Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_1/V15NO177.TXT

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Date: Wed,  9 Sep 92 05:00:14
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #177
To: Space Digest Readers
Precedence: bulk


Space Digest                Wed,  9 Sep 92       Volume 15 : Issue 177

Today's Topics:
            20 Questions About the Delta Clipper (2 msgs)
                      Galileo Update - 09/08/92
         Is NASA really planning to Terraform Mars? (5 msgs)
                        Pluto Direct/ options
                   QUERY Re: Pluto Direct/ options
                              Star Chart
           STS-47 SAREX info and latest prelaunch elements
                             Terraforming
                             TSTO vs SSTO
                WANTED: Cheap cpu cycles and Megaflops
              What is the speed of light measured from?

    Welcome to the Space Digest!!  Please send your messages to
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----------------------------------------------------------------------

Date: 8 Sep 92 14:44:13 GMT
From: Greg Moore <[e-mail]>
Subject: 20 Questions About the Delta Clipper
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>This was prepared as part of a packet of information on the SSRT project
>and the DCX and DCY vehicles. Permission is granted to reproduce and
>distribute any way you want.
>
>   Allen
>--------------------------------
>
>                  20  question about the Delta Clipper
>
>12>  Will it be able to fly to the Moon?
>     A Delta clipper derivative vehicle, re-fueled in Low Earth Orbit,
>would be able to fly to the Moon, land there, and then return to Earth.
>The modifications required, however, would be substantial.
>
    In other words, don't hold your breath.  When I read substantial
modifications, I start thinking "new ship".

>16>  Why should I believe all these claims for the Delta Clipper
>     when similar ones were made for the Shuttle twenty years ago?
>
>     The Shuttle's design was "frozen" in the 1970's.  Using the technology
>available then would have resulted in a SSTO that was extremely large and
>expensive. A Delta Clipper sized SSTO based on 1970's technology would not
>have ben able to reach orbit. In the 20 years since then, we have learned
>a lot about design, light-weight materials, trajectory optimization, avionics,
>computers, and engine design.
>
    This is all nice, but I think it is not really a good answer.  So
what if the shuttle's design was frozen?  And so what if the technology
available then would have resulting in a large SSTO.  No-one claimed the
shuttle wsa to be a SSTO.  This paragraph sounds more like an answer to
the question: "Why didn't we do this with the shuttle 20 years ago?"

    I think in general the real question being asked in this case is
how you plan to meet turn-around requirements and cost requirements.  The
above tells me nothing that relates to that.

>     In addition, the Delta Clipper is being designed with supportability
>and operability as priority considerations. For example, the engines
>on the Delta Clipper won't run at 110% of their design capacity, as the
>Shuttle's do, so they won't have to be torn down and repaired before each
>flight. If on-board diagnostic instruments indicate a problem with a
>Delta Clipper engine or any other component, it is designed so components
>(called line replaceable units) can be pulled and replaced quickly after
>landing.
>
    This is actually more to the point of answering the above question.
However, I now have a couple oif questions of my own.
    The point about not running engines to 110% is a good one.  And
I will grant that you probbaly won't have to tear them down after each
flight.  However, we have no real-world experience on this matter.  Yes,
the RL-10 has been fired for so long and refired so many times, but until
you build the DC-Y and fly it a few times, you have little idea of the
actual wear and tear on the engines.  You may find the atmospheric transit
has strange affects (look at the British Comet) that negatively affect
wear and tear, requiring more maintainance than required.  And this
is assuming you use the RL-10.
    Also, what work is being done to develop the LRU's?  Or can they
in most cases simply be adapted from aircraft LRU's.

>
>--
>+---------------------------------------------------------------------------+
>| Allen W. Sherzer | "If they can put a man on the Moon, why can't they     |
>|  [e-mail]     |  put a man on the Moon?"                               |
>+----------------------234 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 8 Sep 92 15:45:38 GMT
From: Paul Dietz <[e-mail]>
Subject: 20 Questions About the Delta Clipper
Newsgroups: sci.space

In article <0#[e-mail]> [e-mail] (Greg Moore) writes:
>In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:


>>     The Shuttle's design was "frozen" in the 1970's.  Using the technology
>> available then would have resulted in a SSTO that was extremely large and
>> expensive. A Delta Clipper sized SSTO based on 1970's technology would not
>> have ben able to reach orbit. In the 20 years since then, we have learned
>> a lot about design, light-weight materials, trajectory optimization, avionics,
>> computers, and engine design.

