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Subject: SPACE Digest V8 #260

SPACE Digest                                      Volume 8 : Issue 260

Today's Topics:
              Re: Bureaucracy vs.  space
              Re: Bureaucracy vs.  space
                space station
         Re: The launch loop author replies:
            Some more launch loop stuff...
----------------------------------------------------------------------

Date: 31 May 88 05:36:38 GMT
From: jumbo![e-mail]  (Jorge Stolfi)
Subject: Re: Bureaucracy vs.  space


>   ME: An airplane takes off, flies and lands in an horizontal
>   position; it doesn't turn somersaults at takeoff the way a
>   shuttle does.
>
>   HENRY: I wasn't aware of the shuttle turning any somersaults!
>   ...  The shuttle does impose a higher fore-and-aft loading than
>   that of an aircraft, but 3 G is hardly bone-breaking.

Aw, c'mon, won't you allow me a little poetic license?

      "The shuttle now consists of the Orbiter and External Tank.
      It continues to gain speed and altitude; 6.5 minutes into the
      flight you are traveling 15 times the speed of sound at an
      altitude of 80 miles (130 kilometers).  Flying a path resembling
      a roller coaster, the shuttle begins a long shallow DIVE to 72
      miles (120 kilomters).  During this maneuver, you experience the
      maximum acceleration of 3g.  Near the end of the dive, 8.5
      minutes after you left the ground, the MAIN ENGINE CUT-OFF
      (MECO) command is given.  The External tank is discarded 20
      seconds later.  The Orbiter maneuvers down and to the left of the
      tank which will splash down in a remote ocean area.
      Remember - throughout the ascent, you travel "upside down" with
      your head toward the ground."

(From The Space Shuttle Operators Manual, quoted a while ago by Dale Amon).


>   ME: The shuttle payload must whithstand going from 1 atm to
>   vacuum during takeoff, and from frying to freezing many times
>   over when in orbit.

>   HENRY: So must any payload flown on an unmanned launcher, and
>   they have rather less stringent requirements imposed on them.

>   PHIL KARN: Henry is right about the max G loads on the shuttle;
>   they're about 3G.  This *is* gentler than many expendables.
>   From the figures I have, I compute a peak acceleration of about
>   4.5G for the Ariane 1, just before 2nd stage cutoff.
>   ...  The kick motor on AMSAT Phase III-A would have produced
>   about 7-8G just before burnout.

Agreed, but Henry's original posting was comparing shuttles with cargo
planes, not with expendables.

>   HENRY: ...  There is a *large* difference between being
>   space-qualified and being shuttle-qualified.  ...  NASA has no
>   interest in achieving a compromise between safety and utility
>   -- the sort of compromise that is necessary for almost any
>   aircraft.  On the contrary, NASA has every reason to shoot for
>   the highest possible level of safety even if it makes the
>   shuttle nearly useless.

Obviously I cannot tell whether NASA's safety regulations for the
shuttle are excessive or not.  My point is that it is perfectly
reasonable for those regulations to be stricter than for expendables,
given that the shuttle is manned, reusable, and more delicate than an
expendable.

As for being manned, it doesn't matter how much risk the astronauts are
willing to take for the glory of NASA.  Every manager or engineer on
the ground still is morally required to worry about their safety ---
much, much more than what he would be expected to worry in the case of
an unmanned vehicle.

As for reusability, in an expendable launch the only party who really
needs to worry about payload safety is the payload owner, since he is
the only one who stands to lose in case of an accident.  Even when for
expendables carrying multiple payloads, safety requirements should in
principle be a matter of negotiation between the two or three customers
involved.  In contrast, with a reusable shuttle the potential loss to
the launching agency is 10-100 times greater than to any customer; so,
it makes perfect sense for the agency to be fussy about safety, even to
the point of losing customers or defaulting on a couple of contracts.

Finally, a shuttle is necessarily more complex than an expendable, and
hence much more delicate --- there are more critical parts that may go
wrong, the design safety margins are smaller, the operating regimes are
more varied, and so on.  Therefore, damage to the vehicle --- say,
during payload deployment --- can have much more serious consequences
for the shuttle than for expendables.

