Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_5/V15NO527.TXT

Internet Message Format | 1993-07-13 | 35KB

Date: Thu, 10 Dec 92 05:04:06
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #527
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 10 Dec 92       Volume 15 : Issue 527

Today's Topics:
                             anniversary
                        Another Orbit Question
                         Earth Movie (2 msgs)
            Limbaugh Found Not Guilty (was: ...DoD hoax!)
                             Lunar flight
                       NASA TOWN MEETING NOTES
                           Orbit Question?
                             Pop in space
         Rush Limbaugh says problems with HST are a DoD hoax!
        Soaring like and Eagle (was Re: Range Safety and DC-X)
                   stationary orbits over the poles
                 STS-48 and "SDI": Oberg vs. Hoagland
           Terminal Velocity of DCX? (was Re: Shuttle ...)
                             Voyager Icon
         Weekly reminder for Frequently Asked Questions list
                   what the little bird told Henry

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
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    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 8 Dec 92 18:40:54 GMT
From: Bruce Watson <[e-mail]>
Subject: anniversary
Newsgroups: sci.space

In article <[e-mail]| [e-mail] writes:
|In article <[e-mail]| [e-mail] (Henry Spencer)
|writes:
|| Lest we forget...  Twenty years ago today -- to be precise, at 0033 EST --
|| the last ship left for the Moon.
|| --
|| "God willing... we shall return."       | Henry Spencer @ U of Toronto >
|-Gene Cernan, the Moon, Dec 1972      |  [e-mail]  utzoo!henry
|
|... And to think that some of us were only months old when that happened.  And
|we will be very lucky if we see it happen again before we reach our forties.
                                                                     ^^^^^^^

Optimism is alive and well on the Net!

--
Bruce Watson (wats@scicom) Bulletin 629-49 Item 6700 Extract 75,131

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

Date: 8 Dec 92 23:30:52
From: Craig Powderkeg DeForest <[e-mail]>
Subject: Another Orbit Question
Newsgroups: sci.space

In article <biff> [e-mail] writes:
   In article <baz>, [e-mail] (me!) writes:
   >In article <bar> [e-mail] (Gary Coffman) writes:
   >   In article <foo> [e-mail] writes:
   >   >... Is it possible to keep a body at ...
   >   >the same point say about 20000 or so miles above [a pole] of the earth?
   >   [no.]
   >At an altitude of 20,000 miles above the surface, you'd only weigh about
   >1/25 of your surface weight due to the r-squared falloff in the g field.
   >But [still no.]

   I can see how a liquid fueled body could not remain in a stationary polar
   position for very long, but what about if instead of liquid fueled thrusters
   the body was equipped with ion thrusters and a solar array to power them.
   The solar array would be positioned so that it faced the sun at all times.
   Any thoughts?

The problem is that you still need to throw away reaction mass.  A
rocket engine's propellant efficiency is measured in a weird unit
called `specific impulse', measured in seconds.  The specific impulse
of an engine type is essentially the length of time an arbitrarily
large craft (ie mass of propellant >> mass of craft) can support its full
fueled weight in a 1g field, using that type of engine. [note that the
actual maximum amount of hovering time would be longer, as the craft gets
lighter when it ejects propellant, so there's less to support as time
goes on]

The more kinetic energy you shove into the propellant on the way out the
nozzle, the more momentum you're also sticking into it.  This means that,
with more energy per unit propellant, you can hover longer, because you
don't need to use as much of it, to dump the same amount of momentum.

Chemical rockets, which use the propellant as fuel, are limited by the
amount of energy you can stuff into a chemical bond.  The theoretical
maximum energy release per molecule of fuel/propellant is for [someone
correct me if I botch it] a hydrogen-fluorine reaction, and it yields
a specific impulse on the order of a few hundred seconds (maybe 350?).

Nuclear engines (which use a nuclear reactor to heat the propellant)
can do much better, since there's roughly a million times more
available energy per atom of nuclear fuel, than per atom of chemical
fuel.  Existing designs (NERVA) get between 400s and 600s, if I recall
right.

