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Building a Settlement in the Bottom of a lunar Rille Valley
by kokhmmm 
Link: http://www.moonsociety.org/2003-pcsn/14-rillesettlement.html
Building a Settlement in the Bottom of a lunar Rille Valley
"Cross-Section of a Rille-bottom Settlement" is the current "feature image" posted August 8th to the Society front page, top center.
We try to change these featured images every two weeks. This one comes from a design study done by a Lunar Reclamation Society team as an entry to the 1988 NSS Space Settlement Design Contest, Category: "Lunar Settlement for a population of 1,000-5,000."
At the time, "Milwaukee" Lunar Reclamation Society (NSS-Milwaukee) was sharing Moon Miners' Manifesto with the NSS chapter in Seattle, the Seattle L5 Society. They had a standing research team called SLuGs, Seattle Lunar Group Studies (a very appropriate acronym, or mascot, for giant slugs abound in that neck of the woods!) To the point, SLuGs was heavy with Boeing employees, and we were challenged but not intimidated by their talents. So we put together a team of eight persons (one came up all the way from Chicago, a 180 mile round trip, for every design session meeting!).
The constraint of the contest, "for a population of 1,000-5,000," meant that we would not be designing a moonbase or outpost, but a real frontier town. The contest designers clearly wanted us to "think outside the box, 50 years or so beyond the first moonbase." So we did just that. We took a pass on a lavatube-based settlement design, however. The rules required us to specify an exact location. And while we were confident that lavatubes existed, we didn't know at the time just where, exactly, on the Moon to find one. Today, we'd have our pick of several specific locations.
We had another idea. We would have to provide shielding for our habitation areas, and that's a lot of bulldozing if you have to pile regolith "up and over" a structure. Why not build our town in a rille? A rille is a valley created by the collapse of a lavatube ceiling. See illustration below.
If we built our town in such a valley bottom, we could simply pull the regolith down on top of it from the valley shoulders above, letting gravity do much of the work.
We poured over the best photographic atlases of the Moon we could find. We wanted an East-West running rille segment, for maximum sunlight purposes, and we found an ideal rille segment just north of the half-buried crater Prinz, near Aristarchus in the Sea of Storms, Oceanus Procellarum. Of course, with us all being familiar with Gerard O'Neill's Space Studies Institute in Princeton, New Jersey, we just had to name our lunar village "Prinzton!"
We had our rille. Our next consideration is how we could provide a structurally sound "firmament" roof for our village. Taking our inspiration from the Gateway Arch in St. Louis, we decided on an inverted catenary arc. A catenary arc is the form a suspended chain takes. Inverted, it is the most stable form of arch, because all the pressures pass down through the arms/legs of the arch.
Another question was making the arched roof of our settlement strong enough to withstand the upward force of air pressure within, against the vacuum without. We decided to have two arches, with a space between them, stepping down the pressure. We specified 1/2 normal atmospheric pressure for the lower "Town field" level, with the normal amount of oxygen, but reduced nitrogen. For the space between the two arched vaults, we specified 1/4 normal atmospheric pressure, at the same mix. This upper level would be our agricultural area. Each vault would be covered with 25 ft. of regolith, a generous amount for total protection. The total burden adding the regolith over each arch would be 50 ft., enough to counterbalance the 1/2 air pressure in the lower level so that the upward and downward stresses on the arch vaults was fairly well balanced.
You will get an idea from the large image how we would bring in sunlight, and how we would circulate the air between the two levels, so that the farm areas would refresh stale air from the town area.
Our entry had much more to it than that, and you can read all about it. Our paper was serialized under the title "Ventures of the Rille People," in MMMs #26-29, 31-32. This series has now been reedited, reillustrated, and republished in MMM Classics, #3 and #4, and posted online as downloadable pdf files. You can freely access these at: http://www.moonsociety.org/publications/mmm_classics/
You can also read the fully reillustrated paper online in 5 installments with the title: PRINZTON: A Rille-Bottom Settlement for Three Thousand People at:
http://www.lunar-reclamation.org/papers/rille_paper1.htm
Oh yes. the contest. We placed second, and I got to shake Hugh Downs hand. The good part of it was that we beat SLuGs and a host of other also ran entries. The bad part was that we lost to someone who did not at all meet the published design constraints, selected because he was an architecture student, and the judges preferred to award first prize to a student in the field, not to a rag tag team of chapter enthusiasts. The bottom line is that it was a lot of work, a lot of fun, and we learned quite a bit. And it lead to other things, like LUNAX (see the entry on LUNAX in the Lunar Directory in the right hand "destinations" menu on our front page. http://www.moonsociety.org/lunar-directory/
The plan is, each time we introduce a new featured image on the front page, to post a background article about it on the blog. So this is the first of many, hopefully twice a month.
08/15/06 12:41:35 pm,