Jorge Stolfi
[e-mail], ...!decwrl!stolfi
---------------------------------------------------------------------------
    Several workmen, it is true, had paid with their lives for the rashness
    inherent in such dangerous projects. But these fatal accidents are
    impossible to prevent, and Americans worry very little about such
    details. They show more concern for humanity in general than for
    individuals in particular. Barbicane, however, profesed contrary
    principles, and tried to carry them out at every opportunity.
      -- Verne, _From the Earth to the Moon_ (1865)
---------------------------------------------------------------------------

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

Date: 31 May 88 07:28:50 GMT
From: agate!brahms![e-mail]  (David desJardins)
Subject: Re: Bureaucracy vs.  space

In article <[e-mail]> [e-mail] (Jorge Stolfi) writes:
>As for being manned, it doesn't matter how much risk the astronauts are
>willing to take for the glory of NASA.  Every manager or engineer on
>the ground still is morally required to worry about their safety ---
>much, much more than what he would be expected to worry in the case of
>an unmanned vehicle.

   We went through this after the Challenger accident, so I won't belabor
the point.  I just want to point out that, as far as I can see, the people
involved should be far more concerned about the $2G+ orbiter than about
seven people.
   You can argue about what value our society puts on human life, but even a
cursory analysis shows that it is several orders of magnitude short of $300M
apiece.

   -- David desJardins

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

Date: 30 May 88 20:35:47 GMT
From: oxy![e-mail]  (Jeffrey Katsumi Hombo)
Subject: space station

Why not just call it orbital station 1

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

Date: 30 May 88 14:46:36 GMT
From: mcvax!unido!ecrcvax![e-mail]  (John Gregor)
Subject: Re: The launch loop author replies:

In article <[e-mail]> [e-mail] (Keith Lofstrom) writes:
>
>As John Gregor (a former student of mine and an unabashed partisan for
>the launch loop) observes,

Actually, I'm an unabashed partisan for getting to space.  The launch loop
is just much more attractive than learning Russian.  Plus I think it's a
good idea.  If it doesn't make it, it should be on technical grounds
(i.e. we have something better), not because it never got a chance.

>it is hard to make a valid criticism of the launch
>loop without reading the technical paper.

I've only received one request for the paper.  Did anybody out there get
copies on their own.  With all the megabytes flitting over usenet, I'm
curious how many people out there actually take the time to look things up.

>However, John has done an
>able job of answering most of the questions (BRAVO, John), saving me some
>effort.

Thank you very much.

>I've got a new version
>of the paper with the equations in it;  I'll be bringing copies to the
>Denver conference.

Any chance of it making it on sci.space or comp.doc?  If not, can I
get a copy.

>6)  "Okay, smarty pants, if it's so simple, why aren't you building one?"
>Well, first, I'm lazy.  I wrote the "Analog" article to drum up interest.
>I mailed out around 200 copies of the paper, and wrote hundreds of personal
>letters.  I was hoping someone would steal the ball and run with it. Nuh-uh.

Ok net.world, we have an idea.  What can we do with it.  Anybody know how to
get research grants?  This is also a very viable means of storing LARGE
quantities of energy (DOE?).  How about Universities that have the people,
resources, and clout to do some initial studies (I'm a relatively soon
to be grad student looking for a project)?  Come on people, brainstorm!
What can WE do?  The next three paragraphs sum up my feelings about space
as well as any other manifesto ever has.

>8)  "Why do this?"  Well, I want to live and work in space.  I don't want to
>make somebody else pay for it, so it must be affordable.  Since nobody else
>is working on $10/lb low-gee launch systems, I guess it's my job.  Sure the
>thing is too damn big.  So are the alternatives, and they yield a much smaller
>payback for the same investment.  If somebody out there has a system that will
>accomplish the same ends with a smaller investment, PLEASE LET ME KNOW!  I'll
>send them money.  I'll build their electronics.  I'll clean their toilets if
>they need it!

Be careful, Jessica Hahn got started by cleaning toilets :-)

>I may not get into space by working on the launch loop, or even helping on
>some yet-to-be-defined better system.  But I sure as hell WON'T get there
>by telling somebody else how hard it is.  If there were easy solutions, we'd
>already be there!

>Forty years from now, when you're in the back of the ambulance racing to the
>hospital, while the EMT is trying to restart your heart, you may have other
>regrets, but mine will probably be "I didn't make it into space".  Most of
>the current crop of space "activists" will be dead before it's affordable to
>go there.  Whose fault is that?
>--
>Keith Lofstrom   ...!tektronix!vice!keithl   [e-mail]
>MS 59-316, Tektronix, PO 500, Beaverton OR 97077  (503)-627-4052

When I was a kid, I believed all the NASA hype -- shuttle real soon now,
missions to mars, moon bases, 10,000 person colonies etc.  All of it was
supposed to be there by now.  Well, it's now folks.  And now I'm not
sure if any of it is even going to make it in my lifetime any more.

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

John Gregor                                       [e-mail]

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

Date: 30 May 88 14:58:35 GMT
From: mcvax!unido!ecrcvax![e-mail]  (John Gregor)
Subject: Some more launch loop stuff...