Ion engines can do better, because they can use an external or
non-chemical energy source.  (There *is* a problem with calculating
Isp for very high-impulse solar ion engines, because you have to
account for the mass of the solar panels, which is more or less linear
in the amount of thrust you need...)  I don't remember figures for
current ion engines offhand, but we can guess that they're between
1,000 and 10,000 seconds.  Another serious problem is that this
efficiency comes at a very low thrust -- but, for the sake of
argument, let's assume a high-thrust, lightweight ion engine can be
made, with comparable Isp.  Assuming the payload mass is roughly the
same as the fuel mass, we can estimate the maximum hover time as
roughly twice the Isp, adjusted for local gravity.  We find that the
maximum hover time is roughly 50,000 to 500,000 seconds -- from about
12 hours to five days.

That's a long time, but it's just not long enough to be worthwhile;
you'd need to be supporting the payload for a minimum of months,
preferably years.

[Note that, in principle, you could do it with a Lofstrom loop or
similar dynamic structure -- in effect, recycling the propellant.  In
a Lofstrom loop, you have a *really* *long* bicycle chain.  You throw
links up, *really* *fast*, from a ground station.  They fly up to the
height of the payload, and would go higher, except that they hit the
bottom of the payload and are deflected down, depositing their
momentum in it.  Then they fall all the way to the ground station,
where they are thrown up again.  Because they're a continuous chain,
they go right down to the ground station.  As long as the ground
station keeps throwing 'em back up, the whole thing works.]
--
DON'T DRINK SOAP! DILUTE DILUTE! OK!

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

Date: 8 Dec 92 21:05:36 GMT
From: Curtis Roelle <roelle@uars_mag.jhuapl.edu>
Subject: Earth Movie
Newsgroups: alt.sci.planetary,sci.space

In article <[e-mail]>, [e-mail] (Thomas E. Smith [LORAL]) writes...

>I have another question that maybe Ron Baalke can answer. Is Galileo going to
>take any footage of the lunar eclipse tomorrow? I think that would be an awesome
>short movie, and a once in a lifetime chance.

What would be the point?  The best seats for that are right here on earth,
anywhere on the hemisphere from which the eclipse is visible -- no need
for a billion-dollar space ship or awful false-colored imagery (but
please don't tell congress all it takes is a $30 pair of binoculars 8-).

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

Date: 9 Dec 92 14:13:08 GMT
From: David Toland <[e-mail]>
Subject: Earth Movie
Newsgroups: alt.sci.planetary,sci.space

In article <[e-mail]>, [e-mail]
 (Thomas E. Smith [LORAL]) writes...
>I have another question that maybe Ron Baalke can answer. Is Galileo going to
>take any footage of the lunar eclipse tomorrow? I think that would be an awesome
>short movie, and a once in a lifetime chance.

Too bad it's not a solar eclipse.  Footage of the moon's shadow crossing
the earth's surface would really be striking!

--
--------------------------------------------------------------------------
All opinions are MINE MINE MINE, and not necessarily anyone else's.
[e-mail]   |  "Laddie, you'll be needin' something to wash
                           |  that doon with."

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

Date: 8 Dec 92 18:01:32 GMT
From: Curtis Roelle <roelle@uars_mag.jhuapl.edu>
Subject: Limbaugh Found Not Guilty (was: ...DoD hoax!)
Newsgroups: sci.space

[e-mail] (Robert Dyess) writes:

>>>[e-mail] (Ryan Korniloff) writes:
>>>
>>> The popular American radio personality Rush Limbaugh stated today that
>>>the problems with HSTs mirror are a Department of Defense hoax. He
>>>says that the DoD took over control of the HST program so they could study
>>>a strange radio source that could possibly be another civilization's radio
>>> emmisions. And that the DoD cooked up the story of the faulted mirror to
>>> cover up there actions.
>>> Rush has over 13 million listeners and has may connections into the
>>>goings ons of many behind-the-scenes happenings. I don't think that he
>>>would make such a statment without a reason to believe it is true.

>>     If anybody would have listened clostly to what he said, they wouldn't
>>make statements like this.  He said specifically that this was a rumor that
>>was going around (indeed, I heard it here on the net several days before he
>>said it) and, although he didn't like to report rumors, he thought this one
>>was funny enough to talk about.  ONLY AFTER SAYING ALL THIS did he "report"
>>the rumor.
>>
>>     He never said that he thought it was true, nor did he say
>>that he had any sort of (whisper here) inside story.  Keep in mind that
>>the man considers himself a humorist, albeit a conservative one.

