Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_0/V13_053.TXT

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Subject: SPACE Digest V13 #053

SPACE Digest                                      Volume 13 : Issue 53

Today's Topics:
                 SPACE DIGEST
         Cameras in 0G, was: Re: MIR Vacation
               Humanity's Launch Window
        Re: Fwd: NASA Plans To Redesign Space Station
              Magellan Update - 01/15/91
     Galileo's flyby sheds light on lunar mystery (long)
            Re: Barium/Lithium altazimuths
        CRRES 1/14/91 Early Release viewed in Pasadena

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: Mon, 14 Jan 91 12:37 EDT
From: [e-mail]
Subject: SPACE DIGEST

I have not received SPACE DIGEST yet this year.  Why?
                            Jim Apsey
                            [e-mail]

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

Date: 14 Jan 91 20:35:50 GMT
From: mcsun!ukc!harrier.ukc.ac.uk!hobby.ukc.ac.uk![e-mail]  (H.A.Shaw)
Subject: Cameras in 0G, was: Re: MIR Vacation

In article <[e-mail]> [e-mail] (Alan Hepburn) writes:
>Don't tell me that my camera won't work up there;  I have the same camera
>that NASA chose for their flights.  The Hasselblad was chosen because
>it was the only camera that required NO modification for 0G operation.

    Whats all this about modifications for 0G?  I have a reasonably cheap East
German camera, a mid range Japanesse 35mm compact, and before them a Kodak
Instamatic which I got for my 7th birthday and worked perfectly for over 15
years.  I use them the right way up, on their side, facing down for flat
coping and even upside down or pointing straight up for buildings and trees
from odd angles.  I have used them from sea level to 14,000 feet and out of the
windows of aircraft, speedboats and rally cars.  I even changed the film in a
rally car, doing 80 mph across the ploughed fields of France at 1am.  I have
lens, both automatic and manual from 28mm to 1000mm, motor winds, flashguns
etc.  I have around 20,000 slides in my current collection and I've never
knowingly lost a shot because of gravity.  What difference does gravity make?

Maybe it makes using a tripod a little more tricky :-)

This sounds like the $483 space rated hammer again to me!

>Alan Hepburn                    "It's what you learn after you know it all
>National Semiconductor Corp        that counts.
>Santa Clara, Ca                                        - John Wooden
>mail:  [e-mail]

Email: [e-mail]                         | Howard Allan Shaw.
                                             | The Unit for Space Science.
Phone: [phone] Extn: 3785             | Room 165, Physics Laboratory,
                                             | The University,
                                             | Canterbury, England.  CT2 7NZ

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

Date: 14 Jan 91 17:54:22 GMT
From: hpfcso!hpfcdc![e-mail]  (Alan Silverstein)
Subject: Humanity's Launch Window

I solicit your comments on the following essay, here or by mail.  It is
the result of a lifetime of space-interest, recent years of frustration,
and six months of consideration.  I think it embodies a novel, possibly
even frightening, hopefully motivational idea.

If the feedback I get is sufficiently positive, I will seek to spread
this message by getting the (improved) essay published as widely as
possible.

The original is troff, with many text enhancements, so it looks a lot
better on paper.  I put "*" around bold text.  After this round of
comments, I will make the pre-troff source of the next draft available
to anyone who wants a copy to spread the message.

Thank you!

             Humanity's Launch Window

                 Alan Silverstein
                 January 14, 1991


       *Five billion years from now*.  That's about when the Sun will
       expand into a red giant star.  Its atmosphere will engulf and
       vaporize the Earth.  All of our dreams, inventions, creations,
       artifacts, and remains will become a mingled gas.  Also our
       pollution, landfills, war machines, inner cities, and petty
       differences.  The thought is both reassuring and humbling.
       Everything we affect is headed for ultimate oblivion as a hot
       gas...  Unless before then we are able to move off the Earth;
       move the Earth; change the Sun's life cycle; or make something
       *really* exciting happen.

       *Four and a half billion years*.  That's about how long it took
       for self-awareness to appear on the Earth.  As far as we know, we
       are the first Earth species capable of departing the planet.  It
       took over four thousand million years for life on our world to
       reach this point -- for our ``launch window'' to open.

       *Many thousands of people, all peacefully cooperating*.  That's
       what it takes to launch a payload from the Earth.  Discovery of
       the New World by Europeans required a few sailing ships.  The
       exploration could be accomplished and the exploitation (ethical
       or not) begun by perhaps fifty people in one lifetime.  A
       successful space program is at least two orders of magnitude more
       demanding.

       *Thirty years*.  That's about how long humanity's ``launch
       window'' has been open.  There are wonders beyond comprehension
       awaiting us beyond our Earth.  To achieve a toehold, a foothold,
       on those riches requires enormous investment.  It takes raw
       materials and the technology to render them.  It takes many, many
       people, at peace with each other in a stable society, wealthy
       enough to make investments whose return is measured in
       generations.

       Our precious Earth is crowded.  Our raw materials are being
       consumed.  *Our launch window will close*.

