The Mars Gravity Biosatellite: Thermal Design Strategies for a Rotating Partial Gravity Spacecraft 2007-01-3078

A rotating spacecraft which encloses an atmospheric pressure vessel poses unique challenges for thermal control. In any given location, the artificial gravity vector is directed from the center to the periphery of the vehicle. Its local magnitude is determined by the mathematics of centripetal acceleration and is directly proportional to the radius at which the measurement is taken. Accordingly, we have a system with cylindrical symmetry, featuring microgravity at its core and increasingly strong gravity toward the periphery. The tendency for heat to move by convection toward the center of the craft is one consequence which must be addressed. In addition, fluid flow and thermal transfer is markedly different in this unique environment. Our strategy for thermal control represents a novel approach to address these constraints.

We present data to theoretically and experimentally justify design decisions behind the Mars Gravity Biosatellite's proposed payload thermal control subassembly. The baseline system incorporates fans, thermoelectric coolers, heat fins and conducting plates to continuously and reliably remove thermal energy from the spacecraft's atmospheric pressure vessel. We present an assessment of a condensing heat exchanger with novel design enhancements to promote efficient operation in a partial gravity environment. Our approaches are validated by experimental data from a prototype of the thermal control subassembly within a new engineering mockup of the spacecraft's payload module.

This work provides novel insights into issues of thermal control in artificial gravity environments. This research can inform ECLSS designs for future human-rated vehicles which may incorporate centrifugation as a countermeasure for musculoskeletal deconditioning.