>Thanks for clearing this one up. I hadn't heard the radio show, but
>Ryan's message sounded out of character for Rush Limbaugh.

>The interesting phenomenon has been the way in which so many intelligent
>people can be brought to a boil over a message posted by one person who
>made an error. I've been reading this Newsgroup daily and as far as I can
>tell, all of the heated discussion about how stupid Rush is can be traced
>back to Ryan's message quoted above. Incredible isn't it. :-)

Just think how often the press takes a snippet quote from a scientific
figure and starts a feeding frenzy (When is it that S-T will extinct
earth?).  How is this situation different?  Isn't this just the same
outrageous occurrance in reverse?  Limbaugh, a figure from the press
says something and someone from the usenet hears a segment while
listening to his car radio during the lunch hour.  Next it gets posted
out of context to sci.space starting a rabid cascade by people who
even admit having never heard the program!  Using one rumor used to
start another rumor.  How embarrassing!

Curt Roelle

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

Date: 9 Dec 1992 11:10:42 GMT
From: Jeffrey Alan Foust <[e-mail]>
Subject: Lunar flight
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>Inquiring minds want to know:
>A Soyuz capsule costs about $7 million, and has a mass of 7 tons.
>The new Proton KM launcher (due in 1995) will cost about $30 million,
>and be able to  send 7.5 tons in a lunar trajectory.
>
>Why isn't there talk of a circumlunar flight, paid for by the USA, and crewed
>with US astronauts? We could send US astronauts around the poles of the moon
>during the Clinton Administrations' first term......
>
I've been tossing this concept through my mind the last few days as I slogged
through finals, and came up with this idea: instead of having the US or some
other government fund a circumlunar mission as described above, have a
coalition of corporations and/or foundations provide the funding.  At these
costs (or even costs a few times higher) it seems to be in the range of
corporations and well-endowed foundations to foot the bill for a mission.

    One scenario that comes to mind would be to create a non-profit
corporation to oversee the creation and execution of such a mission (lining up
the Russian Proton and Soyuz capsules, finding the funding in the US and
elsewhere, running a full-tilt PR program to get people excited about the
mission, etc.).  Crew selection would probably also be handled by this
organization, although this might be trickier (who decides who is qualified for
such a mission?), although at least broad decisions on the crew makeup would
be possible (i.e., is the crew international or all from one nation).

    The amount of science you could do on a such a mission is a subject
for debate, but the real goal for such a mission would be to get people,
both the general public and ranking individuals in governments and
corporations, energized to work on a permanent return to the moon.  Such a
flight might be basically a publicity stunt, but it may very well be what's
needed to get people really thinking about and committed to a full scale
return to the moon.

--
Jeff Foust                        Senior, Geophysics/Planetary Science, Caltech
[e-mail]                       [e-mail]
        Tom Seaver: "Hey, Yogi, what time is it?"
        Yogi Berra: "You mean now?"

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

Date: Wed, 09 Dec 92 15:52:04 PST
From: Richard Buenneke <[e-mail]>
Subject: NASA TOWN MEETING NOTES

The following is a write-up of Goldin's presentation at the Dec. 3  NASA
Town Meeting in L.A. I'd be interested in reports on subsequent meetings. I
think one was scheduled for Seattle this week or next week.

- ---------------------------------------
GOLDIN CALLS FOR CULTURAL CHANGES AT NASA

        CARSON -- The entire civil space program must undergo a major
cultural change to become more than a "white collar jobs program," says
NASA Administrator Daniel Goldin.

        "It's going to take three to five years to change a culture,"
Goldin told a NASA town meeting.

        Goldin said the agency's work on cutting edge technology will grow
in an era of defense cutbacks. "[In many areas], the last remaining hope
to maintain some capacity of the aerospace industry is our civil space
program."

        With the end of the Cold War, NASA must move beyond a culture
based on "big science" projects.  Instead, the space agency needs to find
better ways to transfer technology to industry and to improve U.S. math
and science education.

         The nature of the geo-political changes was evident at the town
meeting.  Before fielding questions, Goldin invited his Russian
counterpart, Yuri Koptev to speak.  The Russian Space Agency director was
amazed at the spectacle of a space official touring the hustings to
justify his budget. "For the past 35 years, we have had other rules in my
country."

