4 ms·

Probably a stupid question but if rocket launches really became as commonplace as airplane flights, would we see some kind of increase in global temperatures?

eblume 1y ago
Not stupid at all. Definitely yes. Don't have the numbers on hand but it's orders of magnitude more CO2-equivalent released per kg-mile, especially when you factor in the fact that they are using methane. Of course the reality is that this tech won't ever see adoption used that widely, but where is the break-even point?
- bryanlarsen 1y ago
  Rocket launches emit less CO2 than a trans-pacific airline flight.
  - barbazoo 1y ago
    > CO2-equivalent I think what they were trying to get at is GHG emissions in general which there are more of than just CO2.
    - bryanlarsen 1y ago
      Full flow staged combustion engines like Starships do not have significant un-burnt methane. They run slightly fuel-rich, but that results in extra CO emissions rather than CH4 due to the temperatures involve -- methane cracks at 1200C, Starship engine temperature is 3000C. Starship's operations in Boca Chica do emit methane during ground operations. The mitigation for that is to use a pipeline rather than trucks for delivery. Solid rocket motors emit all sorts of nasty stuff, like aluminum particles.
terminalshort 1y ago
The short answer is yes. Airplanes account for 2.5% of CO2 emissions and rockets use massively more fuel than airplanes per flight (falcon 9 is ~10x fuel capacity of a 737). But this is an insane scenario because there are about 100,000 commercial flights per day in the world. In all of 2024 there were ~250 orbital launches. So to hit the same rate as airplanes it would require a ~150,000x increase in the launch rate (or a ~15,000x increase to equal the CO2 emissions of airplanes).
- bryanlarsen 1y ago
  Most of the falcon9 fuel is liquid oxygen. A Falcon9 holds less kerosene than a 737 ER.
  - phire 1y ago
    You are thinking of the 777 ER, which holds more kerosene than the first stage of Falcon 9 (and slightly less fuel than both stages combined) The 737 is a much smaller plane, and its fuel capacity is near the ballpark of 10x smaller.
mr_toad 1y ago
I can’t see that happening for centuries, if ever. And if we haven’t figured out a way to deal with global warming in a few centuries the number of space launches and airline flights will probably both be zero.
numpad0 1y ago
They also disrupt ozone layers and leave combustion byproducts in the trail. CO2 raises temperature but dusts reduce temperature, idk which of those effects are dominant or if it makes sense to mandate an additive or something.

eblume 1y ago

Not stupid at all. Definitely yes. Don't have the numbers on hand but it's orders of magnitude more CO2-equivalent released per kg-mile, especially when you factor in the fact that they are using methane. Of course the reality is that this tech won't ever see adoption used that widely, but where is the break-even point?

bryanlarsen 1y ago
Rocket launches emit less CO2 than a trans-pacific airline flight.
- barbazoo 1y ago
  > CO2-equivalent I think what they were trying to get at is GHG emissions in general which there are more of than just CO2.
  - bryanlarsen 1y ago
    Full flow staged combustion engines like Starships do not have significant un-burnt methane. They run slightly fuel-rich, but that results in extra CO emissions rather than CH4 due to the temperatures involve -- methane cracks at 1200C, Starship engine temperature is 3000C. Starship's operations in Boca Chica do emit methane during ground operations. The mitigation for that is to use a pipeline rather than trucks for delivery. Solid rocket motors emit all sorts of nasty stuff, like aluminum particles.

terminalshort 1y ago

The short answer is yes. Airplanes account for 2.5% of CO2 emissions and rockets use massively more fuel than airplanes per flight (falcon 9 is ~10x fuel capacity of a 737). But this is an insane scenario because there are about 100,000 commercial flights per day in the world. In all of 2024 there were ~250 orbital launches. So to hit the same rate as airplanes it would require a ~150,000x increase in the launch rate (or a ~15,000x increase to equal the CO2 emissions of airplanes).

bryanlarsen 1y ago
Most of the falcon9 fuel is liquid oxygen. A Falcon9 holds less kerosene than a 737 ER.
- phire 1y ago
  You are thinking of the 777 ER, which holds more kerosene than the first stage of Falcon 9 (and slightly less fuel than both stages combined) The 737 is a much smaller plane, and its fuel capacity is near the ballpark of 10x smaller.

mr_toad 1y ago

I can’t see that happening for centuries, if ever. And if we haven’t figured out a way to deal with global warming in a few centuries the number of space launches and airline flights will probably both be zero.

numpad0 1y ago

They also disrupt ozone layers and leave combustion byproducts in the trail. CO2 raises temperature but dusts reduce temperature, idk which of those effects are dominant or if it makes sense to mandate an additive or something.