Obviously, due to enormous transportation costs the bootstrapping must
require minimal effort -- hence it must be done by autonomous and
semiautonomous (telepresence) systems. Due to relativistic delays and
human iterative-control motorics telepresence will be of very, very low
productivty and/or to be not very accurate. Automata must do the bulk of
the job.
The water content in lunar regolith (up to 2 m layer) is afair estimated
to be 1-3%, which may already cause clumping. Nevertheless this is not
solid bedrock, and should be relatively easy to excavate. The automata
must operate in a very dark, cold environment. While there should be
enough power on the supposedly constantly illuminated mountaintop to
operate a largish PV array (either position tracking, or a cylindrical PV
tower) and microwave (due to excellent vacuum, the magnetrons & Co are
reduced to a few exposed metal/isolator parts) the juice to the relay
station on the twin peak facing Earth (later on, a LLO fleet of satellites
could both supply power and uninterrupted communication), there won't be
very much left. Of course we might contemplate a cache of hydrogen/oxygen
electrolyzed from mined water to power the automata fuel cells, but
isotopic batteries and a small (hey, water vapour turbines!) reactor would
seem to make significantly more sense. However, a release of isotopes must
be contained (free path are virtually infinite, can gravity capture part
of radioisotopes of a core gone china?), the potential contamination of
precious surface volatiles considered. Folks, there will be a Lunar
ecology, after all.
Semicontinuous operation by cryotrapping microwaved regolith exhalations
is pretty trivial. The water will be dirty, probably contaminated by H_2S
and NH_3. This can be later metabolized by bacteria -- nitrate is very
important for hydroponics (other minerals can be autoclave-leached from
regolith). Water means reaction mass: liquid oxygen and hydrogen. Water
deliveries to nonpolar locations will be obviously first done by rockets.
Ballistic delivery (damn sturdy containers) by EM drivers might be
contemplated later on. (The age of lunatic truckdrivers has not come yet
;). Water means we can do wet metallurgy (leaching, electrolysis, etc.),
and hydrogen reduction. NASA has already done research on hydrogen
reduction and sintering of lunar soil blocks. Magnetic separation of
reduced Fe/Ni will enrichen the Al/Si/Ti oxide fraction. The need to
devise new technologies from scratch (which microgravity and bone-dry (?)
conditions of most FeNi and silicate asteroids would seem to imply) is
unneccesary.
Since we are talking <<1 closure of autoreplication, the devices must be
reliable/redundant. The more obvious bottlenecks are rocket fuel,
structure elements (bricks, glass fiber and sheet, aluminum/silicon/steel)
and photovoltaics arrays. Melting can be done with a solar oven (parabolic
mirror contamination by sublimates), resistance, microwave and Ebeam
heating. Aluminum/silicon-sputtered glazed surface of a mineral powder can
make usable improvised reflectors ready to be picked off the ground, or PV
arrays. Wafer-grade silicon will be difficult to make. Otoh well worth it,
for beam lithography is trivial there. Another aspect of the lunar
ecology: you would like to keep the vacuum clean and hard for certain
processes.
Essentially, design creativity is a bottleneck. Harnessing the potential
of many people working on (virtual and real) lunar simulators and
teleoperated laboratories will result in a flurry of much more efficient
designs, probably soon resulting in first full-closure autoreplicators.
Lunar water would seem the excellent candy to lure venture capitalists and
general public investments. Monkeys in vacuum suits the public can parse,
the idea of space-based industry of autoreplicating automata would be much
more difficult to sell. After the venture will start making profits, it
won't matter anymore.
If we are to establish a subselenous (thermoinsulation, radiation
shielding) semiautark ecosystem, PV-fed microwave-pumped sulfur vapour
light sources would seem to be best. Bootstrapping a more-or-less stable
ecosystem will be difficult, starting with extremophile pioneers first
would seem a good idea. Much experimenting must be done first, and I do
not mean Biosystem II 'work'.
Can humans work productively outdoors? First, humans are unlikely to be
present at the early bootstrap stage, the necessary transportation
expenses considered. If we have a stable polar ecosystem going, humans
will have to work under a constant radiation load (and nuclear reactor
proximity) and darkness, under cryogenic conditions. Current spacesuits
are heavy (inertia), difficult to don, don't allow long-term untethered
operation (while urination is easy to take care of, defecation is not) and
vastly limit dexterity. And let's don't forget the risks, for lunar
surface is no English countryside. Rapidly dockable, fuelcell-powered
rubber onion-skin vacuum suits in electrically heated lead-lined
tear-proof overalls (puncture kit in the pockets) might be tried out yet.
Especially radiation shielding becomes very difficult here, though.
I have not covered half of what I wanted to outline, but I'd rather end
here. I'd like to get a constructive discussion on such speculative
bootstrapping scenarios going, for the topic is obviously both rich and
fascinating. Please comment.
ciao,
'gene