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Subject: SPACE Digest V13 #265

SPACE Digest                                     Volume 13 : Issue 265

Today's Topics:
                Limits
             Toward 2001 - 11 Mar

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Date: Tue, 12 Mar 91 20:23:05 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Limits


>From: zephyr.ens.tek.com!tektronix!sequent!crg5![e-mail]  (Nick Szabo)
>Subject: Re: Value per pound vs. cost per pound

>>Nick:
>>This "coasting phase to protect the ozone" is yet another constraint that
>>must be imposed on a system already strained to its technical limits.

>In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>>Nick's problem here is that he doesn't know much about launcher design,
>>or he wouldn't make ridiculous statements like "already strained to its
>>technical limits".

>I certainly know a lot more than you've told us about.  If you look
>at the statistics of jet airplanes vs. rockets, for example fuel per pound
>of payload, structural mass per pound of fuel, maximum speed, etc., you
>will find that chemical rockets are stretched farther to the limits than
>airplanes.

If you mean that orbital rockets are more challenging to build and operate
than commercial airplanes, and that higher velocities and greater amounts
of energy are involved, then I agree with you. But "in the direction of the
technical limits" in no way implies "already at the limits". Current digital
electronics pushes toward the limits of its technology quite a bit further
than the electronics of a few years ago, but there's no reason to assume that
we can't get another order of magnitude or so more raw performance with
existing approaches.

>The cost of building jet airplanes has flattened out, and I
>expect the cost of building chemical rockets has or soon will do likewise,
>at similar per vehicle levels for freight ELV's, and much higher levels for
>reusable passenger vehicles.

>If you have any facts to refute this, please present them, but let's
>not go around knocking people for lacking knowledge you yourself seem
>to lack.  I hope that is the extent of this little ad hominem volley :-(

>>Launcher designers commonly trade off performance for
>>reliability, ease of handling, use of existing hardware, etc.; you would
>>not find such tradeoffs in systems that were stretched to their limits.

>All transportation systems have these tradeoffs, including those that have
>reached their economic limits.  Performance, reliability, and ease of
               ---------------
>handling are prerequisite characteristics for even being considered
>"transportation".

>>As a case in point, almost every launcher designer uses 3 or even 4 stages
>>to get to orbit, when Atlas did it with 1.5 over thirty years ago.  There
>>are large margins of performance available if environmental constraints
>>become serious enough to justify major redesign.

>It doesn't seem that Atlas has significantly reduced launch costs.

>Nick Szabo            [e-mail]
>"What are the _facts_, and to how many decimal places?"  -- RAH

First, you assert that chemical rockets are at their *technical* limit,
then when Henry contests this point, you give a batch of arguments that
they're at their *economic limit*. I suppose you are entitled to your views
on the economics (though I have serious misgivings as to their complete
validity), but *technical limits* pertain to strengths of materials,
atmospheric physics, square-cube laws, and so on, while economic limits
relate only to whether a project (which may very well be technically feasible)
is economically attractive or not. For instance, there's no technical reason
that we couldn't mine gold from seawater, and in fact it has been done in the
past, but with current techniques we'd be idiots to undertake it from an
economic point of view. There are clearly established and proven methods of
getting the gold much more cheaply.

If you do not understand the distinction between technical and economic
limits, then Henry's exasperation may be justified. If you do understand
the distinction, then please do not twist the terminology like this.
     John Roberts
     [e-mail]

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

Date: 12 Mar 91 05:18:12 GMT
From: agate!bionet!uwm.edu!wuarchive!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss![e-mail]  (Bev Freed)
Subject: Toward 2001 - 11 Mar


                            ***********
                            TOWARD 2001
                            ***********
                       Week of 11 March 1991
                 A Weekly Feature of SPACE CALENDAR
                   + = Domestic (USA) Earth event
                   * = Domestic (USA) space event
                   o = International Earth event
                   # = International space event
--------------------------------------------------------------------
                        REPRINT INFORMATION
This information is reproduced by permission of the Space Age
Publishing Company.  All rights reserved.  Copyright March 11,
1991.  Reproduction in any form without written permission violates
federal statute with penalty of up to $50,000.  SPACE CALENDAR is
edited and published on the Big `Space' Island of Hawaii.
====================================================================
                           * * * * * * *
+ STS 37 Atlantis
NASA KSC FL

The mission to deploy NASA's second Great Observatory -- the Gamma
Ray Observatory -- remains on schedule for early April. STS 39
Discovery, an unclassified DoD mission, is delayed until at least
late April to repair cracks in its underside doors.
                           * * * * * * *
+ Virginia Outstanding Industrialist
Fairfax VA

The accomplishments of Orbital Sciences Corp continue to bring
honors to founder David W Thompson. In mid-February, Thompson was
presented to both houses of the Virginia legislature and named the
state's outstanding industrialist for 1991.
                           * * * * * * *
o Soviet Almaz Satellite
Baikonur USSR

Currently undergoing checkout with a late March or early April
launch date. Space Commerce Corp, Houston TX, predicts data from the
satellite -- 20m resolution in 6 shades of gray -- will be on the
market by May 1991.
                           * * * * * * *
o Arianespace Asia Plans
Tokyo, Japan

Japan plans to buy 10 to 12 satellites during the next 8 years, said
Arianespace chairman Charles Bigot. During a recent visit Bigot
called on prospective users, including Nippon Telegraph & Telephone
(NTT), Kokusai Denshin Denwa (KDD), and Japan Broadcasting Corp
(NHK).
                           * * * * * * *
+ General Dynamics
San Diego CA

Is replacing Space Systems Div head Alan Lovelace with Michael
Wynne, whose space industry experience is almost nil. Speculation is
rife that GD may leave the commercial space field, despite recent
acquisition of the DoT's first launch operator's license.
                           * * * * * * *
o Aussat
Brisbane, Australia

The federal government is considering extending its protection of a
telecommunications duopoly past 1997 in an effort to stimulate
capital interest in Aussat. For the same reason, the Ministry of
Transport and Communications could issue regional licenses for
cellular mobile services instead of a third national license.
                           * * * * * * *
o Rocket System Corp
Tokyo, Japan

The 75-firm joint venture, which markets the H-2 rocket, plans to
bid on 6 upcoming Intelsat and Inmarsat launch contracts by July.
Lack of commercial space rules and regulations at Tanegashima Space
Center could scuttle the company's near-term chances.
                           * * * * * * *
+ Lunar Exploration Inc
Houston TX

Marketing manager Mark Lawson told Space News recently he has firm
commitments from three American companies for a total of $4.5
million to sponsor the Lunar Prospector. Lawson expects ultimate
project costs of about $11.5 million.
                           * * * * * * *
o Mexico Morelos Sat
Earth Orbit

Canada's Spar Communications Group will provide Mexico with a $3
million national air traffic control network using the Morelos
satellite system. The network will eventually link 45 locations with
voice and data transfer at 9.5 kilobits per second.
                           * * * * * * *
+ Lunar Footnote (Statistic)

6,661 Days Since Moon last visited by humans.
                           * * * * * * *
o International Space Year 1992 (Quote)

      The most important policy objective of the ISY . . . is
  to instill a new Space Age frame of reference in the thoughts and
               actions of governments and individuals."
                  -- The late U S Senator Spark M Matsunaga, Hawaii
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------------------------------

End of SPACE Digest V13 #265
*******************