Mars is a planet commonly brought up when talking about terraforming. Even if we were to manage to get past all economic barriers, and somehow form a thick atmosphere, would the lack of a magnetic field on Mars stop any attempt to terraform it? Would the atmosphere be destroyed by solar wind?

  • $\begingroup$ I think the standard terraforming process would work but at the cost of time. However, a while back I came across an article about tterraforming the moon. It purposed building a closely orbiting transparent sheel built of a cellular membranes attached to a ridged lattace structue. It had a series of airlock like entrypoints. I am not sure of all of the details, but it seems that such an arrangement would solve the problem of atmospheric pressure loss. If interested email me and I will copy you on the link. Cheers. $\endgroup$
    – templerman
    Commented Jun 19, 2022 at 12:03

4 Answers 4


Without a magnetic field any changes we do are seemingly temporary. As we make atmosphere it will be torn away by double solar winds.

Double solar winds are the worst, occurring about 15% of the time this occurs when a faster solar wave catches a slower and rolls into one bigger wave.

And these happen frequently, very frequently!

First Edberg and his colleagues identified 41 doubled solar particle waves and solar powerful particle waves from what are called coronal mass ejections from 2007 to 2008 detected by the Advanced Composition Explorer (ACE) spacecraft that monitors the space weather near Earth. Then they identified 36 of the same events hitting Mars in Mars Express data.

The thin atmosphere left on Mars is due to the small amounts protected at each pole by what remains of the magnetic fields, (which still exist at the poles).

Now I hear you asking, why does Venus have a thick atmosphere but Mars does not?

Mars is much smaller than earth and Venus and it is theorized (not definite) that its liquid outer core cooled and solidified, this had two effects on Mars.

Firstly it meant the large volcanoes became extinct, with no liquid core there was nothing left for them to eject. The volcanoes were responsible for the production of a large amount of the gasses released into the atmosphere, much like they were on Earth millions of years ago. Without these, there was nothing replenishing the atmosphere.

Secondly it meant that the magnetic field slowly died off at all places but the poles, which still retain a small magnetic field. This meant that these double solar waves we mentioned before are now ripping whats left of the atmosphere off of mars.

For the sake of Venus, Venus no longer has a magnetic field, despite popular belief, though the solar winds have torn away all of the lighter hydrogen and oxygen layers. It is unknown to me at this time why the solar winds are unable to tear away the remaining gasses though I think this might be due to them being larger and heavier, such as the carbon dioxide and sulfuric acid layers that make up Venus atmosphere today.

So you could theoretically terra-form Mars by producing atmosphere quicker than its torn away, like the volcanoes tried to do, but that will be expensive and highly resource intensive and not really worth it compared to just sticking a dome there and filling that with air.

There was once talk of liquidating the core with a thermo-nuclear explosion but again, were talking very expensive and difficult.

If one could get the core moving again, presuming it has stopped and solidified, then the magnetic field should replenish itself, and an atmosphere would stay put when generated, but the risks and costs are insanely high compared to finding a planet that already has a magnetic field.

The lack of magnetic field wouldn't stop our attempts, but it would reverse them all over time due to these double solar waves.

The lack of field also wouldn't stop radiation, so any life, such as trees, would die very quickly when exposed to that un-absorbed level.

So yes, terra-forming Mars is theoretically possible, but practically improbable. You are more likely to find bio domes on atmosphere-less planets until we find a simple way to regenerate the magnetic fields.