>    This is all nice, but I think it is not really a good answer.  So
> what if the shuttle's design was frozen?  And so what if the technology
> available then would have resulting in a large SSTO.  No-one claimed the
> shuttle wsa to be a SSTO.  This paragraph sounds more like an answer to
> the question: "Why didn't we do this with the shuttle 20 years ago?"


For a history of the SSTO idea, you might want to look
at this paper:

   AAS 91-643  Gary C. Hudson, "History of the Phoenix VTOL SSTO
   and Recent Developments in Single-Stage Launch Systems", in
   "International Space Year in the Pacific Basin", vol 77, Advances
   in Astronautical Sciences, pages 329-351, Amer. Astro. Soc. 1991.

Hudson argues that the reason SSTO's have become "feasible" is simply
that the customer, the government, has started to ask for them.  Delta
Clipper will use no advanced, NASP-derived materials.  Hudson argues,
as a thought experiment, that expendable SSTOs are quite feasible
using shuttle technology.  A shuttle ET, fitted with 6 SSMEs, can put
some 60 to 70 klb into orbit (more if some structural mods, like
removing the unnecessary SRB and orbiter attach structures, are made
on the ET).  A SIVB stage with a single SSME could put ~12 klb
into orbit.

Hudson adds (* indicates italics):

   It remains to be seen whether VTOL SSTO will become part of the
   means to achieve inexpensive access to space, but if it does,
   the principal question future observers of the space transportation
   business will ask is: *why did it take so long*?

----

    Paul F. Dietz
    [e-mail]


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

Date: 9 Sep 92 01:36:16 GMT
From: Ron Baalke <[e-mail]>
Subject: Galileo Update - 09/08/92
Newsgroups: sci.space,sci.astro

Forwarded from:
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109.  TELEPHONE [phone]


                     GALILEO MISSION STATUS
                        September 8, 1992

     The Galileo spacecraft is almost 107 million kilometers
(66.5 million miles) from Earth.  It is just three months until
the second Earth gravity assist, when the spacecraft will gain
enough energy to fly to Jupiter, arriving just three years later.
It is now almost 230 million kilometers (143 million miles) from
the Sun, and its speed in orbit is 24.4 kilometers per second or
54,640 miles per hour.

     Galileo is operating normally, transmitting coded telemetry
at 40 bits per second.  Today and tomorrow, the flight team are
conducting a diagnostic test of the antenna-deployment mechanism,
in preparation for activities planned for January to try to free
the stuck ribs of the high-gain antenna.

     This week's test will involve two pulses, separated by a
day-long warming period.  A similar operation was carried out in
July, when the spacecraft was farther from the Sun, and therefore
somewhat cooler.  Today, the antenna motor region is estimated to
be about -13 degrees Celsius (8.6 Fahrenheit); tomorrow, after
the warming, it is expected to be about +8 Celsius (46 F).  The
engineers are studying temperature effects on the operation; in
January, conditions will be nearly the warmest, believed most
favorable for releasing the ribs.

                              #####
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Anything is impossible if
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you don't attempt it.
|_____|/  |_|/       |_____|/                     |

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

Date: 8 Sep 92 16:10:25 GMT
From: David Knapp <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Nick Janow) writes:
>[e-mail] (David Knapp) enquires:
>
>> Thomas, would you expound on which bacteria or fungi can exist in a hot
>> sulfuric acid/sulfur dioxide environment [Venus' upper atmosphere]?
>
>I don't know if there are any microorganisms that can survive those conditions
>(I don't know that there aren't, either).  However, Perhaps advances in
>understanding enzymes and other building blocks of life will lead to engineered
>life forms that can survive--even thrive--in that environment.

Since we cannot forcast the future, I cannot argue with you on that.

>These new
>building blocks needn't be based on Terran life; they need only meet the
>requirements for life on Venus (survival and replication, and possibly
>mutation).  They could even be wild & weird, such as buckyballs stuffed with
>sulfur and/or some metal available as dust in the upper atmosphere, and with
>chlorine or fluorine inside or out.

Hmm, have you ever considered writing science fiction ?  ;=)

>Of course, the real problem with Venus is the lack of hydrogen, or the excess
>of oxygen.  Might Venus lose oxygen at a significant rate if there was free
>oxygen in the upper atmosphere?

