Planetary and Lunar Environment Thermal Toolbox Elements (PALETTE) Project Final Results

This paper summarizes the technology development advancements made at the conclusion of the three-year JPL PALETTE project, which was funded by the NASA Game Changing Development (GCD) Program. The project goal was to ensure that a full “palette” of flight-ready (high TRL) thermal “toolbox” elements is available so that engineers are able to create passive, ultra-isolative thermal designs for science instruments on a variety of carriers in lunar/planetary extreme environments. PALETTE was structured to meet the need by increasing thermal toolbox element TRL via four design/build/test efforts (Tasks 1-4) and four analysis/study efforts (Tasks 5-8). Task 1 targeted the development of thermally-switched enclosures (TSE) featuring a thermal switching system that links a reverse-operation DTE thermal switch (ROD-TSW) to a propylene miniaturized loop heat pipe (mini-LHP). Task 2 sought the development of an affordable parabolic reflector radiator (PRR) for lunar instruments operating at low-to-mid latitude sites. Task 3 focused on the development of an ultra-low effective emissivity (e*) multilayer insulation known as “spacerless” MLI (SMLI). Task 4 involved the development of low conductance thermal isolators (LCTI) made from 3D-printable Ultem 9085/1010 and machinable Ultem 1000. Prototype test results for Tasks 1-4 will be summarized in the paper as will the analyzed architectures and the ranking results generated from Tasks 5-8, the four analysis/study tasks. Task 5 focused on optimizing gimbaled optical instruments, Task 6 on optimally combining thermal transport/storage/switching to achieve new capabilities, Task 7 on instrument feed-through (wire/aperture) heat loss minimization, and Task 8 on instrument scalability, extensibility, and planetary use. Also presented in this paper are current plans/opportunities for PALETTE technology mission infusion. These opportunities include two that are currently manifested and several that are still in the planning stages. The two manifested missions are the Farside Seismic Suite (FSS) and the (lunar farside-based) Lunar Surface Electromagnetic Experiment (LuSEE-Night).