Aucbvax.6224
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Fri Feb 19 04:08:17 1982
SPACE Digest V2 #109
>From OTA@S1-A Fri Feb 19 03:37:32 1982
SPACE Digest Volume 2 : Issue 109
Today's Topics:
Heinlein short-story
Heinlein story/ Luna City "home"
"All those lovely Titans going to waste"
Using Titans
L-5 Society
KING can't get this, so rerouting to digest instead
MARCH '82 SHUTTLE LAUNCH DATE?
Twisting of orbital platforms
Re-Ring / my ring better than yours
Re: Re-Ring / my ring better than yours
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Date: 02/18/82 1129-EDT
From: GNC at LL
Subject: Heinlein short-story
To: space @ mit-mc
I believe that the Heinlein story to which Tom Wadlow referred is
"It's Great to be Back", from "The Green Hills of Earth" collection.
Joe Baldassini
-------
[That's the one. Thanks, Joe. --Tom W.]
------------------------------
Date: 18 Feb 1982 09:56 PST
From: Ciccarelli at PARC-MAXC
Subject: Heinlein story/ Luna City "home"
To: SPACE-ENTHUSIASTS at MIT-MC
cc: Ciccarelli
-----
..(where home will be, after a long tour in Luna City is an interesting
question. Heinlein wrote a marvelous story about precisely that,
whose name I can't recall)
-----
Tom Wadlow -- you may be thinking of "The Menace from Earth", or of the
novel "The Moon is a Harsh Mistress".
Regarding "losing touch with the folks" -- regardless of the video bandwidth
used to "call home", Luna citizens have the unavoidable two-seconds-plus delay
between action and reaction.
I think it's something you'd get used to, especially with video, but I know how
annoying the 500msec "hop" delay for today's satellite-relayed long-distance
phone calls can be [I got delays occasionally when calling from Arizona to
Florida, when I lived in Arizona recently].
Speculation -- would cheap "picturephone" service keep people *here on the
planet* from "losing touch with the folks"?
/John
------------------------------
Date: 18 Feb 1982 10:23 PST
From: Ciccarelli at PARC-MAXC
Subject: "All those lovely Titans going to waste"
To: Space at MIT-MC
cc: Ciccarelli
Making an analogy with computer science, I think of "finding uses for" all
the computer hardware built just SEVEN years ago (memory boards with
256-bit chips, "4004" processors) that's now languishing somewhere in
DOD's basement. And I soon dismiss the possibility for several reasons
that are applicable to ANY quickly-evolving technology, i.e. launch
vehicle design. Though the Titan would be "expendable" -- no need to "fix
it" -- these arguments still hold some water
[1] Spare parts availability. You cannot find replacements for many of
the electronic components (logic chips, for example) incorporated into
even fairly recent designs, let alone 30-year-old Titans. And even
"slight" redesign (to work around parts you can't get) is out of the
question.
[2] Documentation. The "science" of documentation of large systems has
been maturing rapidly; it may be prohibitively expensive to educate those
who will be required to learn the equipment.
[3] Basic advances in the state of the art. The equipment may not have
the functions you need, because it was designed when those functions were
too expensive, or not technically realizable, or simply not yet thought
of! Likewise, your support equipment (tracking stations; telemetry
programs...) may use a later, more advanced technology incompatible with
the stuff you'd like to "reuse".
I think we'd better total up the "hidden costs" of reusing ANYTHING before
doing so. The money, time and energy might be better spent on creating
low-cost spinoffs of Shuttle technology. We may find the Titan is no
bargain even for FREE!
/John
------------------------------
Date: 18 Feb 1982 1045-PST
From: Tom Wadlow <TAW AT S1-A>
Subject: Using Titans
To: space at MIT-MC
Unfortunately, the computer analogy is not quite on the mark. We
have Titans, but they are not in mothballs. They are in silos,
surrounded by people who know the intricacies of Titan maintenance
and launch procedures. If we had to re-furbish them, I would
agree, but they are *supposed* to be flight-ready today. If we
allow the technical expertise to disappear, they will be impossible
to use. But that should not be the case yet.
Admittedly, I am in favor of developing Shuttle related launch systems
in any event. But the Titan scheme should be looked at before they
are replaced, to see if the cost is not prohibitive.
An interesting question might be: If we suddenly acquire a massive
launch capability, what would we do with it??
------------------------------
Date: 18 Feb 1982 09:00:59-PST
From: E.jeffc at Berkeley
To: v:space@mit-mc
Subject: L-5 Society
Checking over the latest Silicon Gulch Gazette, it appears that
the L-5 Society has a booth at the next West Coast Computer Faire
in San Francisco. I guess I have no choice but to visit their
booth, as I am dying of curiosity as to what they have to say
to a bunch of hackers.
------------------------------
Date: 18 February 1982 15:57-EST
From: Robert Elton Maas <REM MIT-MC AT>
Subject: KING can't get this, so rerouting to digest instead
To: SPACE at MIT-MC
COMSAT@MIT-MC 02/18/82 04:04:41 Re: Msg of Wednesday, 10 February 1982 01:51-EST
To: REM at MIT-MC
FAILED: KING at KESTREL; Host appears to be permanently down or not accepting mail.