There *is* free oxygen in the upper atmosphere.

>Might free metal in the crust take in some of
>the excess oxygen?

The oxygen in the troposphere is not free.  It is predominantly CO2.

>The possibilities are interesting to think about, if
>nothing else.  :)

Yes.

--
David Knapp                                      University of Colorado, Boulder
Perpetual Student                                   [e-mail]

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

Date: 8 Sep 92 15:49:21 GMT
From: "John F. Woods" <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

[e-mail] (Nick Janow) writes:
>Of course, the real problem with Venus is the lack of hydrogen, or the excess
>of oxygen.  Might Venus lose oxygen at a significant rate if there was free
>oxygen in the upper atmosphere?  Might free metal in the crust take in some of
>the excess oxygen?  The possibilities are interesting to think about, if
>nothing else.  :)

One suggestion I heard was to slam a few large comets into Venus, thus adding
hydrogen and blowing off big chunks of the atmosphere in one fell swoop.
Not exactly a low-budget operation, mind you...

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

Date: 8 Sep 92 17:11:47 GMT
From: "Thomas H. Kunich" <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

Without references it is difficult to remember, but isn't there
water, water vapor and possible liquid water along the interface of
the Martian north pole?

If so, shouldn't this represent a possible seeding area for life forms?

I also seem to remember that the upper atmosphere of Venus was
mostly water vapor even though the bulk of the atmosphere was
sulphuric acid.

Perhaps I didn't make myself clear enough. I don't believe that
Venus could ever be made earthlike. I see the chance, however,
of seeding life there and letting it make it's own way.

The same with Mars. All of the grandiose plans aside I can't see
the bulk of the necessary machinery being transported to Mars to
terraform it and then the project continued for thousands of years.

Earth has been changed dramaticaly by the life forms inhabiting it
and I think that, given a chance, life will find a way to change
both Venus and Mars to suit itself -- or to change itself to suit
the conditions there.

The only necessary assistance that we need make is to supply a large
enough gene pool with enough of the correct survival genes to allow
life to survive while these changes take place.

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

Date: 8 Sep 92 16:53:33 GMT
From: Sam Warden <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

Re Venus: We seem to know more about the Venusian atmosphere than I
knew we knew.  :-)  Since when are the _upper_ clouds H2SO4?  And,
do we really know what the overall composition of the crust and
atmosphere is, to say that there is somehow an "excess" of oxygen?
Were Venus ever to cool off, I would expect ferocious amounts of
oxidation/carbonation weathering to occur, for example.

Re Mars: I'm impressed with the Gaia approach, to this negative
extent: the lack of a fixed atmosphere on Mars seems like strong
evidence that life is not active there now, or it would exhale
one.  I'm not convinced that `seeding' Mars would be impossible,
but it would have to be not isolated spores but a complete
ecosystem capable of maintaining its own microenvironment.  A
blob with a crust, so to speak.  Things like the Dead Sea plankton
that secrete glycerol come to mind.  This is pretty dependent
on whether the Martian crust is a pre-biotic permafrost as
has been speculated, but I'm uncomfortable with dismissing the
possibility out of hand.

As for the morality of this sort of thing, I don't share the
comfortable expectation that we as a civilization _have_
future centuries at our disposal for a conservative planetary
exploration.  The spread of terrestrial life to other
now lifeless environments seems _very_ moral to me, even a
moral imperative, given a possibly limited window of ability
to do so.  My opinion; others of course are free to differ.  ;-)

--

[e-mail] (Sam Warden) -- and not a mere Device.


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

Date: Tue, 8 Sep 1992 19:21:40 GMT
From: Paul Dietz <[e-mail]>
Subject: Is NASA really planning to Terraform Mars?
Newsgroups: sci.space

In article <samw.715971213@bucket> [e-mail] (Sam Warden) writes:

> Re Venus: We seem to know more about the Venusian atmosphere than I
> knew we knew.  :-)  Since when are the _upper_ clouds H2SO4?  And,
> do we really know what the overall composition of the crust and
> atmosphere is, to say that there is somehow an "excess" of oxygen?
> Were Venus ever to cool off, I would expect ferocious amounts of
> oxidation/carbonation weathering to occur, for example.

