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The ultimate plan is actually to make it from water and CO2 in the air, using the same tech they'll use to make methane on Mars for the return trip. They're jus

The ultimate plan is actually to make it from water and CO2 in the air, using the same tech they'll use to make methane on Mars for the return trip. They're just not there yet.

lazide 5y ago
Sure, and I have a bridge to sell you. The technology already exists. Fundamentally (damn laws of thermodynamics) it is also a energy negative process, and hence expensive. It is far cheaper to just frack and burn fossil fuels (where that energy expense was paid however many millions of years ago by someone else), than it is to expend the energy to reverse the process - even if they were getting nearly free energy.
- Denvercoder9 5y ago
  SpaceX wants to make a roundtrip to Mars, though. There's no fossil fuels on Mars.
  - lazide 5y ago
    And if it doesn’t make any economic sense to do it here, where it is super convenient, shipping it to Mars (with nothing of known value there to return or any known economic model that could make it worthwhile) to do it there is going to be worth it? Not saying all human endeavor needs to have a healthy profit margin. SpaceX is a business however and besides doing it for the lulz, or getting a government contract, it doesn’t make much sense to try to spin up colonies or the like there. Everyone will starve and/or their US backers will go bankrupt pretty quick.
    - MPSimmons 5y ago
      > SpaceX is a business however SpaceX has been described as a company with a Mars cult inside of it. I think it's more fair to say that it's a Mars cult that has organized a company. If you think that SpaceX won't do hydrocarbon generation on Mars, then you don't understand why SpaceX exists.
    - politician 5y ago
      So you're just a typical No-Mars skeptic, got it.
    - DennisP 5y ago
      If you want to go to Mars, it's way cheaper to get your return fuel from Mars instead of carrying it all the way to Mars from Earth. If you want to get your return fuel from Mars, then you have to make it, there aren't any convenient natural gas deposits that we know of. This isn't an original SpaceX idea. Robert Zubrin pointed it out back in 1990 with his Mars Direct plan. https://en.wikipedia.org/wiki/Mars_Direct https://en.wikipedia.org/wiki/Mars_Direct
      - lazide 5y ago
        For sure - my point is, that presumes there is enough volume or an economic need to make that sort of infrastructure investment worthwhile (not even dollars, but energetically). Getting the direct equipment let alone supporting equipment there is going to be very, very expensive in energy. For one trip back, or even 5, it’s unlikely to pay off unless there is some cool super miniaturization tech and we’re not in a hurry - and that assumes everything keeps working over multiple missions. And if we have all that, getting a mobile lab there and sending back bits instead of physical chunks of things is even easier. You’d also need to get chemical feedstocks and process them (namely to extract the hydrogen, which is not readily available in the Martian atmosphere but is in the soil in various amounts in minerals and small amounts of dispersed water and methane ice) which would be non-trivial and a huge hassle to get even on Earth where you can go outside and smack the machinery with a shovel or stick your arm in somewhere to unclog something. The existing Mars rovers struggle sometimes with dust on solar panels, let alone a broken bolt in a crusher due to harder than expected rocks or the like. Having done some basic mining and a lot of earth moving over the years, it’s an incredible pain in the ass. It’s also rare you don’t periodically need a human getting hands on, and using every bit of dexterity and strength they have to fix something. Robotic tech is nowhere near good enough to do this remotely. So at a small, very very very slow scale? Maybe? There are a lot of cool thought problems from all this, and some cool potential solutions. My fav is Project Orion [https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propu...] And we’ll just have to see what happens.
