Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_1/V15NO125.TXT

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Date: Wed, 19 Aug 92 05:01:19
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #125
To: Space Digest Readers
Precedence: bulk


Space Digest                Wed, 19 Aug 92       Volume 15 : Issue 125

Today's Topics:
                    ACRV/Soyuz P # of Passengers
                           Balloon Launches
                           Electric Tethers
                              GOES West
                           He-3 and tethers
NASA statement on Earth Data System proposals [NTE 92-71] (Forwarded)
                        Private space ventures
            Quick request:  launches scheduled 9/3 - 9/12?
             SPS feasibility (WAS: SPS fouling astronomy)
             SPS feasibility and other space development
                       Star Trek (anti-)realism
                           Tethers (2 msgs)

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----------------------------------------------------------------------

Date: 18 Aug 92 19:32:57 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: ACRV/Soyuz P # of Passengers
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:

>>Does the word 'comeptition' ring a bell? ...

>Company #2 could not afford to develop the vehicle further.

First of all, both MLV alternatives exist as commercial options today. Of
the HLVs, the development cost is $500M which can easilly afforded. GD
spent that much on commercial Atlas and Douglas also spent that much
on Delta.

If the market is there (and the whole point of this is to make the
market) they will come.

>Go look at ATF. One
>winner, one fighter. One winner, one launch system.

You still don't get it. ATF is where the government says they will
buy one fighter and only one. With expendable Freedom resuply the
government doesn't own anything; it just buys services.

Indeed, ATF just proves my point. Both teams invested twice the money
needed to develop the HLV with only a 50-50 chance of winning. For resuply,
they only need half the money they needed for ATF and at the same time
BOTH companies can make a profit.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "If they can put a man on the Moon, why can't they     |
|  [e-mail]     |  put a man on the Moon?"                               |
+----------------------248 DAYS TO FIRST FLIGHT OF DCX----------------------+

------------------------------

Date: Tue, 18 Aug 92 22:06:00 EDT
From: Tom <[e-mail]>
Subject: Balloon Launches

I don't know if this is a wacko idea or what:

Has there ever been any proposal or even thought of using lighter-than-air
platforms for launching small payloads?  It seems to me that with a
dirigible designed to fly relativly fast, you could get pretty good cost
savings with it, as you could get both velocity and altitude advantages.

-Tommy Mac                     .  "                  +
.------------------------  +                      *       +
|   Tom McWilliams; scrub       ,     .                        "        +
|  astronomy undergrad, at     *       +;.     .  '             There is
| Michigan State University   '                      .    "   no Gosh!
|   [e-mail]                        '      ,   *
|       [phone]       ;  +  '                                 *
'-----------------------

------------------------------

Date: Tue, 18 Aug 92 19:51:13 CDT
From: [e-mail] (Mike Evert)
Subject: Electric Tethers

I have a question about the possibilites of an electric tether system
like that the recent shuttle flight attempted to test.

As I understand it, if a current is put into the tether, then that
would cause the tether and spacecraft to gain kenetic energy and rise
to a higher orbit.  The opposite will happen if current is drawn from
the tether.  Would the acceleration always be in one direction and its
reverse only?  I don't know if this would be in the direction of orbit
or perpindicular to magnetic field.  Is it possible to use the tether
for lateral motion?

It seems possible to put a payload into a high orbit at a cheaper cost
by launching the payload into low orbit.  If that payload carried a
solar powered tether system (or if it could rendevous with one already
in orbit), then the tether can be used to boost the payload the rest
of the way for nearly free.

Now if a tether system could accelerate a spacecraft in a lateral
direction, then you could go anywher in orbit with them.  You could
launch Energyas from CIS at their high lattitudes and use tethers to
make the orbital corrections needed to send them to FRED or to
geosync or anywhere else.  But alas I don't even know if it is
possible.