        Although the civil space program has enjoyed funding increases in
recent years, Goldin said the days of growing budgets are over. "Right
now, Americans are introspective and uncertain," he told a session at the
Dominguez Hills campus of California State University.

        NASA needs to move away from a culture based on minimizing risks
and avoiding accountability. "You can't paperwork in good engineering."

        Goldin emphasized that the challenge extends beyond the
government.  When a Hughes Aircraft engineer said Goldin's changes were
just what his colleagues had discussed among themselves over coffee,
Goldin retorted that the engineer's attitude was part of the problem.

        "All you folks sit around drinking coffee saying, 'What's going to
happen now?'" Goldin said.  Industry also must overcome the "sickness" of
passivity and encourage initiative. "America is afraid of being bold.
We've replaced risk with paperwork."

        The willingness to accept risk also applies to space scientists.
Noting that only two science payloads are under development, Goldin said
the program was following "Augustine's Law." Devised by Martin Marietta
chairman Norman Augustine, this law notes that increasing system
complexity is matched by smaller total purchases.

        As the space science program converges towards one payload, a
mission becomes the only opportunity for experiments.  As these Big
Science programs become linked to national prestige, the space agency
becomes more conservative in program management.  Although this
conservatism only delays science, Goldin said space scientists react "like
stuck pigs" to proposals for smaller, single sensor payloads.

        The National Aeronautics and Space Administration also plans to
take the first part of its name seriously.  Goldin acknowledged that he
once questioned why the agency was involved in aeronautics research. "I
asked, 'Who is our customer?," he said.  But reviews of the program --
only 17% of the agency's total budget -- convinced him of the need to
continue aircraft research. "The aeronautics industry is hurting
powerfully bad."

        To make NASA's dollars go farther, Goldin said the space agency
must do more to exploit cutting edge technology. "If NASA works on
10-year-old technology, it becomes a jobs program."

        Whether Goldin will be able to see these changes through remains
an open question.  Although he's a registered Democrat, the former TRW
executive is a Republican appointee.

        For now, President-elect Bill Clinton and Vice President-elect Al
Gore Jr. are saying little about their plans for space.  The leader of
space transition issues, former astronaut Sally Ride, had little time for
the Bush administration's space agenda.  While Ride isn't commenting on
her work, other Clinton-Gore space advisers support Goldin's efforts to
reform NASA.

        The strength of Goldin's commitment to reform was visible at the
town meeting.  The session was the fourth in a series of six meetings held
around the country.

        The town meetings are part of Goldin's effort to reach beyond
NASA's iron triangle of Congress, field centers and space contractors. "We
picked places to go where NASA was not," he said.  This outreach will help
NASA diversify its technical work force beyond its traditional base of
white, male engineers.

------- End of Forwarded Message

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

Date: 8 Dec 92 18:26:37 GMT
From: Bruce Watson <[e-mail]>
Subject: Orbit Question?
Newsgroups: sci.space

In article <[e-mail]| [e-mail] writes:
|Your polar geosyncronous satellite takes out one equatorial geosynchronous
|satellite every 24 hours as it passes over the equator at 24,000 miles
|altitude.....
|
Just a reminder about how large a volume we're talking about. Why do
you think they call it space?

There are, what?, ~200 satellites, working and non-functional, in the
Clarke Belt? A circle with radius 42,000 km is 265,000 km long, which
means the mean distance between satellites is 1300 km.

The volume between 200 km and 42,000 km is 5 x 10^14 km^3. As of Oct
1, 1992 there are 7074 objects, payload and debris in orbit, so that
on average there is one object for every 7 x 10^10 km^3 of space.


--
Bruce Watson (wats@scicom) Bulletin 629-49 Item 6700 Extract 75,131

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

Date: 8 Dec 92 10:48:51 GMT
From: Charles Stephens <[e-mail]>
Subject: Pop in space
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Peter J. Scott) writes:
>In article <[e-mail]>, [e-mail] (Tor Houghton) writes:
>> I don't know - didn't Coke or Pepsi device special cans for the Space
>> Shuttle crew? :)

>Yes, and you can see the Coke device in the Coca-Cola museum in
>Atlanta, GA.  I know it's a tad far for you to go, but some of
>our other readers might be nearby.


