Originally written: 3 August 2005.
A. From 2006 to permanent, productive lunar base
The good news from this spring was NASA’s decision to replace the space shuttle with separate, simple-configuration heavy-lift and crew-lift vehicles, Ares I and Ares V. This should lower both the cost and risk of getting from earth’s surface to low earth orbit (LEO). It is also very encouraging to see successful private projects to get humans to LEO and geosynchronous orbit (GEO).
But how to really get humans into space? Some people want to go to Mars. It may strike the imagination now, but in the long run I think Mars will be a disappointment. Too small to terraform and inhabit, too big to use as a platform for further space exploration. In fact, I think humans will do best in gravitats–‘wheels in space’–in the long run. The minimum-size gravitat which does not produce a spin-sensation in the average human is one kilometer across, so it is not small. But once built, gravitats can be used in many locations: as stations at Lagrange points, as bases on low-gravity bodies like the moon, and as slow interplanetary vehicles.
Furthermore, we can built most of a gravitat on the moon, as well as many other handy items like monocrystalline silica wafers for semiconductors and efficient photovoltaic cells. Once we build a mass-driver on the moon, we can also lob products off the surface and either glide them down to earth or nudge them out to other orbits or other planets.
The problem is imagining the transition ‘from A to B’: from our present general indifference to space, to having a viable, productive lunar base that manufactures reflectors for massive far-side optical telescopes; wire and bars for structures and machines; and liquid hydrogen and oxygen for propellants.
The following pages are thought-pieces on issues and designs necessary to make that step.
B. First bits
The main challenge in developing a major lunar base is thinking phase-wise about scaling up. The first bits of equipment will need to be manufactured on earth, lifted all the way to the moon, and landed under controlled power. The equipment should be chosen to enable ‘bootstrapping’ up to larger and larger capacities.
These are guesses. But it seems like the earth-made equipment needed to begin the base are:
A pressurized habitat which can be buried under lunar soil.
A small tele-operated robot which can be used in lieu of human space-suited exterior activities (HEAs).
A large tractor which can operate as an earthmover. Call it a crawler.
A strong photovoltaic array.
Big mirrors which can focus enough sunlight to vaporize lunar soil.
Some refining equipment (will have to read up on what is needed here to start with).
C. Second step: bulk refining, basic manufacturing
The lunar base needs, first of all, to develop the capacity to refine and mold metals (aluminum, titanium, and iron) and crystals (mostly silica), and extract and contain gases (oxygen, hydrogen, and whatever else is available).
D. Third step: machining and assembly
In this third phase, the base will need to:
- form basic metal stock into machined members for structures,
- weave wire into cable and fabric, and
- build large, simple machines.
Among the large machines will be bigger crawlers used for paving, mining, and moving items; compulsators and mass-driver components; electric distribution network components; and the parts for gravitats.
E. Beyond the bootstrap phase
After this point, the critical projects become multiple, parallel, and overlapping. The electrical system and mass-driver are highest priority, but at the same time components need to be built and stockpiled so they can be lobbed as soon as the mass-driver is completed. Likewise the gravitat needs to be built, so that longer-term experimentation in closed-loop life-support can begin. Paving the area around the base will be a slow process, and once the mass-driver is online, the same team and equipment will proceed to lay more mag-lev track to other locations around the moon. At this point the purposes and processes of the lunar base will be too complex to predict at the moment. What get learned from ‘bootstrapping’ the base into operation will probably open many possibilities.
One likely ongoing project will be astronomy, particularly in the electromagnetic bands ranging from visible light out to radio waves. All of these require larger collection mechanisms, either reflectors or conductive arrays. The far side of the moon is an excellent location for these telescopes.
The second ongoing project will be as a major factory, building robots, satellites, deep-space probes, and gravitats. As more mag-lev tracks are built in various directions, payloads can be launched in various directions, including straight out from the far side of the moon. This will facilitate not just a Mars mission, but also roving gravitats which can support extremely complex, long-term exploration.
I agree with the various authors who recommend that the first Luna base should be located at one of the poles, where sunlight is always available. With the information available in 2005, I think the south pole is a slightly better choice. In part because the astronomy of the southern hemisphere is very interesting; in part because there is a crater right at the south pole (Shackleton) which may be very useful.