  - elif 5y ago
    Yup and musk also argues in favor of a carbon tax. He is openly hopeful that the fundamental economics will be changed to make producing their own methane via Sabatier economical. It is up to the controllers of incentive structures to change the fundamentals of commerce/ecology.
    - lazide 5y ago
      Pretty sure that would require something like a 5x cost increase in carbon, though I can’t find hard numbers anywhere easily. Do you have any pointers?
      - gpm 5y ago
        > Pretty sure that would require something like a 5x cost increase in carbon 5x over what? The US doesn't have a carbon tax does it?
        lazide 5y ago
        5x over the current baseline cost of fuel. The only studies I could find of doing this were using large scale bulk solar and not counting financing costs into the equation. They found that if avoiding fossil fuel use (natural gas is the cheapest easily available Hydrogen source right now), and cracking water to get it, end to end energy efficiency is between 44-56% (as in electrical efficiency to theoretical available chemical energy in the fuel). Burning said fuel for energy (turbines being one of the most efficient ways) then varies from 40-63% efficiency, rockets can hit up to 70% efficiency (varies immensely by many factors). So, getting what they need from a fossil fuel is up to 70% efficient. Getting what they need from a Sebatier process? 28-41% efficient (combined). Add in extra capital costs and maintenance of acquiring and running the equipment, about 5x more expensive fossil fuel evens out. It’s potentially worse than that of course when you factor in potential increases in electrical rates if fossil fuels did get 5x, but there is nothing saying that would for sure happen. They presumably could run it during oversupply from a large solar plant, but that is already factored into those studies. If you’re doing it at scale, that ‘free energy’ won’t be free for long.
      - 5y ago
- inglor_cz 5y ago
  They will rely on the Sabatier process to produce fuel on other celestial bodies. And the corresponding technology must be tested first - why not in Boca Chica? I don't think that anyone is trying to make the claim that SpaceX will use the Sabatier process to fuel Starships here on Earth right now routinely. As you say, gas is cheaper to buy here on Earth. But they still must have the technology mastered before they fly away from the low Earth orbit.
  - lazide 5y ago
    The process IS already mastered, depending on the bar you set? This isn’t something unknown or theoretical.
    - inglor_cz 5y ago
      Yes, but you still need to design, assemble and test the particular equipment you want to use, unless you can do with off-the-shelf components. And contemporary off-the-shelf components that perform the Sabatier process aren't probably meant to operate outside the Earth.
      - SiempreViernes 5y ago
        But this is merely testing, not any sort of large scale use of this equipment because, as you point out, they are not made to work on Earth.
      - Fnords 5y ago
        "you still need to design, assemble and test" Not if NASA did that decades ago.
        gpm 5y ago
        I certainly hope that there are technological improvements that we can take advantage of that have occurred in the past decades (in manufacturing, modeling of pressure vessels and chemical processes, etc). Mass to mars is incredibly expensive, it's worth spending the time and money to optimize whatever equipment you are sending there.
- DennisP 5y ago
  Of course it's energy-negative, nobody is claiming otherwise. Powering that from renewables will cost more. But the cost of fuel is a very small percentage of launch cost, and if they're doing a lot of launches then being able to say they're carbon-neutral would be pretty helpful for public acceptance. Politics and regulation are much more dangerous to them than a little extra cost in fuel.
mhh__ 5y ago
Is it possible that they are in for the money and the grand plan is just marketing even if they would do it if they could?

