Mars Atmospheric Convective Heat expulsIoN Engine (MACHINE)

NASA has a need for thermal cooling solutions to be integrated into the Portable Life Support System (PLSS) for Martian EVAs. The state-of-the-art components of the PLSS are not suitable for EVA operation on Mars. To fill this gap, MACHINE is intended to replace the current Spacesuit Water Membrane Evaporator thermal control system, with a hybrid forced-air (mainly carbon dioxide from the Martian atmosphere) convection cooling system. An array of Peltier chips and phase change materials are utilized as secondary heat management subsystems. MACHINE represents a significant departure from prior designs by using a 3-stage convection driven thermal management approach that eliminates the need for transporting cooling water from Earth (or risking not finding it on Mars). This will be a closed-loop system with zero consumables use. Feasibility calculations suggest that not only can MACHINE handle 460 W steady-state heat flow and the stated 700 W peaks, but can do so in most of the Martian day-night cycle with forced convective cooling alone. Only during the highest measured equatorial daytime temperatures are the secondary elements needed. To operate, we estimate 175 W maximum power draw and total battery energy use of 550 WH for an 8 hour mission. Our calculations indicate that a flat-plate, finned forced air radiator can be designed in a rectangular flat plate geometry that occupies only half of the PLSS backpack rear panel surface area with a likely total thickness of 5 cm and a mass well under 5 kg. With Phase I funding we will design the MACHINE and conduct a PDR-level design review. NASA, and the growing private space sector have a need for components that enable long-duration, closed-loop, exploration PLSS systems for future astronauts on long-term lunar and Mars operations. Applications also include improvements in advanced training systems for astronauts on Earth as well as potential non- flammable coolant systems for an environmental or firefighting PLSS.