Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_1/V13_170.TXT

Internet Message Format | 1991-06-28 | 18KB

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/kbjrNrG00WBwI=yU4=>;
          Mon, 18 Feb 91 01:38:47 -0500 (EST)
Message-ID: <cbjrNn200WBw4=[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Mon, 18 Feb 91 01:38:43 -0500 (EST)
Subject: SPACE Digest V13 #170

SPACE Digest                                     Volume 13 : Issue 170

Today's Topics:
        Re: Spy satellite coverage of the Gulf
            Commercial Space News (1 of 5)
            Commercial Space News (2 of 5)
              30 foot telescopes
        Re: Fractions (was Re: SPACE Digest V13 #124)
              CRRES hotline info
            Re: 30 foot telescopes

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: 7 Feb 91 01:20:23 GMT
From: munnari.oz.au!uniwa!vax7![e-mail]  (Liam Gumley)
Subject: Re: Spy satellite coverage of the Gulf

In article <[e-mail]>, [e-mail] (Nick Watkins) writes:
> From article <[e-mail]>, by [e-mail] (Conor O'Neill):
>> I realise that the real details are almost certainly classified, but I would
>> like to get some feel for the answers:
>> 5) Are they affected by the dark, or by cloud cover, or is much of the
>> sensing done in the Infra Red?
> Radar isn't, apparently, I think IR will be affected by cloud cover
> though. Maybe somebody who knows about weather satellites can help.

Nothing classified here....

Visible sensors obviously only work during the daytime.  Depending on the
type of orbit, the satellite can be in sunlight for up to about 50% of the
time (sun-synchronous orbit).  I don't know the altitude of the KH-11, but
I imagine it would be low, to maximise image spatial resolution.  This
probably means it does not have a sun-synchronous orbit.  They are usually at
an altitude of 850 km or so.

Infrared sensors are usable both in the day and the night, although if you
want to see targets such as vehicles or people, you would want to do it at
night when the ground is cooler than the objects you are trying to see.
Weather sensors have a different kind of emphasis than an recon imaging system
would have.  Meteorologists are typically more concerned about knowing the
temperature of a given pixel accurately, rather than the spatial resolution
of that pixel.

Most kinds of clouds are either partly or completely opaque to both
visible and infrared radiation - you can't see the ground through them.

I don't know too much about radar, but at microwave wavelengths, clouds are
pretty transparent.  I imagine that synthetic aperture radar (SAR) technology
would be used.  Oceanographic SAR aims for height resolution on the scale
of centimeters, so you can imagine the resolution defense sensors would be
working at.

Check out "Jane's all the world's satellites" - a pretty good reference.

Cheers,
Liam.

--
[e-mail]
#Liam E. Gumley, Department of Applied Physics, Curtin University of Technology#
#Perth, Western Australia.   >>>All opinions expressed are exclusively mine.<<<#

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

Date: 16 Feb 91 04:23:52 GMT
From: cs.utexas.edu!sun-barr!olivea!oliveb!felix!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: Commercial Space News (1 of 5)

This is the second of an irregular series on news from the
commercial space business.  Commentary is my own thoughts on these
developments.  Posted in 5 messages (My apologies - message length
restrictions at my up-load point).

Contents -
  o $200 MILLION IN SATELLITE INSURANCE CLAIMS FILED.
  o SATELLITE NAVIGATION "PURE PLAY" IDENTIFIED
  o COMET CONTRACTS SIGNED
  o ORBITAL SCIENCES OPENS MARKETING OFFICE IN JAPAN
  o SPOT IMAGE PLANNING DIVORCE FROM FRENCH GOVERNMENT?
  o 3 MORE COMMERCIAL LAUNCHES LICENSED
  o GENERAL DYNAMICS POSTS $300 M LOSS FROM COMMERCIAL SPACE

Articles -
------------------------------------------------------------------
$200 MILLION IN SATELLITE INSURANCE CLAIMS FILED.
   Two recent satellite failures have hit the satellite insurance
market with over $200 M in claims. The satellites, TDF-1 (A French
national telecommunications geosat), and Superbird-A (Japanese
domestic telecommunications geosat), have both failed on-orbit well
before the end of their expected lifetimes - both after launch by
Ariane in 1989.   An immediate consequence of these losses is
payment to their operators from the space insurance firms wipes out
the total of profits to the insurance industry from all prior years.
This will result in higher insurance rates and reduced availability
of insurance as the space insurance industry will have to recover
their losses.  International Technology Underwriters (INTEC), one of
the  largest of the half- dozen firms in the space insurance market
in the U.S. and abroad, has already announced plans to hike premiums
and restrict coverage.  Since INTEC controls about 30% of the
current space insurance market, this step is expected to lead to
increased rates across the board.
   [Commentary: these failures are failures of the satellites, and
not the transportation systems.  In the Superbird case, the
satellite, built by Ford Aerospace, had valve that failed allowing
the oxidizer needed for the bi-propellant ACS system to leak out.
Over the past decade and a half, by my estimation, insurance
companies have paid out about $1.4 Billion, while having collected
less than $900 million in premiums.  Not good business and rates
must rise if the insurers are to stay in business.  My guestimate is
current total (launch plus operations) rates of about 20-25% will
rise to about 25-30%, overall.  Of course the exact rate is
dependent upon the different types of launchers, satellites, and
type of coverage requested.  For operators of large satellite
constellations, we will probably see more "self-insurance" as they
try to avoid these increased insurance premiums.  This also further
raises a barrier for new entries into the satellite market.
   Ford Aerospace (now Loral) may also have taken a major blow.
They have been struggling to stay in the communications satellite
business. A previous satellite of theirs (INSAT-1A?), had a very
similar failure, which may reduce their ability to capture new
commercial business. Similarly, TDF-1 was touted as a "shining
example of French technology", and was the cornerstone of the
Aerospatiale's entry into the satellite communications market, as
well as France's entry into Direct Broadcast Satellite TV.  This
failure is expected to somewhat cool this market push.]




