NASA is seeking innovative approaches and techniques for lunar surface payload survival. This payload must survive the large temperature swings of the lunar diurnal cycle and the challenging lunar thermal environment. This lunar environment poses significant difficulties to small, low power (≤100W) payloads, rovers, and landers required for lunar science, especially in the absence of perpetual power supplies, while still demanding operability for many lunar cycles in the extreme lunar environment. To achieve these goals, ThermAvant Technologies, LLC proposes developing a system of interconnected Oscillating Heat Pipes (OHPs) to enable an enhanced thermal wadi. Essentially, the lunar wadi concept is to create a thermal mass by solidifying loose lunar regolith and configuring this mass such that it can be heated during the lunar day and can provide sufficient heat during the lunar night to maintain lunar rovers and other payload equipment above their minimum survival temperatures. An OHP-enhanced thermal wadi is envisioned that takes advantage of completely burying the thermal mass in lunar regolith and using OHPs to capture and transport the heat for storage (Hot Sink), for rover warming (Parking Plate), and, independently, for power generation (Heat Engine).
The OHP-based Hot Sink will provide unique features not found in a state-of-the-art thermal wadi by demonstrating OHPs functioning as variable conductance devices integrated as thermal switches, variable heat flux acquisition and heat load capability depending on temperature demands, application-specific working fluids capable of operating over the extreme lunar temperature conditions, improved effective thermal conductivity, structural body form factor for improved thermal resistance with reduced mass, and gravity independent performance.
NASA's Thermal Control Systems project resides within 2020 NASA Technology Taxonomy TX14: Thermal Management Systems. In particular, within TX14, this OHP-enhanced thermal wadi system has direct application to thermal switches (TX14.1.3), heat acquisition (TX14.2.1), heat transport (TX14.2.2), heat rejection and storage (TX14.2.3), thermal interfaces (TX14.2.4), and thermal protection systems (TX14.3.2).
ThermAvant is aware of a number of applications that could potentially use such thermal control systems, e.g. various commercial space and terrestrial applications involving solar thermal storage. ThermAvant believes there are a multi-million-dollar annual revenue opportunities within each of these industries if the thermal switch and thermal array OHPs are able to successfully be produced.