To a large extent we have good confidence that Mars used to be a very wet world with a thick atmosphere. Now it's clearly very dry and the atmosphere is extremely thin. So if we colonize Mars with the long-term goal of expanding the colony and terraforming Mars so that it becomes more habitable, will the same things that destroyed Mars' environment initially destroy any efforts we make to colonize it now?


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  • $\begingroup$ @JCRM - significant in that we might not colonize it? Fair enough. Elon, at least, is spending a chunk of change to make it happen. $\endgroup$ – Don Branson Jun 24 '18 at 22:55
  • $\begingroup$ Or are you questioning that as a reason we're going to Mars? That's fair. There are a lot of good reasons to go to Mars and that's not the only one. $\endgroup$ – Don Branson Jun 24 '18 at 22:57
  • $\begingroup$ I meant the latter, @DonBranson. While the former is also a valid question, whether or not we do is irrelevant when considering whether the costs of doing so are worthwhile $\endgroup$ – JCRM Jun 25 '18 at 0:54
  • $\begingroup$ The goal of the planned Mars visit is not the colonization. For colonization, the Moon would be a much better target. If the Mars will be ever visited - somewhere in the early 2030s - it will be a single visit and a colonization project is very unlikely. That is the sad situation. I don't say that it would please me. $\endgroup$ – peterh Jun 25 '18 at 3:13

When Mars lost its water and atmosphere, there were no humans with machinery on its surface to prevent it. Mars can't be terraformed to a stable, fully self-sustaining system - at least according to our current theories of how it could work (maybe our descendants will think of something better.) It will always be a resource hog, requiring constant resupply of water and raw materials to keep it going.

...about the same way as cities. Cities don't produce nearly enough food to sustain themselves. They depend on the out-of-city agriculture for sustenance, they require raw materials for production and construction, and for maintenance of existing infrastructure - and any city without external supply of goods will quickly fall, using up all of its stockpile.

Is it a waste of time and resources to build cities?

The artificial ecosystem of Mars would quickly fall apart without these supplies, without human intervention. But that doesn't mean we shouldn't do it - it just means streamlining and automating maintenance of Mars will be a necessity. We can't create a fully self-sustainable natural system - but we can create an artificial one, with autonomous spacecraft hunting for comets to deliver water, autonomous maintenance and service robots for keeping production of air running, to replace what is lost to vacuum of space, systems monitoring and maintaining ecosystem balance. I

It's possible it would all fall apart if there's no-one to maintain it, keep it running. But if it came to that, who would be left to care?

  • $\begingroup$ Do you know at what rate Mars would lose atmosphere if we were to suddenly restore it today? My thought is, Mars lost its atmosphere over billions of years. Would it lose it at a rapid rate where replenishing it would be a serious effort, or is it something where we're talking a few tons of nitrogen and oxygen per year would handle it? $\endgroup$ – David Morris Jun 25 '18 at 2:30
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    $\begingroup$ The oxygen content of the Martian soil is high, but it is very energy intensive to extract it. But it could be done by a huge array of terraforming plants, which could be built by robots. Such an artificial athmosphere would destabilize only on a larger time scale as some tens of million years. $\endgroup$ – peterh Jun 25 '18 at 3:18
  • $\begingroup$ There's still the shortage of neutral gas. Nitrogen is unreasonably scarce on Mars. Carbon dioxide has nasty side effects in higher concentrations. I'm actually unsure what sort of gas could reasonably serve as a 'filler' for the Martian atmosphere. $\endgroup$ – SF. Jun 25 '18 at 12:05

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