Submitted by marketrent t3_10ufb9b in science
Findings in title quoted from the linked summary^1 and its hyperlinked journal paper T. Brown, et al.^2
From the 3 Feb. 2023 summary^1 by the authors of T. Brown, et al.:
>Rockets have exciting potential to enable industrial-level access to near-Earth space and exploration throughout the solar system.
>This makes them “charismatic technology” – and the promise of what the technology can enable drives deep emotional investment.
>The allure of possibility can get in the way of even discussing how to make rockets achieve these aspirational goals without damage. We have to be able to have clear discussions.
>The ozone layer is on track to heal within four decades, according to a recent UN report, but this progress could be undone by an upsurge in rocket launches expected during the same period.
>As we show in our new review, the gases and particulates rockets emit as they punch through the atmosphere could lead to delays in the ozone layer’s recovery.
>Fortunately, the number of launches to date is so small that the impacts on the ozone layer are currently insignificant.
>However, over coming decades the launch industry is set to expand considerably.
>
>As we outline, rocket emissions in the upper atmosphere can affect the ozone layer but are not regulated. We argue this policy gap must be filled to ensure sustainable growth of the rocket launch industry and protection of the ozone layer.
>The launch industry today relies on four major fuel types for rocket propulsion: liquid kerosene, cryogenic, hypergolic and solid.
>The combustion of these fuels means contemporary rockets create a suite of gaseous and particulate exhaust products, including carbon dioxide, water vapour, black carbon, alumina, reactive chloride and nitrogen oxides. These products are known to destroy ozone.
>A new fuel is methane, which is used in multiple rocket engines under development by major launch companies. The emissions products of methane are as yet poorly understood.
>In the stratosphere, an upper level of the atmosphere where the protective ozone layer resides, emissions linger for much longer than lower down.
>Small amounts of an exhaust byproduct can have greater destructive effects in the upper atmosphere than when close to Earth’s surface.
^1 Rocket industry could undo decades of work to save the ozone layer, 3 Feb. 2023, https://www.canterbury.ac.nz/news/2023/rocket-industry-could-undo-decades-of-work-to-save-the-ozone-layer.html
^2 T. Brown, M. Bannister, and L. Revell. Envisioning a sustainable future for space launches: a review of current research and policy. Journal of the Royal Society of New Zealand 2023. https://doi.org/10.1080/03036758.2022.2152467
> A new fuel is methane, which is used in multiple rocket engines under development by major launch companies. The emissions products of methane are as yet poorly understood.
????? What? The combustion byproducts of a methalox rocket is mostly H2O and CO2.
And it isn’t poorly characterized. The report authors just don’t look into it. NASA has a wonderful piece of software/web site that you can run Computational Chemical Equilibrium simulations, even simulated rocket engines. And it is pretty accurate.
And for a 300 bar , sea level methalox engine it spits out the following mass fractions of various species at the Comustion Chamber, the throat, and most importantly for this discussion the Exit. (Forgive the formatting, on mobile)
Species. Chamber Throat Exit
*CO 0.22048 0.20984 0.13790
*CO2 0.27689 0.29368 0.40681
COOH 0.00009 0.00005 0.00000
*H 0.00071 0.00060 0.00001
HCO 0.00004 0.00002 0.00000
HO2 0.00028 0.00016 0.00000
*H2 0.00681 0.00644 0.00695
HCOOH 0.00002 0.00001 0.00000
H2O 0.41879 0.42748 0.44829
H2O2 0.00008 0.00004 0.00000
*O 0.00481 0.00356 0.00000
*OH 0.04585 0.03779 0.00005
*O2 0.02515 0.02032 0.00000
So as you can see, the vast majority of the exhaust is Water, Carbon Dioxide, and Carbon Monoxide. Now there will be other trace components because the system assumes the LOX and Methane are totally pure, but even then those will be trace.
As you have shown the percentages can you also give us a link to the mass of the fuel reflected in these percentages. I think that would help in quantifying the amount of admission being dumped into the different layers of our atmosphere.
Each launch is roughly the equivalent of a 747's worth of fuel (kerosene or methane).
About 650 kg/s for the inputs according to Wikipedia. 510 kg/s of LOX and 140 kg/s of CH4 for a Raptor engine.
But it really depends on the engine in question and the throttle level.
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