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Comment by donatj | Hacker News Reader

How do you propose we relocate any significant volume of water?

Science fiction has proposed a number of possible-if-difficult ways.

Comets, to start, are mostly water. If you're patient, you can redirect some very sightly while they're in the far end of the system and have them impact Mars. Takes a while though. Also, big boom when they arrive.

Really though, there's plenty of carbon <edit>oxygen, in the form of carbon dioxide</edit> on Mars- you just need hydrogen. Jupiter is mostly that. With a very large fleet of ships, you might be able to bring some to Mars. Solar sails might help keep costs low, and ideally they're fully autonomous. Heck, if that works, you'd probably want to start doing the same trick and pouring hydrogen into Venus while taking away CO2.

I'm sure there's other ways too. Plus, we know there is some water on Mars already. If we can use it carefully, reuse exhaustively, it could sustain a large population.

>Plus, we know there is some water on Mars already

do we know that?

what i'm reading with regards to this article and comments is that now we're back to not having any concrete evidence of this

We are fairly certainly that the ice caps are mostly water ice with a much smaller and more seasonal dry ice layer; what this article means is that the indication of liquid water on the surface seems to have been wrong.

You need oxygen, not carbon, to make water.

Ah, teaches me for trying to write before my morning caffeine.

Oxygen. Oxygen is what Mars already has, in the form of CO2, carbon dioxide.

I’m guessing he meant carbon dioxide, rather than just carbon.

Without a decent atmosphere water will just boil / sublimate off and get blown away; Mars would need a magnetosphere to retain anything.

A sufficiently large radio system built on Mars or at its solar LaGrange point could provide the shielding effect that is normally the responsibility of the magnetosphere. It was studied for feasibility by NASA and found possible with current technology. Of course, possible doesn't imply practical and the natural formation of Martian atmosphere if we did that would be on geologic timescales.

Water would get blown away over a period of millions of years though. I think that's not much of a problem.

Even if you could increase the atmospheric density, the lack of magnetosphere is still a problem when it comes to human habitation, however. Any long-term habitats would need to be built underground, or at least heavily shielded against solar radiation.

Could people go out at night?

I've previously seem ideas such as nuking the poles. It implied there were enough gases stored in the ice to created a sufficient atmosphere. The loss of the atmosphere due to lack of a magnetosphere would take millions of years.

We shall no longer call our race mankind, but Galactus, the planet eaters!

Shai-Hulud

Isn't there significant amounts of ice at the poles?

A long hose?

A portal from Earth, maybe.

https://what-if.xkcd.com/54/

With copious amounts of thrust

'How' is not interesting, the real question is 'why'.

There's nothing there on Mars that would ever make human habitation profitable or self-sustaining.

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