ASI W9600611r1.2
#91 December 1995
Section 6.9.3.2.091.of the Artemis Data Book
I was glad to read your article in the July MMM about Space Oases and see your emphasis on modularity. This is a concept I've long advocated for both space development and the development of a powerful space advocate community. I think the space enthusiast community is going to come around on the issue of modular space infrastructure development, to some degree and eventually. But I wonder how much good it will do most people without a similar approach toward building a politico-economic power base.
Anyway, with regard to modular oases -- whether in space or on a planetary surface:
It is feasible to build a large sphere modularly. One must merely divide the sphere into appropriately sized and shaped sector volumes. There are a number of ways to do that. Latitudinal slicing and geodesic segmenting are the easiest two for me to think of off the top of my head. Regardless of the particular geometry used one must merely begin with a balanced rotational system (since we are talking artificial G systems). In the design cycle the "sectors" (habitable volumes) would be sized as dictated by economics, required crew size, and various other factors. The two initial masses (whether both were living spaces or one were merely a counter weight) would be either hard or soft tethered with further tethers added (if necessary) as more modules are added. As an example, for the longitudinal slicing method, the first modules would be equatorial, as would all further modules until a torus was completed. Then additional modules could be added at "higher" latitudes (requiring careful balancing) or nearer the center of rotation (only requiring equal masses on evenly spaced sides).
As regards workers shifts: I would propose (if three shifts is the case) that the factories be located in modules between the living modules (one to three modules in addition to the living modules). My thoughts are that factories tend to be noisy, they would pose an unnecessary risk of pollution to the general population's environment, they pose an unnecessary risk of catastrophic damage to the living area's life support functions, and they could be in a constant state of "day time" without affecting any living volume's schedule.
I agree with you regarding modern America's risk aversion and the nonsensicalness of 1 G bias. But where it is inexpensive enough economically and logistically I wouldn't rule out lowering risk or raising gravity levels.
The Torus [Helix?] is an elegant solution. I like it! The most exiting future would see many different options developed and used.
Modularity both in architecture and in development/construction schedule would be useful on planetary surfaces as well. For instance, if a small robotic/remote control digger/hauler were at work now, how ready could it have an area on the moon for an oasis in ten or fifteen years? And if every year or two another robot some with similar some with other capabilities were also sent then how far along could an oasis be when it finally became feasible to send humans? And as construction progressed there would be greater and greater incentive to send humans and less and less of an infrastructure hurdle to overcome.
Richard Richardson,Doering,Alaska
Nature doesn't use the triple helix very much. Myoglobin molecules, which somewhat resemble triple helices, are crosss-braced. Even Watson amd Crick's abortive initial attempt at modeling DNA as a triple helix had an internal backbone holding everything together. It's a rather ungainly structure.
- Jeff Sanburg, Skokie, Illinois
EDITOR'S REPLY: Just as the torus space colony has a hub, the helix, double or single has a hub-shaft. And just as the torus has supporting spokes connecting it concentrically to the hub, so will the helix, double or triple, have rhythmically spaced spokes to the central shaft. I was incapable of illustrating this structural feature in my crude MacPaint graphics program and hoped that the reader would assume it.
Whether nature uses the triple helix or not is immaterial. The design is structurally stable from an engineering point of view, and if growth from all three end points is kept apace, dynamic equilibrium will be maintained. Nature does use the radial plan (starfish, octopus, flowers, etc.) and the triple helix can be seen as a radial derivative. Peter Kokh
"Dust Control" [MMM #89, pp. 5-7] was an execllent article. There is a way that we could get some of this hardware developed prior to returning to the moon. The universal door-lock and the turtle-back suit would appear to have real application in the area of radioactive waste management and other hazardous environments. The concepts of keeping the nasties out, shielding, and working at a positive pressure with respect to your environment are common to both the radioactive waste problem and the moon.
It is becoming increasingly clear that there is an enormous clean-up effort that must be done in the wake of weapons production and nuclear power generation both in this country and elsewere. If we could steer some of the design concepts in this area, the result would be technologies highly adaptable to the moon.
David Graham
EDITOR'S REPLY: Your suggestion is a perfect example of what I've dubbed "spin-up," pre-developing a technology that will be needed eventually on the space frontier, now, here on Earth for for-profit terrestrial applications. The ulterior result is relatively free technology, ready to go or apply, when we need it in space.
With walls made of bricks or sandbags of lunar soil, and a roof made of <mumble> supporting more lunar soil, we can provide the same protection and still have access to the exterior surface of the habitat.
