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I Terraforming Mars by using Europa

  1. Aug 18, 2017 #26
    What is technically feasible in foreseeable future (a few ~100s of years) is nudging some long-period comets which already pass near Mars, into colliding with it. The necessary dV to adjust orbits is small if you do it far away from perihelion, say at something like Neptune's distance from Sun.

    To reduce damage to Mars, a very oblique entry into atmosphere may be best. Also, mining into the comet and putting in a several megaton fusion bomb(s) would allow you a controlled disintegration at a controlled altitude in Mars atmosphere. Another possibility worth looking into is aerocapture of the comet into a Mars orbit, and gradual dismantling (however I have doubts it can survive g forces intact).
     
  2. Aug 18, 2017 #27
    If it didn't survive g forces there would still be smaller chunks that could be de-orbited and anyway, I would think if something of that magnitude was to be done, it would be done before humans arrive so nobody would get hurt.

    There still would be an ethical issue to deal with: We don't know if there is life there, but if there is, and we start slamming down comets raining destruction of the hypothetical eco-system, could we ethically do that to life on another planet in our zeal to terraform Mars?
     
  3. Aug 18, 2017 #28

    mfb

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    Do you think people in 1800 could foresee how our world looks today?
    I expect the world to change much more in the next 200 years than it did in the previous 200 years.
    We will probably have the technology to go to Mars within 20 years. Deflecting comets will take longer.

    Concerning possible life on Mars: That is actively studied.
     
  4. Aug 19, 2017 #29
    I don't have ethical issues with killing bacteria and such. I brush my teeth every day :D

    Cordoning off Mars forever just because there might be some bacteria is completely unreasonable decision on cost/benefit metrics. However, I fully expect that enviro-nuts will promptly go off the rails on this issue and label anyone who disagrees with them "murderous fascists hell bent on exterminating poor oppressed Martian bacteria" and such.
     
  5. Aug 19, 2017 #30

    mfb

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    Even if you completely ignore ethical questions (and I don't think you should), there are huge scientific and even economic benefits of studying very foreign life - we would learn much more about life in general.
     
  6. Aug 19, 2017 #31
    Sure. But nothing prevents studying Martian life while Mars colonization is underway. It's certain to be different enough from Earth bacteria so that "contamination" of Earth origin should not be a huge problem for analysis. Real-world example: Genesis' spacecraft crashed on landing and contaminated its samples with Earth materials, however analysis was still largely successful.
     
  7. Aug 24, 2017 #32
    Surely crashing a few puny comets to the surface of Mars would do nothing to the so called bacteria living on Mars, if there is life on Mars then it would need to have adapted to the harsh Martian climate and solar flares and other cosmic events, dust storms, high carbon dioxide levels and such, a few comets crashing would be the least of their worries...
     
  8. Aug 24, 2017 #33
    But what if we found surviving pockets of higher life forms, squidy things in a buried lake or hydrovent?
     
  9. Aug 29, 2017 #34

    stefan r

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    The less it effects the climate the more useless the action.

    Plants on earth evolved to grow in shade usually die when they get too much sun. Desert plants tend to develop root rot when you water them. Tundra will not grow in the tropics, tropical plants die when leaves freeze. Climate change is highly disruptive and makes it very difficult to study what the ecology was like before disruption.

    Any organism starves if some other organism eats its food. Organisms die when they are eaten. Few organisms that are adapted to a martian atmosphere would be able to survive for long in a earth atmosphere. The likelihood of competing against organisms that are adapted comes close to zero.
     
  10. Aug 29, 2017 #35
    Getting several billion tonnes of water off of Earth would require several billion tonnes of rocket fuel, and a fleet of rockets numbering several thousands.
     
  11. Aug 29, 2017 #36

    mfb

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    Why would you launch this with rockets? There are better ways to get huge amounts of matter into orbit or beyond. They are not worth the investment today, but with larger demand they would be built.
     
  12. Aug 29, 2017 #37

    stefan r

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    Would be impressive rocket if it can lift a million tons. Space shuttle could launch almost 4 tons to GEO. The shuttle program launch 134 times.

    Lifting water off earth is much harder than Ceres, Europa or a lot of comets.

    Pluto-Charon may have been demoted from planet status but there is lots of water and nitrogen.
     
  13. Sep 1, 2017 #38
  14. Sep 1, 2017 #39
    Assuming we understand the mechanism for Earth's magnetic field correctly, the method would need to create something similar for Mars..
    That is we would need to liquify the core then spin it up.
    It doesn't break any laws of physics but the amount of energy involved would be enormous, and certainly well beyond any present technology.
     
  15. Sep 1, 2017 #40
    IMO when terraforming Mars (as opposed to more promising options like Venus and Mercury say, or colonising spacecraft or asteroids) is discussed, religious rage takes over where rationality leaves off.

    All quite unnecessary really; freezing water from Earth's oceans and shooting the ice to Mars indeed! As someone pointed out, pointed out, parts of Mars have large quantities of brine, even in comparison to some parts of the Atacama desert. All the colonists need do is install a few open-cast frozen-brine mines and power generators, and brine desalination plants, and Robert is your mother's brother. Of course, grabbing a bit of H2, NH3, and CH4 from Jupiter and various moons would be equally easy.

    Mars will be ours, and flushing green around our colonial cities.

    Or something...
     
  16. Sep 1, 2017 #41
    Looking at the earlier suggestion to put a superconducting ring around Mars -- would that not gradually heat the core through hysteresis, for instance? Granted, the time scale would be ridiculous. But maybe multiple lines of attack? Superconductiong ring providing inductive heating, plus H-bombs dropped down a deep shaft, plus microwave energy being beamed to the poles and used in some kind of either heating or further induction...

    I'm just spitballing, and I freely admit I haven't a clue.
     
