Design Consideration Regarding the Impact of Suit Mass on Astronaut Performance

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Design Consideration Regarding the Impact of Suit Mass on Astronaut Performance

Research shows that when it comes to optimizing human performance in reduced gravity (e.g. Moon and Mars) the lightest suit may not be the best solution. Research carried out at NASA JSC (Figure 1) show that by increasing suit mass/weight under simulated lunar gravity, test subjects expended less energy to perform various exploration tasks [1]. This is believed to be due to the fact that humans have evolved to perform best under 1-g conditions. Therefore, by increasing suit mass, the subject is brought closer to 1-g conditions. This in turn means improved stability, traction and locomotion.


Figure 1: Effect of suit weight on performance in reduced gravity [1]

It is true that minimizing non-consumable mass (i.e. overall suit mass) provides greater opportunity to send additional consumables and useful hardware to allow longer mission operations and may increase margin of safety in other areas. However, it is also important to recognize that reduced performance during EVA means increased consumption of essential consumables due to increased metabolic rates and increasing risk to crew health and safety. This in turn could potentially negate the potential time gained from the increased consumables launched to the lunar surface by reducing suit mass. In addition, it may not be sufficient to addition lunar rocks to suit pockets and to effectively increase the mass of the suit.

This, however, does not mean that mass needs to be added to the suit until the subject reaches 1-g equivalent condition on the lunar surface. Instead, there may needs to be more extensive trade-offs and risk analysis to define optimum suit mass to ensure maximum crew safety, optimum crew performance and mission success. A possible solution is to use lunar rocks or useful hardware (e.g. tools) to increase suit effective mass. However, when considering the abrasive nature of lunar regolith, the importance of eliminating hard surface contacts in the suit, ensuring a proper mass distribution, and minimizing center of gravity offset, one must take precaution when implementing this.


[1] NASA JSC, 2008. Risk of Comprised EVA Performance and Crew Health due to Inadequate EVA Suit Systems, Human Research Evidence Book 2008. Full text available at:

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