4 ms·

I have a few interesting questions ... to be fair, I've done no science or math to make a conclusion but there would certainly be a sense of irony involved. 1.

by smoyer 7y ago

I have a few interesting questions ... to be fair, I've done no science or math to make a conclusion but there would certainly be a sense of irony involved. 1. Could the green-house gases produced to launch a civilization to Mars be the final straw that breaks our eco-system's back? 2. What are the moral implications of terra-forming Mars and moving a small population there, knowing that the population remaining on Earth is doomed? 3. If you're willing to allow an epic depopulation of the Earth, why not stay here and let it happen? 4. If any of the above are true, why would you expect the (current) larger population of the Earth to fund the colonization of Mars? I realize this is a very dystopian view ... and that I read/watch too much science fiction, but if this is a novel (or a Netflix original), the Mars population moves back to Earth after it's "recovered" EDIT: I'm not against the StarShip, SpaceX or Musk at all - in fact I'm a big fan as I was in elementary school during the Apollo missions and believe that SpaceX in particular has reinvigorated the passion for engineering and tackling big problems. This is only a Gedankenerfahrung.

hughes 7y ago
Methane-oxygen propellant can be near carbon-neutral when using huge solar farms to produce it from CO2 and water in the surrounding air. No net increase in greenhouse gasses. However, the ingredients of this process would be redistributed to the upper atmosphere - the effects of this should be carefully studied.
perlgeek 7y ago
> 1. Could the green-house gases produced to launch a civilization to Mars be the final straw that breaks our eco-system's back? That seems very unlikely to me. > 2. What are the moral implications of terra-forming Mars and moving a small population there, knowing that the population remaining on Earth is doomed? Even if we spent half of our resources on sending people to mars and hurting Earth's biosphere in the process, Earth would still be much more habitable than Mars. Heck, even worst-case scenarios for man-made climate change "just" reduce the areas where humans can live on earth (and that's a huge catastrophe for everybody), but there's literally NO PLACE on Mars where you can survive at all without pressurized residence etc.
PaulHoule 7y ago
I want to use a Starship to put a solar sail factory on an NEO and send the sails to Earth-Moon L1 to block sunlight to buy us some time. If you think you can change human nature fast enough to curb climate change you should think again; introduce new energy sources that are cheaper than fossil fuels and you can make them.obsolete.
- chr1 7y ago
  "buying some time" would be the most underwhelming use of such a technology. If you are putting large enough sunshade to change the climate, you can use it to actually control the weather, make sahara green, make siberia warm, melt greenland ice sheet in controlled way moving it to antarctic.
  - _ph_ 7y ago
    Making the Sahara green is a good idea, Siberia warm, much less so. Actually the thawing of the perma frost is currently one big danger, as it would release a massive amount of greenhous gases (mostly methane).
    - chr1 7y ago
      You would do it in a controlled manner so that the amount of released gases from arctic is compensated by gases absorbed by greening deserts.
  - PaulHoule 7y ago
    Increasing CO2 is very bad for the oceans and has mixed effects on crops. We may want to remove carbon with biochar, iron seeding, etc. Fast or thermal breeder reactors with a high outlet temperature (e.g. Fast Flux Test Facility) coupled to a low cost gas turbine generator set could push fossil fuels out of the market in some places.
sp332 7y ago
Each launch puts a few hundred tons of CO2 into the atmosphere, not counting emissions during construction. So each one is not a disaster, but if they're doing a ton of launches per year that adds up quickly.
- gpm 7y ago
  Does it add up though? If each launch moves 100 american-person-years of CO2 production off of the planet, that's... 1600 tons of CO2 that isn't being released. 100 person years per launch seems like a vast under-estimate too. (Number sourced from the first paper that appeared when I searched "CO2 footprint of the average american" - https://externalassets.cooleffect.org/lib/content/wp-content/uploads/2018/04/05172819/CarbonFootprint_AverageAmerican.pdf https://externalassets.cooleffect.org/lib/content/wp-content...) In the grand scheme of things I doubt enough people will go to mars to make a significant positive difference, but that's nearly synonymous with saying I doubt there will be enough rocket launches to make a difference.
MPSimmons 7y ago
The system is harvesting methane from Earth and converting it to carbon dioxide (another greenhouse gas, but less potent). If the system uses the Sabatier method to produce methane from CO2, then it's using solar power (I can't imagine doing it in any other way sanely) to convert CO2 to CH4, which is then converted back to CO2 by the rocket. Net gain of no greenhouse gas.

