max) particularly as it relates to the metabolic demands of a surface ambulation, in defining successful completion of planetary-based exploration field tests.