What Launch Life Cycle Assessment Should Count for Starship-Scale Fleets: Ozone Health Damage Factors and a Failed Warming Potential

Abstract Purpose Life cycle assessments (LCA) of spaceflight count launch mainly through CO 2 and report black carbon only as mass, with one untested high-altitude warming potential as the alternative. As Starship-class vehicles could raise the propellant burned each year by orders of magnitude, this study asks what launch LCA should count: which pathways can be characterized at the endpoint, and which should stay out. Methods We built human health damage factors (disability-adjusted life years per kilogram, DALY/kg) for black carbon (BC), chlorine, and nitrogen oxides in stated altitude layers, each from one traceable source, with public model output recomputed using area weighting. A health chain converts column ozone loss to skin cancer and cataract burden. We applied the factors to Starship and Falcon 9, per launch and per tonne of payload capacity, compared fleet emissions with simulated doses, and tested the only high-altitude global warming potential (GWP) we found. Results and discussion If the heating-driven ozone response to BC holds, one Starship launch’s exhaust causes 11 DALY of UV damage at 5 g BC per kg propellant and 48 DALY at 22 g/kg, or 2.9–13 times the damage from its combustion CO 2 over 100 year and 0.65–2.8 times over 500 year. A surface-ozone co-benefit offsets about 75% of this on central assumptions, leaving the net sign undetermined. Methane-engine BC, never measured in flight, decides whether Starship does less UV damage than Falcon 9 per tonne of payload capacity. At 3,000 launches a year, BC in the 15–70 km layer reaches simulated doses. The GWP implies about seven times the simulated instantaneous forcing, and 0.61 K at 10 Gg/yr where an interactive-ocean simulation shows no detectable change. Conclusions Launch LCA should count stratospheric ozone loss, show results with and without a dedicated BC line, and report the surface-ozone co-benefit separately. It should not add a BC climate term from the available GWP. Re-entry, stratospheric water vapor, and the BC climate term cannot yet be characterized, so totals that omit them should say so. Measuring BC from methane engines at altitude is the most useful next step.