Newsgroups: sci.space.shuttle
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: best of all worlds
Message-ID: <1990Oct8.224453.12852@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <10265.2708917a@pbs.org> <1017@dg.dg.com> <1990Oct5.163422.25830@zoo.toronto.edu> <1990Oct8.033542.27179@loft386.uucp>
Date: Mon, 8 Oct 90 22:44:53 GMT

In article <1990Oct8.033542.27179@loft386.uucp> wes@loft386.uucp (Wes Peters) writes:
>On the other hand, if you have some way of creating fuel on the Lunar
>surface, Low Lunar Orbit is much easier to obtain that Low Earth Orbit.
>Both would, presumably, provide a suitable microgravity environment for
>such edeavors as manufacturing fine ball bearings, optic fibers, and
>optic filters.

We can do the oxidizer part easily enough on the lunar surface, but fuel
will be tricky unless there really are frozen volatiles at the lunar poles.
Almost all useful fuels need hydrogen, which is quite rare on the lunar
surface in general.  There are proposals for aluminum-oxygen rockets, but
there are some non-trivial problems there.

As for low lunar orbit, there is one major problem with it:  you can't get
a *sustained* microgravity environment there, because you need constant
orbit corrections.  The Moon's gravitational field is so lumpy and uneven
that anything simply left in low lunar orbit crashes before too very long.
As I recall, the Space Studies Institute's RFP for its private-lunar-polar-
orbiter project specified corrections nominally once a month.  This will
eat up fuel and limit the period of uninterrupted microgravity.
-- 
Imagine life with OS/360 the standard  | Henry Spencer at U of Toronto Zoology
operating system.  Now think about X.  |  henry@zoo.toronto.edu   utzoo!henry