Regardless, I think tethers have such possibilities that the
government should divert all social program money to their
development.  Well maybe some of that money could also be diverted
to DCX/DCY, NASP, solar sails and any other super great investment
opportunities that come our way.

Thank you,

Mike


--
+----------------------------------+---------------------------------------+
|  Mike Evert                      | "You are helplessly hypnotized.  You  |
|  Internet: [e-mail] |  will believe everything I tell you.  |
|    Delphi: [e-mail]   |  This quoted message does not exist." |
+----------------------------------+---------------------------------------+

------------------------------

Date: Tue, 18 Aug 1992 19:10:00 GMT
From: Gavin Adams <[e-mail]>
Subject: GOES West
Newsgroups: sci.space

--- Gavin
Visualize Whirled Peas!

------------------------------

Date: Tue, 18 Aug 92 21:58:45 EDT
From: Tom <[e-mail]>
Subject: He-3 and tethers

>   Extracting He-3 from lunar soil is cheap and simple - heat it up a
>little, using solar mirrors.   The cost of storing He-3 in its refined
>state is more expensive than handling lunar soil, so it might be cheaper to
>launch lunar soil to Earth, rather than the He-3, despite the fact that the
>mass of the soil is much higher, the cost of transporting it is very low.

If we were to launch lunar soil to Earth, for processing, we would have a
handy and cheap solution to center-of-mass changes in a tether, as the
raw rock could be rationed out to match the mass of the lifted payload.

ps- This is for Bill Higgins:  Do you have multiple E-mail accounts, or
do you randomly change your sig. file all the time?

-Tommy Mac                     .  "                  +
.------------------------  +                      *       +
|   Tom McWilliams; scrub       ,     .                        "        +
|  astronomy undergrad, at     *       +;.     .  '             There is
| Michigan State University   '                      .    "   no Gosh!
|   [e-mail]                        '      ,   *
|       [phone]       ;  +  '                                 *
'-----------------------

------------------------------

Date: 17 Aug 92 14:17:15 GMT
From: Dani Eder <[e-mail]>
Subject: NASA statement on Earth Data System proposals [NTE 92-71] (Forwarded)
Newsgroups: sci.space

[e-mail] (Greg Moore) writes:

>>    NASA has elected, therefore, to offer an additional
>>opportunity for offerers in the competitive range to
>>adjust the proposed costs to a more realistic level.  In
>>instructions issued by the Goddard Space Flight Center
>>on Aug.10, 1992, as an amendment to the solicitation,
>>NASA has directed the offerers to submit revised cost
>>proposals. Changes to the previously submitted technical
>>and business management proposals will not be
>>considered.
>>
>>    In addition, Goddard Space Flight Center has
>>provided the offerers with the provision that will be
>>used to evaluate the contractor's cost performance
>>during the contract period.  This provision assesses
>>significant reductions to the award fee if the
>>contractor fails to manage and control the program in
>>accordance with the costs proposed.

This may be an example of the impact of the new NASA Administrator,
or it may just be a artifact of the type of project.  In many past
projects, the thing being built was a first-of-it's-kind.  Thus there
was no real basis for anyone (contractor or government) to say what
it should cost.  Hence the frequent use of 'cost-plus-fee' type
contracts, where the contractor gets paid for whatever it actually
costs, plus a profit (fee).

Despite the fact that no one knows what the project will really cost,
the US Congress wants NASA to tell them in advance what the budget
will be for that project.  So NASA tells them something.  In the
past they wanted to tell congress a small number, on the theory that
a cheaper program has more chance of being approved.  It is useful
in this case to have a small number from a contractor to point to
as justification.  Then when the real program cost is incurred, which
is several times the budget amount, NASA can point their finger and
say 'those bad contractors overran the budget' (and we NASA people
are blameless).

Now, in the long run, constant overruns gets you a bad reputation
anyway for bad management, which image problem NASA has with the
Congress now, and which Administrator Goldin has, I believe, spoken
out against.