       *How long do we have?*  It is anyone's guess.  I think no more
       than fifty years.  Perhaps much less.  After that -- no one, no
       group, will have the resources, the time, the energy, to spare on
       expanding into space.  The Dream might survive, but as an
       escapist fantasy on a crowded world become a prison.  A world of
       inmates bound by gravity's bars.

       *Imagine it*.  Nine billion years for Earth.  An eighty year
       launch window for humanity.  Now *that* is the big picture.
       Perhaps, in the long run, it is the only perspective that counts.

       *Now is our species's crux move*.  Our one shot at virtually
       infinite wealth and discovery.  We can pursue the Great
       Adventure.  Or we can fritter away our opportunity -- and wake up
       one day to discover it's too late.  We can let our launch window
       close.  *Which do we choose?*

       ``It has yet to be proven that intelligence has any survival
       value.'' -- Arthur C. Clarke

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

Date: 15 Jan 91 18:12:29 GMT
From: rochester!sol![e-mail]  (Brian Yamauchi)
Subject: Re: Fwd: NASA Plans To Redesign Space Station

In article <[e-mail]> [e-mail] ("Allen W. Sherzer") writes:
   >2) The Truss: In particular, building it in orbit.  Someone mentioned
   >that the truss was cut in the latest redesign -- did this refer to
   >just the dual keel design (which was cut earlier) or the *entire*
   >truss?

   One of the designs proposed when Congress mandated the design be evaluated
   eliminated most of the truss. A small part would be left to hang experiments
   on and the rest removed. This approach also used smaller modules for building
   the station. Each module would be self contained and could go up on a single
   Shuttle flight. A module would be flown up, docked, and ready to go.

Hmmm...  So where would this design place the solar panels?

--
_______________________________________________________________________________

Brian Yamauchi                University of Rochester
[e-mail]        Computer Science Department
_______________________________________________________________________________

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

Date: 15 Jan 91 19:34:19 GMT
From: snorkelwacker.mit.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 01/15/91


                          MAGELLAN STATUS REPORT
                            January 15, 1991

     The Magellan spacecraft and its radar system continue to perform
nominally.  All STARCALS (star calibrations) and DESATS (desaturations)
during the past 24 hours were successful.  As of 10:49 AM (PST), Magellan
has completed 789 mapping orbits.

     Later today, the spacecraft controllers will send updates of the radar
control parameter and mapping quaternion files.  There will be no "tweak" of
the command sequences.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 14 Jan 91 18:36:48 GMT
From: eagle![e-mail]  (Ronald E. Graham)
Subject: Galileo's flyby sheds light on lunar mystery (long)

[The following article was published in the Cleveland Plain Dealer, 01/13/91.
 It was written by Ron Haybron, associate professor of physics at Cleveland
 State, in his weekly "Science Notebook."  - RG]

In these tight-money days, scientists are careful to capitalize on every
opportunity to gather any scrap of data that becomes available.  For instance,
they got a chance to snatch a glance at the back side of the Moon last month
as the Galileo spacecraft whizzed by on its long voyage to Jupiter.

That Galileo came anywhere near the moon on this trip was strictly an accident:
its objective is to investigate Jupiter and some of its satellites, starting
in December 1995.  But a series of events that began with the loss of the
space shuttle Challenger culminated in the close encounter in December [1990],
which produced some welcome information about our nearest planetary neighbor.

The spacecraft, which carries an orbiter for a prolonged imaging mission and a
probe that will parachute into the Jovian atmosphere to monitor conditions
there, was carried into an orbit above the Earth's atmosphere by the shuttle
Atlantis, from which it was launched.  In the original plan, the rocket to
propel Galileo toward Jupiter was the Centaur, a LH_2/LO_2-powered "upper
stage" that was developed at NASA Lewis Research Center.

This powerful engine was originally designed to be put atop a primary booster,
such as the Atlas, to carry heavy interplanetary probes, such as the Voyager
spacecraft, from low Earth orbit to their distant goal.  And it seemed perfect
for Galileo.

But after the Challenger accident, planners at the Johnson Space Center in
Texas decided that putting the Centaur in the cargo bay of a shuttle was too
risky.  The rocket had not been planned for use on missions with a crew, and
even though the Lewis launch team had acquired a lot of experience with
Centaur and was confident it could do the job safely [Amen.  I was there.],
Centaur was replaced with a lower-powered solid-fuel rocket.  Such devices
are basically large-scale versions of Fourth of July bottle rockets.  They
are considered much safer than liquid-fueled engines.

Once that decision had been made, the short, fast trajectory to Jupiter that
had been possible for Galileo when driven by the powerful centaur was now
impossible.  Instead, planners had to come up with a very complex mission
profile involving several flybys of various bodies in the inner part of the
solar system.

This was necessary to take advantage of the "slingshot effect," in which a
spacecraft flies very near a moon or planet, speeds up as it falls toward the
larger body, and flies off at a greater speed than it had before the encounter.

Such a result, at first glance, seems to violate conservation of energy, but
in fact the large body slows down slightly.  The slingshot effect has become
a routine way of flinging low-powered spacecraft off to the outer reaches of
the solar system, but the path for such a maneuver is very long, so such
missions are considerably extended, subjecting the spacecraft to prolonged
exposure to the hostile environment of space and thus an increased risk of
damage by radiation or by tiny meteoroids.

