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.
Benefits: NASA has a need for long-duration exploration portable life support systems for future astronauts on both long-term lunar and Mars operations. Current systems consume water as an element of the cooling system. The need to minimize or eliminate the water used for evaporative cooling of the spacesuit during an EVA increases with the EVA count and mission duration as water is not readily available from the environment. MACHINE eliminates the use of water for evaporative cooling by introducing an all-solid-state solution for heat transfer that is well-suited to Mars EVA. As such, MACHINE addresses gaps in spacesuit capabilities for operation on Mars as identified by NASA’s Science and Technology Mission Directorate (STMD). MACHINE can be used for future Mars missions where long-duration stays are required. This work can be traced to the Exploration Systems Development Mission Directorate (ESDMD) and Space Operations Mission Directorate (SOMD). Eventually, NASA astronauts will not be the only humans working in Martian environments. The elements of a Portable Life Support System (PLSS) as proposed in this work could be implemented in EVA suits for other national space programs as well as for the growing private space sector. Additionally, since our original work in this area began not with actual EVA suits but with training units for use in Johnson Space Center’s Neutral Buoyancy Facility we believe that advances we make on this topic in a Mars-oriented PLSS will translate back to more immediate use in more advanced training systems for astronauts here on Earth as well as potential non-flammable coolant systems for environmental and firefighting portable life support systems.