Thermal System Design of the Mars Ascent Vehicle for the Mars Sample Return Mission Surface Phase

The Mars Ascent Vehicle (MAV) is the rocket designed to bring samples from the surface of Mars back to Earth for scientific investigation as part of the Mars Sample Return (MSR) mission. This endeavor would be the first attempt in human history to return a spacecraft with collected material from another planet. Although samples from smaller bodies and interstellar particles have been successfully returned to Earth, return missions from planets present additional challenges to overcome, including the larger gravitational field to access. In this manuscript, we present the baseline architecture and design of the MAV thermal control system necessary to maintain its hardware, including the solid rocket motors, its control and guidance system, and associated avionics within temperature requirements during all flight phases starting from launch until landing and mission completion after successful transfer of the samples to the Earth Return Orbiter. Design challenges are imposed by the cold-biased, large temperature oscillation environment on Mars (in excess of a 100 C swing during a diurnal cycle), and the limited thermal power generated by the solar panels. The overall thermal design of the MAV includes both passive and active control to survive the harsh conditions on Mars. CO2 gas gap insulation and conductive and radiative heat loss management are the hallmarks of the MAV-to-Lander thermal interface design described in this paper.