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Atmospheric Pollution from Rockets [pdf]
- TedShiller 4y agoNobody wants to talk about this because it doesn't fit the narrative
- tejtm 4y agoCan confirm, I love space stuff, cubesats, radio communication with space, hate thinking about how it get there from here ... the first 100km problem.
- planetsprite 4y agoWhat narrative? That rockets can never be bad? I think rockets' contribution to greenhouse gasses are insignificant as a ratio to emissions:value to society compared to airplane flights/commercial travel.
- zionic 4y agoI’ll talk about it. Methalox engines will be solar powered within 5-10 years. Kerolox is dying off in that time frame.
- ncmncm 4y agoThat is fine, as far as it goes. But it doesn't go very far. Injecting huge amounts of H, CO and H2O into the upper stratosphere and ozone layer will have important consequences, even if the launch cadence SpaceX wants does not happen. (Which it won't.) We might need regulation.
- modeless 4y agoSpaceX is imminently switching to methane fuel, and an engine design that should offer much more complete combustion of the fuel. I was hoping to see at least a comment about this in the paper.
- credit_guy 4y ago> much more complete combustion of the fuel More complete combustion of the fuel they intend to burn. But since their mixture is very fuel rich, they emit a lot of methane. No amount of engine design can eliminate that methane from their exhaust.
- AnimalMuppet 4y agoWhy is their mixture very rich? Wouldn't a balanced mixture give them more energy, and therefore more thrust?
- HarryHirsch 4y agoYou are looking for maximum impulse, not maximum energy. If you run fuel-rich, the extra fuel converts heat into impulse, it acts as reaction mass, so to speak. Water injection in jet engines works along the same principles, convert heat into volume of vapour.
- AnimalMuppet 4y agoOK, but couldn't you do the exact same thing by running lean? Then the extra oxygen would convert heat into impulse. Or, as you said, by steam injection? (But then you'd need an extra tank for the steam, so that's probably less than optimal...) (I'm not saying they're wrong. I'm asking for an explanation.)
- HarryHirsch 4y agoThe real-life application for an oxygen-rich mixture is a cutting torch, you really don't want that. Also, maximum impulse means high exhaust velocity, that means exhaust gasses with low molecular mass. Oxygen wouldn't qualify.
- ncmncm 4y agoYes, burning away the interior surface of your combustion chamber runs into a resource limit pretty quickly, shortly followed by rapid uncontrolled dissociation. The exhaust colors leading up to that are often pretty, and finally dramatic. There have been rockets that ran lean during the first few seconds, deliberately eroding away a layer of the combustion chamber, to get higher-mass particles into the exhaust while trying to clear the launch tower. The higher-mass exhaust particles gives you less efficiency but more thrust, which is most important just then.