On the other hand, the subject contract above is for the data system
for the Earth Observing System.  In this case, the job is similar to
things that have been done before on Earth (i.e. a large data management
and delivery system).  There is data from experience to judge what
a project like this should take - It will take x gigabytes of storage,
so many user terminals, this much software, etc., things that have
been done before.

So, it may just be the nature of the job that caused the evaluation
people to say, hey, this is unrealisitically low, give us some
real bids, guys.

Dani

>
--
Dani Eder/Boeing/Advanced Civil Space/[phone](w)/232-7467(h)/
Rt.1, Box 188-2, Athens AL 35611/Member: Space Studies Institute
Physical Location: 34deg 37' N 86deg 43' W +100m alt.
***THE ABOVE IS NOT THE OPINION OF THE BOEING COMPANY OR ITS MANAGEMENT.***

------------------------------

Date: 19 Aug 92 01:09:00 GMT
From: [e-mail]
Subject: Private space ventures
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (William Naylor) writes...
>A private company called "Astrotech" has been trying to get
>into the space business (Astrotech is a public company; its stock
>trades on the American stock exchange in the USA).
>
>2 years ago they tried to convince NASA to sell them a space shuttle,
>which they would finance by a public share offering.  NASA refused for
>various reasons.
>

Astrotech is in the space business now.  They are located at the spaceport
Florida industrial center on the NASA causway (or nearbouts).  They provide
payload integration services to a varitey of customers both military and
commercial.

Also in response to another post about the Shuttle and its availability, the
routine landing of the Shuttle at KSC cancels the longer time in orbit
for the Shuttles and lowers the cost per mission by 3-4 million dollars.
Also for Allan's benefit that 8 per year launch rate was achieved BEFORE
Endeavour came on line.

A possible other use for Shuttle is to provide service to the CIS station
as well as to SS Freedom.  Don't think your Atlas/Soyuz can do that Allan.
That is of course launching out of KSC.

Experimenting with lowering the message rate and reply overhead by responding
to multiple posts in one.

Dennis, university of Alabama in Huntsville

------------------------------

Date: 18 Aug 92 20:51:22 GMT
From: Jordin Kare <[e-mail]>
Subject: Quick request:  launches scheduled 9/3 - 9/12?
Newsgroups: sci.space

Anyone have a schedule handy of Kennedy Space Center launches?
I was curious if anything is due to go up between 9/3 and 9/12
when I'll be in Florida.  Thanks.

    Jordin Kare [e-mail]

--

    Jordin Kare    [e-mail]    510-426-0363

------------------------------

Date: 17 Aug 92 15:48:05 GMT
From: Dani Eder <[e-mail]>
Subject: SPS feasibility (WAS: SPS fouling astronomy)
Newsgroups: sci.space

[e-mail] (Gary Coffman) writes:

In reference to Earth heat balance calculations, I disagree with
Mr. Coffman.  If terrestrial solar power is used, whether PV or
thermal, you have to locally increase absorbtion of sunlight, since
both PV cells and solar collectors are effectively darker than the
ground over which they are built.  A darker earth is a warmer earth,
despite the shifting of the heat load from the collector to the end
using machines by way of electrical transmission lines.

In the case of microwave (not laser) SPS, the receiving antenna
(rectenna) is metal, which tends to reflect more sunlight than
the gound over which it is built.  If needed, the rectenna can
be painted white to reflect even more.  The reduced absorbtion of
sunlight is compensated by the increased absorbtion of microwaves.
If you choose your parameters carefully, you can make the total
impact on the Earth's heat balance zero.  Another free variable
you can play with is that if SPS's are in orbit around the Earth,
the ones on the sunward side cast shadows, and the ones on the
opposite side reflect sunlight back to the Earth.  By engineering
and how you aim them, you can adjust the effect on the Earth's
heat balance by some undetermined amount (it will have to wait
until you get a design).