The "excess" of oxygen is that if the CO2 is converted to biomass
and oxygen, we now have 100x more oxygen that in Earth's atmosphere.
What that really means is that it is impossible to convert more
than a tiny fraction of the carbon to reduced form before it is
oxidized back to CO2 again.  So the planet doesn't cool off.

    Paul F. Dietz
    [e-mail]

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

Date: 8 Sep 92 23:21:11 GMT
From: Ron Baalke <[e-mail]>
Subject: Pluto Direct/ options
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Pat) writes...
>
>I saw parts of the pluto direct flyby talk by staehle from JPL.
>they are talking of sending a 1-200 kg orbiter to pluto.
>
>Did they consider using energia?  most of the charts I remember
>were using titan or delta class launchers?

A Pluto mission has always been a high priority since it is the only
planet we have not sent a probe to.  Also, since 1979, Pluto is closer to the
Sun than Neptune and will not cross back over until February 10, 1999, and
this is the closest Pluto will be for another 248 years.  The proposed plan
is to send two small spacecraft on a direct trajectory to Pluto for a
flyby encounter.  There will be no gravity assists, not even
from Jupiter.  The cruise time would be from 7 to 8 years with a
Titan-4/Centaur launch, or 10 to 12 years with a backup Proton/D1E launch
vehicle.   Each spacecraft would weigh 330 pounds and carry a science payload
of 15 pounds consisting of an imaging system (expected resolution at 1km), an
infrared spectrometer and an ultraviolet spectrometer.  The atmosphere of
Pluto would also be studied with radio occultation.  The reason for two
spacecraft is that Pluto/Charon have a 6.4 day rotation rate, and a
single spacecraft can only study one side from close range with a flyby
encounter.  The launches of the two spacecraft will be staggered by 3.2
days to allow observations of both sides of Pluto and Charon.
The total cost of the mission would be no more than 400 million dollars
and the launch dates would be in 1998 or 1999.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Anything is impossible if
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you don't attempt it.
|_____|/  |_|/       |_____|/                     |

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

Date: 8 Sep 92 10:56:18 GMT
From: Tom A Baker <[e-mail]>
Subject: QUERY Re: Pluto Direct/ options
Newsgroups: sci.space

In article <[e-mail]> [e-mail]
(Josh 'K' Hopkins) writes:

>[e-mail] (Pat) writes:
>>they are talking of sending a 1-200 kg orbiter to pluto.
>
>Actually, they'd like to send two so that they can image both sides of the
>planet.

>>I was thinking an energia would allow a bigger bird or possibility of
>>more thrust to slow down the encounter.
>

Could you clarify whether this craft is supposed to just flyby (a la
Voyager) or is truly a Pluto "orbiter"?  From the discussion, it does
sound like a 'quick encounter' mission, which also makes more sense
from a budgetary standpoint.

Tom Baker

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

Date: 8 Sep 92 09:11:50 GMT
From: Ridley McIntyre <[e-mail]>
Subject: Star Chart
Newsgroups: sci.space

Hi,

Is it possible for me to find a star chart (or set of charts) that show
Sol's position in the Milky Way compared to other stars? All I can find
here are charts of the Milky Way *from Earth* which don't actually show
where we fit in to the rest of the universe. Is there one on archive
somewhere?

Well, I was kinda hoping it would be in a planar format (like a topographical
map - 2-dimensional) and I would need the distances between the stars in
parsecs (3-dimensional... [or +5... -5 from the x-plane in parsecs]). Does
this make any sense?

I hope it does.

Thanks in advance,

--
             **Ridley McIntyre - Ronin Ironpig**
             [e-mail]
         -----------------------------------
     "It'll be a cold night tonight... If it's cold." - Iain Morales

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

Date: 8 Sep 1992 16:08:29 GMT
From: Jay Maynard <[e-mail]>
Subject: STS-47 SAREX info and latest prelaunch elements
Newsgroups: sci.space,sci.space.shuttle,rec.radio.amateur.misc

[These are the latest elements from the JSC Amateur Radio Club...see the
comments below. In case your tracking program cares, these elements, like all
NASA element sets, are equator-based. --K5ZC]

FROM: G.L.CARMAN
SUBJECT: STS-47 elements for Sep 12 launch

I'm not sure if I already send you this or not.  It's my element set
for a Sep 12 launch with the new post OMS-2 vector that's a couple of
miles higher.