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

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

Date: 16 Feb 91 04:25:31 GMT
From: pacific.mps.ohio-state.edu!linac!uwm.edu!cs.utexas.edu!sun-barr!olivea!oliveb!felix!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: Commercial Space News (2 of 5)

SATELLITE NAVIGATION "PURE PLAY" IDENTIFIED
  Trimble Navigation of Sunnyvale CA has been identified as a pure
play for satellite navigation systems.  They specialize in
commercial and defense navigation units using the U.S. Global
Positioning Satellite (GPS) system. They have recently gone public
with a stock offering on July 1990, and are targeting the $100
million annual market for commercial GPS equipment, as well as the
DOD market.  They are traded on the NASDQ exchanges, currently
selling for about 11 3/4 per share (very near their 52 week high),
probably driven by their recent receipt of a "rush" order from the
DoD for hand-held GPS navigation units for Desert Storm.
  [Commentary:  I ran across a reference to this company in a trade
publication.  The only other "pure play" navigation company is
Geostar, which uses their own navigation system, based upon Comsats.
Geostar is having financial problems, and is not yet available for
common investors.
  Trimble provides a much more accessible "pure play" space
navigation investment.  Among their interesting products is the
Satellite Cruising System (AVIC-1) developed in conjunction with
Pioneer Electronics of Japan, which uses road maps stored on CD-ROM
with the GPS signals to provide a position of a car (or truck) on a
color CRT map.  Linkage with Pioneer Electronics is interesting
since Pioneer is marketing this system in the high-end after-market
for auto accessories - selling a package that includes a high
quality CD player, AM/FM tuner and TV to be installed in an auto
after it has left the assembly line - which is a large potential
market.  According to the trade press, Japanese car companies are
already installing over 5,000 auto navigation units per month - and
competition is heating up with several firms including Mazda/Japan
Radio corp.
   As always with any investment, you should check out the company's
financial status yourselves and DO YOUR HOMEWORK on the investment
to understand the risks involved.  This is not a solicitation for an
investment, but is provided as an point of interest to space
investors.  Annual reports and copies of SEC filings are available
from Trimble Navigation, 645 North Mary Avenue, P.O. Box 3642,
Sunnyvale, CA 94088-3642, or call 1-800-TRIMBLE.]



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

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

Date: 17 Feb 91 18:28:27 GMT
From: [e-mail]  (Allan Adler)
Subject: 30 foot telescopes


According to a book I am reading on telescope making, if one could make
a 30 foot mirror, one could see the disk of a star other than the sun,
something which has never been seen. I assume that means enlarging the
image of a star so that it looks like the sun looks, like a disk and not
like a point.

Can someone confirm that a mirror of that size would be adequate for that
purpose ?

I'm also curious about the problems of building and using such a telescope
(relax, I am not thinking of doing this myself...). I am told that the
weight of a 30 foot telescope mirror would cause strains in the glass that
would in turn affect the optics. But why does the mirror have to be
made of glass ? With all the experimentation with materials, why has no
substitute been found for glass ? And even if one insists on glass, why
could such a mirror not be made and used in outer space, where gravity
would not be such a problem ? I'm also told of something called NTT's
(New Technology Telescopes) where instead of using a single piece mirror,
one uses a lot of smaller mirrors and coordinates their movements so that
they behave like one big mirror. If the US government can contemplate
placing complicated Star Wars technology in space, why can't it contemplate
coordinating the pieces of a 30 foot NTT mirror in orbit ? But of course,
there is the Hubble, which I regrettably know nothing about ? What size is
the Hubble ?

Allan Adler
[e-mail]

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

Date: 18 Feb 91 03:59:39 GMT
From: zephyr.ens.tek.com!tektronix!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Re: Fractions (was Re: SPACE Digest V13 #124)

In article <[e-mail]> [e-mail] (Jonathan Leech) writes:
>In article <[e-mail]> [e-mail] (Nick Szabo) writes:
>>Coincidentally enough, the typical communications satellite also costs
>>1/10 of 1% of our GNP, and pays for itself.  The smaller space probes
>
>    Comsats cost $3 billion? This is news to me.

