Estimating Compressive Spinal Loads Due to Planetary Space Suits

Date

2020-07-31

Journal Title

Journal ISSN

Volume Title

Publisher

2020 International Conference on Environmental Systems

Abstract

Space suits provide protection during extravehicular activity (EVA) when the human leaves the vehicle. The Mark III (MKIII) space suit technology demonstrator contains a rigid torso and hip bearing assembly, with soft structure legs. The space suit load is distributed between the occupant and the suit itself, with this load being modified through adjustable straps. This paper considers the effect of body-borne loads from the space suit on the spinal compression in the context of potential injury risk. An OpenSim musculoskeletal model of the trunk was used to estimate spinal loading during stance. Loads from 0-22.7 kgs (0-50 lbs) were applied to the model at each shoulder in the vertical direction and loads from 0-9.1 kgs (0-20 lbs) were applied to the model at each shoulder in the shear direction, based on previous measured loads during terrestrial testing of the MKIII. Compressive loads of the thoracic and lumbar spine were estimated when varying the applied load magnitude and direction on the shoulder, as well as the spinal curvature of the model. With increased loads at the shoulder, an increase in spinal compressive loads was observed. Largest compressive spine loads were observed in the lower thoracic spine (T10–T12) for all shoulder load simulations, and most spine curvature simulations. The observed loads were below reported vertebral strengths in the literature. Subject-specific loads are affected by individual spinal curvature and muscle strength. Increasing spine curvature generally caused larger loads in the low thoracic spine, while decreasing spine curvature caused larger loads in the lumbar spine. The risk of lower back pain may increase in planetary environments when the spacesuit contributes a compressive load. The risk of pain will depend on the conditioning of the person and the ability to maintain bone and muscle strength during microgravity and low gravity exposures.

Description

Katelyn Burkhart, Beth Israel Deaconess Medical Center (BIDMC)/Harvard Medical School, US
Dennis Anderson, Beth Israel Deaconess Medical Center (BIDMC)/Harvard Medical School, US
Leia Stirling, Massachusetts Institute of Technology (MIT)/University of Michigan, US
ICES513: Computational Modeling for Human Health and Performance Analysis
The proceedings for the 2020 International Conference on Environmental Systems were published from July 31, 2020. The technical papers were not presented in person due to the inability to hold the event as scheduled in Lisbon, Portugal because of the COVID-19 global pandemic.

Keywords

Space suit, Spine loading, Astronaut, Biomechanics, Extravehicular activity (EVA)

Citation