5 ms·
Space rockets should all switch to hydrolox, at least that burns clean. Like Delta IV. (yeah, yeah, terrible impulse density..)
by jabl 6y ago
Space rockets should all switch to hydrolox, at least that burns clean. Like Delta IV.
(yeah, yeah, terrible impulse density..)
- cryptonector 6y agoWhat's wrong with methane/oxygen?
- jabl 6y ago- methane is a very potent greenhouse gas. What's the effect of methane in the stratosphere? - there are some results suggesting soot emissions in the stratosphere could be a problem if space launches increase a lot. Methane burns a lot cleaner than kerosene, but afaiu some soot is still formed. Now all things considered, given nobody seems interested in a pure hydrolox lower stage due to the poor impulse density, methalox certainly looks better than alternatives.
- chris_va 6y agoGHG emissions from rocketry are so trivially small that it's really not worth optimizing at this point. Maybe if SpaceX flew 500 rockets per day. (disclaimer: I work in a climate research group)
- jabl 6y agoTotal volume is trivial compared to all other human activity, but like I mentioned there is some concern about the effect of rocket emissions in the middle and upper atmosphere given that we're likely to see a substantial increase in launch rate. See https://eos.org/features/the-coming-surge-of-rocket-emissions https://eos.org/features/the-coming-surge-of-rocket-emission... for a recent overview.
- LargoLasskhyfv 6y agoUse rotating detonation engines instead.
- namibj 6y agoRotating... amateurs. Just use a detonation-based scramjet burner. Bonus: could be air-breathing for a large part of the first stage. The downside would be the massive instability from the need to keep a supersonic flow matched up perfectly with the detonation velocity. I'd figure stochiometric deviation would be a feasible way to control the detonation velocity, but the control loop would be hard to get right. And it might be necessary to use film cooling with liquid cryogenics to prevent the shock front from melting the engine wall.
- cryptonector 6y agoThe methane gets burn, you know.
- jabl 6y agoMost of it, yes. A quite substantial fraction of rocket exhaust is not the stoichiometric products we learned in high school chemistry.
- cryptonector 6y agoBut it isn't methane either, mostly. And we're talking about very small amounts.
- m4rtink 6y agoAnd thrust in general.