Load Responsive MLI: Thermal Insulation with High In-Atmosphere and On-Orbit Performance

Long term storage of cryopropellants with minimal loss is required for new Exploration spacecraft. Multi-Layer Insulation (MLI) is used to insulate cryotanks, but is a high risk for Earth Departure Stage and Altair propellant maintenance. An ultra-high performance thermal insulation, Integrated MLI, is being developed for NASA as an MLI replacement, and offers significantly improved thermal performance under space vacuum conditions. This proposal is for Load Responsive MLI (LRMLI), an innovative thermal system that under atmospheric pressure compresses dynamic Posts to support an integrated, thin vacuum shell for high performance in-atmosphere operation, then disconnects the Posts during on-orbit and Lunar surface operation to provide ultra-high performance thermal insulation. LRMLI will use micro-molded Center-Beam Tripod Posts between radiation barriers with a novel combination of low area-to-length spoke arms to reduce heat leak via conduction under no load, and a dynamic center beam to support a vacuum shell under load. For on-orbit space operation the theoretical thermal conductance is 0.22 W/m² (e* = 0.00048). For in-atmosphere operation, atmospheric pressure compresses the Post until the center beam contacts the underlying layer, supporting an integrated 0.020" aluminum vacuum shell. The load bearing configuration has higher heat leak through the center beam (0.84 W/m²), but has a heat leak 93X less than SOFI. LRMLI could offer superior on-orbit performance to MLI, much lower heat leak than SOFI during launch, and no need for N2 or He purge. Cryopropellant boiloff could be significantly reduced during pre-launch and launch operations, especially beneficial for Altair and EDS. In Phase I we would model, design, fabricate LRMLI prototypes and test thermal performance in vacuum and atmosphere, reaching TRL4. In Phase II we would move toward a commercially viable product and a TRL5.