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I Terraforming Mars by using Europa

  1. Aug 2, 2017 #1
    Hi,
    Do you think there is any feasibility at all to terraform Mars be crashing Europa into it? Of course, you have the near impossible task of knocking Europa out of Jupiter's orbit and guiding into Mars without ruining its orbit...but if it worked maybe this would give Mars the extra mass, heat and water to sustain life (after 1,000 years or so) Thanks! or also maybe guiding asteroid to fly by Venus to help expel enough of its thick atmosphere to help terraform it?
    Thanks!
     
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  3. Aug 2, 2017 #2

    mfb

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    The impact would melt the Martian surface and spread debris all over the inner solar system, which leads to many large impacts on Earth. I don't think that is a good idea.

    The additional mass for Mars would be negligible. The additional water, after the surface cooled down sufficiently (that will take a long time), would be sufficient to cover all of Mars with an ocean with an average depth of 20 km. Olympus Mons might still be above the ocean.

    Even if we ignore the logistics of the impact, I'm not sure if the result would be good. Why not deliver some of the water without the rest of the moon?

    Mars still has a lot of water. It is just frozen at the moment.
     
  4. Aug 2, 2017 #3
  5. Aug 2, 2017 #4

    mfb

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    Even without magnetic field, atmospheric losses would be small, and only relevant over millions of years. Way beyond the planning horizon we have today. We don't have to solve 40,000th century problems with 21st century ideas.
     
  6. Aug 3, 2017 #5
    maybe with all that water it would drastically reduce the time needed to cool and additionally burn off a lot of that water so it wouldn't so flooded. or how about Venus? any way to reduce the thick atmosphere?
     
  7. Aug 3, 2017 #6

    mfb

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    The impact energy would correspond to the energy Mars receives from the Sun in about 1 million years.
    Sure, some water would escape, but probably not much, and water vapor is a very good greenhouse gas - it would slow down cooling.
    There are some ideas how to remove most of the CO2, but they are very speculative.
     
  8. Aug 5, 2017 #7
    A linear accelerator (railgun) on the surface of Europa hurling 10 kg hunks of ice at Mars would be a better way: Would either vaporize when they hit atmosphere, or churn up some crust on impact. In either case the water ends up in the atmosphere as a greenhouse gas.

    Magnetic field: It would take 250,000,000 A in a superconducting ring around the equator of Mars to generate a 1/2 gauss field. Yeah. Quibble about the geometry.

    This is a small project compared to moving Europa.
     
  9. Aug 12, 2017 #8
    Last edited by a moderator: Aug 13, 2017
  10. Aug 13, 2017 #9
    I'm hesitant about saying 'never' when talking about engineering. In 1700 landing on the moon was a 'never' job.

    While moving moons is beyond my current view of present and future technology, moving comets out of the Oort cloud is not.

    ***
    Smashing Europa into Mars even if done at minimum velocity is likely to splash enough rocks that the whole inner solar system becomes a riskier place.

    OTOH, firing off 10 Kg ice cubes (pick a size that will vaporize in the atmosphere) may be a way both to make Mars wet again, and to warm it up. Something like a rail gun with a resuable bucket, as Stine proposed for moving lunar rock to a Lagrange point in "The Third Industrial Revolution" A cubic km of water weighs a billion kg. 33 kg / second sends a km^3 per year.
     
  11. Aug 13, 2017 #10

    stefan r

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    Why Europa. Ceres is much closer to Mars and is not inside of Jupiter's gravity well. An object orbiting outside of Neptune's orbit would take much less energy to move into a more elliptical orbit. You could time perihelion so that one of the gas giants pulls an object into a lower or more elliptical orbit which intersects Mars orbit.

    Building a space habitat with larger surface area than mars would take significantly less energy. Would be available for occupation when completed and could be completed in a sequence of smaller pieces.

    I don not see how asteroid flybys will help remove Venus's atmosphere. If you expend the energy and effort lifting CO2 off of Venus why not use it? Carbon fiber objects can be manufactured using less energy than is required to lift the carbon off of Venus. Carbon is scarce on Mercury and on Earth's moon.