Some questions: How quickly does the habitat need to be shielded? Does it have to be accomplished during the initial manned mission or can it be done telerobotically after the first team leaves?
As far as brickmaking is concerned, do we know how to make bricks at the Moonbase using equipment that will fit into the first mission's mass budget? I thought brickmaking would involve producing a glass base product, melting it and using it as a bonding agent in the bricks. Is there another way? Maybe using the regolith's natural clinging properties and a gas operated pressurized ram mold?
Similar concerns for "sandbagging" lunar soil. Several hundred lightweight plastic and fiber reinforced plastic bags wouldn't weigh that much. But it would probably take a little time to fill them up by hand. The process could be automated but that means the machinery would have to be there to do it. Maybe a simple frame holding an electric vibrating hopper with a bag changer/end-closure device at the outfeed. Still have to have some sort of lunar earth mover to keep adding material to the hopper as well as a mechanism to remove and stack the bags as they are completed. Sounds like a system that would work best if there were people around to clear any malfunctions. Supervising it might be a full time job.
Simply piling dirt on top of the compound with a teleoperated scooper may be the best way to go at first. Although taking a brickmaking outfit and setting up business might do a lot to make people understand that we are serious about building a full fledged moonbase and that we are there to stay. You don't start a brick factory if you aren't serious about construction!
If it's essential to have external access to the first habitat then I suppose an aluminum frame could be set up like a spindly greenhouse (without the glazing) covering the habitat. The center "roof" supports could be attached to the habitat itself. A reinforced tarp or blanket draped over the frame and the whole thing buried using the scooper. Won't be beautiful.
Jim Nobles, TennesseeEDITOR'S REPLY: Given the angularity of lunar regolith particles, tamping soil into a mold and lightly sintering it with solar heat or microwaves should produce serviceable bricks or blocks. Fiberglass reinforcement should not be necessary for most low performance applications.
If the first setup crew stays only a week or so, the amount of radiation they receive will be tolerable. So the shielding could be put in place telerobotically after the first crew departs and before the next arrives.
Your automated bagging process suggestion has merit. It will have to compete, in terms of equipment mass to be imported from Earth, with sinter-block making.
While simply bulldozing regolith is far the simplest method, it backs the moonbase operation into a corner so far as future expansion options are concerned. It may be wiser, as you suggest, to build a shed hanger and place modules underneath where they can be hooked up to one another in a growing complex with much less complication. See MMM #89 OCT '95 "Shielding on the Moon: Digging in for longer stays."
They summarily dismiss all the entrepreneurial proposals.
They prejudge the X-33 configuration before the studies are complete.
They award the X-34 contract for a vehicle intended to be costlier to operate than the Russian Tsyklon.
They permit expensive launch infrastructure not allowed for Taurus, in the proposals.
They send time savers to the contractor facilities with the intent of showing private enterprise how to save money.
They hand the agency's favorite lap dog Rockwell (X-15, Mercury, Apollo, Space Shuttle) two contracts, more than anyone else.
They subject the Clipper team to the torments of the damned.
And they release less than half of RLV funds to contractor teams.
- Jeff Sandburg, Skokie, Illinois
EDITOR'S REPLY: While most space activists rejoiced and sang Hallelujah when NASA agreed to take the single stage rocket technology program under its wing, we shuddered, seeing in the move the probable death knell for "Cheap Access." That NASA could do such a program right is so counterintuitive as to be a textbook case of an oxymoron.
Nonetheless, I'd be delighted to have my fears and suspicions proven groundless. It is with this hope that I am wrong that MMM regularly carries the Space Access Update column of Henry Vanderbilt (which we did not receive this month in time for inclusion) - Peter Kokh
I finally got to see "Apollo 13" and it was a strange emotional experience. I was probably the only person in the theatre who has actually ever met any of the people involved. So it was a lonely, personal event. I understood virtually every line of dialogue and knew so much about other events that were going on that weren't mentioned - the pogo, the problems convincing the computers that they really should do a sep with the LEM still attached - that I was there.
Ron Howard brought it alive and my own knowledge and my private memories from my days as a CMU Sophomore made it 1970 again.
And afterwards - blind rage. I left the theatre and stopped for a pint on the way back. With every sip I cursed the political wanks who killed Apollo. May their souls be damned to eternal torment in the deepest foulest pits that hell has to offer. May dogs piss on their graves.
There is no smiley to this. I have no pity on those who stole my future.
Dale Amon, Belfast,Northern Ireland
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