Among multiple "loops" around the Sun, Venus, and Earth, Galileo passed very
close to the back side of the Moon, providing an opportunity to take a look
at that seldom-seen region with the modern imaging tools carried by the
spacecraft.  Researchers hope they can learn more about the composition of
the Moon's far side from this data.

This interest is actually a continuation of the work begun in the '60s with
the Apollo landings on the lunar surface.  Although many regard these brave
accomplishments as primarily political, some prominent members of the science
community gave the enterprise vigorous support as a way to learn about the
Moon's origins.

How the Moon was formed has been a controversial topic almost since French
astronomer and mathematician Pierre Simone de Laplace [Laplace transforms]
proposed at the end of the 18th century his condensation theory of the
formation of the solar system.

In this picture, the planets "condensed" from a primordial cloud of gas and
dust that surrounded the newly-formed Sun.  In the swirling mess, particles
collided and stuck to form larger pieces, then chunks, then bigger chunks,
and finally the planets as we see them today.

This explanation for the formation of the planets, including Earth, seems
just as suited to the Moon.  Isn't it likely that the Moon formed at the
same time as the Earth and by the same mechanisms?  The data available even
before Apollo and the lunar samples returned by Soviet robot probes in the
'60s belied this notion.  The Moon is less dense than Earth and has a
different chemical composition.

To explain these differences, some theorists proposed that the Moon had formed
in a different part of the pre-planetary nebula, at a different distance from
the Sun, where the chemical composition [of the nebula?] would be different.
Then it was somehow captured by the Earth.  The catch with this picture was
finding a way to model the complicated encounters needed for the capture.

A third explanation was that early on, Earth broke into two pieces, with the
Moon originally a piece of the low-density outer crust of the Earth.  This
was the popular theory when I was a student - that the cavity occupied by
the Pacific Ocean was the hole left by stuff that became the Moon.

The Apollo data led to a new vision, that the Moon was formed when the young
Earth was hit by a giant meteoroid.  We will continue this "Moon-mystery"
discussion next week.

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

Date: 15 Jan 91 00:39:03 GMT
From: sdd.hp.com!zaphod!caen!umich!sharkey!cfctech![e-mail]  (Norman J. Meluch)
Subject: Re: Barium/Lithium altazimuths

[e-mail] (Ray Sterner) writes:

{R}    This is to be a large barium cloud or lithium.  Tables for two alternate
{R}    times are given below.  From hotline information as of 1:08 pm EST.
{R}    Note: the alternate release times below are actually the start and end
{R}    times of a time window.  That may mean that the release could occur
{R}    anytime within the window.  Call the hotline to get the latest release
{R}    time.

As of 7:15 EST there are 5 exact times available for possible releases.

The time of the first small barium release has been decided upon.

       EST          Long Deg W Lat Deg N Height km
       +-------------+----------+---------+---------+
       |Jan. 14 23:11|     97.7 |    17.9 |    14800|
       +-------------+----------+---------+---------+


The second attempted release will be another large lithium (difficult to see
so they say :-) release at any of the following times:

       EST          Long Deg W Lat Deg N Height km
       +-------------+----------+---------+---------+
       |Jan. 15 02:35|    101.6 |     9.3 |    33400|
       |Jan. 15 03:05|    104.9 |     8.1 |    33500|
       |Jan. 15 03:35|    108.1 |     6.8 |    33100|
       |Jan. 15 04:05|    111.2 |     5.4 |    32000|
       |Jan. 15 04:35|    114.0 |     3.9 |    30370|
       +-------------+----------+---------+---------+

Happy viewing.  Still overcast here ... grumble.

                        - Norm.

P.S.    Great updates Ray!  Keep 'em coming.  Perhaps you could add Detroit?
    Right now I kind of interpolate between Columbus and Chicago.

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Norman J. Meluch ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|
| Mail: [e-mail]           Fax:[phone]  Voice:[phone] |
| Note: The opinions expressed here are in no way to be confused with valid   |
|_______ideas or corporate policy.____________________________________________|

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

Date: 14 Jan 91 23:30:31 GMT
From: usc!julius.cs.uiuc.edu!zaphod!swrinde!elroy.jpl.nasa.gov!mipl3![e-mail]
Subject: CRRES 1/14/91 Early Release viewed in Pasadena

We observed the CRRES release at 8:13 p.m. PST in Pasadena, CA., from
the balcony at Tom's place.
(No thanks to L.A.'s lights---fortunately it was relatively clear).
The release appeared as a grey expanding disk that gained in
luminance for about 30-45 seconds and faded rapidly.  We were
lucky enough to spot the emission early in its release and were
able to watch nearly the entire duration.  It would have been easy
to miss if you weren't lucky enough to spot it early.  The
azimuth and elevation data posted were particularly helpful.
We anticipate catching a glimpse of the next release, hopefully
it will be before we have to go catch some Z's.

Stephen Watson
Tom Kelly

Jet Propulsion Laboratory
Pasadena, CA

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

End of SPACE Digest V13 #053
*******************