I sent this to Dani Eder by email, but I don't see any reason not to
put it on the net.  Also, I'd really like to see more discussion on the
following:

1) The launch loop -- obviously.
2) Other methods to orbit within todays technology.
3) What we can do.  In industry, academia, on usenet, via letters
   to congresscritters, etc.

>>>>---------- ------------- ------------- ------------ ------------ ---
In article <[e-mail]> you write:
>Not only have I read the paper, but I know Keith.  In fact, he was
>on usenet at one time (you out there?).  The advanced propulsion
>community is really a very small one.
>
I know Keith also.  Way back when, when I was in high school, I
worked on his "floater" (suspended magnetic bar) demo.

I know he is still around on the net.  I saw his vote in the summary
for sci.nanotech a few weeks back.

>400 tons of cargo is a piddly-ass amount.  One airport runway
>with a stream of 727s taking off represents 1200 tons of
>passengers and cargo.

I was comparing it to what our present launch capacity is, not what we
do with planes.  Do you know of some launch devices that could handle
jet sized cargo?

>Define 'we'.

It was late.  Not my best literary work.  I guess in the broadest
category, 'we' could mean humanity, but I didn't mail it to kremvax. :-)
So, I guess it meant the US (my current location not withstanding).  In
the most specific sense, I guess 'we' could mean myself and the person
reading the posting.  I guess I should have rephrased it to be:  "Why
haven't I heard more about this (and other) design ideas.  Who has looked
at it?  What do you think?  Why?"

>My personal opinion of the launch loop is that is is an overly
>complex solution to the problem with failure modes that could
>be used for special effects in a George Lucas film.
>
True.  The megaSagans (million and billions) of Joules being dumped
into the ocean would make a rather spectacular scene...

> [ Lots of stuff regarding the ribbon composition and D-magnets ]
>The turnarounds at each end are done by big magnets.

14km diameter....big.... yeah, I guess they are big. :-)

>What I worry about is what happens if one of the turning magnets
>fails (keeping in mind that everything manmade fails eventually)
>then the ribbon continues straight into the ground behind
>the turning magnet, creating a pile of slag in a crater , as
>for several minutes a continuous stream of one pound
>slugs hits the ground at 11,000 rounds per second.

More likely the magnets would be sea based.  No crater, but many
suprised (and cooked) fish.  The D-magnet segments are the most
critical portion of the loop.  I think they can stand the failure of
a few segments, but loss of power or a clever terrorist would
lead to failure.  I think a lot of the structure could be salvaged
from such a failure however.

>On the
>return leg of the loop, a part of the ribbon is missing.
>The resulting unbalanaced forces may leave metal strips
>flying every which way in earth orbit.

I had never thought of the instability of having a missing W->E ribbon.
I'd need a very good model of the system and a few cray hours to know
if control would still be possible.  My guess is yes.  The track is
there to damp oscillations in the ribbon,  I think it could still do
that while falling.  Also, the segments wouldn't wind up in Earth orbit.
They would go into solar orbit.  Nothing like having a few thousand
one kilo chunks of iron flying about in an earth intersecting solar
orbit. :-(  Maybe it would be a good test of our ability to clean up
space junk.

>To my way of looking at design, I would like my support
>structure to be passive rather than active.  The loop in the
>launch loop is what holds up the structure by moving
>at super-orbital speeds.  The same result can be obtained
>with a tower made of modern structural materials
>(such as graphite epoxy for compressive columns and
>fiberglass/kevlar/polyethelyne fo guy wires.)

Is this possible now?  I think stability of that structure would be
almost as hard as for the loop.  What are some of the non-rocket,
non-classified methods of launching that you have looked at?
References to papers are welcome.

Active systems fail.  That's a fact of life.  Airplanes use a much
more active support system than trains.  They also fail in many more
and spectacular ways.  We use them, however, because they are more
cost effective.  The shuttle and NASP aren't exactly the most passive
systems around either.

>You can support an accelerator (linear motor, mass
>driver, whatever) from a series of towers of increasing
>height with suspension bridges strung between the
>towers.  If the power goes down, your structure does not
>fall out of the sky.
>
>Using towers also allows for incremental construction.

Again, is this within the capability of today's materials?  Any references?

BTW, Glad to know you are still around, I hadn't seen any postings for
a while.

>34 40 N latitude 86 40 W longitude +280 ft altitude, Earth

And all this time I though you were working out of Seattle.  I should
read signatures more often.  So much for getting a tour when I go home...:-)

                   John
--
--------------------------------------------------------------------------------

John Gregor                                       [e-mail]

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

End of SPACE Digest V8 #260
*******************