You are correct in the case of a laser SPS that there will be
large amounts of waste heat to deal with, since laser-->electric
conversion efficiencies are no better than 50%, while microwave
--> electric conversion efficiencies are closer to 85%.


>Earth's heat balance. Normal heat input from the Sun for the Earth is
>about 140 TW so the additional 1 TW is less than a 1% change. But due to

The radius of the Earth is 6378000m.  Thus the cross sectional area
is 1.278x10^14 square meters.  The solar constant is 1390 Watts/sqaure
meter, so the total flux impinging on the Earth is 1.776x10^17 Watts.
The albedo of the Earth is 0.36, so 64% of the flux is absorbed, i.e.
1.137x10^17 Watts, or 113,700 TW.

>Now what's happening on the Moon? Gas lasers are very inefficient devices.
>I don't have CO2 numbers at hand, but He-Ne efficiencies are around 0.1%.
>Giving an advanced CO2 laser a 10% efficiency is likely generous. Now to
>convert the IR back to electricity the Earth based receiver is either going
>to be photovoltaic cells, or some thermal system. In either case, efficiency
>is under 30%. That means that 34 TW of electricity has to be input to the laser
Gas lasers are not proposed by power beaming researchers (by the way,
I currently AM a power beaming researcher for NASA.).  At the Laser
Power Beaming Photovoltaics/FEL Interactions workshop, 25 March 1992

The Jet Propulsion Laboratory reported measured actual laser-->PV
conversion efficiencies of 29% for Gallium Arsenide cells.  The
theoretical limit is 57% for GaAs at 800 nm, which is slightly into
the infra-red.

It is proposed to use a free-electron laser for making the beam.  The
FEL in theory is an efficient device.  In practice, large ones are
expected to work in the 5-10% efficiency range.  Personally, I prefer
the microwave SPS to the laser SPS, since the conversion efficiencies
at both ends are much higher.


>>> No we say that we must finally open up the last frontier to development. No
>>> single technology or service from space will justify the expense BUT, taken
>>> together, the development of the resources of the solar system, whether it
>>> be solar energy from space, materials from the Moon, asteroids, and other
>>> planets will raise the planetary standard of living to a height that will
>>> make today look like the abode of dirt dwellers.

>So we lose money on every sale, but we make it up in volume?

I take issue with both statements above.  The comsat business alone
is sufficient market to stimulate the initial opening of space as a
frontier, if you are smart about serving that market.  Launching
comsats on chemical rockets is not being smart about it, because they
are terribly expensive one-use throw-aways.  Rocket performance has
stagnated in the mid-300 second specific impulse range for earth-to-
orbit for 30 years.  It's no wonder the market has not opened up.

The second comment misses the point - if you have more markets to
spread the development cost of your transportation system over, you
can justify it where a single market would not.

>>>(the point of this thread is to find out), but why should we want to
>>>import bulk material from space to Earth? Few extraterrestrial ores
>>>match the quality of those found on Earth, save for iron-nickel
>>>asteroids, and there's already plenty of steel in landfills. Even if
>>>you could import diamonds from the Moon, gold from the asteroids, or
>>>star sapphires from Mars, could you beat the transportation costs?

Iron-nickel asteroids, being a type of steel (9% Ni, 1% Co), have
a ready market on Earth on the order of $200 billion per year.  The
quality of steel would be higher than that used on Earth today for
most applications.  What is needed is a way of retrieving it for less
than $400/ton.

