Aucbvax.6267
fa.space
utcsrgv!utzoo!decvax!ucbvax!space
Tue Feb 23 03:58:25 1982
SPACE Digest V2 #113
>From OTA@S1-A Tue Feb 23 03:53:57 1982
SPACE Digest Volume 2 : Issue 113
Today's Topics:
Recycling Titans
More Politics & Marginal Costs
"30-year-old Titans... oops!"
"Man's guts were not made for orbital mechanics..."
SPS tidal stabilization
Re: twisting of orbital platforms
Twisting of orbital platforms
SPS tidal stabilization
launching old titans
Tidal stabilization
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Date: 22 Feb 1982 0950-CST
From: Clyde Hoover <CC.CLYDE AT UTEXAS-20>
Subject: Recycling Titans
To: space at MIT-MC
Unless you use the silos the Titans are in now, you have the
cost of emptying them of propellant (Titan propellants are noxious
liquids), hauling them out to KSC (where you can use LC 43) to launch
them. This would not be cheap.
On the other hand, you can't launch them from where they are now
because the first stages would drop on somebody (unless you shot them
all into near-polar orbit, even then Candians probably would not like to
have 10 ton+ hunks of junk falling from 30 miles up on to their
territory). Remember, the Titan silos were placed for a one-shot, over
the pole trajectory to the USSR, and if you get to the point of lighting
those babies it really doesn't matter if a crashing first stage kills
some caribou.
Nice idea, though - using the old beasts would save some
hardware purchase costs, though the launch costs would not be
appreicably less than that of the Titan III (a favorite of the Air Force
for launching recon sattellites and used for Viking and Voyager).
-------
------------------------------
Date: 22 Feb 1982 0813-PST
Sender: WARD at USC-ISIF
Subject: More Politics & Marginal Costs
From: Craig E. Ward <WARD USC-ISIF AT>
To: Space at MIT-MC
Cc: Ward at USC-ISIF, Pourne at MIT-MC, TCS at ECL, Riedel at ECL, Katz at USC-ISIF, REM at MIT-MC
Message-ID: <[USC-ISIF]22-FEB-82 08:13:13.WARD>
I don't want to say "I told you so", but I told you so. In this
Saturday's (Feb. 20) Santa Ana Register an article appeared with
the headline "Space shuttle: an economic 'monstrosity'?
$2-billion- a-year savings seen if project is scrapped". It was
written by a Peter Larson of the Orlando Sentinel Star. One of
the article's main points is that James Van Allen says so in his
Science article.
The reporter also interviewed a NASA spokesman named Charles
Redmond who is quoted as saying NASA isn't sure about the Shuttle
paying off. ("There's a lot of corridor talk..."). I wonder
about this.
Has anyone ever tried to figure out what the marginal cost of a
shuttle launch is? (The marginal cost of something is the cost
of doing or making one more of it). In my view, the money spent
on developing the shuttle can not be used in figuring the
marginal cost. That money is a sunk cost and is gone. We can
only look at future expenses and returns. The Shuttle is here
and we would be losing everything to drop it now. Also, it would
seem to me that the marginal cost of throw-aways will be much
greater because you have to keep building new ones.
Anyone have figures?
Craig
P.S. It may also be worthy of note that the AP article below
Larson's was headlined "Shuttle test troubled, but called
'success'". It reported some of the problems during Friday's
test run. The article itself was not bad, but that headline
makes it sound as if NASA is trying to hide something. Do we
also have a problem with press coverage?
------------------------------
Date: 22 Feb 1982 08:40 PST
From: Ciccarelli at PARC-MAXC
Subject: "30-year-old Titans... oops!"
To: SPACE at MIT-MC
Oops! Somehow my mind transmuted Jerry Pournelle's comment about "30- year-
old PROPULSION TECHNOLOGY" (SPACE V2 #108) ...into... "30-year-old Titans".
A quick subtraction puts "30 years ago" as 1952, which may be valid for the
technology, but not for the missile...
(Apologies...)
/John
------------------------------
Date: 22 Feb 1982 08:51 PST
From: Ciccarelli at PARC-MAXC
Subject: "Man's guts were not made for orbital mechanics..."
To: SPACE at MIT-MC
cc: Ciccarelli
Methinks you speak of dirt-siders, spasebaw!
The first generation that is born and raised in orbit will have no problem with
the everyday mechanics... Playing catch, that parabolic pastime for Grounders,
might be one of the ways a kid will learn physics "up there".
