Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V13_3/V13_328.ZIP/V13_328

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Subject: SPACE Digest V13 #328

SPACE Digest                                     Volume 13 : Issue 328

Today's Topics:
              Dilithium crystals
              RE: SPACE Digest V13 #300
           Commercial Space news (8 of 12)
            Re: Inter-probe communication
             Re: Shuttle Velocity
           Commercial Space news (5 of 12)
    MAJOR GEOMAGNETIC STORM UPDATE #2 - 26 MARCH - STILL STORMING
           Commercial Space News (6 of 12)

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
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Date: Wed, 27 Mar 91 21:45:42 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Dilithium crystals


>From: [e-mail] (Marvin Minsky)
>Newsgroups: sci.space,sci.space.shuttle
>Subject: Re: I want to go to orbit...
>Date: 25 Mar 91 22:57:29 GMT
>Organization: MIT Media Lab, Cambridge MA

>In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>>In article <[e-mail]> [e-mail] (Mark SOKOLOWSKI) writes:
>>>    What are the steps in order to build a reliable space-shuttle like
>>>spaceship in order to send myself to orbit for the summer holidays?
>>
>>First you need to locate a source of dilithium crystals.  You're not going
>>to get off the ground without them.

>How much energy does one get, in fact, by fusing lithium to carbon?
>And what is the potential barrier to be crossed. The design of my
>dilithium reactor is coming along just fine, but a few parameters need
>to be filled in.  Oh, in case you didn't know, all you have to do is
>form an exponentially tapered slug of the crystalline material, and
>tap one end of it.

Surely we can't abandon this important topic without first mentioning
"Miners in the Sky" by Murray Leinster (aka Will F. Jenkins). In this
1967 novel, spaceships use "abyssal crystals" as transducers in their
drive systems, and the crystals are of course mined in the asteroid belts
of various star systems. The novel is somewhat interesting in that it
attempts to set up a plausible rationale for space activity and for the
sociological structure it describes. It would be easy to claim that this
was the inspiration for the Star Trek dilithium crystals, except that a
1966 episode ("Mudd's Women", or some such) uses "lithium crystals" as
a major theme. Of course, there may have been an earlier short story,
and Leinster was involved in the television industry (I think he wrote
what developed into the "Time Tunnel" series), so he may have had a hand
in it directly.

I believe the "Crystal Singer" novels came much later. (Hm, I wonder where
the crystal-chanting New Agers got their ideas? :-)

Crystals of course have many real-world applications, including limited
use as power transducers and concentrators.
    John Roberts
    [e-mail]

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

Date: 27 Mar 91 07:51:00 GMT+109:13
From: "O STEVEN" <[e-mail]>
Subject: RE: SPACE Digest V13 #300
To: "space+" <[e-mail]>

please take me off your list

Thank You!!

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

Date: 26 Mar 91 05:26:49 GMT
From: swrinde!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: Commercial Space news (8 of 12)

(cont)
ranks are also decreasing) will be more important.  The forecast can
only be for more intensified competition here.
   Lastly, I have some problems with the increased lifetime of new
satellites going to 16 years or more.  A GEO slot is a very valuable
piece of "real estate" - such that a commercial firm would like to
put the best, most profitable piece of equipment they have up there
to maximize their return on investment.  The replacement of GEO
satellites every 8-10 years as seen over the last couple of
satellite generations has allowed a firm to replace their older,
less-efficient satellites with newer technology, more profitable
(higher capability at lower cost and weight) systems.  This has
allowed satellite operators to drop their prices, while still
maintaining a high rate of return, and has encouraged the
replacement of old design satellites with higher capacity satellites
of newer design.  Waiting 16 years to replace a satellite indicates
the rate of increase in communications satellite technology is
rapidly decreasing (which I disagree with) or that the replacement
cost/benefit ratio of satellites has fallen to such a level that it
is now less beneficial to replace older, less-efficient satellites
with newer, more profitable satellites (again, I disagree with
this).  I'll have to update some of my satellite replacement
economics spreadsheets to see if some numbers have changed...]



