If we made a large moon near Mars, the tidal forces would encourage the tectonic system to rev up again, and start up the inner dynamo effect. There would be volcanoes, producing a new atmosphere, which would capture more of the sun's heat and promote warm humid conditions for life.

To make the moon, it would be necessary to merge Phobos and Deimos and to figure out a domino effect among large bodies of the solar system which would send them all into the same orbit of Mars somewhere where they would join up.

Would we be able to make Mars have oceans again?

What technology plans could we develop to make a new moon possible?

  • $\begingroup$ What level of technology do you have in mind? Remember: Sufficiently advanced technology tends to be indistinguishable from magic. $\endgroup$
    – user
    Commented Nov 29, 2016 at 14:39
  • $\begingroup$ I bet it will be easier to paint Mars black. $\endgroup$ Commented Nov 29, 2016 at 14:40
  • 3
    $\begingroup$ @AntoineHejlík let me guess: You see a red Mars and you want it painted black? $\endgroup$
    – dot_Sp0T
    Commented Nov 29, 2016 at 15:04
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    $\begingroup$ Why build a moon? Just move Ceres into orbit around Mars. Avoids all the messy splattering effects of smashing small asteroids into each other. $\endgroup$
    – jamesqf
    Commented Nov 29, 2016 at 18:11
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    $\begingroup$ The question doesn't really make much sense. A lack of a moon isn't what's stopping Mars from being habitable. It wouldn't start up the core again either, at least none of the papers I've read on the subject suggest this. $\endgroup$
    – Feyre
    Commented Nov 29, 2016 at 21:30

2 Answers 2


Assuming that you are right that a large moon could actually gets Mars tectonic and magnetic system working again... (which is an interesting idea)
So after merging Phobos and Deimos and getting them in the right orbit, take the four largest asteroids in our solar system and send probes to them. Set up some nuclear reactors and a lot of EM drives and put them on a transfer orbit to Mars.
Several years/decades go by while the delta V for all that mass is adjusted and the transfer happens, and during that time the asteroids can be shaped by robots to fit better together. While the new moons gravity will have an effect on Mars, Mars will also have an effect on the new moon, and tidal forces could break it apart, which would be disastrous for any teraforming plans. Having the pieces fit together could make permanently fusing them much easier.

Once a magnetic field has been restarted, which will help deflect solar rays and keep them from removing the atmosphere, you need to make an atmosphere. Get a bunch of ice chunks and send them toward Mars the same way. These you can impact into Mars in the Borealis basin, as that area will all be under water eventually anyway.


You could just 'magic' the moon into existence. It's not like there was any technology involved in the creation of any existing moon. It's possible that a small rogue planetoid we haven't noticed just so happens to be on the perfect trajectory to wind up orbiting Mars. It would surely have a substantial effect on Mars' orbit and surface for a while while this interaction settled in, but hey, why not?


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