STS-47
1 00047U          92256.65952624  .00092000  00000-0  29200-3 0    59
2 00047  57.0020 107.3007 0012178 278.2332  81.7337 15.89557971    29

Satellite: STS-47
Catalog number: 00047
Epoch time:      92256.65952624 =====> (12 SEP 92   15:49:43.06 UTC)
Element set:     JSC-005
Inclination:       57.0020 deg
RA of node:       107.3007 deg          Space Shuttle Flight STS-47
Eccentricity:     .0012178           Prelaunch SGP4 Keplerian Elements
Arg of perigee:   278.2332 deg         Launch:  12 SEP 92  14:23 UTC
Mean anomaly:      81.7337 deg
Mean motion:   15.89557971 rev/day              G. L. Carman
Decay rate:     9.2000e-04 rev/day*2      NASA Johnson Space Center
Epoch rev:               2

-----------------
[...and here's a reposting of the STS-47 SAREX fact sheet, in case you missed
it the first time around. --K5ZC]

           Shuttle Amateur Radio Experiment (SAREX) Fact Sheet

                    STS-47    Space Shuttle Endeavour

When:      Mid-September, 1992 for 6 days of 2 meter operations.

Where:     Earth Orbit. Altitude 300 kilometers, with radio coverage of
           latitudes from 70 degrees North to 70 degrees South.

Operators: Dr. Jay Apt N5QWL and Dr. Mamoru Mohri 7L2NJY.
           N5QWL is the flight engineer for STS-47 and will operate the
           shuttle systems during the "night" shift, while 7L2NJY will be
           one of the scientists performing experiments in a laboratory
           in the shuttle's cargo bay during the "day" shift.

Modes:     FM Voice
                VOICE CALL SIGNS: N5QWL and 7L2NJY

           Packet (Beacons giving daily mission activities by N5QWL daily
                if I get a chance, and robot QSOs - successful connects
                will be issued a contact number by the robot)
                PACKET CALL SIGN: W5RRR-1

Frequencies: We will operate split.  PLEASE DO NOT TRANSMIT ON THE
             DOWNLINK FREQUENCY!

        VOICE:   Downlink (shuttle transmits) on 145.55 MHz
                 Uplink (ground transmits) on 144.95, 144.91, 144.97
                         (except over Europe) - we'll listen on those 3
                         frequencies to spread out the pileup a bit.
                 Uplink for Europe only: 144.80, 144.75, 144.70

                 Successful QSOs on voice will be facilitated by using
                 standard international phonetics for your call sign.  We
                 will not answer any stations using non-standard
                 phonetics.  Use your entire call sign - we log with an
                 audio tape recorder.  Do not use our call sign - passes
                 are very short, and we want to work as many folks as
                 possible.

        PACKET:  Downlink (shuttle transmits) on 145.55
                 Uplink (ground transmits) on 144.70 (worldwide)

        If you can, decrease your radio's deviation to 3 KHz (most are
        initially set at 5 KHz) and compensate for the Doppler shift.  If
        you cannot, wait until a minute or 90 seconds after we come over
        your horizon to transmit - that will put you within our IF.  If
        a station transmits without following these suggestions, we just
        hear what sounds like a noisy carrier.  The above applies to both
        voice and packet.


QSL via:   N5QWL, 806 Shorewood Drive, Seabrook, Texas 77586 USA

     Include a self-addressed stamped envelope (SASE).

     Non-US stations include a self addressed envelope with $0.50 of US
     postage affixed or appropriate IRCs.

     Include the Callsign worked, Date, UTC, Mode, and Frequency.
     For packet contacts, include the QSO number issued by the robot.

     SWL QSL's: Include the Callsign heard, Date, UTC, Mode, and
     Frequency.


Information during the mission:
     AMSAT bulletins, Compuserve, Genie, Prodigy, local packet bulletin
     boards, ARRL bulletins, and HF voice from NASA Johnson Space Center
     ARC, Houston, Texas, W5RRR, or NASA Goddard Spaceflight Center ARC,
     Greenbelt, Maryland, WA3NAN, frequencies listed below.

     W5RRR may be found on or near: 7.215, 14.280, 21.360, and 28.400.
     WA3NAN retransmits NASA Select Audio and SAREX bulletins
     simultaneously on or near 3.860, 7.185, 14.295, 21.395, and 28.650.

