The Thermal Subsystem of Mars Connect: Miniature Probes for a Meteorological Network on the Mars Surface

Over the last decades, several missions have successfully landed on Mars, placing scientific instrumentation onboard landers and rovers in different landing sites. However, a qualitative leap in “in-situ” climate science could happen via larger-scale observations targeting multiple locations simultaneously. Mars Connect is an INTA program aimed to develop microprobes with scientific instruments that, thanks to their reduced mass, volume and power consumption, could be conveyed piggyback to Mars by a single carrier, and deployed on the Martian surface in large numbers to set up planetary atmospheric networks. The approximately 12.5 kg probe consists of a rigid aeroshell enclosing a 7 kg, 3-section, hard-impact penetrator that can accommodate up to 1 kg of payload. The simplified aeroshell, which decelerates and stabilizes itself during the descent, includes an ablative heatshield to guarantee the probe’s integrity. Preliminary estimations of aerothermal loads for a range of trajectories and atmospheric conditions yield heat flux peaks of 200 W/cm² and integrated heat loads of up to 11,000 J/cm². Once on the Mars surface, the penetrator relies on the wide allowable temperature range of most of its equipment, subjected to extensive qualification campaigns for previous missions. It also includes a highly insulated “warm compartment” for elements to be maintained within more stringent limits. The landing site latitude will determine the surface temperature and solar irradiance along the year, and thus the power production of the penetrator solar cells and the energy needed by its thermal control heaters. The current work will firstly describe the mission environments relevant to the dimensioning of the probe thermal sub-system. Then, it will provide an overview of the preliminary thermal design for both the aeroshell and the penetrator. Finally, surface operations will be addressed, to assess the scientific capabilities depending on the latitude and the feasibility to survive throughout the Martian year.