Effects of Standing, Upright Seated, vs. Reclined Seated Postures on Astronaut Injury Biomechanics for Lunar Landings.

Abstract

Astronauts may pilot a future lunar lander in a standing or upright/reclined seated posture. This study compared kinematics and injury risk for the upright/reclined (30°; 60°) seated vs. standing postures for lunar launch/landing using human body modeling across 30 simulations. While head metrics for standing and upright seated postures were comparable to 30cm height jumps, those of reclined postures were closer to 60cm height jumps. Head linear acceleration for 60° reclined posture in the 5g/10ms pulse exceeded NASA's tolerance (10.1g; tolerance: 10g). Lower extremity metrics exceeding NASA's tolerance in the standing posture (revised tibia index: 0.36-0.53; tolerance: 0.43) were lowered in seated postures (0.00-0.04). Head displacement was higher in standing vs. seated (9.0cm vs. 2.4cm forward, 7.0cm vs. 1.3cm backward, 2.1cm vs. 1.2cm upward, 7.3cm vs. 0.8cm downward, 2.4cm vs. 3.2cm lateral). Higher arm movement was seen with seated vs. standing (40cm vs. 25cm forward, 60cm vs. 15cm upward, 30cm vs. 20cm downward). Pulse-nature contributed more than 40% to the injury metrics for seated postures compared to 80% in the standing posture. Seat recline angle contributed about 22% to the injury metrics in the seated posture. This study established a computational methodology to simulate the different postures of an astronaut for lunar landings and generated baseline injury risk and body kinematics data.