Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v11_0/v11_087.txt

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Subject: SPACE Digest V11 #87

SPACE Digest                                      Volume 11 : Issue 87

Today's Topics:
                LLNL & Kevlar
          LDEF - Protection from atmosphere?
            Extrasolar pictures of the sun
      Re: Fun Space Facts #1: Launcher Development Costs (long)
          navigation at relativistic speeds
      Re: Fun Space Fact #1: Launcher Development Costs
                 Launch costs
----------------------------------------------------------------------

Date: Tue, 27 Feb 90 14:19 CST
From: [e-mail]
Subject: LLNL & Kevlar

Does anybody out there know where the LLNL folks published their kevlar
space station ideas?
I want to build one...

George K. Ott

University of WI - Madison High Energy Physics Dept.
Internet [e-mail]
Bitnet   gott@wishep
USPS     1150 University Ave. Madison, WI 53706

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

Date:     Tue, 27 Feb 90 9:11:48 CST
From: Will Martin <[e-mail]>
Subject:  LDEF - Protection from atmosphere?

One thing about the LDEF retrieval has been confusing me, and this confusion
was increased by recent postings, such as the reference to one LDEF
experimenter taking his subassembly back with him to his lab in his
station wagon. I would have thought that the LDEF is being so contaminated
by exposure to Earth's atmosphere that a lot of the information that could
have been obtained from it has been lost. I realize that it is a *big*
device, but I would have thought that some method of keeping it in vacuum
or at least in an inert atmosphere would have been necessary.

After all, were not the moon rocks kept isolated from exposure to atmosphere
after descent to Earth and during preliminary testing phases, and the ones
being held in reserve remain in a sealed environment?  I would think the LDEF
segments would have to be kept isolated in the same way, at least until the
necessary tests had been run or readings made on them.  Afterwards, of course,
especially for the samples designed to just test structural integrity or
materials strength, they could be exposed to sea-level atmosphere.  But the
portions designed to measure or accumulate particles from LEO or determine
radiation effects in space would be ruined by being exposed to the air,
wouldn't they?

Or were there enough instruments and time during the post-retrieval phase
of the shuttle flight to perform these tests and experiments and take
the necessary readings while still in orbit, when the LDEF was still in
space even though drawn into the payload bay? If so, I certainly didn't
see anything about this. All I recall were superficial visual inspections
by the crew, and remarks about this or that surface looking good or bad.

By the way, during the retrieval, at least several of the thin-film panels
were fluttering, as if in a breeze. What was causing that? Thruster exhaust
from the shuttle? If so, didn't THAT contaminate and ruin some of the test
panels?

Can anyone point me to a source for general information on this subject?
Something more comprehensive than individual-experiment papers or descriptions,
but with a level of detail that would answer this kind of question on the LDEF?

Thanks!

Regards, Will
[e-mail] OR [e-mail]

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

Date: 26 Feb 90 18:30:18 GMT
From: nih-csl!csl-sun3.dcrt.nih.gov![e-mail]  (Sullivan)
Subject: Extrasolar pictures of the sun


    Now that we have four picture taking spacecraft at the fringes
    of the solar system, I was wondering if there are pictures of
    the sun, against a field of stars.  I'd love to get a copy
    even if it had to be enhanced.  A picture of our sun, sitting
    as a bright star amongst millions of others would go right
    over the mantel!  Anyone know if such photos exist and where I
    could get one?  I was at JPL a few weeks ago and didn't see
    any in the gift shop.

                    Jim Sullivan
                    [e-mail]

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

Date: Mon, 26 Feb 90 15:21:49 CST
From: [e-mail]
Subject: Re: Fun Space Facts #1: Launcher Development Costs (long)

>> "bfmny0![e-mail]  (Tom Neff)"

>> In the vast article <[e-mail]> [e-mail]

Just mark me down as an opponent of the trendy cliche and bumper
sticker exposition that all too often substitutes for real thinking
in this country, Tom.  Sorry to have exceeded your attention span
with my "vast article".

>> >And the Shuttle, despite all its flaws, has overall been about as
>> >reliable a system as any other experimental vehicle.

>> This is damning with faint praise, since while the Shuttle may possess
>> the soul of an experimental vehicle (and the problems of one), it is
>> being used (and, indeed, billed) as an *operational* vehicle.

