MMM Classics Year 10: MMM #s 91-100 - Moon Society

y Peter Kokh
By “stuffs” we mean commodities any which we may
wish to ship to orbit or space destinations beyond in relatively
high volume and over a long period of time, on a regular basis -
which, however, can be shipped in any quantity. A lot of small
pay-loads do the trick as well as a few big ones. We are talking
about materials or substances, not hardware of set and indivisible
fully assembled size. Some examples are water, hydrogen,
oxygen, nitrogen, methane, ammonia, (volatiles of which the
Moon seems to have a paltry endowment) other gases and
liquids, powders, compacted pellets, computer chips and other
micro-assemblies etc. In other words we are talking “pipeline”
items, not “truckload cargoes”, items which at their destination
can be placed in tank/bin/silo farms, etc.
That such “stuffs” can be sent to orbit and beyond in
piecemeal fashion, does not in itself warrant a conclusion that
that is the most efficient way to ship them. It only means that
pipeline analogs ought to be considered on their own merits
with any high system development costs weighed against the
accelerated amortization expected from high volume, individual
stuff category by category, or collectively en masse.
The pipeline concept of regular supply, can be satisfied
in several ways. Assembly line manufactured cheap small
rockets launched often, is but one way. A high per unit time
volume of traditional rockets, even if they are small, might add
polluting exhaust gases to the atmosphere at a worrisome rate.
The option would be to carry aloft only an orbit insertion/circularization
engine to ignite well above the atmosphere. The
initial boost to high altitude / high velocity suborbital trajectory
would be made by an Earth-bound device such as a mag-lev
mass driver or a gas gun.
Sandia National Laboratory in Albuquerque is one
outfit investigating the possibility, and, of course, the military
is very interested for the tactical applications it imagines.
A launch gun or launch track is only part of a working
system, however, and promises to be a very capital-intensive,
high upfront cost device. Further, it (either) could only accelerate
projectiles and their hardy or hardened mini-payloads, at
very high Gs (thousands!) into a forward position from which
they could be, and would have to be, inserted into orbit by
another part of the system.
The partnering part of the system could be a small
onboard non-reused motor, or, in the case of commodities
bound for geosynchronous orbit in a slot handy to an equatorially
sited launch device, some kind of orbiting mass-catcher,
anchored by the balance of its inertia and distance permanently
overhead and downrange, ever poised to “catch” the steady
stream, and somehow able to put the accumulated momentum
from the catching process to good use in station-keeping. This
can be arranged by putting the catcher at a slightly lower and
normally faster altitude, with the steady momentum addition
calculated to keep it at geosynchronous velocity all the same. I
yield to the orbital mechanics experts.
Launch guns not on or very near to the equator would
scatter their charges shotgun style to a whole equator-stradling
range of crisscrossing orbits, unless launch was restricted to
just one narrow window a day. That would make poor economic
sense, so the incentives to find a genuinely equatorial
site should be “insistent”.
Launch guns or tracks discharging at relatively high
altitude above the thicker layers of atmosphere, would gain the
further advantage duo of earning more altitude and velocity for
the energy buck, while requiring less faring mass.
What about the pellet containers or capsules carrying
the commodities? Three obvious possibilities are (1) Nonvolatile
self-contained solids might need no protective envelope,
the minor ablation being deemed the cheaper option. (ice
cubes as a container free way of shipping water would not
seem very promising, however). (2) Empty the contents at
destination and shipping the empty capsules or pellet projectiles
back to Earth as cheap dunnage. And (3) make the
container-farings of a material that is badly needed at the
destination, in effect smuggling that material aloft as a stowaway
co-shipment. Stainless steel, copper, brass, bronze, zinc,
lead, platinum, gold, silver are just some of the choices. Effectively,
this third method would produce maximum pipeline
efficiency.
In the next article, we will talk about prime turf for
such a pipelining facility. For this purpose, political, national,
military and other usually primary considerations mean little.
Location, location, location - as in real estate, for pipeline
launch operations, location will be everything, the only thing.
Once assured volume of traffic warrants, for “stuffs”
that can be pipelined, the Cheap Access to Space (CATS)
answer(s) developed for large payloads and for personnel
traffic may be an unsuitably expensive choice. However, until
we have orbital or lunar facilities which will require relatively
large reusable launch vehicles to bring up massive and bulky
assemblies (habitat structure, energy production, material processing
equipment - all in an earlier time frame), the demand
for pipeline items will continue to be too low to justify the
capital expense of a pipeline launcher. But it’s never to early to
do the research on the tree of engineering options on which the
eventual designers and builders of such a system will rely.
Moon Miners’ Manifesto Classics - Year 10 - Republished January 2006 - Page 81