Diamonds currently go for about $1000 per carat, or $5 M per kg.
Even today the transport cost to and from the Lunar surface is
more like $100,000 per kg, so diamonds would make sense.  Gold
is not known to be present in quantity in asteroids, but platinum
group metals are (in association with the Iron-nickel.)  On Earth
Pt-group metals are rare precisely because they were soluble in the
iron, and sank to the core of the planet when the Fe-Ni core formed.
In asteroidal Fe-Ni, the cores have been exposed by impact, and the
material is accessible.  Now, Pt goes for about $400/oz, or $13,000/kg.
Currently this is about what it costs to launch stuff to Earth orbit,
so a mining return ratio of more than 1 would be required to make
money (return more than one kg of platinum per kg of mining equipment
brought to Earth orbit).  If launch costs were reduced greatly,
then it would be easier to make money this way.

>I am realistic enough to know it won't make a material difference here on
>Earth. Like Columbus' "discovery" of the New World, the riches ultimately
>fall to the inhabitants of the New World, not those left behind in the Old
>World. So it is with space. People living in space will be the primary
>beneficiaries of space activity. Earth can attempt to play Hudson Bay
>Company, but eventually Earth has to manage by itself. I don't have a
>problem with that as a justification for supporting space. "To boldly go..."
>is sufficient reason to support space activities. The human race, wherever
>they may be, will be the beneficiaries of that process, not Earthlings.

As a final comment: the SPS discussion has sidestepped any question
of fusion becoming a power source for the Earth.  By this I mean
plain ordinary fusion rather than He-3 based hype.  I am aware of two
lines of inquiry that may lead to easily produced fusion power
(i.e. Mr. Fusion).  The first is the Plasmak type machine being worked
on by Paul Koloc, wherein the plasma confinenment fields are run
in the plasma itself (rather than in a surrounding machine, such as
the Tokamak design).  The second appraoch is the Electric Fusion
machine being designed by Robert Bussard.  This uses an electric
potential well to cause the protons to collide in the center.  Both
have great potential.  If cheap and easy fusion is available, a lot
of current problems could go away.

Dani

--
Dani Eder/Boeing/Advanced Civil Space/[phone](w)/232-7467(h)/
Rt.1, Box 188-2, Athens AL 35611/Member: Space Studies Institute
Physical Location: 34deg 37' N 86deg 43' W +100m alt.
***THE ABOVE IS NOT THE OPINION OF THE BOEING COMPANY OR ITS MANAGEMENT.***

------------------------------

Date: 19 Aug 92 01:44:00 GMT
From: [e-mail]
Subject: SPS feasibility and other space development
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Frederick A. Ringwald) writes...
>
>Listen, Dennis, a scientist's job is ask questions: and the harder they
>are, and the more skeptical they are, the better they are. That's how
>you get important results!

The job of a scientist is to ask questions, BUT far too many scientist
simply ask questions as a kind of perpetual what if? scenario without rolling
up their sleeves and doing an experiment to check anything out.  Case in
point is Chaos theory.  We now have physical systems to verify a lot of the
theory behind chaos theory. Why do we? Because a EE got a great idea and
hooked up a simple circuit in 30 minutes and with a small power supply and
an oscilliscope proved a great number of the so called scientists who with
their theorys and what ifs wrong.

>I am doing my job. What are you doing?
>

This is my job.  I build experiments to prove or disprove ideas and
theorys.  With the flight of our Get Away Special Experiment on STS 46 I
proved hundreds of aerospace engineers wrong by demonstrating the successful
operation of Winchester disk drives hooked to a MacIntosh personal computer
in the Cargo bay of the Orbiter.  This little feat will help to drive
down the cost of experiment controllers in this application by about a
factor of ten. That is one thing.

Another little thing is that we are the FIRST technology test bed for:

Boeing/Kopin high efficiency (26%) tandem solar cells
Eagle Picher NiMH batteries with twice the energy density of conventional
NiCads
Also we will be the first flight of a super high integration parallel
processing system that has 3 Zoran 32 bit DSP's a Transputer, 4 meg of
ram and four 20 mbit serial ports on a card that measures 53mm X 73mm X 10 mm.

