As of yet, I haven't seen the need to.kunkmiester wrote:So far no one has asked for access to revise the spreadsheet. Is no one interested in that?
I'd be mostly concerned about the lack of reinforcement across the ceiling as compared to a poured or molded ceiling.kunkmiester wrote: Quick search finds a website suggesting at least one meter of regolith for shielding, NASA would probably demand 5. What are the chances of collapse of piling 5 meters of regolith on top of a habitat, versus cutting a tunnel five meters down? Collapse is probably marginal risk, if you make your tunnel right, but the opportunity to kill a few thousand kilos of needed mass is a good point. I'm of the opinion though that if you want more than a few hundred square feet of space--such as a large colony--you'll want to tunnel, but a tunnel digger can probably be made in situ at that point.
Issues of heat loss, atmosphere retention, and power distribution are going to keep your habitable areas close together. This is probably an area where you want to overplan.kunkmiester wrote: The point here is to be able to send 7+ person trips to the moon to spend two weeks on the moon at a time, in comfort. Everything sent needs to be long term use--you buy something like a tractor or scraper on earth, it tends to hang around for decades in use, it's a very durable good. This is because after people start going to the moon, people will be interested in going longer, and eventually colonizing. If my fleet of robots can also prepare colony sites, that's that much less you have to spend on a colony effort. Frankly, aside from technologies like hydroponics and fabbing that a temporary base wouldn't deal with, the difference between a colony and a base is a matter of scale--a colony is bigger and uses more of the various materials than a base.
Make sure you take a look at the pdf I linked. Lots of good stuff there.