Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V13_2/V13_219.ZIP/V13_219

Internet Message Format | 1991-06-28 | 13KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from hogtown.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/wbnoJnu00WBwQ2d04u>;
          Sat,  2 Mar 91 01:25:56 -0500 (EST)
Message-ID: <[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Sat,  2 Mar 91 01:25:47 -0500 (EST)
Subject: SPACE Digest V13 #219

SPACE Digest                                     Volume 13 : Issue 219

Today's Topics:
            Commercial Space News (6 of 8)
             Re: Terraforming, sun shield
                 Re: dynasoar
        Re: Value per pound vs. cost per pound
             Martian surface map

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription requests,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 1 Mar 91 03:01:03 GMT
From: agate!bionet!uwm.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: Commercial Space News (6 of 8)

ASIAN BIDS FOCUS COMMUNICATIONS SATELLITE MARKET EFFORTS
  Two significant upcoming bids for GEO communications satellites
are attracting a lot of attention in the market.  Nippon Telephone
and Telegraph (NTT) of Tokyo is expected to release Request for
Proposals (RFP) in July for the construction and launch of a large
Japanese communications satellite, and for launch services for this
satellites.  The NTT contracts could be worth $150-200 M (both
satellite and launcher).
   Korea Telecom is also planning for the launch of a 2 GEO
communications satellites in 1995, and again is expected to release
a RFP this summer for satellite construction and for launch
services.  These are expected to be worth $150-300 M (depending on
the second satellite option).
   [Commentary:  The Asian market is really a hot area this year.
The demand for satellite communications services is very rapidly
growing there and has attracted a lot of interest as there is some
slowing down in the rest of the world market.
   The Japanese communications satellite market has been a major
item of discussion in the US/Japan trade talks.  The Japanese
government had originally fenced off the Japanese telecommunications
and satellite market to allow Japanese firms to develop this
technology free of U.S. competition.  However, in 1990, the US
succeeding in opening this market to competition.  The Japanese
cancelled a Japan-only government test satellite, and very quickly
there were procurements for two Japanese domestic communications
satellite networks with US-built satellites launched on US and
European rockets.  The NTT satellite is expected to be quite large -
rivaling the largest Intelsat satellites (previously the largest
non-military communications satellites launched), and had attracted
the usual list of competitors - Hughes (teamed with NEC), GE (with
Toshiba) and Loral/Ford (Mitsubishi), British Aerospace, and
Aerospatiale.  For launch services, this includes Arianespace,
McDonnell Douglas, General Dynamics, Great Wall Corp (Long March),
and Martin Marietta.
   Korea originally wanted to launch its GEO satellite in time to
provide coverage for the Seoul Olympics in 1988, so this project has
been in planning this venture for some time. Recent trade talks
between the US and S. Korea have included the domestic content of
the satellite and trade offset requirements on this contract as
topics.  Expected competitors for the satellite system are Hughes
(teamed with Samsung), British Aerospace, Loral/Ford (with Hyndai).
Launch services competitors include Arianespace, McDonnell Douglas,
General Dynamics, Martin Marietta, and surprisingly, Lockheed.
   Elsewhere, there will also be a contract for satellites for
Thailand, and possibly Fiji, a 3rd Japanese sat network, and the
Philippines.  Replacements for the existing Japanese networks,
Palapa (Indonesia), India, and Australia make this market pretty
active over the next 10 years.]



--
Wales Larrison
Internet: [e-mail]
Compuserve: >internet:[e-mail]
--------------------------------------------------------------------------

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

Date: 1 Mar 91 06:23:04 GMT
From: agate!bionet!uwm.edu!caen!sdd.hp.com!spool.mu.edu!news.cs.indiana.edu!news.nd.edu!mentor.cc.purdue.edu![e-mail]  (Mark Gellis)
Subject: Re: Terraforming, sun shield


I agree that building habitats is more likely than terraforming, although
my suspicion is that we'll get around to it eventually, but only when we're
wealthy enough to afford that kind of luxury--before then, if we're in space
at all and we want more living room, we'll do it piece by piece (i.e.,
habitat by habitat) since habitats will be cheaper to build as units on
demand than terraforming a planet, even if terraforming a planet would be
cheaper overall than building habitats for the same number of people (I
have no idea which would be which).

But who says habitats have to be space slums.  Once a society becomes
wealthy enough (and I have a feeling that self-replicating machinery, even
if it was controlled by governments and corporations, would make societies
very wealthy in terms of material, and fusion and solar and anti-matter
power will make them wealthy in terms of energy) habitats could be spacious
and pleasant, truly microworlds, instead of "habitats."

By the way, while we are on the subject of space cities, etc., I have a
question for anyone who is interested in addressing it.  I write sf as
a hobby, and I try to get my facts as straight as I can (personal pride
in my work, very bad habit).  I am interested in the various kinds of
space propulsion systems you might develop with advanced technology.  I
have heard that fusion and anti-matter are good candidates, because of
the high Isp, but that they suffer from "low thrust."

My questions are as follows.  1) What is meant by "low thrust"?  One
tenth of a gee as the max. you could get?  Less?  2) With this "low
thrust," what kind of Isp are you talking about for fusion and/or
antimatter drives?  3) Assuming that the basic laws of the universe
are unchanged, but that we have extensive technological advances
(the stories are set in the far future), could the problem of low
thrust be solved--it seems to me that "low thrust" simply means a
lousy efficiency of the engine, you need a big engine to get a certain
amount of thrust, which means you have that much more mass to push
around.  Is this a correct assumption?  And what could one realistically
expect in terms of how much more efficient you could make an engine
compared to what we might expect from the first or second generation
of fusion or antimatter drives?  (Would contemporary jet engines
and proposed jet engines compared to the first generation of jets
from the 1940s offer a useful analogy?)

