5 ms·

A Falcon 9 caries just a bit more fuel than a fully loaded 777. Which is big, to be sure, but still a drop in the bucket just in terms of transportation.

mlyle 5y ago
This isn't quite a fair comparison, though, because it doesn't consider the energy requirements to refine lox.
- maccam94 5y ago
  How significant are those? 2x 777 flights worth? 10? There are thousands of airplane flights every day, but only a couple of these per month.
- Symmetry 5y ago
  It takes about .7 MJ to refine a kg of lox, compared to 43 MJ released by a kg of kerosene. So that's not really a significant fraction.
  - mlyle 5y ago
    It's estimated that about 260g of CO2 is emitted per kg of liquid oxygen delivered to end users. And the oxidizer to fuel ratio is 2.5, so basically this doubles the impact. (And let's not get started on the rest of energy intensive things involved in space launch). Yes, space launch isn't ridiculously energy intensive, but it does put the 777 to shame.
    - Symmetry 5y ago
      Ok, so with each kg of kerosene burned emitting 3.6 kg of CO2 about 85% of a launch is due to the kerosene. Whether 15% is significant or not is in the eye of the beholder but I don't think my contention was unreasonable. There are, of course, ground crews and radars and tarmacs and so forth associated with a rocket launch but the same is true with a 777 flight as well. Most 777 flights aren't to the plane's max range, this is more of a Pacific crossing fuel consumption but I still think its broadly comparable. The big difference, I guess, is that a Falcon 9 might only make it through 10 or 20 flights while a 777 might do thousands. That is a big difference in energy usage but I don't feel competent to try to quantify it.
croes 5y ago
First of all, the last straw that breaks the camel's back. These flights are additional and more are coming. Second rockets reach higher parts of the atmosphere and the impact is higher compared to the lower flying planes.
asdff 5y ago
The falcon 9 first stage has been tested to be reused 11 times so far. A boeing airframe on the other hand lasts 30 years. There is therefore the cost of bringing these rare earth materials found perhaps around the world together in one place to launch a finished falcon 9 rocket, independent of any fuel considerations, that should also be thought about.

mlyle 5y ago

This isn't quite a fair comparison, though, because it doesn't consider the energy requirements to refine lox.

maccam94 5y ago
How significant are those? 2x 777 flights worth? 10? There are thousands of airplane flights every day, but only a couple of these per month.
Symmetry 5y ago
It takes about .7 MJ to refine a kg of lox, compared to 43 MJ released by a kg of kerosene. So that's not really a significant fraction.
- mlyle 5y ago
  It's estimated that about 260g of CO2 is emitted per kg of liquid oxygen delivered to end users. And the oxidizer to fuel ratio is 2.5, so basically this doubles the impact. (And let's not get started on the rest of energy intensive things involved in space launch). Yes, space launch isn't ridiculously energy intensive, but it does put the 777 to shame.
  - Symmetry 5y ago
    Ok, so with each kg of kerosene burned emitting 3.6 kg of CO2 about 85% of a launch is due to the kerosene. Whether 15% is significant or not is in the eye of the beholder but I don't think my contention was unreasonable. There are, of course, ground crews and radars and tarmacs and so forth associated with a rocket launch but the same is true with a 777 flight as well. Most 777 flights aren't to the plane's max range, this is more of a Pacific crossing fuel consumption but I still think its broadly comparable. The big difference, I guess, is that a Falcon 9 might only make it through 10 or 20 flights while a 777 might do thousands. That is a big difference in energy usage but I don't feel competent to try to quantify it.

croes 5y ago

First of all, the last straw that breaks the camel's back. These flights are additional and more are coming. Second rockets reach higher parts of the atmosphere and the impact is higher compared to the lower flying planes.

asdff 5y ago

The falcon 9 first stage has been tested to be reused 11 times so far. A boeing airframe on the other hand lasts 30 years. There is therefore the cost of bringing these rare earth materials found perhaps around the world together in one place to launch a finished falcon 9 rocket, independent of any fuel considerations, that should also be thought about.