Moon Miners' Manifesto

#111 December 1997

Lunar Skyscrapers

[see MMM # 55 MAY '92, pp. 5-6, "SKYSCRAPERS on the Moon? Beyond Mole Hill City"]
The conventional wisdom is that surface-embedded or surface-burrowing lunar settlements will be monotonous complexes of "mole hills" unrelieved except by docking ports, communications antennae and other systems hardware that must be on the surface or surface-exposed. Yes, we have all seen science fiction artist renderings of skyscraper studded lunar and Martian cities on great glass domes. But that is an eventuality for realization somewhat further down the road, if ever. And as to settlements within lunar lavatubes, some with ceiling heights a thousand feet high or more, - why, what we'll have there, are ceiling-scrapers (or even ceiling-touchers). In both these cases within pressurized mega structures, the first manmade, the second provided by nature), the skyscrapers are likely to be conventional copies of what is current construction structure and form on Earth.

But what excited me when I wrote the first article five and a half years ago, was the realization that the starter premise just wasn't necessarily true. We could build fully shielded "skyscrapers" to centralize the downtowns of lunar settlements built the way settlements on Old Earth always have been, the old fashioned way, one structure at a time.

The "Pent Roof" makes it possible

Egyptian pyramids, Mesopotamian ziggurats, ant the Tower of Babel notwithstanding, the practical skyscraper was an urban innovation that awaited two inventions: the steel girder, and more importantly, the first people mover - the elevator. (Yes we know the Russians have built high rises without elevators, so, what's your point?)

For anyone imagineering a lunar surface settlement cozily tucked under its regolith security blanket for protection from the local cosmic weather and for thermal averaging, the idea of a skyscraper-studded "downtown" just did not occur. How would you shield something like that?
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Enter by happenstance, a picture of a Chinese "pagoda" in some book I was perusing, and a eureka brainstorming avalanche was on its way cascading down the brainslopes of my mind.

A little redesign slight of hand with those pent roofs (pent as in penthouse), and they could serve as overhanging retainers that could hold a couple of meters of lunar regolith shielding - not prohibitively heavy in the light lunar "sixthweight".

For people on the Moon for long duration or indefinite stays, it is important to be very, very conservative in minimizing accumulative radiation exposure. "Windows" providing the satisfaction of regular views out onto the local moonscape should incorporate broken pathways, using mirrors, so that the observer is protected in every direction by adequate shielding, so that the habitat or moon manor has not "hot spots". The same is true of any type of structure in which people regularly work or spend significant accumulative time.

In comparison, the "pent roof" balcony overhangs would provide safely set back vertically narrow eye level slit windows, and through them, horizontally constrained views of the moonscape. Looking out through one of these, the observer would see just enough "sky" to frame the view, a sky with very few square degrees of exposure to the naked cosmic heavens and its hot delights.

If you wanted to build a pentroofed office building, you would have to tweak the internal layout so that the interior space sporting these view ports was reserved for use principally by visitors, and, compromisingly, for regular office personnel and daily maintenance staff people "on break". The principal break room and lounge areas, however, would be in interior parts of the building that did not sport such direct-view windows). In other words, lunar office towers would have such slit windows only here or there. The architect could always resort to rows of fake trompe l'oeil windows to create the right external effect. After all, the architect has two goals in mind: an optimum, occupant / user-friendly interior arrangement, with a full suite of desirable function areas; and, a pleasing, readily identified, and positive image-creating external appearance on display for the potential using public passing by.

Such pent roof windows might be used with more abandon in buildings more heavily used by visitors, such as the Luna City Hotel. Even so, for the protection of guest room cleaning staff especially, the architect would want to tweak the internal room layout to minimize the total accumulative fraction of daily time spent in the hot spot pools of naked sky exposure. And hotel management will be constrained by law to rotate staff duties to minimize the chances of anyone getting too much accumulative exposure.

KEY: (1) Outer retaining wall of pent roof; (2) shielding; (3) "Hull" wall of Hotel, with narrow, high, window slit; (4) Interior, shielded, viewing "balcony"; (5) an interior "shielding partition"; (6) Guest Room proper

In that article we looked at three possibilities: (a) single or multiple vertical cylinders with pagoda like pentroof balconies holding shielding mass, yet which allowed vertically narrow views of the surroundings; (b) Stagger-stacked horizontal cylinders, again with pentroof shielded and windows; (c) a circular pyramid of horizontal cylinder sections of decreasing diameters.

In retrospect, this last design option seems the most strained. Pressurization stresses would make it the most likely to fail. This article offers a radical rethinking of the round pyramid format.

Instead of stacked cylinder sections of decreasing diameter, we now propose stacked torus units of decreasing outer diameter, but of set inner diameter (of the donut hole). And they would be stacked over and around a vertical cylinder which would carry the elevator shaft and service chases for electricity, communications, thermal control, and plumbing. If this seems reminiscent of a popular children's building block toy, it is with reason. Here lies the humble source of our inspiration.

In the design shown below, for illustration purposes only, the upper torus tier would be sized to include floor to ceiling clearance for one floor, The next tier, two floors, the bottom tier three floors. The exposed roof overhang of each torus would be covered with shielding, pentroof style, as illustrated in the previous article, partial pent balconies at each intermediate floor level. Not a very visually pleasing design, however structurally sound.

One possible building top embellishment is a geodesic dome or hydroshield dome (a Marshall Savage idea) serving as an observation area, the later much better shielded. Another obvious topper option is a service core shaft extension to a revolving rooftop restaurant, à la the Space Needle in Seattle (just the first of many copycat structures now highlighting downtown skylines around the world). With possible structures like these, the analogy of the downtown centered Earth city is wonderfully translated into the construction idiom of incrementally growing regolith blanket shielded lunar, or Martian, surface settlements. Marketable uses are for bank office buildings, corporate headquarters, and hotels.

KEY: (left ) see-thru observation dome skyscraper (right) outside view of twin tower with revolving restaurant. Both have 23 occupiable floors.

The illustration effort above yielded rather ugly results. The important thing about the torus - central shaft stack is its dynamic stability pressurization-wise. Why not, for this application, shuck the pent roofs for cylindrical caisson sections holding shielding up against the building. These bulkheads would not be pressurized and can be vertically flat.

This results in a much more conventional look. These are some ideas thrown out for improvement. We'd like to see now good artist renderings of a downtown-centered lunar urban panorama.

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