Anyway, I would be grateful to anyone who would be interested in
addressing these questions.  If you don't want to fill up the newsgroup
with responses, please feel free to send me email at
[e-mail].  Thanks in advance.

Mark

P.S.  Why did I post this question here?  Because I assumed that anyone
interested in reading about terraforming would also be interested in
spacecraft.  Seemed like a simple idea to me.  :)

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

Date: Fri, 1 Mar 91 13:26:18 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: dynasoar


>From: [e-mail] (Nick Watkins)
>Subject: Re: dynasoar
>Date: 28 Feb 91 11:53:55 GMT
>Organization: University of Sussex

>>From article <[e-mail]>, by [e-mail] (Steven King):

>>  It was terminated due to the decision to
>>  demilitarize America's space efforts.
>*What* decision to demilitarise America's space efforts ... ?

>Substitute "manned space" for "space" and I might believe you, but I see
>no sign of such a decision ever having been made. I'm curious as to what
>you meant here. Decisions to make military role less overt have been
>made, e.g higher classification of spy satellites under Kennedy, but an
>overall demilitarisation is a different thing entirely.

According to Norman Augustine (I still have to transcribe my notes from
that lecture), the US military space budget is roughly two times the US
civil space budget. It would be useful to take this into account when
considering the relative magnitude of items such as Shuttle budgets.
      John Roberts
      [e-mail]

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

Date: 1 Mar 91 19:32:21 GMT
From: agate!bionet!uwm.edu!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Value per pound vs. cost per pound

In article <[e-mail]> [e-mail] (Nick Szabo) writes:
>>I am unconvinced that existing chemical
>>launchers are anywhere near optimal.  The ultimate cost limit, set by
>>the cost of fuel, is orders of magnitude less than current cost.
>
>There are several limits besides fuel costs:
>* The earth's atmosphere and the aerodynamic constraints it presents

Relatively insignificant.  Rockets get out of the atmosphere as quickly
as they can for several reasons.  This is basically a solved problem,
representing no significant constraint on costs, unless you really insist
on doing things the hard way a la NASP.

>* Environmental costs of large-volume launches: even the Shuttle
>  at current launch rates has been cited for possible damage to
>  the ozone layer

The shuttle's main environmental problem is the ill-advised use of solid
fuels in its boosters, done solely to lower development costs very slightly.
A large-volume launch system would use better fuels anyway.  The existing
large-volume systems -- all Soviet -- do.  Hydrocarbon fuels (hydrogen
being a degenerate case of hydrocarbons) are already in use by the gigaton
for other purposes, and no conceivable space-launch system will add
significantly to the volume of hydrocarbon exhaust products in the lower
atmosphere.  There may be a slight constraint to avoid major releases
into sensitive regions of the upper atmosphere, but I can't imagine this
having much impact, given that launchers climb through those regions
very quickly for other reasons already.

>* Safety and handling costs of handling large structures and large
>  amounts of fuel in one gravity and an atmosphere filled with
>  oxygen.

Long since solved completely in other industries, and by the Soviets.
Is this really the best you can come up with, Nick? :-)

>The fact is, value per pound has been increasing at a much faster rate
>than cost per pound has been decreasing...

This is hardly surprising, given that cost per pound has not been decreasing
at all (in the West).  Nobody has had any real incentive to cut cost per
pound.

>... Research into increasing value per pound is
>far more effective, dollar for dollar, than research into decreasing
>cost per pound.

A curious statement, since I know of little serious research on decreasing
cost per pound on which such a conclusion could be based.  Can you elaborate
on how you reached this conclusion, and what your evidence is?

In fact, the emphasis on increasing value per pound is a large part of the
problem, because value tends to mean cost as well as results.  Studies of
the launch-cost situation have repeatedly identified enormously expensive
payloads as a major contributing factor:  as long as the payloads are
custom-built, at horrendous expense, to squeeze maximum results out of
every gram, launcher work will focus almost entirely on reliability and
performance and will ignore cost.  Emphasis on increasing payload value
only locks us tighter into this vicious circle of enormously costly
spaceflight.
--
"But this *is* the simplified version   | Henry Spencer @ U of Toronto Zoology
for the general public."     -S. Harris |  [e-mail]  utzoo!henry

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

Date: 2 Mar 91 01:21:40 GMT
From: swrinde!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!dali.cs.montana.edu!milton![e-mail]  (Wendell Joost)
Subject: Martian surface map


I have downloaded (anonymous FTP) the digital terrain map "data samplers" available
from Ames (Thank you Lew Hitchener!).  I think that there is some noise in
the data but am not sure.  Can anyone else who has DLed the data tell me
how "clean" their data is?  I've been seeing "horizontal streaks" across
my data set.
I am going to try to set up a small "virtual mars" here at UW, time, and
computer permitting.
I would really like to here from anyone else who has downloaded the data
and worked with it.
The ftp number is 128.102.21.44,
once in (use anonymous),
cd to "pub" and then DL the README file and the other informative file.
.

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

End of SPACE Digest V13 #219
*******************