The ultimate plan is actually to make it from water and CO2 in the air, using the same tech they'll use to make methane on Mars for the return trip. They're just not there yet.

lazide 5y ago

Sure, and I have a bridge to sell you. The technology already exists. Fundamentally (damn laws of thermodynamics) it is also a energy negative process, and hence expensive. It is far cheaper to just frack and burn fossil fuels (where that energy expense was paid however many millions of years ago by someone else), than it is to expend the energy to reverse the process - even if they were getting nearly free energy.

Denvercoder9 5y ago
SpaceX wants to make a roundtrip to Mars, though. There's no fossil fuels on Mars.
- lazide 5y ago
  And if it doesn’t make any economic sense to do it here, where it is super convenient, shipping it to Mars (with nothing of known value there to return or any known economic model that could make it worthwhile) to do it there is going to be worth it? Not saying all human endeavor needs to have a healthy profit margin. SpaceX is a business however and besides doing it for the lulz, or getting a government contract, it doesn’t make much sense to try to spin up colonies or the like there. Everyone will starve and/or their US backers will go bankrupt pretty quick.
  - MPSimmons 5y ago
    > SpaceX is a business however SpaceX has been described as a company with a Mars cult inside of it. I think it's more fair to say that it's a Mars cult that has organized a company. If you think that SpaceX won't do hydrocarbon generation on Mars, then you don't understand why SpaceX exists.
  - politician 5y ago
    So you're just a typical No-Mars skeptic, got it.
  - DennisP 5y ago
    If you want to go to Mars, it's way cheaper to get your return fuel from Mars instead of carrying it all the way to Mars from Earth. If you want to get your return fuel from Mars, then you have to make it, there aren't any convenient natural gas deposits that we know of. This isn't an original SpaceX idea. Robert Zubrin pointed it out back in 1990 with his Mars Direct plan. https://en.wikipedia.org/wiki/Mars_Direct https://en.wikipedia.org/wiki/Mars_Direct
    - lazide 5y ago
      For sure - my point is, that presumes there is enough volume or an economic need to make that sort of infrastructure investment worthwhile (not even dollars, but energetically). Getting the direct equipment let alone supporting equipment there is going to be very, very expensive in energy. For one trip back, or even 5, it’s unlikely to pay off unless there is some cool super miniaturization tech and we’re not in a hurry - and that assumes everything keeps working over multiple missions. And if we have all that, getting a mobile lab there and sending back bits instead of physical chunks of things is even easier. You’d also need to get chemical feedstocks and process them (namely to extract the hydrogen, which is not readily available in the Martian atmosphere but is in the soil in various amounts in minerals and small amounts of dispersed water and methane ice) which would be non-trivial and a huge hassle to get even on Earth where you can go outside and smack the machinery with a shovel or stick your arm in somewhere to unclog something. The existing Mars rovers struggle sometimes with dust on solar panels, let alone a broken bolt in a crusher due to harder than expected rocks or the like. Having done some basic mining and a lot of earth moving over the years, it’s an incredible pain in the ass. It’s also rare you don’t periodically need a human getting hands on, and using every bit of dexterity and strength they have to fix something. Robotic tech is nowhere near good enough to do this remotely. So at a small, very very very slow scale? Maybe? There are a lot of cool thought problems from all this, and some cool potential solutions. My fav is Project Orion [https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propu...] And we’ll just have to see what happens.
- elif 5y ago
  Yup and musk also argues in favor of a carbon tax. He is openly hopeful that the fundamental economics will be changed to make producing their own methane via Sabatier economical. It is up to the controllers of incentive structures to change the fundamentals of commerce/ecology.
  - lazide 5y ago
    Pretty sure that would require something like a 5x cost increase in carbon, though I can’t find hard numbers anywhere easily. Do you have any pointers?
    - gpm 5y ago
      > Pretty sure that would require something like a 5x cost increase in carbon 5x over what? The US doesn't have a carbon tax does it?
      - lazide 5y ago
        5x over the current baseline cost of fuel. The only studies I could find of doing this were using large scale bulk solar and not counting financing costs into the equation. They found that if avoiding fossil fuel use (natural gas is the cheapest easily available Hydrogen source right now), and cracking water to get it, end to end energy efficiency is between 44-56% (as in electrical efficiency to theoretical available chemical energy in the fuel). Burning said fuel for energy (turbines being one of the most efficient ways) then varies from 40-63% efficiency, rockets can hit up to 70% efficiency (varies immensely by many factors). So, getting what they need from a fossil fuel is up to 70% efficient. Getting what they need from a Sebatier process? 28-41% efficient (combined). Add in extra capital costs and maintenance of acquiring and running the equipment, about 5x more expensive fossil fuel evens out. It’s potentially worse than that of course when you factor in potential increases in electrical rates if fossil fuels did get 5x, but there is nothing saying that would for sure happen. They presumably could run it during oversupply from a large solar plant, but that is already factored into those studies. If you’re doing it at scale, that ‘free energy’ won’t be free for long.
    - 5y ago
inglor_cz 5y ago
They will rely on the Sabatier process to produce fuel on other celestial bodies. And the corresponding technology must be tested first - why not in Boca Chica? I don't think that anyone is trying to make the claim that SpaceX will use the Sabatier process to fuel Starships here on Earth right now routinely. As you say, gas is cheaper to buy here on Earth. But they still must have the technology mastered before they fly away from the low Earth orbit.
- lazide 5y ago
  The process IS already mastered, depending on the bar you set? This isn’t something unknown or theoretical.
  - inglor_cz 5y ago
    Yes, but you still need to design, assemble and test the particular equipment you want to use, unless you can do with off-the-shelf components. And contemporary off-the-shelf components that perform the Sabatier process aren't probably meant to operate outside the Earth.
    - SiempreViernes 5y ago
      But this is merely testing, not any sort of large scale use of this equipment because, as you point out, they are not made to work on Earth.
    - Fnords 5y ago
      "you still need to design, assemble and test" Not if NASA did that decades ago.
      - gpm 5y ago
        I certainly hope that there are technological improvements that we can take advantage of that have occurred in the past decades (in manufacturing, modeling of pressure vessels and chemical processes, etc). Mass to mars is incredibly expensive, it's worth spending the time and money to optimize whatever equipment you are sending there.
DennisP 5y ago
Of course it's energy-negative, nobody is claiming otherwise. Powering that from renewables will cost more. But the cost of fuel is a very small percentage of launch cost, and if they're doing a lot of launches then being able to say they're carbon-neutral would be pretty helpful for public acceptance. Politics and regulation are much more dangerous to them than a little extra cost in fuel.

mhh__ 5y ago

Is it possible that they are in for the money and the grand plan is just marketing even if they would do it if they could?