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    $\begingroup$ This answer explains why Venus still have an atmosphere: astronomy.stackexchange.com/a/640/2093 $\endgroup$
    – Metalcoder
    Commented Jul 23, 2014 at 11:51
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    $\begingroup$ If Venus has an induced atmospheric magnetic field, maybe Mars could be designed to have one too? Not saying it would be easy, but might be possible. $\endgroup$
    – userLTK
    Commented May 22, 2017 at 7:13
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    $\begingroup$ If you have the capability of creating an atmosphere in the first place; this assume science fiction level technology. No point speculating about magnetic fields when you reach that level of unknown. $\endgroup$
    – Antzi
    Commented Oct 20, 2017 at 6:40
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    $\begingroup$ This answer is rather disappointing. Atmospheric loss due to solar winds takes place on geologic timescales. Topping up the atmosphere would be a simple matter (compared to almost any other aspect of terraforming) and would only need to be done every few million years. $\endgroup$
    – Harabeck
    Commented Jul 19, 2019 at 14:30
  • $\begingroup$ Also, a planetary magnetic field isn't the only thing that stops radiation. An atmosphere does this as well. This is why astronauts on the ISS (for example) receive more radiation than those on the Earth's surface: they're protected by Earth's magnetic field but not by its atmosphere. This is explained here: en.wikipedia.org/wiki/Health_threat_from_cosmic_rays. Thickening Mars' atmosphere would provide at least some protection against radiation. $\endgroup$
    – Pitto
    Commented Jul 18, 2020 at 1:54

Using liberally "The Case For Mars" second edition. Here's a few facts that help out in the discussion.

  1. There is substantial Carbon Dioxide at the poles, which if all of it melted, would thicken the atmosphere considerably.
  2. The theory is current that a 4 degree centigrade rise in temperature in the South Pole (Sustained) would trigger a run away greenhouse effect, more drastic than is predicted by Earth global warming scenarios.
  3. We don't really know how much gas Mars loses every day, but there is definitely some lost.
  4. The absence of a magnetic field is a significant contributor to the loss of atmosphere on Mars.
  5. The atmospheric levels change rapidly as a result of gas being switched between poles during season changes. That level is 30%. I believe that accounts for the 30% @RhysW quoted in his answer, but it comes back on a regular basis.

Bottom line, some level of terraforming on Mars is entirely possible. We would likely have to replenish the atmosphere periodically, perhaps once every thousand or tens of thousands of years. MAVEN will answer many of the unanswered questions (Specifically, what is the rate of loss of atmosphere on Mars)

  • $\begingroup$ Small point to add, but I don't think there's "that much" frozen Co2 on Mars. Certainly there's some, but a quick check, Mars has about 24 trillion tons of CO2 in it's atmosphere (this can fluctuate by as much as 25% seasonally - so it's pretty ballpark). And a discovery of a lake superior sized amount of dry ice - (lake Superior, 12,100 KM^3) - so, that's less than half what's already in the atmosphere. It depends what you mean by "thicken considerably", but it could be more than half of the CO2 on Mars is already in the atmosphere. Sources to follow: $\endgroup$
    – userLTK
    Commented Jun 2, 2015 at 3:45
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    $\begingroup$ Mars atmosphere, 25 teratonnes (96% of that is CO2) en.wikipedia.org/wiki/Atmosphere_of_Mars New discovery, more CO2 than they thought (Lake superior sized): content.time.com/time/health/article/0,8599,2067286,00.html - suggests melting the CO2 would double the atmosphere (still very thin by earth standards) $\endgroup$
    – userLTK
    Commented Jun 2, 2015 at 3:48

A global terraforming would cost incredible amount of energy, work and money, but I think it's possible by starting with some giant domes that acts like green houses for the vegetation and then connecting them with additional green house tunnels and then, slowly expanding them. It terraforms the surface, but without the defense of domes, it would be useless, though.

Adding enormous amount of oxygen, nitrogen, ozone, carbon-dioxide and other components would help making pressure and composition of air to non-lethal - vegetation would help making this method easier by releasing oxygen they create. Then, the domes may be removed.

It's just my theory, and might be totally useless, so feel free to vote down. However, I think it's a possible way of terraforming.


I would say, probably "no".

Mars has now a thin atmosphere because of the magnetic field, and because of its mass (1/10 the Earth one). The gravity of the planet depends on its mass, and it is the gravity which keeps the atmosphere there.

Therefore, if you want to have an earth-like atmosphere, you should have the magnetic field of the Earth, and its gravity. Otherwise you will progressively lose atmosphere. This means that the atmosphere needs to be artificially maintained, which is again a matter of costs (assuming that we have the technology to generate it...).

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    $\begingroup$ Note that Venus has a) less mass than Earth; b) no magnetic field; but c) a much thicker atmosphere! So it's not quite as simple as you've stated. $\endgroup$ Commented Aug 19, 2015 at 3:31

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