--
Wales Larrison
Internet: [e-mail]
Compuserve: >internet:[e-mail]
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Date: 25 Mar 91 23:19:50 GMT
From: agate!bionet!uwm.edu!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!rpi!uupsi!cci632!ritcsh!ultb!ritvax.isc.rit.edu![e-mail]  (DAVIS, SW)
Subject: Re: Inter-probe communication

In article <[e-mail]>, [e-mail] (Perry Pederson) writes...
>
>    I was telling my girlfriend's 11-year old cousin about the
>probes that exist in outer space; Magellan, the Voyagers, and
>Gallileo.  He asked me a question I couldn't answer: If something
>'went wrong' and a probe lost communications from Earth, could one
>spacecraft be given commands from Earth to redirect its radio dish and
>relay/forward commands to another probe that couldn't receive commands
>from Earth?
>
>    Just curious,
>
>Perry Pederson
>[e-mail]

    I don't think that any of the probes that have been sent out in the
past have the transmitter "umph" to communicate with another probe. If I recall
correctly,the output on the transmitter of,say,the Pioneer 11 probe was only a
fraction of a watt. It takes antennas in the deep space network in the U.S.,
Austrailia (and I heard that radio antennas in Spain and U.K. occasionaly lend
a hand)to transmitt a signal. Also...it would be next to impossible to
determine the actual direction that the antenna on the "lost" probe was
pointing. The antenna might only be off by a fraction of an arcsecond,or it
might just be gyrating wildly in space (in which case the antenna would not be
oriented long enough to receive a signal).

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

Date: 28 Mar 91 00:10:59 GMT
From: usc!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Shuttle Velocity

In article <910327.151234.CST.S105646@UMRVMA> [e-mail] (JD) writes:
>... fact I thought I had heard--that when the
>shuttle clears the tower it is going over 100 mph.  He didn't believe me and
>said that would be to fast and it would create to many G's for human to take.

100 mph is 50 m/s, roughly.  The tower is on the order of 100m high.  v^2=2ad,
so this requires an acceleration of 1.25G, which means a G-loading of 2.25G
since you lose 1G fighting gravity.  This is well within human tolerance, and
indeed the shuttle, which is suitable for little old ladies compared to some
of the other man-rated launchers, hits 3G later on.  However, I suspect your
number is nevertheless wrong, because liftoff accelerations generally are
lower than that.  I could be wrong; my references aren't handy.
--
"The stories one hears about putting up | Henry Spencer @ U of Toronto Zoology
SunOS 4.1.1 are all true."  -D. Harrison|  [e-mail]  utzoo!henry

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

Date: 26 Mar 91 05:23:39 GMT
From: swrinde!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: Commercial Space news (5 of 12)

(cont)
demonstrating communications satellite technologies.  The AMSC
program was set up to demonstrate and commercialize technologies
which will probably be very useful in the commercial world.
Originally the concept for this satellite was suggested by the
Canadians who desired a mobile communications satellite for use in
the "Great White North" where there is little installed
communications.  A similar NASA program, called the ACTS (Advanced
Communications Technology Satellite) is also in the works to
demonstrate advanced GEO switching, higher comm frequencies, mobile
spot-beams and other technologies for the next generation of
communications satellites.  However, ACTS has not advanced as far,
and the consortium to operate and commercialize the technology is
not as far along.
   However, this latest move from the Federal Appeals Board will
probably throw a great monkeywrench into the AMSC.  Yes, I can see
the point of the several firms who were left out of the consortium -
but those firms are primarily small firms without the money to
demonstrate the required technologies (or else they could have
bought into the consortium).  We need to protect their rights, but
we also need to find a mechanism to allow the pooling of money to
demonstrate expensive or risky new technology systems.  Hopefully,
the FCC will just grant a license to the other firms (if there is
communications spectrum for them), and also to the AMSC.
   As a last note, the ACTS and AMSC programs were instituted in
response to European and Japanese government support of advanced
comsat technologies, which were being used to promote the competi-
tiveness of European and Japanese firms.  However, the NASA
participation with the AMSC has recently drawn fire from Inmarsat
(which offers a different type of mobile communications service),
and from some European governments as being government support for a
commercial industry.]



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

Date: Tue, 26 Mar 91 11:45:59 MST
From: [e-mail] (CARY OLER)
Subject: MAJOR GEOMAGNETIC STORM UPDATE #2 - 26 MARCH - STILL STORMING
X-St-Vmsmail-To: st%"[e-mail]"

                       /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

                            GEOMAGNETIC STORM UPDATE

                       /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

                               18:30 UT, 26 March

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


STORM UPDATE INFORMATION:

     Minor to severe geomagnetic storming has been observed over the past
twelve to fourteen hours over middle latitudes.  A period of very intense
and rapid magnetic pulsations were observed between 13:00 UT and 14:10 UT.
Other middle latitude stations have also reported severe storming during
this period.  The geomagnetic field has calmed down somewhat as of 18:00 UT,
although intensification back to storm levels is expected by 24:00 UT on 26
March.