by smoyer 7y ago

hughes 7y ago

Methane-oxygen propellant can be near carbon-neutral when using huge solar farms to produce it from CO2 and water in the surrounding air. No net increase in greenhouse gasses. However, the ingredients of this process would be redistributed to the upper atmosphere - the effects of this should be carefully studied.

perlgeek 7y ago

> 1. Could the green-house gases produced to launch a civilization to Mars be the final straw that breaks our eco-system's back? That seems very unlikely to me. > 2. What are the moral implications of terra-forming Mars and moving a small population there, knowing that the population remaining on Earth is doomed? Even if we spent half of our resources on sending people to mars and hurting Earth's biosphere in the process, Earth would still be much more habitable than Mars. Heck, even worst-case scenarios for man-made climate change "just" reduce the areas where humans can live on earth (and that's a huge catastrophe for everybody), but there's literally NO PLACE on Mars where you can survive at all without pressurized residence etc.

PaulHoule 7y ago

I want to use a Starship to put a solar sail factory on an NEO and send the sails to Earth-Moon L1 to block sunlight to buy us some time. If you think you can change human nature fast enough to curb climate change you should think again; introduce new energy sources that are cheaper than fossil fuels and you can make them.obsolete.

chr1 7y ago
"buying some time" would be the most underwhelming use of such a technology. If you are putting large enough sunshade to change the climate, you can use it to actually control the weather, make sahara green, make siberia warm, melt greenland ice sheet in controlled way moving it to antarctic.
- _ph_ 7y ago
  Making the Sahara green is a good idea, Siberia warm, much less so. Actually the thawing of the perma frost is currently one big danger, as it would release a massive amount of greenhous gases (mostly methane).
  - chr1 7y ago
    You would do it in a controlled manner so that the amount of released gases from arctic is compensated by gases absorbed by greening deserts.
- PaulHoule 7y ago
  Increasing CO2 is very bad for the oceans and has mixed effects on crops. We may want to remove carbon with biochar, iron seeding, etc. Fast or thermal breeder reactors with a high outlet temperature (e.g. Fast Flux Test Facility) coupled to a low cost gas turbine generator set could push fossil fuels out of the market in some places.

sp332 7y ago

Each launch puts a few hundred tons of CO2 into the atmosphere, not counting emissions during construction. So each one is not a disaster, but if they're doing a ton of launches per year that adds up quickly.

gpm 7y ago
Does it add up though? If each launch moves 100 american-person-years of CO2 production off of the planet, that's... 1600 tons of CO2 that isn't being released. 100 person years per launch seems like a vast under-estimate too. (Number sourced from the first paper that appeared when I searched "CO2 footprint of the average american" - https://externalassets.cooleffect.org/lib/content/wp-content/uploads/2018/04/05172819/CarbonFootprint_AverageAmerican.pdf https://externalassets.cooleffect.org/lib/content/wp-content...) In the grand scheme of things I doubt enough people will go to mars to make a significant positive difference, but that's nearly synonymous with saying I doubt there will be enough rocket launches to make a difference.

MPSimmons 7y ago

The system is harvesting methane from Earth and converting it to carbon dioxide (another greenhouse gas, but less potent). If the system uses the Sabatier method to produce methane from CO2, then it's using solar power (I can't imagine doing it in any other way sanely) to convert CO2 to CH4, which is then converted back to CO2 by the rocket. Net gain of no greenhouse gas.