Source Review: Handmer — Long Duration Propellant Stability in Starship (2025)

Verdict: Consistent Confidence: high

Handmer's 1,200 t/Starship + 7 t cooling infrastructure + 1 t/day MLI boiloff figures are the most quantitatively detailed public analysis of Starship depot economics. Directly supports q6.c5 depot- throughput calc. The 8-tanker-vs-16-tanker question is partly addressed: Handmer's MLI analysis suggests boiloff is more manageable than NASA's 16-launch estimate implied, supporting Musk's 8-launch figure as architecturally feasible. No conflicts with tier S; this is the canonical technical-depth source on Starship propellant operations.

Abstract

Handmer's technical analysis of Starship cryogenic propellant stability in LEO and on the lunar surface. Per-Starship propellant load is 1,200 t (250 t methane + 950 t oxygen at 3.8:1 mixture ratio). Unshielded LEO heat absorption is ~33 kW; shielded with active cooling requires 507 kW electrical + 2000 m² solar array + 1350 m² radiators (adding ~7 t of infrastructure). Lunar surface: unshielded Starship boils off completely in two weeks at 300 kW heating rate; multi-layer insulation reduces boiloff to ~1 t/day. The post quantifies the propellant infrastructure mass overhead per Starship-class mission: orbital storage of 1,200 t requires ~7 t of supporting infrastructure per ship, scaling to significant aggregate mass demand for a 10-100 ship/window Mars program.

Key claims

• per-starship-propellant: 1,200 t total propellant per Starship (250 t CH4 + 950 t LOX at 3.8:1 mixture).
• leo-heat-load-unshielded: ~33 kW unshielded heat absorption in LEO.
• leo-cooling-active-power: 507 kW electrical + 2000 m² solar + 1350 m² radiators required for active cooling.
• leo-infrastructure-overhead: Cooling infrastructure adds ~7 t per ship.
• lunar-boiloff-unshielded: Unshielded Starship boils off completely in two weeks on lunar surface at 300 kW heat rate.
• mli-boiloff-mitigation: Multi-layer insulation reduces lunar boiloff to "less than 1 ton per day."

Reviewer notes

Tier C: credentialed-expert blog. Handmer's propellant analysis is the most quantitatively detailed public technical analysis of Starship depot economics. The 1,200 t/ship, 7 t infrastructure/ship, and 1 t/day boiloff figures are load-bearing for q6's propellant-depot demand calc. Handmer is also reviewed as a tier B public figure for his broader cislunar-economy and orbital-compute quoted statements.