Why Are Subterranean Colonies Rarely Proposed in Space Colonization Scenarios?

[#Thomas#]

I've been investigating hypothetical scenarios for space colonization and something struck me odd:

Over 90% of all proposals involve constructing some sort of surface habitats, but almost none are willing to entertain the notion of having subterranean colonies. Why is that?

Why is building preferable to digging?

 

[rootone]

There certainly have been some proposals of subsurface construction for off-Earth colonies, it does solve a number of potential hazards.
The downside is that excavating and mining would probably require much more energy and other resources.
I think it's likely that any such colonies would probably utilize both above and below ground constructions within the overall scheme

 

[#Thomas#]

Of course I am being reasonable and fully expect that we must begin with at least some surface infrastructure to support those drilling operations, but overall, in terms of longevity, it is the preferable alternative!

After all, colonization is about actually staying there!

 

[CalcNerd]

Most or our plans for colonization are for small planets / moons with little to no atmosphere. Both are vacuums in comparison to our needs and an underground structure may have a fracture or leak and if it can't be found quickly enough, valuable non-renewable O2 may be lost and doom the colony. Of course a small meteor (size of a bullet) can wreck havoc on a surface structure too.

 

[#Thomas#]

If you have a crack underground, the air has almost nowhere to go, it can leak for hours before any danger is incurred. And if you're worried about micrometeorites... just dig deeper!

But if there is a problem... compartmentalization can easily fix it. Your arguments are invalid.

 

[CalcNerd]

I see that you have investigated this deeply and do not require my input. By the way, you might read my last line on my previous post.

 

[#Thomas#]

I have read what you said, you are being fair, and I respect that, I was merely elaborating on what you've said. Also oxygen depletion worries you, this has been considered as well, there is almost a consensus between colonization proponents that the first colony should have access to "local" water-ice, which they can electrolyze into breatheable air... and rocket fuel!

The purpose of this topic is not to discuss which is better because both have already been determined to be generally equal in the ratio of advantages/disadvantages. The purpose of this topic is to answer the question of "why haven't underground colonies been considered more seriously by proponents of colonization?"

We've already established that drilling equipment would be difficult to transport, but that can't be the only reason... can it?

 

[JBA]

I believe that it could possibly be because the geologic conditions would have to be fully determined at any proposed subsurface facility location and the conceptual design of a proposed facility will be based upon that site's specific conditions. A this point, most studies are focused upon first stage preliminary exploration survival that would be required to determine what might represent an appropriate concept for later (probably, much later) colonization.