Why are we able to do this? Because too many engineering managers and
scientist are afraid to fly anthing that was not built in 1960 because they
want to cover their ass far more than they want to get a job done right.
Risk takers are an endangered species in America in large part because too
many "experts" are on the sidelines asking questions to infinity and not enough
engineers have the testicles to tell them to shove off.

>Uncritical acceptance of ideas, no matter how appealing they might
>seem, is harmful to any field. Space is no exception. People will hold
>you to promises you make, and will hold it against you if you tell
>them things that aren't right. Undisciplined grand speculation isn't
>even good science fiction. At best, boosterism (good pun intended) is
>misleading; at worst, it makes you look kooky. Believe me, kooky is
>NOT an image you want to project when writing a research proposal,
>especially not when you get to the budget section!

Blind questioning of everything that anyone tries to do is more harmful
than the other extreme that you posit.  It is far better to do something,
make a mistake, and try again than to sit on your part that you are busy
covering and continually ask questions. If you fear to make mistakes
then you never will do anything of note.  The present American cover your
ass and never do anything that might be percieved as a failure is the
primary cause of the decline of our once great nation.

PS to this Dr. Ringwald, I include a lot of folk in the above statment.

As for quasi-religious; why are you so hung up on that phrase? Does it
have some special meaning for you? My religion or lack thereof does not
enter in to this discussion.

?
Everthing that I posted about SPS is right out of Dr Criswell (Director
of the Texas Space Grant Consortium's papers that he has presented at
several conferences.  I also posted relavent conference proceedings such
as the ASCE Space 92 conference June 1,5 1992. Where were you when I did
that?

>If you can't provide me with even approximate literature references,
>better than newspaper articles, especially when I repeatedly request
>them,

Which articles are you talking about? What kind of references do you want.
Heck I can give you a month full if you tell me what the heck you are
talking aobut.

>P.P.S. Your new postings about reviving the Saturn are *much* more like
>it. Not only is this of potential long-term interest, but there's
>nothing like the immediate applicability of the rumble of a rocket
>engine. With all the excitement lately, I'm almost scared to ask
>another question, but ask I will: what are the F1A engines for? Why
>revive the Saturn class? It makes no sense to develop capability for no
>reason; the taxpayers won't like it. So, what are the reasons? More
>interestingly, what are the payloads? SSF parts? Large comsats? Lunar
>or planetary spacecraft?

No if you had looked at my posts you would have seen a progression of
launch vehicles starting with one in the Titan V class and progressing
upward toward and surpassing the Saturn V of the sixties capability.  There
is a demonstrated need for larger lift capability.  I started with the single
engine F1A engined bird as a justification for restarting the line, as was
done for the Delta and Atlas programs at Rockewll after Challenger. The two
engine version would use two F1A's with a Lox/H2 upper stage (as would the
one engine verison) to double the payload to orbit without major retooling
of the manufacturing jig for the tanks and external skins.  This would
put us up in the real Heavy lift league (110,000 to orbit) for only an
incremental cost, in the spirit of Allen Sherzier. Then as the need generated
the opportunity the second phase would be implemented which would build a
new jig for the larger diameter tanks on the first stage & second stage for
a three engine version with 180,000 to orbit. Then the same incremental
philosophy would hold for stretching the tanks and adding engines till the
full up Saturn V configuration could be reached with only incremental costs.

That is the reason that is backed up by the same market dynamics that Allen
pursues.  My only argument with Allen is that the HL Delta and Atlas is
fundamentally limited to his next step.  The path that I propose begins with
Allen's next step and goes upward from there as the need and political
will develops.

Thats all for now folks
Dennis, University of Alabama in Huntsville

------------------------------

Date: 16 Aug 92 10:19:01 GMT
From: Chris Ralph <[e-mail]>
Subject: Star Trek (anti-)realism
Newsgroups: sci.space

DP>From: [e-mail] (David Parkins)
DP>Organization: Cornell Theory Center

DP>In response to the statement that no real navy would let a 35 year captain
DP>a ship. Reference Captain John Paul Jones US or Colonial navy during
DP>the US revolutionary war, I'm pretty shure he was around 35 when he got
DP>his first command.

