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I wonder at which point we will start worrying about the carbon footprint of these launches, though. I didn't do the math, but it seems it might become a global

by jwr 8y ago

I wonder at which point we will start worrying about the carbon footprint of these launches, though. I didn't do the math, but it seems it might become a global factor once you get to multiple launches per week.

ceejayoz 8y ago
https://www.smithsonianmag.com/science-nature/spacex-environmentally-responsible-180968098/ https://www.smithsonianmag.com/science-nature/spacex-environ... says: > if the SpaceX’s plan for a rocket launch every two weeks comes to fruition, this amount of carbon (approximately 4,000 tonnes per year) will rapidly become a bigger problem So, that gives us a number... and it's also very weird for the Smithsonian to describe that as a "problem". 4,000 tonnes per year is about a thousand cars worth per the EPA's numbers (https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-t...) - pretty much a drop in the bucket.
- XorNot 8y ago
  Rockets and the rocket fuel are also in the "easy to substitute" category. They'll never not be hydrocarbons, but significant work has been done on producing rocket-compatible fuels from biological sources, and the marginal increase in cost if you scaled up to industrial production is possibly going to be entirely unnoticeable considering the general purity and refining requirements of anything you load into a spacecraft. This, similarly, is also the answer when it comes to aviation by and large. The real problems on Earth are ground transportation and electricity.
  - bumby 8y ago
    How do the biological propellants compare in terms of stability? Maybe not an issue for launches, but I'm curious about their viability in satellite thrusters that hang out for years/decades (although this is a digression from the GRG emission concern)
    - simonh 8y ago
      Satellite thrusters generally use stable hypergolics, to avoid the need for an ignition system, or electric systems such as ion or Hall thrusters.
  - avmich 8y ago
    Hydrogen as the only fuel was in the X-33 project, which technically had a lot of success (before finally closing).
Robotbeat 8y ago
Not even close. A Falcon 9 has no more fuel than a 777. A few 777s per week is inconsequential in a world where there are 100,000 flights per day. Aviation is responsible for only about 3.5% of anthropogenic emissions per year. So even multiple flights per week are just a rounding error on a rounding error.
lutorm 8y ago
World CO2 emissions last year was ~ 37Gigatons of carbon. A F9 launch uses of order 100 tons of RP1, so global emissions correspond to about 370 million launches...
- p1mrx 8y ago
  Note that 1 ton of fuel yields more than 1 ton of CO₂: https://www.fueleconomy.gov/feg/contentIncludes/co2_inc.htm https://www.fueleconomy.gov/feg/contentIncludes/co2_inc.htm (Though it's still comparable in "order of magnitude" terms.)
geuis 8y ago
Here’s some numbers I looked up: Average co2 from a car per year: 4.6 metric tons (https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-t...) co2 output from a Falcon 9 launch: 440,000kg or 440 metric tons (https://space.stackexchange.com/questions/13082/calculate-falcon-9-co2-emissions https://space.stackexchange.com/questions/13082/calculate-fa...) So a single launch is about 95 cars worth of exhaust a year, give or take. There were 21 SpaceX launches last year (https://en.m.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_Heavy_launches https://en.m.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_...) The number of launches is expect to increase to 30-40 a year (previous source). Let’s go with 35 launches per year. And remember we’re disregarding all other rockets launches in the world. 35 x 95 = 3325 cars worth of emissions per year. It’s definitely not great. However it’s such a tiny drop in the bucket overall that it’s not even a rounding error. I think cows produce more methane per year. I’m on mobile at the moment so not gonna look up those numbers. Rockets get terrible gas mileage.

by jwr 8y ago

ceejayoz 8y ago

https://www.smithsonianmag.com/science-nature/spacex-environmentally-responsible-180968098/ https://www.smithsonianmag.com/science-nature/spacex-environ... says: > if the SpaceX’s plan for a rocket launch every two weeks comes to fruition, this amount of carbon (approximately 4,000 tonnes per year) will rapidly become a bigger problem So, that gives us a number... and it's also very weird for the Smithsonian to describe that as a "problem". 4,000 tonnes per year is about a thousand cars worth per the EPA's numbers (https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-t...) - pretty much a drop in the bucket.

XorNot 8y ago
Rockets and the rocket fuel are also in the "easy to substitute" category. They'll never not be hydrocarbons, but significant work has been done on producing rocket-compatible fuels from biological sources, and the marginal increase in cost if you scaled up to industrial production is possibly going to be entirely unnoticeable considering the general purity and refining requirements of anything you load into a spacecraft. This, similarly, is also the answer when it comes to aviation by and large. The real problems on Earth are ground transportation and electricity.
- bumby 8y ago
  How do the biological propellants compare in terms of stability? Maybe not an issue for launches, but I'm curious about their viability in satellite thrusters that hang out for years/decades (although this is a digression from the GRG emission concern)
  - simonh 8y ago
    Satellite thrusters generally use stable hypergolics, to avoid the need for an ignition system, or electric systems such as ion or Hall thrusters.
- avmich 8y ago
  Hydrogen as the only fuel was in the X-33 project, which technically had a lot of success (before finally closing).

Robotbeat 8y ago

Not even close. A Falcon 9 has no more fuel than a 777. A few 777s per week is inconsequential in a world where there are 100,000 flights per day. Aviation is responsible for only about 3.5% of anthropogenic emissions per year. So even multiple flights per week are just a rounding error on a rounding error.

lutorm 8y ago

World CO2 emissions last year was ~ 37Gigatons of carbon. A F9 launch uses of order 100 tons of RP1, so global emissions correspond to about 370 million launches...

p1mrx 8y ago
Note that 1 ton of fuel yields more than 1 ton of CO₂: https://www.fueleconomy.gov/feg/contentIncludes/co2_inc.htm https://www.fueleconomy.gov/feg/contentIncludes/co2_inc.htm (Though it's still comparable in "order of magnitude" terms.)

geuis 8y ago

Here’s some numbers I looked up: Average co2 from a car per year: 4.6 metric tons (https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-t...) co2 output from a Falcon 9 launch: 440,000kg or 440 metric tons (https://space.stackexchange.com/questions/13082/calculate-falcon-9-co2-emissions https://space.stackexchange.com/questions/13082/calculate-fa...) So a single launch is about 95 cars worth of exhaust a year, give or take. There were 21 SpaceX launches last year (https://en.m.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_Heavy_launches https://en.m.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_...) The number of launches is expect to increase to 30-40 a year (previous source). Let’s go with 35 launches per year. And remember we’re disregarding all other rockets launches in the world. 35 x 95 = 3325 cars worth of emissions per year. It’s definitely not great. However it’s such a tiny drop in the bucket overall that it’s not even a rounding error. I think cows produce more methane per year. I’m on mobile at the moment so not gonna look up those numbers. Rockets get terrible gas mileage.