    Breathable air floats in CO2 the way helium floats in Earth's atmosphere. If you feel strongly that someone should occupy Venus you could put them in a dirigible or balloon. There are difficulties with that idea but removing the atmosphere is very difficult. Venus poses some geology problems. Venus's rotation is so slow that with a thinner atmosphere the surface temperature would go through extreme swings.

    A 10 kg ice cube would sublime in the vacuum of space. Free water molecules would interact with the solar wind and most (all?) of it would miss Mars.
     
  12. Aug 13, 2017 #11

    mfb

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    Let's see. We start with a liter-sized sphere of ice (easier to calculate later), let's say we want to keep evaporation below 1 cm of surface layer to keep most ice. Here is a model. Sublimation will only be interesting closer to Mars where the block of ice is warmer, let's take 1 year = 10000 hours with relevant sublimation. To stay below 1g/cm2, we need a temperature below 165 K. Note the extremely logarithmic scale: The temperature we need doesn't change much if we change the evaporation rate a lot. Let's take 160 K, that gives an additional safety factor of ~3.

    What is the albedo of our ice? This website suggests 0.73 in the visible light and 0.33 in the near infrared for "bare non-melting sea ice thicker than 0.5 m". I'll assume 0.6 for sunlight here, should be conservative. Emission should be close to a perfect blackbody. Then our sphere has an equilibrium given by ##\displaystyle 0.4 \frac{L_{sun}}{4 \pi R^2} \pi r^2 = 4 \pi r^2 \sigma T^4## where the radius r of the ice cancels out. Simplified: ##\frac{L_{sun}}{ 40 \pi T^4 \sigma} = R^2##. Plugging in T=160 K leads to R=1.9 AU. Mars is at 1.38-1.67 AU. Solving in reverse, we get 180 K, or an evaporation rate that is a factor ~20 larger. This evaporation rate will only be reached very close to Mars, however. We can also aim for Mars' aphelion, at 172 K we are very close to the original target of 165 K.

    If this calculation is accurate (I doubt it), then sending kg to ton-scale objects might work. Evaporation and its effect on the trajectory should be quite predictable.

    This does not take solar wind or similar effects into account.
     
  13. Aug 14, 2017 #12

    stefan r

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    We could bag the ice. Then we just need vapor pressure to be below the pressure that pops the bag. Polyethylene contains hydrogen too.

    Anyone know how 1,000,000 rail guns shooting 10 kg compare to 1000 shooting 10 tons and 1 shooting 10,000 tons? The only detailed descriptions I have read assumed an earth based launch. Most also assume a human or sensitive instruments in the payload.

    If the rail is on the surface (or in, under, and out of) how often is a launch window open? How many degrees spread can we get adjusting the velocity and still hit Mars? Could you launch toward Jupiter or away to get 2 windows?

    If they launched 1 projectile with 9,990 tons of ice and a 10 ton rocket vehicle with sun shield/solar array they could correct the aim in route to Mars. They could electrolyze some ice to make H2LOx fuel. A rocket burn close to Mars would still dump most the hydrogen into Mars' gravity. So the shuttle would disconnect from the ice ball and fly back to Europa.

    A hydrogen tank might work out better.

    Should be easier to shoot ammonia Ice from Callisto than water ice from Europa. Ammonia has more Hydrogen per kilo. Callisto has water too. Just getting Mars wet does not recreate an Earth like atmosphere.
     
  14. Aug 16, 2017 #13
    Most of these ideas seem to require more advanced technology than we have today and some don't have the practicality to actually work, like rail guns, you'd need quite a lot of rail guns shooting 10 KG of ice to warm and make Mars wet again. You'd have to get there and assemble the thing, not counting the resources you'd have to spend building all those rail guns. This project would be a logistical disaster. By the time we'd be capable of doing this in a short amount of time, terraforming mars would be a piece of cake. The original idea of crashing Europa into Mars is even more impractical.

