How will Mars terraforming missions really work, how do pioneers like SpaceX plan on conquering Mars? [duplicate]

Question

We know Mars is now dead in the water (or space), it is now merely an oversized rock hurtling through space, with a bit of atmosphere.

I was reading up on terraforming the planet, and learned that pretty much everything we would do would be undone by relentless double solar winds, making it quite a challenge. SpaceX has plans for a 2020 mission putting an experiment called MOXIE on Mars that will supposedly “extract the oxygen from the 90% CO2 atmosphere,” yet I don’t see how that will be going anywhere as the outer atmosphere of Mars is so weak.

So I guess my question is how will these missions work, how do pioneers like SpaceX plan on conquering Mars, and is this fully possible?

Answer 1

Possibly there need to be some definitions here in 'Conquer Mars'. Humanity has had the capability since the Apollo program to fly a small number of people to mars, land them there and maybe even get them back home as long as a large enough pile of money was available (on the order of the entire Apollo budget per mission, but less than US GNP).

This concept is the focus of current planning and with time/tech advance reducing the 'pile of money' to something a private enterprise rather than a nation might have access to.

For this the faintness of Mars atmosphere does not matter since there is still 25 teratonnes of it to harvest for a temporary base of no more than 100.

The next hypothetical step would be building a base of <100 into something vaguely self sufficient, with population in 10ks but still living inside cans and for this there is still plenty of O2 available in total.

Some very rough math at 1kg of breathing air per cubic meter and a 2 meter ceiling height gives a total living/plant growing area of 12.5 billion square Kms if you harvest the entire atmosphere, where total Martian surface area is 144 million. So the entire surface could be built over with sealed habitats without running out of gas volume. The gas mix would be a problem and building to this scale would run out of nitrogen and almost certainly other materials critical to life and technology. For example Helium collection is a byproduct of natural gas extraction and may be vanishingly rare on mars.

Where the total atmosphere quantity starts to matter is in terraforming, turning mars into something where you can live without life support. As you note this would require getting enough gas into the atmosphere to at least stop life getting freeze dried, and plans for that generally include relocation of mass to take the atmosphere from 25 teratonnes to something closer to earths 5000 teratonnes. Any plan to do this will require massive amounts of energy, noting that total human effort to date has got 'only' 8000 tonnes into space, and this mass would most likely be coming from Jupiter or even further out.

So conquering mars as a cities in a bottle is very hard but something where at least the problems can be understood using today's tech. To conquer mars to the point you can walk around outside in shorts the best guesses that can be made today is that the time scales will be in human life times, and involve energy production measurable in % of total sun solar output.

Answer 2

With advances in genetics, implants, prosthetics and so on, it seems much more likely that humans will change, not Mars.

It shouldn't be too difficult to engineer a sugar, fat or carbs and oxygen powered artificial lung, at least 20 or 30 years from now. The cold can be dealt with clothing, ideally with some heater. The thin atmosphere will not transport too much heat away - a little extra hole to connect an artificial lung to the outside should be enough to avoid freezing of nose and mouth, under normal conditions.

The low pressure, like high pressure for deep sea divers, might have some consequences on gene expression and other cell functions which may not go away after a while. But some other adaptions - genes, medicine or technology - are probably enough to deal with that.

In the meantime, we will probably just get used to thin pressure suits with oxygen tanks/generators. It's probably not much more bulky than a bike outfit, as we don't need the same level of protection as in free space.

In theory, it would be possible to make Mars pretty Earth-like by making it collide with a few ammonia- and water-rich asteroids and let algae convert the co2 into oxygen. However, that puts Mars deeper into a gravity well, which is bad if you want to travel from Mars to other places (or leave the asteroid belt unperturbed). So no-one is going to do that.