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>From OTA@S1-A Tue Feb  9 03:16:30 1982

SPACE Digest                                      Volume 2 : Issue 102

Today's Topics:
		    Re: sri-unix.707: Horseshoe Orbits
		  RE: dennis' reply to Horseshoe Orbits
		      half-time power  from the moon
			    Politics of Space
			     Scramjet Request
			     horseshoe orbits
			 polar lunar solar power
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Date: Sun Feb  7 10:51:10 1982
To: Space at MIT-MC
From: hplabs!menlo70!ucbvax!ihnss!cbosg!harpo!chico!duke!phs!dennis
       at Berkeley
Subject: Re: sri-unix.707: Horseshoe Orbits
Source-Info:  From (or Sender) name not authenticated.


Nope -- it's not ignorance, it's just a point of view problem.  Higher
orbits are slower only in terms of angular velocity (speed relative to
the surface).  In linear velocity (yeah, orbits are ellipses, but
that's the idea) higher orbits are faster.  You need to accelerate from
a low orbit to achieve a higher one.  The ground speed is slower
because the circumference grows quickly wrt speed and it has more
distance to cover than it has extra speed to do it with.

Thus, the two moons exchange kinetic energy (orbital speed) via
gravitational attraction, and they BOTH (mutual and opposite) change
orbits.  The higher moon (the one caught up on) is decelerated and the
lower moon is accelerated, causing them to exchange orbits.  This will
collapse eventually (tidal forces ALWAYS eat some of that kinetic
energy), and either they will collide or just take up the same orbit;
I suspect collision.

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Date: Mon Feb  8 00:24:53 1982
To: Space at MIT-MC
From: hplabs!menlo70!ucbvax!ihnss!houxi!houxg!lime!gdg at Berkeley
Subject: RE: dennis' reply to Horseshoe Orbits
Source-Info:  From (or Sender) name not authenticated.


speaking, angular velocity is the rate at which an orbiting body subtends
a given angle relative to the orbital *focus* (CG), which, in the case of
relatively light moons orbiting relatively round, heavy planets, can be
considered to be the center of the planet. Simply put, radians/second. *It has
nothing to do with speed relative to the surface.* For example, a
geosynchronous satellite has no motion relative to the Earth's surface, yet
its angular velocity is considerable. If the earth suddenly stopped rotating,
the satellite's angular velocity would remain the same (360 degrees/day), and
it would remain in orbit at the original altitude. (Of course it would no
longer be geosync either.) We just tend to think of orbital speeds as relative
to the planet surface, but that is *apparent* angular velocity. Luckily for
us, that's all it is. If the earth had no angular velocity (spin) of its own we
wouldn't be able to have geosync satellites at all because no matter what orbit
we put them in they'd always have some velocity relative to the surface.

				- Glenn Golden

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Date: Monday, 8 February 1982  08:07-PST
From: KING at KESTREL
To: Jerry E. Pournelle <POURNE at MIT-MC>
cc: SPACE at MIT-MC, King at KESTREL
Subject: half-time power  from the moon

	In that case,  unless the moon's  equator happens to  coincide
almost exactly with the ecliptic (does it?) the power station will  be
out of service for six months out  of the year.  (There is NO  pointof
the Earth's surface that has continuous sunlight.)
	In addition, note that the sun's angle changes.  If the moon's
equator IS aimed at the sun, then only half of the sun is visible from
the poles,  and you  would need  a tall  tower (built  againstgravity,
don't forget) and a rotator to take advantage of the continuous  power
available.

					Dick

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Date: 8 Feb 1982 0926-PST
Sender: WARD at USC-ISIF
Subject: Politics of Space
From: Craig E. Ward <Ward at USC-ISIF>
To: SPACE at MIT-MC
Cc: Ward at USC-ISIF
Message-ID: <[USC-ISIF] 8-Feb-82 09:26:10.WARD>

Yesterday I got around to reading my copy of "The Planetary
Report" and I found a reprint of an article by James Van Allen.
I contend that this article illustrates one of the problems we
have in getting the space program funded, namely, that many of
the big names of the scientific community are politically naive
and give the political opponents of science weapons to use
against us.

Very quickly, the article contends that we can not complain about
the level of funding of the space program (6 billion NASA and 3
billion DoD), that if several scientific probes have been
cancelled, we must remember that it is because the nation spends
almost all its money on manned space flight.  He hints that he
thinks the space shuttle is going to be a "financial monstrosity"
being 20-50 years ahead of its time.

I disagree on several of his points.  The NASA budget is not by
any reasonable accounting adequate, nor is the general level of
scientific funding.  For something so vitally important to the
country to receive such a small piece of the pie is a disgrace.
I also contend that the manned space program has more than
justified itself by its returns in science and technology.  And
finally, to illustrate my point, to assume that money taken from
the manned program will go to the unmanned demonstrates great
political naivity.

Van Allen's arguments sound rather similar to those made by
people like Senator Proxmire (a real tail-gunner if there ever
was one).  I think that Proxmire's statements have shown that he
lacks an understanding of the scientific method and such
statements as those of Van Allen allow him to claim allies in the
scientific world (See, even their own agree with me).  The battle
over funding must be fought in the political arena and we must
learn how to fight there if we are going to get anywhere.

I do not want to give the impression that I think either Dr. Van
Allen or Senator Proxmire are stupid or evil.  I would very
likely like both if I were to meet them.  I would, however, like
to caution people in positions like that of Dr. Van Allen to be
careful of what they say and to whom they say it.  The budget you
save may be your own.

/Craig

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Date:  8 Feb 1982 1313-CST
From: John Otken <CC.Otken at UTEXAS-20>
Subject: Scramjet Request
To: Space at MIT-MC

Could anyone supply some references to SStO technology?
-------

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Date: 8 Feb 1982 06:47:05-PST
From: menlo70!sytek!intelqa!murray at Berkeley

HOORAY!!!!!! Finally some REAL space news! Please keep it up.

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Date: Mon Feb  8 10:10:52 1982
To: Space at MIT-MC
From: ucbvax!decvax!duke!phs!dennis at Berkeley
Subject: horseshoe orbits
Source-Info:  From (or Sender) name not authenticated.


Nuts.  I fell into the point-of-view trap myself.

Anyway, correcting for that, my remarks still apply, unless
somebody who has taken more than one astrophysics course
can correct me.

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Date: Mon Feb  8 11:01:44 1982
To: Space at MIT-MC
From: ucbvax!decvax!duke!cjp at Berkeley
Subject: polar lunar solar power
Source-Info:  From (or Sender) name not authenticated.


I can see problems with moon-based solar power stations even at the
poles.  If you could get continuous power there, I could maybe see
beaming it to earth from such a close tangent to the lunar surface.
The moon's orbit is the problem.  It is not quite in the same plane
as the earth's orbit around the sun.  So, the polar regions will
cycle in and out of sunlight on a yearly basis.
Even when the sun lights the pole, it is low on the lunar horizon.
This means that the collectors would have to be huge and/or highly
tilted, relative to the amount of power you'd get.  And you would still
have to build a power station at both poles to get year-round power.

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End of SPACE Digest
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