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From: @S1-A.ARPA,@MIT-MC.ARPA:DIETZ@RUTGERS.ARPA
Newsgroups: net.space
Subject: Shoot the Moon
Message-ID: <2378@mordor.UUCP>
Date: Sat, 22-Jun-85 22:09:22 EDT
Article-I.D.: mordor.2378
Posted: Sat Jun 22 22:09:22 1985
Date-Received: Sun, 30-Jun-85 00:35:56 EDT
Sender: daemon@mordor.UUCP
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From: DIETZ@RUTGERS.ARPA

The Apollo missions revealed one serious obstacle to lunar colonization
and exploitation: an almost total lack of volatile elements in lunar
rock.  There is very little carbon, nitrogen, hydrogen or halogens;
even lead is seriously depleted.  This is now thought to have been
a consequence of the formation of the moon from debris blasted from
the earth by a collision with a mars-size body early in the history of the
solar system.  A volatile elements were disbursed before the cloud could
condense into dust particles.

At any rate, this is a serious obstacle to any would-be colonist.  Hydrogen
is necessary for water, food and rocket fuel.  Carbon and nitrogen are
needed for food and plastics.  Fluorine is vital in the chemical processing
of lunar materials.

Delivering this material to the moon by rocket is expensive, even with
advanced orbital transfer vehicles.  Delivering it to near lunar space
is somewaht cheaper, since you don't have to ferry it down, but still
expensive.

I propose a very cheap method for shipping bulk supplies to the lunar surface.
The idea is to build a large electromagnetic accelerator on the Earth's
surface.  Payloads consisting of ~100 kg of plastic are launched at the moon.
These payloads hit the moon at several km/sec, completely destroying them;
however, the target area is covered with a layer of fine soil to absorb the
kinetic energy.  Periodically the soil is sifted to remove debris, which is
then refined to extract needed volatiles.

Assuming the accelerator can be built sufficiently cheaply, the main problem
is guidance.  Travelling up through the atmosphere, the payloads will ablate
and be pushed about by winds.  Their velocities will have a significant
random component.  Some sort of active guidance will be needed to make
course corrections.  I suggest placing in each payload package a small
microwave transceiver, some control electronics, a battery, and some
low power thruster rockets.  The position of the payload is determined
by triangulation from large satellites placed in earth orbit, at the L4
and L5 points, and somewhere out of Earth/Moon system plane.  Course
correction calculations are made at a central computing facility on
Earth and relayed back to the payloads.

All the elements I mentioned above can be delivered by this mechanism.
Hydrogen and carbon are delivered as polyethylene.  Fluorine is delivered
as Teflon.  Nitrogen can be delivered as Nylon.  The guidance and control
package will be destroyed on impact, but perhaps some useful metal can be
extracted.

A rough guess of cost can be made by calculating energy cost (~$3/kg
at 30% launcher efficiency and $.05/KWHr) and capital costs (at
$5 billion dollars spread over five years at 100,000 tonnes/year, about
$10/kg).  This ignores guidance package costs, which might add another
$10/kg (if the package costs ~$1000, probably an overestimate).
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