Characterizing a transient heat flux envelope for lunar-surface spacesuit thermal control applications

In this paper, a transient thermal simulation approach is used to characterize the heat flux and heat flux rates between the lunar surface and a moving spacesuit model. Five different lunar-surface settings are simulated with craters and boulders at three solar elevation angles (θ = 2, 10, 90 deg). Heat fluxes and rates are evaluated for different parts of the suit and different characteristic tasks along a given path. The simulated paths are based on Apollo mobility studies. The results indicate that, at lower solar elevation angles, which imply lower lunar-surface temperatures, the thermal impact of surface features becomes more pronounced. In all simulated cases, and for more than85%of the time, the infrared heat fluxes vary at rates below 20 W · m2 · s1. The incidence versus magnitude of infrared heat flux rates follows a power law with a negative exponent. Smaller heat flux rates have a higher occurrence at lower surface temperatures, and vice versa. The created lookup tables with task, solar elevation angle, and incident heat fluxes can be used as a baseline in the design and sizing of thermal control hardware for moving objects on the surface of the Moon.