    I've seen it, really high-tech.  I looks like one of those old portable PC's.
It has a screen and some other really weird hardware.  Now I have faith that my tax
dollars are really going to a good cause.


--
Charles Stephens
[e-mail]

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

From: Curtis Roelle <roelle@uars_mag.jhuapl.edu>
Subject: Rush Limbaugh says problems with HST are a DoD hoax!
Newsgroups: sci.space

Organization: Johns Hopkins University
References: <[e-mail]>
Date:  8 Dec 92 17:28:33 GMT
Lines: 18
Source-Info:  Sender is really [e-mail]
Source-Info:  Sender is really [e-mail]

[e-mail] (Robert Dyess) writes:

>The interesting phenomenon has been the way in which so many intelligent
>people can be brought to a boil over a message posted by one person who
>made an error. I've been reading this Newsgroup daily and as far as I can
>tell, all of the heated discussion about how stupid Rush is can be traced
>back to Ryan's message quoted above. Incredible isn't it. :-)

Just think how often the press takes a snippet quote from a scientific
figure and starts a feeding frenzy (When is it that S-T will extinct
earth?).  How is this situation different?  Isn't this just the same
outrageous occurrance in reverse?  Limbaugh, a figure from the press
says something and someone from sci.space hears a few words listening
to his car radio during his lunch hour.  Next it gets posted out of
context starting a rabid cascade by people who admit having never
heard the program!  How embarassing.

Curt Roelle

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

Date: 9 Dec 92 13:31:40 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Soaring like and Eagle (was Re: Range Safety and DC-X)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bill Higgins-- Beam Jockey) writes:
>In article <[e-mail]>, [e-mail] (Gary Coffman) writes:
>> Let's hope it flies like a Pheonix, rising gracefully out of it's own flames.
>> It certainly can't soar like an Eagle. :-)
>
>Oh, I don't know, Gary.  The thrust-to-weight ratio on DC-X probably
>compares favorably with an F-15 Eagle...

Yeah, but an Eagle has "wangs" (such as they are). :-)

Gary

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

Date: Wed, 09 Dec 92 18:01:04 EST
From: Tom <[e-mail]>
Subject: stationary orbits over the poles

[e-mail] writes:
[what about holding them there with ion thrusters powered by sunlight?]

Josh sez:
>Ion thrusters still require fuel their just much more efficient than chemical
>rockets.  The only system that can stay stationary over long terms is a solar
>sail.  Nature may permit some neat tricks with magnetodynamic tethers but I
>can't think of any that would work in this situation.

For the poles, forget about tethers.  What you want is some kind of giant
charged ring that you use sunlight to spin, creating a force from the
magnetic field of the Earth that balances gravity.  It can also be solar
powered.  "Only one, really BIG moving part!"  It has incredible stability
and power requirements, but at least you lose the need for reaction mass,
which is the big problem with the other kind of stationary satellite.

Actually, you can cut power requirments by using a giant wire, and just
pump a bazillion amps through it (I haven't worked out the math :-)
The force/mass-unit is the same, but the mass would be a lot less.

You could have two wires, with currrent running in opposite directions.
The first would be your "power ring", while the second would be "Vertical
postioning".  Keeping it on the axis would be a trick, though, since the
shape of the Earth's field would create a positive instability.

-Tommy Mac
-----------------------------============================================
Tom McWilliams              | What a tangled web we weave, when at   ". |
[e-mail]      |              ,  .first we .practice .*'  .|
[phone] -or- 353-2986|            '. '  . . to decieve    ,      |
a scrub Astronomy undergrad | After that, the  ,          +             |
at Michigan State University| improvement is tremendous! '.  , .'       |
------------------------------===========================================

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

Date: Wed, 9 Dec 92 12:18:11 GMT
From: Dean Adams <[e-mail]>
Subject: STS-48 and "SDI": Oberg vs. Hoagland
Newsgroups: sci.skeptic,sci.astro,sci.space,alt.alien.visitors

[e-mail] (Steve Gamble x3293) writes:
 >Does the fact that Robert Sheaffer is a member of CSICOP and James Oberg
 >is a friend of his and they both know Phil Klass mean that their solution
 >to the video is incorrect?