     Geomagnetic activity is expected to remain at minor to major storm
levels for the next 24 to possibly 48 hours.  Periods of major to severe
storming remain possible through the UT day on 27 March.  However, for the
most part, minor storming should dominate.

     Auroral activity may be possible to observe at low latitudes tonight
(27 March, UT time) for North American observers, although the phase and
luminosity of the moon will make observations very difficult.

     VHF and/or UHF auroral backscatter may also be possible tonight over
southerly middle and low latitudes.

     Polar and high latitude signal blackouts will continue for the next 24
hours at least.  Periodic near-blackout conditions are still possible over
middle latitudes as well.

     Current projections estimate a return to more normal propagation
conditions with quieter geomagnetic and auroral activity on 28 or 29 March.
Overall geomagnetic activity is declining slowly, but periods of strong
activity are still evident.  The best periods to attempt HF propagation
are between 9 am and 3 pm local time, particularly for southerly signal
paths (or northerly paths for southern hemisphere operators).  Northerly paths
can be heavily affected by absorption.  Eastward and westward paths are
unstable during these periods due to transitions in the diurnal magnetic and
ionospheric activity.

     The next update will be posted near 06:00 UT on 27 March.


The following alerts remain IN PROGRESS until at least 18:00 UT, 26 March:

   - MAJOR GEOMAGNETIC STORM ALERT
   - GEOMAGNETICALLY INDUCED CURRENT (GIC) ALERT
   - LOW LATITUDE AURORAL ACTIVITY ALERT
   - SATELLITE PROTON EVENT ALERT
   - POLAR CAP ABSORPTION EVENT ALERT
   - POLAR AND HIGH LATITUDE RADIO SIGNAL BLACKOUT ALERT


The following warnings are IN PROGRESS:

   - POTENTIAL MAJOR SOLAR FLARE WARNING
   - POTENTIAL PROTON FLARE WARNING


                       /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

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

Date: 26 Mar 91 05:24:34 GMT
From: sdd.hp.com!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: Commercial Space News (6 of 12)

LOCSTAR PROCEEDS TOWARDS EUROPEAN NAVIGATION SATELLITE SYSTEM
   In comparison to Geostar's financial woes (reported elsewhere in
this issue), Locstar in Europe is proceeding at full speed to being
offering the equivalent of Geostar services throughout Europe and
the Mediterranean area by early 1993.  Using patented technology
licensed from Geostar, they will use 2 satellites built for them by
Matra Espace in France, which are planned to be launched on Ariane
in April and Dec of 1992.  Locstar has encountered some difficulties
in lining up the 2.5 billion francs (about $500 M) needed to build,
launch, and operate the satellites, but fully expects to turn a
profit by 1995.  This is despite the fact that Locstar has not met
its original financial planning to generate 800 M francs (about
$160M) in equity from selling shares in the firm to interested
companies (current sales are only about 712 M francs), although
Locstar claims it has informal commitments for more than the
remaining 88 M francs.
   Locstar in a 21 Feb press conference claimed they should continue
to grow independent of Geostar's fate, since their investors had
invested more for the long term and were not looking for near-term
profitability.  Locstar claimed the potential market for Geostar
technology in North America remained strong, and they might consider
entering the U.S. market if their business grows to meet current
projections. They fully expect to begin offering position location
services to users (such as operators of trucking fleets) with 2-way
message services beginning in late 1992, and are expecting sales of
these mobile position-location terminals to reach 1 million by 2000.
They have already been granted an operating license in Germany (and
probably also in France) for their equipment.
   [Commentary: Sigh... Locstar at least, seems to be avoiding some
of the pitfalls Geostar has happened upon.  They are trying for a
much larger initial capitalization (Geostar started with a very
small investment), are going for dedicated satellites (Geostar used
add-ons to other satellites - and suffered when these satellites had
problems), and is trying for a longer pay-back period.  They have
also been able to benefit from Geostar proving out the technology
and taking much of the risk to demonstrate the concept and develop
the supporting systems, before they had to invest big bucks. Also,
the use of competing systems has not been as prevalent in Europe -
possibly due to semi-military nature of GPS, with more of a
reluctance by users to rely upon the U.S. GPS.
   On the other hand, their projection of market sales and costs
are very aggressive - and potentially very risky.  Recovering $500 M
in investment requires a substantial amount of annual business - and
I think they may be hard pressed to get the 1M in unit sales done in
time to meet their cash flow projections - particularly if they see
any competing systems come into the market.  At the moment they
have little competition - but this may change dramatically in the
next several years.]



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

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End of SPACE Digest V13 #328
*******************