Yes, it *is* damning with faint praise.  But then, wherever did you
get the idea that my intent was to praise the Shuttle *or* the
marketeering mentality that has left you with the disappointing
impression that the Shuttle is supposed to be a mundane operational
vehicle.

There are no "operational" space vehicles, in that sense, with the
possible exception of the Proton.  *Any* vehicle of which there are
only 4 copies and which has only flown a few handfulls of times is
experimental by definition.  So that seems to say that almost *all*
'operational' use of space is really experimental.

Big surprise.

>> >the political games of Mr. Bowery and simply declare that a system
>> >which hasn't flown will be "likely to work very well", or we can
>> >play the emotionalist games of Mr. Neff and talk about the Shuttle
>> >that catastrophically failed
>>
>> Name calling is an embarrassment to the readership.  The best and most
>> experienced posters know to address the issue, not the poster.  Enough
>> said.

Yes, it is.  But then, it's rather difficult to respond to certain
classes of postings in any way which *doesn't* reflect at least
somewhat on the poster, since it's the tone and style of those
postings which are the 'message' (such as it is).

Such is the case with your "ironic assent", and I'm afraid that in
my opinion the greater share of any blame which attaches due to the
lowering of tone of the general discussion lies with the original
poster.

So if you, as I, don't particularly care for such personal remarks,
perhaps you would be better served to emulate those "best and most
experienced posters" you mention and address the issues rather than
indulging in low debating tactics.

And I trust that that *is* enough said.

>> one could hardly point to Challenger as evidence that the Shuttle
>> DOES work well.

And one can hardly point to a something less than 4% failure rate as
proof that it doesn't.

>> Keep in mind that STS is supposed to be a SYSTEM, i.e.  a working
>> program, not just a vehicle.  The failure of that SYSTEM to work
>> properly is what brought on Challenger.

I think you're a bit all-encompassing with your definition of
'system' when you refer to the STS.  The *failure* was primarily in
the bureaucratic administrative system within NASA rather than in the
STS.  One generally doesn't include that sort of thing in the
definition of 'system' when speaking of something like STS, any more
than one would include the folks in the cafeteria who make lunch for
all those workers.

>> Of what use is a vehicle that won't launch in the cold when it's been
>> tasked to launch all the time, anytime, as a reliable space 'truck'?

Other than the phrase "space truck", and the NASA phrase of "routine
access to space", I don't recall ever seeing anything that stated
that the Shuttle was "tasked to launch all the time, anytime".

In fact, such a belief is rather silly on its face, since one would
hardly expect to put one up in the middle of a hurricane, nor would
one expect to launch under any of several other sets of extreme
environmental conditions that exceed the design requirements of the
vehicle.

Things like excessive temperatures are *known* to be bad for
rockets.  That's why we have thermometers in missile magazines and a
requirement that the temperatures therein be monitored.

As for the usefulness of a vehicle that won't launch in the cold,
just where do you think KSC is?  How many days would they have been
unable to launch out of an average year if the restriction of not
launching below 50 or 55 degrees had been put in place?

As far as I'm concerned, the man who had the 'go' decision is where
the buck stops, and there should have been some criminal negligence
charges filed.  But that says nothing at all about the reliability,
one way or the other, of the Shuttle system.

>> And are the ring-burning SRB's supposed to be considered as having
>> 'worked well' even though the few engineers who knew the whole
>> disquieting truth beforehand cringed inwardly at every launch?

In point of fact, strange as it sounds, the answer to this is yes.
Other than the fact that it's inherently bad engineering to put
people on something that you can't get them off of if something goes
sour, the facts say that those SRB's were indeed relatively reliable.

Of course, all bets are indeed off once someone makes the decision
to exceed design and shoot them off outside their environmental
envelope.


