THERMOS: Translunar HEat Rejection and Mixing for Orbital Sustainability

THERMOS (Jan 2025 – May 2025)
Translunar HEat Rejection and Mixing for Orbital Sustainability

Winner of Third Place Overall Award: NASA Human Lander Challenge 2025 – Advanced Cryogenics Theme

Challenge: Design a boil-off management and propellant mixing system for long-term storage of cryogenic propellants on Artemis missions

Approach: A systems-engineering solution combining high-performance passive Multi-Layer Insulation (MLI) featuring mass, structural and thermal synergies with an active Broad Area Cooling (BAC) loop, together with our novel ETHER hydrodynamic mixing subsystem, to mitigate both radiative heat loads and thermal stratification.

Outputs:
A model-based parametric system design environment to explore technology options and their effect on system performance

A hybrid MLI + BAC jacket reducing heat leak to ≈1 400 W at NRHO

ETHER baffles and axial cryopumps that destratify propellants within 24 h under 0.02–0.05 g centrifugal forces

A 2U CubeSat microgravity prototype flight of ETHER on Oligo Space, planned for Feb 2026.

Overview

THERMOS is an innovative, largely additive system tailored for Starship HLS and Depot vehicles to achieve near-zero boil-off (NZBO) of cryogenic liquids during prolonged loiter in NRHO and on the lunar surface. By architecting a multi-layer Kapton-Dacron MLI blanket integrated into steel cooling tubes, exploiting lunar/Vacuum environments, and combining that with broad area cooling via neon-circulating cryocoolers, THERMOS limits daily boil-off to <0.1 % of propellant mass—even under conservative degradation and subsystem failures. Our complementary ETHER mixing subsystem, inspired by ships' propellers, prevents thermal stratification, ensuring propellant readiness for engine ignition and enhancing mission safety.

Key Technologies

MLI Blanket & Whipple Shield: Alternating aluminized Kapton and Dacron layers (40 layers front, 60 layers side) with Kevlar/aeroshell outer layers for MMOD and charging protection. Effective emissivity ≈0.016–0.019; mass ≈12.8 t.

Broad Area Cooling (BAC): Seven Creare 150 W@90 K Reverse Turbo-Brayton cryocoolers driving neon gas through 28 flat-welded steel tubes. Total cooling capacity 1,050 W; power draw 8.4 kW; mass 3.4 t.

ETHER Mixing System: Spiraled “propeller” baffles welded to existing rings to harness 2–3 RPM spin-stabilization for passive mixing. Axial cryopumps circulating full tank volume every 24 h; combined mass ≈0.6 t

Leadership & Team

The student co-leads were Daniel Rojas'27 and Beverly Ma'26. Team members included Stone Smith'27, Pranav Bala'27, Nicole Ding'27. The faculty advisors were myself, Dr. George Lordos (lead), together with Prof. Olivier De Weck and Prof. Jeffrey Hoffman.