Critical mission tasks that are required by crews immediately after landing on a planetary surface are seat egress, jump, and walk. To be able to define an effective and comprehensive countermeasure strategy for preserving crew performance during exploration-class missions, there is a need to understand how these functional tasks are actually performed in partial gravity such as on the Moon or Mars. The researchers aim to analyze the execution of four critical mission tasks during the partial gravity and hypergravity phases of parabolic flight by using the same equipment and procedures as those previously used on astronauts returning from International Space Station (ISS) missions and ground-based subjects during axial body unloading.
The goals of this study are (a) to determine the dose-response relationship between the performance of these tasks versus gravity levels between 0 and 1 g; and (b) to identify the vestibular, sensorimotor, and cardiovascular factors that would likely affect their execution.
Twelve subjects (six male and six female) will be tested during 3 flights of 30 parabolas, including 10 parabolas at 0.25 g, 10 parabolas at 0.5 g and 10 parabolas at 0.75 g. Performance metrics will include (a) the time for the subject to complete the test (Seat Egress and Walk, Recovery from Fall and Stand); (b) the time elapsed between the start of motion and the stabilization of upright posture (Recovery from Fall and Stand, Jump Down); (c) the mean sway speed during quiet standing (Recovery from Fall and Stand, Jump Down); (d) changes in heart rate and blood pressure (Recovery from Fall and Stand); (e) the percentage of correct steps and torso acceleration (Tandem Walk); and (f) the severity of motion sickness symptoms. The subjects will not be offered anti-motion sickness medication because the drug could alter their task performance.
The functional tasks tests in this study challenge balance control, a function that is paramount to the efficient completion of critical mission tasks. Knowledge gained from this study will allow the researchers to characterize the risk for partial gravity levels, thus ensuring a more effective and comprehensive countermeasure strategy for preserving crew performance during exploration-class missions.
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