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Thread: Launching from Mars

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    Launching from Mars

    I've heard if we land astronauts on Mars, it involves so much mass that we'd need to make fuel from Mars resources to take off again - e.g. methane. But wouldn't you need an oxidiser too? Is this a realistic plan or is it far more likely we'd need to launch with hypergolic fuels, which probably couldn't be manufactured from Mars resources and so would need to be flown in and stockpiled ahead of a crewed mission. Welcome any comments - thanks.

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    CO2 & water ice as proposed source materials. So oxygen should be a plentiful by product.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    In Situ Resource Utliization is the phrase used.
    Carbon dioxide and water are what you get when you burn methane in oxygen. So you use energy to reverse the process, using locally sourced carbon dioxide and water to produce methane and oxygen, which you can then store to burn later in your rocket.

    Grant Hutchison

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    Splitting CO2 into carbon monoxide and oxygen is another option. It is probably simpler and has surprisingly good performance.

    Carbon Monoxide and Oxygen Combustion Experiments: A Demonstration of Mars In Situ Propellants (pdf)

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    Quote Originally Posted by grant hutchison View Post
    In Situ Resource Utliization is the phrase used.
    Carbon dioxide and water are what you get when you burn methane in oxygen. So you use energy to reverse the process, using locally sourced carbon dioxide and water to produce methane and oxygen, which you can then store to burn later in your rocket.

    Grant Hutchison
    Understood, but wouldn't you have to store it at ambient temperature in some kind of huge tank and then cool it to liquid form to load into your rocket tanks just before launch? Sounds feasible on paper, but involves some serious infrastructure to achieve in practice. I figure pre-manufactured, pre-shipped hypergolics might be an easier solution?

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    Quote Originally Posted by Cheap Astronomy View Post
    Understood, but wouldn't you have to store it at ambient temperature in some kind of huge tank and then cool it to liquid form to load into your rocket tanks just before launch? Sounds feasible on paper, but involves some serious infrastructure to achieve in practice. I figure pre-manufactured, pre-shipped hypergolics might be an easier solution?
    Storing them as gases would be thoroughly unworkable. Even if you had those huge high-pressure tanks, you'd need massive radiators and a huge power source (even in terms of the already-large power source needed to manufacture the fuel in the first place) to liquefy them just before launch. They'd be stored in the form they're to be used in, as cryogenic liquids, just like we store LNG here on Earth.

    Given the mass requirements, no, hypergolics are not at all an easier solution. They are also completely uneconomical, as you'd have to land many vehicle loads of hypergolic propellants (instead of materials more useful on the ground) to get just one vehicle back, making useful reuse impossible.

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    Quote Originally Posted by cjameshuff View Post
    Storing them as gases would be thoroughly unworkable. Even if you had those huge high-pressure tanks, you'd need massive radiators and a huge power source (even in terms of the already-large power source needed to manufacture the fuel in the first place) to liquefy them just before launch. They'd be stored in the form they're to be used in, as cryogenic liquids, just like we store LNG here on Earth.

    Given the mass requirements, no, hypergolics are not at all an easier solution. They are also completely uneconomical, as you'd have to land many vehicle loads of hypergolic propellants (instead of materials more useful on the ground) to get just one vehicle back, making useful reuse impossible.
    Fair enough - thanks

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    I think Ceres might be the place to go. Enough of a "down" to keep things from floating. Water by the ton--and less surface gravity than the Moon or Mars

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    Quote Originally Posted by publiusr View Post
    I think Ceres might be the place to go. Enough of a "down" to keep things from floating. Water by the ton--and less surface gravity than the Moon or Mars
    It's changing depth or orbital plane in the gravity well that gets you, not the surface acceleration, and you can't neglect the biggest gravity well in the system, the sun's. It takes about 10 km/s to get from LEO to Ceres, only about 3 km/s of that being for getting out of Earth orbit. The reverse is easier because Earth's gravity well keeps a nice layer of atmosphere around for efficient braking.

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    Mars' moons Phobos and Deimos probably have the stuff, and they're right in the neighborhood. It's digging it up that's the problem; we don't know how much regolith might overlie any ices that might be there.
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    Quote Originally Posted by publiusr View Post
    I think Ceres might be the place to go. Enough of a "down" to keep things from floating. Water by the ton--and less surface gravity than the Moon or Mars
    publiusr

    You have an entirely too long a history of posting off-topic posts, for which you've been warned many, many times. A very specific Q&A post on launching from Mars is not an invite for your random thoughts about Ceres. Maybe a suspension will help you to be more careful in the future.
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    Quote Originally Posted by glappkaeft View Post
    Splitting CO2 into carbon monoxide and oxygen is another option. It is probably simpler and has surprisingly good performance.

    Carbon Monoxide and Oxygen Combustion Experiments: A Demonstration of Mars In Situ Propellants (pdf)
    Methanol is also easily produced from the Martian atmosphere and water. Methanol/LOX rocket engines have been demonstrated and there are some advantages of this fuel combination.

    https://sbir.gsfc.nasa.gov/SBIR/abst....03-0890B.html

    https://arc.aiaa.org/doi/pdf/10.2514/6.1998-3209

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    Quote Originally Posted by kzb View Post
    Methanol is also easily produced from the Martian atmosphere and water. Methanol/LOX rocket engines have been demonstrated and there are some advantages of this fuel combination.

    https://sbir.gsfc.nasa.gov/SBIR/abst....03-0890B.html

    https://arc.aiaa.org/doi/pdf/10.2514/6.1998-3209
    I get that it's easily produced, if the raw materials are available and I get that CO2 is readily available from the Martian atmosphere. Accessing sufficient water is another matter. There might be some in the regolith or deeper down in sufficient quantities - and if not, you could build pipelines to ship it from the poles. My point is that these are not straight-forward engineering solutions. In the end it might by easier (albeit almost as hugely complex and almost as hugely expensive) to drop pre-manufactured fuel stores onto the surface. At least then you could be confident about the purity and consistency of the product.

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    Quote Originally Posted by Cheap Astronomy View Post
    I get that it's easily produced, if the raw materials are available and I get that CO2 is readily available from the Martian atmosphere. Accessing sufficient water is another matter. There might be some in the regolith or deeper down in sufficient quantities - and if not, you could build pipelines to ship it from the poles. My point is that these are not straight-forward engineering solutions. In the end it might by easier (albeit almost as hugely complex and almost as hugely expensive) to drop pre-manufactured fuel stores onto the surface. At least then you could be confident about the purity and consistency of the product.
    It boils down to how many launches each process would require. And for Mars missions, the mass ratio is terrible. You end up with a relative few drops of fuel delivered per rocket.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Cheap Astronomy View Post
    I get that it's easily produced, if the raw materials are available and I get that CO2 is readily available from the Martian atmosphere. Accessing sufficient water is another matter. There might be some in the regolith or deeper down in sufficient quantities - and if not, you could build pipelines to ship it from the poles. My point is that these are not straight-forward engineering solutions. In the end it might by easier (albeit almost as hugely complex and almost as hugely expensive) to drop pre-manufactured fuel stores onto the surface. At least then you could be confident about the purity and consistency of the product.
    Water ice is widespread on Mars. One of the sites SpaceX is looking at is Arcadia Planitia, which has an ice sheet tens of meters thick under a few meters of regolith, estimated to contain around 10000 cubic kilometers of water ice.

    You're far better off importing equipment to mine ice and supplies to sustain the colony than hundreds of tons of fuel.

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