Failed message follows:
-------
Date: 10 February 1982 01:51-EST
From: Robert Elton Maas <REM MIT-MC AT>
Subject: half-time power from the moon
To: KING at KESTREL
It would be rather silly to put a power station on the far side of the
moon and make an electrical conduit to bring the electricity 1500 miles
to the polar region where it would face Earth half the year, and not bring
it a few hundred more miles so it'd face the Earth year around.
I think your design is a straw man. The expense of that extra few hundred
miles of conduit would be small compared to the money already invested,
and would double the uptime.
------------------------------
From: HQM@MIT-ML
Date: 02/18/82 16:34:34
Subject: MARCH '82 SHUTTLE LAUNCH DATE?
HQM@MIT-ML 02/18/82 16:34:34 Re: MARCH '82 SHUTTLE LAUNCH DATE?
To: SPACE at MIT-MC
DOES ANYONE KNOW THE PROJEECTED LAUNCH DATE FOR THE NEXT
SHUTTLE MISSION?
AND POSSIBLY ANY INTERESTING GOALS OF THIS FLIGHT?
(PLEASE SEND A REPLY TO HQM@AI, AS I AM NOT ON
SPACE MAILING LIST)
THANK YOU
HENRY MINSKY
------------------------------
Date: 18 February 1982 18:21-EST
From: Robert Elton Maas <REM MIT-MC AT>
Subject: Twisting of orbital platforms
To: CARLF at MIT-AI
cc: SPACE at MIT-MC
A long thin rope doesn't work because it provides only longitudinal
force, no torque. If the weight pulls sideways in an effort to
restore the SPS to its correct attitude, the rope just bends
instead of applying torque at the other end where it attaches to
the SPS or other object. You need either a small weight on the end
of a long rigid object such as a beam with supports:
**********--------
* * --------
* * --------
* S P S *========================WEIGHT
* * --------
* * --------
**********--------
or a larger weight closer:
**********====*********
* * * VERY *
* S P S *====* LARGE *
* * * WEIGHT*
**********====*********
In either case the supports must be resistant to torque, thus with
a long weight with support wires tapering back to opposite sides
of the SPS (first diagram above) the force on the guide wires
will be several times the sidewards force on the conter-weight.
Does anybody have figures on the total mass of an SPS capable of
supplying 10% of USA electricity needs, on the restoring torque
needed to maintain its angular position within 10 degrees
either way from center, the diameter of the SPS capable of
holding the support wires, the proposed mass of the counterweight
and its proposed distance from the SPS, and thus the tension
needed in the guy wires?
------------------------------
Date: 18 February 1982 18:44-EST
From: Robert Elton Maas <REM MIT-MC AT>
Subject: Re-Ring / my ring better than yours
To: HAGERTY at RUTGERS
cc: SPACE at MIT-MC
Date: 16 Feb 1982 2146-EST
From: HAGERTY at RUTGERS
Since then, REM and I have exchanged a
couple of thoughts on the matter (COSMOS Ringed Planet...)- he feels
that it would not be practical around a star for energy capturing
reasons.
No, you have it backwards. I said a ring around a planet as shown in
Cosmos (located about 1/2 radius above the surface where orbital speed
is about 12 orbits per day, but complete with about 40 columns reaching
down to the surface forcing it to go only 1 orbit per day thus forcing
the columns to support it from below), wouldn't be especially good for
catching energy, and would be too dangerous but a ring of SPSs around
the Sun would be dandy. (Sagan's planet-ring would span 8000 miles
across whereas a ring around the sun would span 292,000,000 miles
and thus collect 36,000 times as much sunlight if it had the same
width in the polar direction and the same optical density and
efficiency. Other factors are that putting stuff in orbit around
the Sun costs more than putting in LEO around Earth, but putting
up rigid ring with lots of physical support beams is probably much
more expensive than just orbiting stuff anywhere in the solar system,
so I think the ring-around-sun would be better than a ring-around-planet.
Re use of ring-around-planet as spaceport. I wonder if it would be
any cheaper than building a dome around the Earth to keep in the
atmoshere, evacuating the air above the dome, and launching spaceships
by mass drivers above the dome??
(Just for fun, imagine the environmental impact report for EITHER.)
------------------------------
Date: 18 Feb 1982 2011-EST
From: C. Greg Hagerty <HAGERTY AT RUTGERS>
Subject: Re: Re-Ring / my ring better than yours
To: REM at MIT-MC
cc: : ;
In-Reply-To: Your message of 18-Feb-82 1844-EST
Well, that makes sense. A dome would be quite expensive and REALLY
throw off the environmental balance. One may wonder how fragile this
balance really is: How much arisol-spray do you use. If you throw too
many pennies into Odell Lake, fish type B will die, causing fish type
A to die.. Skylab? ..
NOW, Skylabs (instead of threatening the last two KooKoo birds in
existance (on a hidden island of course)) along with the other
falling/unfalling junk and satellites, could be harnessed togeather in
the days of the space shuttle.[Yielding a ring with production
possibility, political controvercy and all] Instead of killing the
last 2 KooKoo birds with fallout from fusion-powered spacecraft (which
could be built on the ring), we can kill them with the trivial shade
of our ring (a thin ring), falling nuts and bolts, possibly the ring
itself (after the explosion of a fusion-powered space ship) - but have
enough fusion-powered spaceships to find another habitable planet (to
breed KooKoo birds on). /Greg:
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------------------------------
End of SPACE Digest
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