I want a colony on Mars that builds BOTH ways, up and down. Domes or structures that go up normally, but a large portion of the colony would be levels underground.

I think this would allow you to take advantage of keeping things pressurized (I think - with help of course, not just plain caves) and keep people safe from dangers of the surface. Possibly help with temperature regulation?

Colonists could travel to the surface to act in various capacities, but mainly live in the underground section.

So would it be viable to have say 20-40 levels? If it were 20 feet per level (to account for space between, infrastructure, etc) at 40 levels that's not even 1KM down. What would be the pros/cons of this approach?

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    $\begingroup$ Can you reference where you read about the digging limit on Mars? I am curious about it $\endgroup$
    – L.Dutch
    Commented Dec 17, 2020 at 16:31
  • $\begingroup$ Sure thing, I found some info here and then googled to confirm some of the points made. astronomy.stackexchange.com/questions/14875/… $\endgroup$
    – MajorTom
    Commented Dec 17, 2020 at 16:35
  • $\begingroup$ Are you asking if it is possible to dig 400-800 ft below the Martian surface, or if it is beneficial compared to living on the surface? $\endgroup$
    – void_ptr
    Commented Dec 17, 2020 at 17:39
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    $\begingroup$ It's fitting that @MajorTom is soliciting help about ground control $\endgroup$ Commented Dec 17, 2020 at 21:08
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    $\begingroup$ @L.Dutch-ReinstateMonica - has a few answers turning on the idea of increased atmospheric pressure at depth: worldbuilding.stackexchange.com/questions/135396/… $\endgroup$
    – Willk
    Commented Dec 17, 2020 at 22:50

2 Answers 2


More viable than building up.

Its so viable that we will probably build down on Mars before we build up. This is a published idea already. The fictional "Mars" on Netflix shows a hypothetical 2030 colony on Mars in lava tubes beneath the surface.

Building down will protect you from dust storms, meteors, and radiation. It's also probably easier to build a pressure door on a lava tube than build a dome on the surface.

It's pretty straightforward to see that settlement would start from lava tubes, then carve out an underground city, then eventually build above the surface when we get confident enough to withstand the environmental hazards.

  • $\begingroup$ Thanks for the article link, that's helpful. I'm astounded at the potential size of some of the tubes. I suppose the levels could be built traditionally right inside some of these huge tubes. $\endgroup$
    – MajorTom
    Commented Dec 17, 2020 at 16:20
  • $\begingroup$ Are ancient lava tubes airtight? I would assume you'd need to line the inner surface of the tube to maintain pressure reliably. $\endgroup$
    – Cadence
    Commented Dec 17, 2020 at 17:17
  • $\begingroup$ Yeah that is my point too - I think the tubes are the basis but you'd need to build them out, especially for long term. Especially because they are massive. It would be a huge waste of space to set up with loads of open space above. $\endgroup$
    – MajorTom
    Commented Dec 17, 2020 at 19:35

You need something to build up out of.

When you build up on Mars, what is your building made of? Maybe you could build out of the stuff you find under your building, erecting walls of rammed earth. In real life I understand that earth for rammed earth walls is often brought from offsite as opposed to used excavated soil but if the soil was the same everywhere (as is probably the case on Mars) the soil from under your building would be as good as that from anywhere else.

So you dig to get stuff to build your walls out of, and build walls around the hole you made.


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