  17. Sep 1, 2017 #42

    mfb

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    The global thermonuclear arsenal is about 6*1018 J (number from here), divided by the mass of Mars we get 10 µJ/kg. If you somehow manage to heat 10% of Mars only you get 0.1 mJ/kg. Utterly negligible.

    As comparison: It is about the energy Mars receives as sunlight every 10 seconds.
     
  18. Sep 1, 2017 #43

    stefan r

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    If you build huge superconducting rings why would you heat Mars' core? Would already be a huge magnet.

    The only reason to bother with the magnet is to avoid some of the ionizing radiation. Detonating nuclear bombs is not a way to reduce exposure to ionizing radiation.

    Microwaves are usually considered safe radiation but microwaves do not penetrate. You will only get convective flow if the inside is hotter than the outside.
     
  19. Sep 3, 2017 #44
    I like the idea of sending some of earths ocean water to Mars. I'm not sure about railguns and the like though.
    I assume by the time we are ready for anything even remotely close to this we should have an operating space tether/elevator.
    Could it even be possible in the future to siphon the ocean water up through the middle of a space tether and send it on to mars from there? Once in space and frozen you could then shoot it to mars however you like.
    Probably need multiple space tethers to keep the weight down too.
     
  20. Sep 3, 2017 #45

    stefan r

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    Hydrogen is much lighter than water. Methane is also lighter and can easily be converted to water on other planets. I have doubts about the friction on 40 million meters of pipe. One large pipe will transport more fluid without bursting. A space tether pipe material would have to be much stronger than a space tether material because internal pressure adds stress.

    Materials that exist could build an elevator on Europa, Ceres, or a bridge from Pluto to Charon.

    You might like the space fountain idea. If hydrogen ions or molecules are the particle stream then you could collect some in space instead of sending them back down.
     
  21. Sep 10, 2017 #46
    Finally someone who understands me, by the time we got through political trouble and annoyances on Earth, we'd most likely have the technology to have a space elevator sort of contraption or a way to siphon water up to a planetary space station or at least a Moon base, firing frozen water from the Moon is MUCH easier than from Earth due to the Moon having negligible, but building a space tether to Mars may be out of reach for quite a while, that's not counting it being worth it or not, by the time the construction was completed we'd probably have been able to cover Mars with water

    But why terraform Mars when even if it had water would still be relatively uninhabitable? I mean if Mars lost its magnetic field once, who's to say it will lose it again once we resort it? Unless we made the magnetic field nearly as strong as Earth's, the magnetic field would most likely be lost. Also the fact that Mar's atmosphere is basically carbon dioxide might make it a little hard to breath in don't you think?
     
    Last edited by a moderator: Sep 10, 2017
  22. Sep 10, 2017 #47

    mfb

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    We cannot restore the magnetic field of Mars. We don't have to do so either.
    Getting some oxygen into the atmosphere is easier than large amounts of water.
     
  23. Sep 10, 2017 #48

    stefan r

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    I believe the space elevator is a materials science problem. What political opposition do you know of?

    Water is in short supply on the moon. Highly unlikely that any lunar water will be fired to Mars. It is possible that rockets traveling to Mars will burn fuel collected on the moon. Rocket fuel would not add any water to Mars' surface.

    If you mean lifting water from Earth to the Moon and then relaunching to Mars then no it is not easier. A direct shot would be much lower energy. Flying past the moon for a gravity assist could help.

    The mass of a Mars skyhook attached to Phobos would be much lower than the mass of an ocean. A cubic kilometer of water would not be an ocean. A million tons of water compared to 10,000 tons of materials. Most of the material for the Phobos skyhook could be acquired on Mars and likely on Phobos.


    Removing the CO2 would be much easier than bringing in Nitrogen. The pressure is less than 1% of Earth's atmosphere. Ejecting carbon into space from Mars would be the same energy scale as escaping Jupiter's gravity from Europa. Depositing coal would be much lower energy and mechanically easier. Overall may be more than 1000x less effort. Terraforming would also include adding plants which need the CO2 so removing would be counter productive.

    Of course Europa is short on Nitrogen. But we can repeat this nonsense using Titan instead.
     
  24. Sep 10, 2017 #49

    mfb

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    Phobos has a mass of 1016 kg. You are fine with moving that to a significantly higher orbit (and probably moving Deimos as well, another 1.5*1015 kg), but you are worried about 1012 kg for a cubic kilometer of water?

    1016 kg of water, corresponding to the mass of Phobos, could give Mars a uniform 7 cm layer of water. Or many reasonably sized lakes in many interesting places.
     
  25. Sep 10, 2017 #50

    stefan r

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    My first thought when I read that was "I said skyhook not elevator". A skyhook hanging off of Phobos does not require any moving of Phobos.

    Then I looked at the numbers. Going from Phobos to Deimos takes 745 m/s delta v. I believe that figure includes take off and landing. Is also overkill for anything in between including geosynchronous (areosynchronous?) . Delta V launching from Earth's surface to low earth orbit is around 9,000 m/s.
    9000/745 = 12

    Tsoilkovsky rocket equation:
    Δv = vexh ln(m0/mf)
    or
    m0/mf=e(Δv/v)
    To get 12 times the delta V the mass ratio needs to increase by e12 which = 1.7 x 105 So order of magnitude estimate the 1 km3 of water takes 10x more fuel even if just moving to LEO. The starting mass and final mass need to include rocket engines and tanks which could be worse for the water lift. Phobos is not made out of rocket fuel so it is not that simple. But if you have a large cable you can catapult material and plug it into the Tsoilkovsky equation.

    Maybe you could also use a tether to catch and de-orbit the ice from Europa. I am inclined toward thinking Phobos is well placed right where it is now. :)
     
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