Hi folks - sorry if this topic has already been covered elsewhere... I had a quick search but couldn't find anything.

Is it possible to permanantly terraform Mars ? E.g. to manipulate matters so that humans could live on the surface without additional life-support systems ?

I'm not thinking in terms of the specific technologies that would be required, but more from a physics point of view. Does anyone know if Mars has sufficient gravity to hold an atmosphere with a pressure at ground level equal to - or similar to - Earths ? Or would the atmosphere just boil away into space ?

Does Mars have a magnetic field in the same sense as Earth has ? I gather this is important in shielding us from a variety of harmfull radiations ?

Is the Sun "bright" enough on Mars to sustain agriculture ? If it where possible to produce a suitable atmosphere (suitable for humans and Terran livestock) that had a 'greenhouse' effect, would the Sun produce enough energy to sustain a comfortable surface/air temperature ? E.g. is their a sufficient net energy budget ?

I gather that the Martian rotation period and axial tilt is broadly similar to Earths... but how would humans cope living under 30% less gravity ? (if that's what it is.... )

Your thoughts or observations ?

Meow Purr.

Nasa thinks it's theoretically possible

As Mars is today, it has no magnetosphere and the atmosphere does boil away into space. However, that does not preclude a dense atmosphere, which would minimize the solar radiation. The sun is bright enough, but the problem appear to be the cold temps. Any terraforming would actually require global warming or a greenhouse effect. Here is an excellant link.

first you need to make the planet warmer, then put algi to make some oxygen then put trees and other plants on mars until it's habital for humans.

Thanks thus far folks.

I take it the current concensus is that the planet has sufficient gravity to hold an atmosphere, if one could first be produced ?

Meow Purr.

It's a probable theory, but if it could be done. It would be a quite expensive project that the whole world needs to cooperate to get it finish.

For a period of time anyway. Even the moon could hold a breathable atmosphere for a while. I seem to remember reading that if you could magically put a breathable atmospere on the Moon it would last for a million years. A lon time by human standards but a blink of the eye in terms of the solar system's existence.

Besides, in the time periods we are contemplating here it would be possible to repeat the procedure several times (if we would find a source for enough gases and water).

Now, I always wonder why people think that greenhouse gases would heat up Mars and then turn around and claim that it has no effect on Earth....

Please, we have enough threads about climae change on Earth, let's stick to the topic here.

I've heard this theory as well.

They do indeed.
So do I.


However, that's theoretically...not pragmatically.

Greenhouse gasses (water vapor being the most prominent and effective among them), and their effect, are the reasons why the Earth is at the temperate, life supporting state that it's in, and theoretically, why such an introduction on Mars would work to do the same there. That's how it works.

People think it would work on Mars because it worked here on Earth. It's a natural mechanism that's been observed.

No one of any intelligence claims that they have no effect on Earth...they are the reason why the stable, albeit complex atmosphere and temperature realm we live in exists. Terraforming Mars theorizes about doing the same thing on another world.


However, there smacks an inference to man-made global warming, and those who don't think that the current hype has substance.

I'll have to agree with Waspie: it's irrelevant to this thread.

I think it is certainly possible, although the atmosphere would probably be thinner (but still breathable) over the long term, along with the planet cooler.

Just get enough percentage of O2 and greenhouse gases in the atmosphere, complement it with an inert gas which is not toxic to humans (since oxygen in too high percentages and quantity is both highly flammable and poisonous to life), and build a planetary biosphere on the warmer and hopefully wetter planet. The main problem is time constraints - unless you have almost magical technology like the ability to genetically engineer algae and lichen that rapidly produce oxygen from CO2, it's going to take a while (probably thousands of years).

I would suggest that terraforming Mars is technologically and economically unfeasible.

At the surface temperature on Mars CO2 is not a gas, so could not be used to 'kick-start' a greenhouse effect. Other, effective, gases (such as methane) would have to be used and these bleed off far more quickly than the heavier gases, such as CO2, O2 etc.

Using chlorofluorocarbons would provide too small a warming effect to significantly alter the ability of the Martian atmosphere to retain heat, and the amount of CO2 that would have to be pumped into the atmosphere would either require unbelievably (probably impossibly) massive/numerous 'converters' or take such a long time that our civilisation would probably have disappeared before the terraforming processes complete.

Rather than terraforming, bio-habitats (either domes on the surface or underground) are the most feasible option for colonisation of non-Earthlike planets.

The Martian atmosphere is 95% CO₂, if that did not initiate a greenhouse effect -adding more CO₂ isn't gonna make it happen.