    Why couldn't we just build a machine that freezes salt water from our oceans and a rail gun that shoots this frozen salt water? We could actually have a use for our ocean water that mostly gets unused, much more practical than shooting ice from Europa
     
  15. Aug 16, 2017 #14

    mfb

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    Shooting things through an atmosphere is very difficult. And while it would slow down the sea level rise a bit if done on a terraforming scale, I think most people would like to keep the water here.

    Installing a railgun on a moon is orders of magnitude easier than moving the moon.
     
  16. Aug 16, 2017 #15
    Surely shooting ocean water on to Mars won't do deplete our plentiful supply of it, also it's ocean water, no one cares about it too much, if we were to shoot fresh water there'd be a problem. Also you wouldn't have to literally shoot our entire ocean over to Mars, just enough so the ice caps melt and warm the planet.

    On the bright side it'll "reverse" all the damage done to the sea level in the past years and even decrease sea levels before the Industrial Revolution. Gigantic amounts of sea water don't have to be sent over to Mars as Mars has frozen water at its poles anyways.

    I think it's a feasible way of terraforming Mars over a period of time. We'd just need a strong enough cannon to shoot ice at escape velocity without it melting in the atmosphere. Another solution could be to make a orbital station that gets supplied with frozen sea water. This station could include a lot of cannons which wouldn't have to be as powerful as they would be on the ground. Much less energy would be needed to shoot the payload. The method of supplying the station could be thought of later like how the ISS is supplied
     
  17. Aug 16, 2017 #16

    mfb

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    Mars' surface area is 1/3 the surface area of Earth's oceans. If you want to shoot 1 million km3 of water there, about 1/3 the water in the Martian ice caps, enough for a 9 m layer of water on Mars, you would reduce the ocean levels by 3 meters. That would make a lot of people very unhappy.

    If you just want the impact to heat Mars, there is no need to use water, every random asteroid will do the job as well.
     
  18. Aug 16, 2017 #17
    A 3 metre drop in sea level might be a little troublesome for people but this is a small matter compared to the terraforming of Mars, a feet mankind has never accomplished before, if people don't sacrifice something to gain something else we'll never progress. The 3 metre reduction in sea levels may introduce more land to the planet and helping to reduce over population. The benefits far out weight the side effects of 3 metre reduction in sea levels
     
  19. Aug 17, 2017 #18

    mfb

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    A little troublesome? If we had this drop now and suddenly it would probably start an unprecedented recession and maybe even wide-spread famine because large parts of the global trade would stop working. If you can anticipate it you can dig every harbor deeper, but that would be a giant project on its own.

    Sure, you can, but as I said: Many people wouldn't be happy about it. And where is the point? There is so much water available elsewhere.
     
  20. Aug 17, 2017 #19
    As of right now you've already anticipated that sea levels would drop, so a huge project of digging the most important harbors essential to global trade routes deeper wouldn't be too hard even with our current technology, the hardest part would be to fund the project, but logistics and funding can be worried about later as that's too complicated. We could start digging our main harbors deeper while the station or whatever platform we're shooting from is being built. Our planet is the closest planet that contains water to Mars, it would be much faster getting our water and shooting it to Mars than it would be say a distant frozen Moon like Europa. And on Earth the project would be much more controlled due to the ease of access to it, if something went wrong we could fix it much faster than if it were elsewhere.

    Returning back to my solution to your predicament, digging the main harbours such as Singapore, Hong Kong, Dubai and all the large ports essential to trade routes. This would still allow for global trading to be possible, even though smaller ports will be dug deeper later, the trading system of the world won't be hurt too badly. What's stopping us from doing a big project? Funds? Let's forget about that.

    Though I do agree there would need to be a lot of planning involved in executing two gigantic global projects side by side. But what's stopped mankind from doing these large feets? Might as well try...
     
  21. Aug 17, 2017 #20

    mfb

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    Mars has water.

    Shooting through the atmosphere is very difficult, evaporation would be a huge issue at 1 AU, and the moons of Jupiter have a much lower escape velocity.
    This would never fly simply for political reasons even if it wouldn't cost any money.
     
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