==============================================================================
| Fred McCall  ([e-mail]) | My boss doesn't agree with anything  |
| Military Computer Systems           | I say, so I don't think the company  |
| Defense Systems & Electronics Group | does, either.  That must mean I'm    |
| Texas Instruments, Inc.             | stuck with any opinions stated here. |
==============================================================================

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

Date: Tue, 27 Feb 90 23:01:24 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: navigation at relativistic speeds


>From: <[e-mail]>
>Subject:  Approaching light speed in space travel

>>There is yet another major problem ... with the relativistic time dialation,
>>  piloting a vessel safely at such speeds will become quite a pain.  Not only
>>  will the computer become enormously slow at reacting to potential dangers,
>>  but these objects will be very difficult to detect due to high speed, large
>>  blueshift, and relativistic "tunnel vision".
>        It is hard to see what you mean here.  The computer will not
>slow down at all - at least not for those on the ship.  However, one
>does have to worry about light travel time.  For example, consider a
>ship travelling at 0.5c.  It sends out a radar signal that reflects off
>of an asteroid that is 1 ly in front of the ship the instant the signal
>is sent out.  By the time that the ship receives the reflection, 2/3 of
>a ly will have been travelled already by the ship.  There is some time
>to react, but not overly much.  At higher speeds, the available reaction
>time goes down even more.

Obstacles *will* be encountered much more often (ship time) at higher speeds,
and the time to detect them by radar will be reduced. However, we are nowhere
near any fundamental limit for computational speed, so computers of the future
may be fast enough for navigation at considerable speed.

Question: Suppose a large space ship at a great distance is moving toward
the Earth at 99% of c. On its way, it nicks the edge of Pluto (bright flash
of light.) The flash of light takes several hours to reach Earth, and the
ship arrives only a few minutes later (Earth time). Visually, how would
an observer on Earth account for the apparent motion of the ship at many
times the speed of light? A Doppler radar would presumably show the true
velocity.

>Makes one wonder how a starship can effectively maneuver at
>warp speeds. :-)
>...Of course, E.E. Smith just uses the interstellar
>gas/dust as a friction source to keep his inertialess ships from hitting
>infinite speeds.  :-)

Well, Smith had ultrawaves and spy rays that propagated at many times the
speed of light. In any event, if the inertialess ship hit an asteroid, the
ship would just stick there until the crew thought to change the course. :-)

>|  Arnold Gill                          |
>|  Queen's University at Kingston       |
>|  BITNET:    gill@qucdnast             |
>|  INTERNET:  [e-mail]  |
                              John Roberts
                              [e-mail]

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

Date: Mon, 26 Feb 90 10:20:09 PST
From: [e-mail] (Peter Scott)
Subject: Re: Fun Space Fact #1: Launcher Development Costs

mcsun!ukc!icdoc!syma![e-mail]  (Nick Watkins) writes:

>On a related point, Feynman's memoirs suggest that Donald Kutyna (USAF
>general) put him onto the trail of the solid booster problem. Is there a
>feeling that the USAF knew, but just needed the commision to confirm it?

Well, Kutyna may have known as well, but in a talk which I attended at
Caltech (which was later worked into an article, "Mr. Feynman Goes to
Washington"), Feynman said that the day after he decided to join the
commission, he went to JPL for an intensive meeting, and almost the first
thing in the notes he took was the suggestion that the accident was due
to O-ring failure in the SRB.  That page of his notes was reproduced in
the article, wish I could remember where the darn thing was published.

As I recall, there never was much doubt (we were all pretty sure here from
the day after the accident) as to the cause, but commissions have to
consider *every* possible cause.  As it happened, they wound up identifying
a number of other critical areas.

Peter Scott ([e-mail])

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

Date: Tue, 27 Feb 90 22:34:01 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Launch costs


>From: samsung!umich!umeecs!itivax!vax3![e-mail]  (Allen W. Sherzer)
>Subject: Re: Fun Space Fact #1: Launcher Development Costs

>Which it doesn't. It is by far the high cost suplier of launch services.
>It requires too much processing, too many people to make it ever work
>in a cost effective manner. Two pads and 10 launches a year aren't enough
>to bring costs down.

>At the moment, that's about all which is needed. However, as AMROC
>gets going, markets will build. At AMROC prices, every grad student
>in the country will be able to put up a payload for their thesis.

>| Allen W. Sherzer     | Cthulhu for President -                           |
>|  [e-mail]         | If you're tired of choosing the LESSER of 2 evils |

Remember that AMROC launches are cheaper *per launch*, which is achieved
partly by having a small payload. I believe AMROC launches are still more
expensive per pound of payload than shuttle launches. This may change in
the future.

(You must know of some pretty rich universities. :-)
                     John Roberts
                     [e-mail]

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

End of SPACE Digest V11 #87
*******************