Thanks for the correction -- the approximation should be 1/100 of 1%.
The figure for Fred was correct at 1%, or 100 times the cost of a
comsat (c. $300 million vs. $30 billion).



--
Nick Szabo            [e-mail]
Embrace Change...  Keep the Values...  Hold Dear the Laughter...

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

Date: 7 Feb 91 22:23:25 GMT
From: att!linac!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!warper.jhuapl.edu![e-mail]  (Ray Sterner)
Subject: CRRES hotline info


   The CRRES hot-line (205-544-5356) at 4:50 pm EST Thu 7 Feb, 1991
   gave the following information.

   There will be two releases in February, a high altitude barium
   release and a high altitude lithium release.  All times below
   are Central Standard Time (as given on the hot-line).  The
   possible release times are:

   9 Feb    8:00 pm to 12:00 am at 30 min intervals.
  11 Feb    9:15 pm to  1:15 am at 30 min intervals.
  13 Feb   10:30 pm to  2:30 am at 30 min intervals.
  16 Feb    9:00 pm to 11:30 am at 30 min intervals.
  18 Feb   11:20 pm, 11:50 pm, 12:20 am, 12:40 am.

  The hot-line stated that moonlight was considered in selecting
  the intervals late in the month.


  Unfortunately there are too many possible release times (37) to
  allow posting of the release altazimuths as I did for early
  releases.  All I can suggest is that you call the hot-line closer
  to the release time to get the latest times.  Also make sure you
  convert the times from Central Standard Time to your time zone.
  I would like to thank Mike McCants for sending me a CRRES orbital
  calculation for the earlier releases, perhaps if Mike or somebody
  else posts the sub-satellite latitude and longitude and satellite
  altitude for the possible release times those of you that have the
  program I posted in January can compute altazimuths for your
  location.

  Ray Sterner                     [e-mail]
  Johns Hopkins University        North latitude 39.16 degrees.
  Applied Physics Laboratory      West longitude 76.90 degrees.
  Laurel, MD 20723-6099

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

Date: 17 Feb 91 19:08:57 GMT
From: pacific.mps.ohio-state.edu!linac!uwm.edu!wuarchive!usc!elroy.jpl.nasa.gov!jarthur!nntp-server.caltech.edu![e-mail]  (David Palmer)
Subject: Re: 30 foot telescopes

[e-mail] (Allan Adler) writes:


>According to a book I am reading on telescope making, if one could make
>a 30 foot mirror, one could see the disk of a star other than the sun,
>something which has never been seen. I assume that means enlarging the
>image of a star so that it looks like the sun looks, like a disk and not
>like a point.

The disk of Betelgeuse has been seen, using a puny 17 foot mirror (200"
Palomar) back in the 70's.  Betelgeuse is a big star.  However, it
requires fancy techniques (in this case, Speckle imaging) to compensate
for the distorting effects of the atmosphere.

>Can someone confirm that a mirror of that size would be adequate for that
>purpose ?

>I'm also curious about the problems of building and using such a telescope
>(relax, I am not thinking of doing this myself...). I am told that the
>weight of a 30 foot telescope mirror would cause strains in the glass that
>would in turn affect the optics. But why does the mirror have to be
>made of glass ? With all the experimentation with materials, why has no
>substitute been found for glass ? And even if one insists on glass, why
>could such a mirror not be made and used in outer space, where gravity
>would not be such a problem ? I'm also told of something called NTT's
>(New Technology Telescopes) where instead of using a single piece mirror,
>one uses a lot of smaller mirrors and coordinates their movements so that
>they behave like one big mirror. If the US government can contemplate
>placing complicated Star Wars technology in space, why can't it contemplate
>coordinating the pieces of a 30 foot NTT mirror in orbit ? But of course,
>there is the Hubble, which I regrettably know nothing about ? What size is
>the Hubble ?

A 33-foot telescope is currently being built on the top of Mauna Kea.
The Keck 10 meter telescope uses 36 hexagonal glass mirrors, with
feedback mechanisms to keep all of the mirrors in postion relative to
eachother at the sub-angstrom level.  Official 'first light' was
December 1990, when only 8 mirrors were in place and it had only as
much aperture as (but better image quality than) the 200" at Palomar.  It
will be fully operational, with all of the mirror segments, later this
year.

However, once you get past half a meter or so of aperture, resolution
is determined by the atmosphere, rather than by the diameter of
the optics.  If you want diffraction-limited images you have to use
special tricks that only work for bright stars.

A 10m telescope in space is not likely in the near future, given
the trouble we're having with the puny 2.4m, single-mirror Hubble
telescope.

--
        David Palmer
        [e-mail]
        ...rutgers!cit-vax!gap.cco.caltech.edu!palmer
    "Operator, get me the number for 911"  --Homer Simpson

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

End of SPACE Digest V13 #170
*******************