Some do think that way.  Personally, I have to think that anyone who could
call what is obviously TINY ice particles a "UFO" is sadly about absolute
epitome of a completely ignorant "ufo-nut".  The same people also called
the insulation/debris ejected during the last TDRS deploy a "UFO" as well,
and once again the Shuttle was being "attacked by aliens"...<ugh>

I watch (and tape) countless hours of live coverage from every
Shuttle mission, and when people who would not know a water dump from
a water closet start seeing "aliens" everywhere it just makes me sick.

 >I am happy that Oberg's explanation fits with what is shown on the video.
 >The UFOs and the missile which shoots them down

Oh, brother!  With examples like this how are people supposed to
ever take *ANY* "sightings" reports at ALL seriously??

 >are nothing other than small debris close to the camera, probably ice
 >crystals. The change in motion is caused by the firing of a thruster
 >just out of camera shot.

EXACTLY, and to anyone at all familar with space or the Space Shuttle,
that is an almost immediate thing to see.  It's very plain.  It took
really wild imagination to dream up that "missile" (??) nonsense.

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

Date: 9 Dec 92 13:30:30 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Terminal Velocity of DCX? (was Re: Shuttle ...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (_Floor_) writes:
>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>] always mean higher reliability. A truck engine is usually good for
>] a million miles while a formula one engine may last 100. They both
>] put out roughly the same amount of power, but one masses a lot more
>] than the other.
>]
>
>What?!? What kind of a comparison is that? I don't really think this is
>an appropriate example of your point. A formula one engine is tortured
>by blipping rapidly back and forth between 3,000 and 13,000 rpm continually
>for two hours. It isn't the size that's the factor, is the use! I think
>a tree trunk versus a twig is a better example of your scale/reliability
>dependence point.

Actually, both engines have narrow torque bands. Thanks to multi-speed
gearboxes, both engines are kept near their torque peak at all times
in service. The RPM levels are grossly different, 1800 for the truck
and 12,500 for the F1 engine. That's because the smaller engine has
to wind tighter to make the same power. IE it's stressed harder because
it has to be small to maintain an acceptable mass ratio in a race car.

Power to weight ratios are critical to good race car performance as they
are to good SSTO performance, and for the same reason. Light high output
engines are less reliable than heavy high output engines. The margins
are thiner in the racecar than the truck. The truck can afford to throw
away a couple of thousand pounds of payload for a more reliable engine,
the race car cannot.

An SSTO has to haul all of it's engine and structure mass to orbit so
these have to be lighter than a staged rocket that can discard engines
and structure along the way. This is inherent in SSTO design. So a
staged rocket can be made to have lower stresses than a SSTO for the
same payload.

Shuttle is only high stress because it emphasizes large payload in
what is essentially a 1.5 stage design. Thus the SSME have to push
much harder than they otherwise would have to. With a 2 or 2.5 stage
design, the engines could operate at lower stress levels since they
would be pushing less dead weight. The wings impose a mass penalty,
but that's offset by not having to carry landing fuel and it's tankage
for VTOL operation.

Gary

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

Date: Wed, 9 Dec 92 09:37:00 PST
From: "UTADNX::UTDSSA::GREER"@utspan.span.nasa.gov
Subject: Voyager Icon

In Space Digest V15 #522,
"Matt J. Martin" <[e-mail]> writes:

>  A friend of mine is looking for a printout of the DeVinchi "Man in Motion"
>(or whatever the name of it is) that was printed on the side of the Voyager
>probes (along with the gold record of the sounds of humanity and the other
>memorabilia for any casual passers by to inspect.)  Is this picture
>on ftp somewhere?
>
>  Thanks in advance,
>  ##  //   ## Matt J. Martin, Technosociology and Space Politics ##  //   ##
>  ##   //  ##        Purdue University, West Lafayette, IN       ##   //  ##
>  ##   /   ##           [e-mail]            ##   /   ##

Argh!  Should I fear for our nation's future, or have young folks always
been this ignorant?

Leonardo DA VINCI's famous drawing never appeared on any space probes.
As for finding a "printout" of the plaque that was affixed to the Voyagers,
I'm sure your university has a LIBRARY.