I think the best bet in terraforming Mars, lays in creating water vapor there. That however, is a daunting task as one has to first overcome the tremendous cold for it to happen (As Leo pointed out near the polar regions CO₂ is not even a gas, Brrrr thats cold!). I remember reading a paper about using large solar mirrors to heat the planet at its polar regions, thought that may provide some heat to the planet I'm not sure how much water vapor could be supplied in this method.

I have to agree with Leo that it is likely not economically or technologically feasible.

I was being a bit pessimistic when I said all the CO2 was non-gaseous. Bear in mind the Martian atmosphere is 1% as dense as Earth's, and there's not much gaseous CO2 floating around. Most of it is locked in the polar caps or as CO2 ice either in the atmosphere or on/in the ground.

Theoretically, adding more CO2 [gaseous, into the atmosphere] would initiate a warming effect, as it is the density of the atmosphere that has a major effect on its' ability to retain heat. But then we get into the time/benefit analysis plus you'd have to chuck out a LOT of CO2 initially in a very short time to get the mean atmospheric temp up to a level where it wouldn't all just precipitate out.

Not really feasible, imo.

It seems like they'd have to do things in stages, activating one "tipping point" at a time.

First they'd introduce a substance that would stay gaseous at a much lower temperature but would trigger global warming (maybe using polar mirrors). When the temperature went up, then they'd introduce more CO2. Then they'd remove the first gas from the atmosphere.

I would suggest you are absolutely correct, Leonardo. Theoretically, a possibility, but not feasible.


Further, terraforming speaks to modifying anothere worlds environment to suit us, and other life like that which we know. The possibility, theoretically, and pragmatically, of actually doing that requires a dead world. The verdict hasn't come in on that aspect of Mars yet.

If we do find any life there...the entire concept shall be filed away in the "Not Permitted on Mars" bin...

Not yet any way. If there is one thing that the rapid rise of technology in the 20th century has taught us is that yesterdays infeasible idea is tomorrow reality.


I couldn't agree with you more on this (or with Gene Roddenberry... Star Trek frequently got there first). We must not change Mars at the cost of life there.

One interesting thought, no one has mentioned Venus yet. Terraforming Venus is also theoretically possible. It would require the reduction of greenhouse gasses allowing the temperature to drop. Given that Venus already has a thick atmosphere it may actually be preferable to modify this world than Mars (although the extremely long days would be weird).

The current Martian atmosphere is far too thin, and thinner than what it could be (meaning what Mars could hold long-term). If you could get more CO2 into the atmosphere, that would help to warm it up - I've heard suggestions of dropping either one of Mars' moons or an asteroid that comes by onto the southern ice cap, which is mostly frozen CO2.

But as he pointed out, what atmosphere Mars has is made of CO2, so you can get a CO2 atmosphere, and a thicker one. The main problem is simply time and liquid water - you'd need to get some organisms (plants) on the surface to slowly transform that CO2 into oxygen, while building a biosphere on the planet under a warmer, thicker atmosphere.

Couldn't you simply hammer the southern ice cap (which is mostly CO2 ice) with asteroids or the like to heat it up? Mars' gravity is high enough that that wouldn't simply knock the gas into space, but it would gasify it, raising enough CO2 into the air to make it thicker, while also increasing the surface temperature simply through the heat transfer from the asteroid impact. Plus, while they wouldn't be a good long-term support for higher temperatures, you could make use of much stronger greenhouse gases like methane and the super fluerocarbons in the short term to raise the surface temperature.

It is definitely a "time" issue, though.

In any case, Mars is far more friendly to terraforming than Venus. On Mars, you only need to thicken the atmosphere, raise the temperature, and get some liquid water on the surface to build a biosphere from - whereas on Venus, you start with far too much atmosphere and temperature. I almost wonder if it would be better to simply get one of the moons from the gas giants and ram it into Venus so hard that it blows off most of the planet's atmosphere. And then, of course, there is the whole "day longer than its year" problem (which could be rectified with a thick atmosphere to transfer heat, but then you get back to the "greenhouse" problem again), as well as the fact that you would probably have to import all of the liquid water from farther out in the solar system for terraforming purposes.

The impact theory is possible, GB, but I see it as being fraught with uncertainty. For one, I'm concerned that so much dust etc would be kicked up that the net effect would be a cooling (similar to a 'nuclear winter effect') and another possibility I see is that the impact would impart so much energy to the material injected into the atmosphere that a lot of it would be lost to space. You say the Martian gravity is sufficient for this not to happen but I'm not so sure, the impact would be extremely energetic. Even using a comet (and thus reducing the non-gaseous particulate emission as much as possible) I suspect enough of the Martian soil would be injected into the atmosphere to negate any warming effect of the increased CO2/other greenhouse gases.