Many people have asked what pollutants are added to the atmosphere by a rocket launch. I did some research and made a table estimating the effluence of a launch.
What a Rocket Leaves Behind
Estimated exhaust products per launch, by vehicle
| Rocket | Propellants by Stage | Estimated Emissions per Launch | Notes |
|---|---|---|---|
| Falcon 9 SpaceX |
Stage 1: RP-1 kerosene + LOX (9 × Merlin) Stage 2: RP-1 kerosene + LOX (1 × Merlin Vacuum) |
|
Each Falcon 9 launch burns roughly 50,000 gallons (~155 tonnes) of RP-1 kerosene. The open-cycle Merlin engines run fuel-rich in their gas generators, which is where most of the visible soot comes from. |
| Atlas V United Launch Alliance |
Stage 1: RP-1 kerosene + LOX (1 × RD-180) Centaur upper: LH₂ + LOX (RL10) Optional: 0–5 GEM 63 solid boosters (AP composite + aluminum) |
Values below reflect the N22 config with 2 SRBs; emissions scale significantly with SRB count.
|
An Atlas V 401 (no SRBs) produces no alumina or HCl. An Atlas V 551 (5 SRBs) produces roughly 2.5× the SRB-derived emissions of the N22. |
| Vulcan Centaur United Launch Alliance |
Stage 1: Liquid methane (LNG) + LOX (2 × BE-4) Centaur V upper: LH₂ + LOX (2 × RL10) Optional: 0, 2, 4, or 6 GEM 63XL solid boosters |
Values below reflect a 2-SRB config; emissions scale with SRB count (0–6).
|
The Vulcan EA states overall launch emissions are “similar to current Atlas V launch emissions” with reductions in particulates due to methane. CO₂/H₂O values are calculated from FAA-reported BE-4 propellant consumption (150k lb LNG + 500k lb LOX per engine per flight). |
| New Glenn Blue Origin |
Stage 1: Liquid methane (LNG) + LOX (7 × BE-4) Stage 2: LH₂ + LOX (2 × BE-3U) Boosters: None |
|
With seven BE-4 engines on the first stage, New Glenn’s first-stage CO₂ and H₂O output would be roughly 3.5× that of Vulcan’s two-BE-4 core, but Blue Origin has not published a detailed per-launch emissions breakdown. |
| Starship SpaceX |
Super Heavy (S1): Liquid methane + LOX (33 × Raptor) Starship (S2): Liquid methane + LOX (6 × Raptor) Boosters: None |
Full-stack expendable mission. Current V2/V3 Starship carries more propellant than the 2020-era design these estimates are based on.
|
The CO₂/H₂O totals are from a 2020 analysis of an earlier 9-meter Starship design. SpaceX’s FAA plume analysis for the 33-engine Super Heavy predicts no soot from the Raptor 2 engine cycle. |
A note on the numbers: These are estimates, not measured values. Rocket emissions vary with trajectory, engine throttle profile, stage-separation timing, and atmospheric conditions. CO₂ and water-vapor figures marked with source [1] come from a widely-cited 2020 analysis that the author describes as accurate to within roughly ±5–10%. Where values are shown as “not publicly quantified,” the chemistry is well understood but the specific per-launch mass has not been reported in the sources reviewed.
Sources:
[1] Dodd, T. (Everyday Astronaut), “How much do rockets pollute?” (March 2020).
[2] Ryan, R. G. et al., and reporting in Undark / NOAA atmospheric research (2024–2026).
[3] Derived from published GEM 63 / GEM 63XL propellant masses (~44 t propellant per GEM 63XL; ~70% ammonium perchlorate, ~16% aluminum powder) and standard AP-composite combustion stoichiometry.
[4] Derived from FAA/USAF Environmental Assessment: Vulcan Centaur Program (May 2019), which reports BE-4 propellant consumption of ~150,000 lb LNG + ~500,000 lb LOX per engine per flight.
[5] FAA, Appendix G: Exhaust Plume Calculations (SpaceX Starship Super Heavy Raptor 2 analysis, 2022).
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