_____________
Dale M. Greer, whose opinions are not to be confused with those of the
Center for Space Sciences, U.T. at Dallas, UTSPAN::UTADNX::UTDSSA::GREER
Remember: Half of all people are of below average intelligence.

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

Date: 9 Dec 92 14:43:13 GMT
From: Jon Leech <[e-mail]>
Subject: Weekly reminder for Frequently Asked Questions list
Newsgroups: sci.space,sci.astro,sci.space.shuttle

    This notice will be posted weekly in sci.space, sci.astro, and
sci.space.shuttle.

    The Frequently Asked Questions (FAQ) list for sci.space and sci.astro is
posted approximately monthly. It also covers many questions that come up on
sci.space.shuttle (for shuttle launch dates, see below).

    The FAQ is posted with a long expiration date, so a copy may be in your
news spool directory (look at old articles in sci.space). If not, here are
two ways to get a copy without waiting for the next posting:

    (1) If your machine is on the Internet, it can be obtained by anonymous
FTP from the SPACE archive at ames.arc.nasa.gov (128.102.18.3) in directory
pub/SPACE/FAQ.

    (2) Otherwise, send email to '[e-mail]'
containing the single line:

help

    The archive server will return directions on how to use it. To get an
index of files in the FAQ directory, send email containing the lines:

send space FAQ/Index
send space FAQ/faq1

    Use these files as a guide to which other files to retrieve to answer
your questions.

    Shuttle launch dates are posted by Ken Hollis periodically in
sci.space.shuttle. A copy of his manifest is now available in the Ames
archive in pub/SPACE/FAQ/manifest and may be requested from the email
archive-server with 'send space FAQ/manifest'. Please get this document
instead of posting requests for information on launches and landings.

    Do not post followups to this article; respond to the author.

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

Date: Wed, 9 Dec 92 12:09:21 -0600
From: [e-mail] (Phil G. Fraering)
Subject: what the little bird told Henry

Begin partial excerpt:
Crucial technology improvements over shuttle.  Engine performance similar
(not quite as good, but close) without staged combustion.  GOX/GH2 reaction
control system, Al-Li LOX tanks, graphite-epoxy LH2 tank, composite primary
structures, ceramic composite thermal protection.  NASP efforts demonstrate
desired structural weight at greater loads and much higher temperatures.
Structural materials already in use -- composites on ATF fighter prototypes,
existing spacecraft (including Hubble); Al-Li on heavy cargo aircraft.
...
DC thermal protection:  carbon/silicon-carbide for nose and other hot
spots (maneuvering flaps), multiwall construction with refractory alloys
for most of fuselage, titanium on the lee side and the base.  All
temperatures below NASP and shuttle, well below material limits.

END OF EXCERPT

Hmm... every report that seems to come out says that the reason it's possible
now is because of the NASP materials research.

BUT: if the main place where NASP materials seem to be being used is
the heat shielding, and its re-entry temperature is lower than the
shuttle's, wouldn't shuttle re-entry materials be just as useful?
Given the design margins below, I doubt that there would be any
weight penalty...

You may want to save this article, I'm about to say something good
about the Shuttle: has anyone out there stopped and thought that the
most criticized part of the shuttle program at its start, the heat
shielding, has been giving little to no trouble, and in retrospect
is behind the SRB's _and_ the SSME's _and_ aerodynamic problems
of an unspecified sort (which is why the landing limit is 40K lbs.)
in being a risk to astronaut's lives and the investment of money
represented by the orbiters...

In short, one good thing the shuttle did, that all reusable spacecraft
following it can benefit from, (except for wierd design specs like
NASP) is its pioneering use of the first reusable heat shield.

Also, I've heard that the major problems in between-flights overhaul
in the shuttle are the SSME's. While this doesn't neccesarily mean
the tiles are good, it implies that they need less overhaul than the
engines and aren't the source of headache and worry everyone said they
would be at the start of the program.

Or were before they found out about the scotch guard.

What sort of overhauls do the tiles get?

\Ample margins to reduce development risk.  Design margins of 15% on dry
/weight, 20% on T/W ratio while still preserving ample operational margin.

Look, Gary! Weight margins!

\"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
/       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

--
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_
PGP key available if and when I ever get around to compiling PGP...

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End of Space Digest Volume 15 : Issue 527
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