Possibly, someone raised in "free fall" would just develop "orbital chauvinism"
with regard to mechanics, just as we surface-dwellers have our "planetary
chauvinism".
/John
------------------------------
Date: 22 Feb 1982 10:28 PST
From: Wedekind.ES at PARC-MAXC
Subject: SPS tidal stabilization
To: King at KESTREL, REM at mit-mc
cc: SPACE@MIT-MC, Wedekind.es
I missed some things here. Could someone recap and tell me precisely the
problem you are trying to solve? Does it arise from the fact that an SPS
would be so big that the gravity gradient becomes relevant?
Jerry
------------------------------
Date: 22 February 1982 1226-cst
From: Bill Vaughan <VAUGHANW AT HI-MULTICS>
Subject: Re: twisting of orbital platforms
To: REM at MIT-MC
Cc: space at mc
yup, weight is just to increase tidal forces. Moment arm is simply
distance between upper & lower attachment points, which can be several
feet; or distance between single attachment point and bird's center of
mass when only one pendulum is used.
My recollection (possibly faulty) says the cables were *quite* long
(several hundred meters) and that it took quite a few orbits before
everything settled down nicely. I notice that comsats don't seem to use
gravity-gradient stabilization so maybe it turned out to be a failure
practically. The results are probably in some NASA tech brief somewhere
but I don't want to hunt through NTIS for it.
------------------------------
From: CARLF@MIT-AI
Date: 02/22/82 13:40:34
Subject: Twisting of orbital platforms
CARLF@MIT-AI 02/22/82 13:40:34 Re: Twisting of orbital platforms
To: CARLF at MIT-AI, REM at MIT-MC
CC: SPACE at MIT-MC
Everybody seems to be talking about putting weights on the
end of ropes. My idea is to get rid of the weight on the end by
replacing it with more rope. I figured this out recursively by
noticing that a weight could be replaced by a rope with a
smaller weight on the end, and then that weight could be
replaced by more rope and an even smaller weight, and so on.
This can be very economical, since moment of inertia goes as
the square of the distance while tidal acceleration is
proportional to distance. I never meant that a rope alone could
be a stabilizing device.
-- Carl
------------------------------
Date: Monday, 22 February 1982 13:18-PST
From: KING at KESTREL
To: Wedekind.ES at PARC-MAXC
cc: REM at mit-mc, SPACE at MIT-MC, King at KESTREL
Subject: SPS tidal stabilization
Yes. That's exactly the problem. You have two extended parts
to an SPS: the microwave antenna (always more-or-less perpendicular to
a line from it through the Earth's center) and the solar collector
(varying orientations). The (much larger) solar collector is usually
not in a stable position and the position of the (much heavier but
smaller) antenna is always metastable.
Dick
------------------------------
Date: 22 February 1982 1533-cst
From: Bill Vaughan <VAUGHANW AT HI-MULTICS>
Subject: launching old titans
To: space at mc
Gee, maybe we *should* launch them directly from the silos. I mean,
most everybody in Tucson wants to get rid of them, plus the L-5 society
sort of lives there, so we could combine the whole thing -- put together
a nice big cheering section for the launch, led by Mo Udall of course;
give the southwesterners a chance to see a spaceship go up without
having to pay airfare to Canaveral; incidentally destroy the silos so
they can't put Minutemen in them (nobody araund Tucson wants that to
happen anyway) and - at least temporarily - take the "smog capital of
Arizona" title away from Phoenix (*my* hometown)!
------------------------------
Date: 22 Feb 1982 1413-PST
From: Ted Anderson <OTA AT S1-A>
Subject: Tidal stabilization
To: space at MIT-MC
I would like to suggest that since someone who is presumably an expert on
the subject has studies the problem of tidal stabilization of satellites
we should check with that source. Bill Vaughan suggest that a NASA
technical brief exists on the subject, perhaps someone should look up that
paper and report back to the digest.
As some people have suggested the problem is quite complex. In particular
the SPS itself needs to point to the sun, not the earth. The microwave
transmitting antenna needs to point to the earth, so these two systems need
to be connected by a heavy power cable but decoupled enough to allow them to
point in different directions.
Clearly this is a system that is much too complicated to be designed over
a once-a-day general distribution digest.
Ted Anderson
------------------------------
End of SPACE Digest
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