Preliminary Investigation of the Design of a Mechanically Antagonistic, Actuating Countermeasure Garment

Countermeasure garments are worn by all NASA crew during Earth reentry, landing, and egress in accordance with NASA-STD-3001. These lower-body compression garments are designed to mitigate lower body blood pooling, which can impair a crew member’s ability to complete critical landing tasks. The likelihood of cardiovascular deconditioning increases with mission duration; therefore, countermeasure garments are a critical safeguard to astronaut health as we push the bounds of space exploration into 3+ year missions (e.g. Journey to Mars). Current on-body compression technologies are either a mobility hazard, such as tethered inflatable compression systems, or uncomfortable and cumbersome due to their static design, such as undersized, elastane garments. Shapeshifting fabrics enable an alternative solution – compression garments that can be donned in a loose, relaxed configuration and contract and stiffen in response to small changes in temperature. Prior work has found that knitted actuator fabrics have actuation pull forces capable of providing suitable cardiovascular protection during astronaut landing activities. Additionally, prior work has presented and validated the use of custom SMA chemistries that can actuate below 40℃, the NASA-STD-3001 maximum allowable touch temperature. This work presents a preliminary investigation of the design of an actuating orthostatic intolerance garment using these high-force, low-temperature actuator fabrics in parallel with passive elastane fabrics to form a mechanically antagonistic wearable system. This mechanically antagonistic wearable system will be conceptually defined and built in the form of a prototype calf sleeve with two goals in mind. First, we present the first implementation of a new design methodology and use operation to observe the functional challenges of this mechanically antagonistic actuating countermeasure system. Secondly, we present system performance data, covering 2D mechanical performance testing and on-body user compression testing. The resulting trial run documentation and feedback paves the way for future, full garment actuating countermeasure garment prototypes.