DP> * Origin: FidoNet/ACSNet Gateway [csource.oz.au] Melbourne, OZ
(3:632/400.0)

John Paul Jones was 21 when he first took command of a vessel.  He was
en route to Scotland as a passenger when both skipper and 1st mate died
of fever.

In 1775 he was commissioned a senior lieutenant in the new Continental
Navy.  In 1776, at the age of 29, he commanded the Providence.  He was also
appointed by Congress to the Ranger in June 1777.  At the age of 40 he was
appointed rear admiral and seconded to the Russian Navy.

Reference Encyclopaedia Brittannica, 15th Ed.

Hope this helps the discussion.  Regards, Chris.
 ~ SLMR 2.0 ~ Backup not found: (A)bort (R)etry (P)anic
 * Origin: Peninsular B.B.S. [phone] (3:635/573)

------------------------------

Date: 17 Aug 92 15:55:43 GMT
From: Dani Eder <[e-mail]>
Subject: Tethers
Newsgroups: sci.space

[e-mail] (Mark Evans) writes:

>[e-mail] writes:
>: Would it be possible to put something in near orbit over Nevada and
>: attach tethers to it so that people could reach the object via
>: elevators?  I know it wouldn't be easy, but is there a way to pull
>: this off?

>read 'The fountains of paradise' bye Clake.

>The only way you can get something to orbit above  point of the earth's
>surface is to have it in geo-sync orbit.
>Thus, the point you have your satellite above must be on the equator.
>(if you want it to be over pointelse where on the globe, then it is
>not in orbit and must run thrusters virtually continuiously to stay in
>position)

I do not believe this is correct.  It is true that the center of
gravity of the 'beanstalk' needs to be in Clarke Orbit so it does
not wobble.  The attachment point on the ground, however, can be
off the equator.  You elevator in this case will form a catenary,
i.e. it will be curved.  This will require more structure than the
simpler vertical case, so it is not usually considered, but it is
not ruled out on physical grounds.

 Dani

--
Dani Eder/Boeing/Advanced Civil Space/[phone](w)/232-7467(h)/
Rt.1, Box 188-2, Athens AL 35611/Member: Space Studies Institute
Physical Location: 34deg 37' N 86deg 43' W +100m alt.
***THE ABOVE IS NOT THE OPINION OF THE BOEING COMPANY OR ITS MANAGEMENT.***

------------------------------

Date: 19 Aug 92 02:46:15 GMT
From: [e-mail]
Subject: Tethers
Newsgroups: sci.space

"I would suggest you look into Lofstrom Loops and other active,
surface based structures. Theoretically you can build a tower 100km
high with this technology.

Should be something on it in the FAQ's. It's been discussed over and
over again all the way back to Space Digest V1 in 80-81."

Could you send me the FAQs?  I couldn't find them.

                                                          Eric Klien

------------------------------

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Path: crabapple.srv.cs.cmu.edu!cantaloupe.srv.cs.cmu.edu!rochester!cornell!calvin.ee.cornell.edu!johnc
From: John Cho <[e-mail]>
Subject: Satellite orbit info needed
Organization: Cornell Space Plasma Physics
Date: Tue, 18 Aug 92 18:32:33 GMT
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Does anyone know where I could obtain information regarding the orbits of
satellites?  The objective is to try to calibrate an atmospheric radar
using a satellite with a known cross section.  In order to do this, I need
to know which satellite passed directly overhead a certain point on the
ground at a given time and altitude.  I suppose NORAD would have this
kind of data.  But does someone know of a contact there?

If you have any clues, please reply to [e-mail] since
I do not subscribe to this newsgroup.

________
John Cho

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End of Space Digest Volume 15 : Issue 125
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