     The NASA Info BBS at Johnson Space Center, Houston, will also carry
     Keplerian elements and SAREX bulletins.  [phone], 1200 baud,
     8-N-1.  At the ENTER NUMBER: prompt, type 62511 <return> and log
     onto the BBS.  The Keps and bulletins will be in the welcome
     message.  Disconnect rapidly to facilitate access by others.

Operations Notes:

     N5QWL will be asleep over most USA passes, and 7L2NJY will be busy
with laboratory duties for most US passes, so try us on packet over the
USA.  Remember, our packet call sign is W5RRR-1.  We'll try to work voice
(1) when we are not otherwise engaged, and (2) at night or when the
ground is cloudy (we are generally busy taking pictures of the Earth
during clear daylight passes).  Our orbit will carry us over the Northern
hemisphere in daylight.

     We plan to work 6 schools on this mission: 2 in the US, 3 in
Australia, and 1 in Europe or Africa.

     We do not plan any orbiter maneuvers after the first 6 hours of the
flight, so orbital elements obtained early in the flight ought to be
pretty good for the entire flight.  If I can get to it, I'll activate the
SAREX about 3 hours into the mission; deactivation will occur at about 6
days, 8 hours after launch.

     The orbiter attitude is planned to be tail down, payload bay south.
The SAREX antenna will be in the right forward window, so most contacts
should have a good antenna pattern from AOS to TCA (time of closest
approach).

73, N5QWL  12 July 1992
--
Jay Maynard, EMT-P, K5ZC, PP-ASEL | Never ascribe to malice that which can
[e-mail]      | adequately be explained by stupidity.
 "Keep in mind that Amateur Radio As We Know It Today will cease to exist
            at midnight tonight." -- Dave Newkirk, WJ1Z

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

Date: Tue, 8 Sep 92 18:22:11 BST
From: [e-mail]
Subject: Terraforming

Mars may not be so difficult to terraform after all, if Dr. Robert
Zubrin is correct. Two standard large fission plants put to work for
a decade producing Methane are sufficient to push Mars into a
"runaway greenhouse" that will very quickly (ie ~ 10 years) lead to a
1/3 Bar atmosphere of CO2, shirtsleeve temperature range and liquid
water on the surface.

In a luncheon talk at the recent ISDC he showed graphs which showed
how Mars fell into a deep freeze a billion or so years ago when it
hit the upper unstable point. But in the ensuing years, the sun has
warmed up and the lower unstable point is now within 5F average
planetary temperature of a runaway back to the original state.

This might even happen on its own if theories are correct about Mars
going through warm up cycles when its orbital parameters bring it
into a warmer climactic periond. Zubrin then, is only suggesting we
hurry it up by a few 100K years.

I warm, wet CO2 atmosphere will lead to rapid spread of plant life.
(At least plant life that does not require bees & other pollinators!)

This is both a blessing and a problem. If the atmosphere is changed
from CO2 rich to an O2, it will become transparent and may go back
into deep freeze. Of course this would all take so many centuries
that I'm sure it will not be considered difficult to fix by the far
future descendants who have to deal with it: even the most
pessimistic among us would have to assume we have full nanotechnology
within ten or twenty thousand years!! (They may well preserve the
outer kilometer as a museum of ancient human history and the rest of
the body for more important uses, like building a Dysan Sphere or
billions and billions of O'Neill Cylinders.)

This brings up an interesting idea (copyright, all rights reserved)
what if there is a dormant form of photosynthesizing bacteria on
Mars? Then, when Mars goes into a warm period, Zubrin's runaway green
house would occur; followed by massive thaws, as suggested by the
presence of flood outflow channels on the Martian surface; the native
"plant" life would bloom hysterically. It would shift the atmosphere
towards greater transparency and as Mars continued to precess away
from the warm max, it would fall back into the runaway deep-freeze
and kill of the plantlife... I can account for the lack of
unambiguously positive findings by Viking by the sterilizing effects
of heavy surface UV over the large interrignum between thaws. No real
evidence for the idea, but if true it would suggest that there would
be dormant cells in stable, out of the way, well protected places.
And for the uninitiated, yes, cells (on Earth) have been found to be
viable after thousands of years of dormancy.

I have hopes that Ad Astra will publish a popular account of Zubrin's
work. I think their Mars special issue will be due out soon...

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

Date: Tue, 08 Sep 92 15:18:49 EST
From: [e-mail]
Subject: TSTO vs SSTO

In article SECRET AIRCRAFT ENCOMPASSES QUALITIES OF HIGH-SPEED LAUNCHER
FOR SPACECRAFT (Aviation Week & Space Technology, August 24, 1992)
William B. Scott writes:
"............
   Observers descriptions, discussions with industry experts, and
 AVIATION WEEK & SPACE TECHNOLOGY analyses suggest that the large
 aircraft could be the first of a two-stage system designed to launch
 small payloads into orbit. Released at Mach 6-8 from a raised section
 on the aircraft aft deck, an unmanned vehicle would accelerate to
 orbital velocities, then release a small satellite in space. It could
 remain in the atmosphere or fly a suborbital flight path, carrying
 its own suite of reconnaissance sensors.
   This concept, at present, has not been confirmed by any U.S.
 government agency or military service. However, aeronautics and space
 experts agreed the concept has considerable merit, particularly for
 orbiting payloads essential to national security.
   Such a two-stage-to-orbit concept is hardly a new one, having
 surfaced as a candidate U.S. launching system in the 1950s. It
 also is the basis for Germany's Saenger design. Advancements in
 strong, lightweight and heat-tolerant materials - as well as
 breakthrough in hybrid propulsion systems - may have made the
 two-stage concept attractive for limited-weight, critical payloads.
   According to William R. Laidlaw, a former vice president of
 advanced systems for North American Rockwell and current founder/
 CEO of Aerotest, early studies defined the characteristics of such
 an aircraft. He said a high-speed, air-breathing vehicle would
 tend to be long, with a high fineness ratio; have a broad, delta
 planform; probably would have wingtip-mounted vertical fins; use
 a multi-cycle propulsion system capable of reaching the Mach 6-8
 regime, and be large enough to carry hydrogene, methane or other
 advanced, high-energy cryogenic fuel.
 ...................."
._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._.

If this is not fiction, but reality, could this (or an improved
version) be a rival of the SSTO ? This project was probably
initiated some ten years ago, and now there is no longer cold war:
a civilian version may appear. Have the U.S. enough money to make
both the TSTO and the SSTO ?

J. Pharabod

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

Date: 8 Sep 92 15:54:51 GMT
From: [e-mail]
Subject: WANTED: Cheap cpu cycles and Megaflops
Newsgroups: sci.image.processing,sci.math.num-analysis,sci.physics,sci.space,comp.graphics,comp.visualization

Please post replies to sci.image.processing or e-mail me directly.  I will
post a summaries of replies to sci.image.processing.

I am interested in inexpensive hardware for large amounts
of images processing.  By inexpensive I mean for only
a few thousand dollars or less.  I am thinking along the
lines of a additional processor board for a PC or SUN.  I have seen PC
mother boards with a Intel i860 coprocessor.
Does anyone have any experience with this
chip.  I understand the gcc compiler (a free C complier) will generate
code for the chip.  Again, does anyone have any experience with this product
or any other inexpensive number crunchers.

Thanks in Advance


Keith S Cover
Physics, UBC
Vancouver, BC
Canada
[e-mail]


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

Date: 8 Sep 92 03:03:41 GMT
From: Keith Harwood <[e-mail]>
Subject: What is the speed of light measured from?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Richard Ottolini) writes:
> In article <[e-mail]> [e-mail] (pete) writes:
> >Neglecting the engineering problems of high speed travel through an
> >imperfect vacuum, you can travel light centuries in subjective
> >hours if you accelerate long enough. If you arrive at the Andromeda
> >galaxy 2 weeks after leaving earth, you could be justified in
> >thinking you travelled faster than c. It's just that the rest of
> >the universe will have aged 2x10^8 years.
>
> No. You would not feel you are going faaster, but the universe got smaller
> and slower.  These are stardard result of Special Relativity.

Neither of the above. The trick is that you are measuring the distance
in one reference frame and the time in different frame. Divide one by
the other and you get a number bigger than c. (Interstellar travellers
might find this useful for navigational purposes.) However, if you
measure distance and time in the same frame, you always get an answer
less than c.

Keith Harwood.

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

End of Space Digest Volume 15 : Issue 177
------------------------------