Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v09_4/v9_453.txt

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Date: Tue, 23 May 89 03:17:33 -0400 (EDT)
Subject: SPACE Digest V9 #453

SPACE Digest                                      Volume 9 : Issue 453

Today's Topics:
               Ancient asteroid impact
            Re: New Orbiter Name Announced
              Re: Magellan & SRB exhaust
             RE:  Space telescope delays
               Andromeda Strain
                  Re: Giotto
   Re: Asteroids and Dinosaurs (was Re: asteroid almost hits earth)
   Re: Asteroids and Dinosaurs (was Re: asteroid almost hits earth)
               explosive bolts
             Re: The late NEMESIS Theory
   Re: Asteroids and Dinosaurs (was Re: asteroid almost hits earth)
----------------------------------------------------------------------

Date: Fri, 19 May 89 15:57:36 EDT
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Ancient asteroid impact

>From: [e-mail]  (Eugene Miya)
>Subject: Re: asteroid almost hits earth
>> Alverz et al extinction theory as plausible.
>Luis and Walter (and all the others) still got lots of respect,
>but one of the people who came up, Peter Ray, a botanist at Stanford,
>I won't just say "He shot holes thru the theory," but he did raise
>interesting unanswered questions from the botanical community.

I think it's likely that a large object did hit the earth at about this time,
but there are a few obvious questions the popular presentations of the model
don't seem to address, which involve the weighting that should be used to
estimate the relative significance of factors, for calculations of the size
of the object involved, etc.

Under normal conditions, a sea bed being built up (later to be turned into
rock) would consist of inorganic matter washed from the land (clay, sand),
biologically produced material from the sea (CaCO3, later to be limestone),
and extraterrestrial matter from numerous tiny meteorites (rich in the
metals in question). One would expect the ratio of these materials not to
vary too much. At the point in time in question, however, the contribution
from living organisms (and by inference, the total number of living
organisms) drops off dramatically. The layers above and below are mostly
limestone, while the layer in question is mostly clay with a trace of
apparently extraterrestrial matter. Possible inferences other than the
stated model:

 - Something else killed the organisms, and only clay was left as the major
   contributor to the buildup. Deposition was much slower, so there was a lot
   more time for trace extraterrestrial material to appear and concentrate.

 - An asteroid did hit and kill life, but then during a long recovery period
   conditions were as described above, so only a portion of the material found
   is from the original asteroid, meaning that it was smaller than now thought.

 - The rate of deposition of clay was not constant, and in fact was much
   higher than usual during this period, skewing the results. (Something
   that killed the ground cover would probably lead to increased erosion.)

These alternate models could be tested to some extent, but reports in the
popular press don't say whether this has been done.
                                    John Roberts
                                    [e-mail]

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

Date: 18 May 89 14:24:36 GMT
From: asuvax!anasaz![e-mail]  (Scott Gibson)
Subject: Re: New Orbiter Name Announced

Peter Scott writes:
>whether one name will be painted on one side and one on the other, or why on
>earth they felt it necessary to use non-American spelling at all...

The Endeavour is named for a British sailing vessel of some exploratory
reknown (in keeping with NASA's supposed policy of naming shuttles for
famous exploring vessels).  It seems silly to spell it Endeavor (because
we spell the word that way) when the original is clearly called Endeavour.
Simply put:  If the ship was named Endeavour, the shuttle should be too.

Scott

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

Date: 18 May 89 09:32:38 GMT
From: mcvax!ukc!icdoc!syma![e-mail]  (Andy Clews)
Subject: Re: Magellan & SRB exhaust

From article <[e-mail]>, by [e-mail] (Stuart Warmink):
>    ..... The worry is that
>    exhaust particles could damage or dirty the orbiter's windows.

Hmmm. Perhaps the orbiter should be fitted with windscreen wipers :-) :-)

Thanks for the answers to my queries. I'm impressed with the speed - I get
answers from the US within a couple of days of posting in the UK.

Cheers!
--
Andy Clews, Computing Service, Univ. of Sussex, Brighton BN1 9QN, ENGLAND
JANET: [e-mail]   BITNET: [e-mail]
Voice: [phone] ext.2129

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

Date:     Fri, 19 May 89 10:53 EST
From: <[e-mail]>
Subject:  RE:  Space telescope delays

Henry Spencer writes:
>In article <[e-mail]> [e-mail] (Jason Gabler)
> writes:
>>After the Challenger explosion I stopped keeping track of all the reasons
>>for the delay with the H.S. Telescope.  Besides that tragedy, can anyone
>>give me the other reasons behind its late arrival.
>
>A combination of not wanting to fly it on the first post-Challenger mission,
>not wanting to fly it until the TDRS network for returning data from it was
>relatively complete, and not being able to fly it until after flying a
>couple of military missions to shut the USAF up.

     I also seem to remember a lot of software difficulties, starting
right from the time of the Challenger explosion.  Included in this is a
new software bug that was discovered about 6 months ago, which they are
just fixing up right now.  For the programmers at the Space Telescope
Institute, the Challenger disaster was a godsend, because it gave them
the extra years they needed to finish AND clean up their software.

     And they still expect SDI to work correctly!  Hah!!

                                         -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Arnold Gill                             | If you don't complain to those who  |
Queen's University at Kingston          | implemented the problem, you have   |
gill @ qucdnast.bitnet                  | no right to complain at all !       |
                                         -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

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

Date: 20 May 89 03:35:56 GMT
From: [e-mail]
Subject: Andromeda Strain


    In the *movie* version it was not an asteroid, it was a space
    probe.  It has been a long time since I saw it, but there was I
    think the implication of a possibility that the probe was lanched
    by the military in order to collect extraterrestrial material.
    Also, It didn't decompose plastics at all.  It caused blood to
    coagulate comletely, which kind of slowed the heart down.  In the
    end it was found that it didn't do well in an oxygen environment.
    However, all of the high-tech machines broke down, for stupid reasons
    that the movie maker thought representative of engineering narrow
    mindedness, and so it took them much too long to figure this out.

    By the way, I do think it is possible that an extraterrestrial bug
    could cause problems on earth, although very unlikely. ~rI am thinking
    that something couldevolve to live in an incredibly harsh and spartan
    extraterrestrial environment by being able to extract energy from
    almost any kind of molecule.  }iConsider for example, molds and
    such.  They will grow on any kind of decomposing organic matter.
    They are not in any sense host-specific.  Now imagine one that grew
    much more rapidly in a suitable environment, say inside the lungs.

    Chris Eliot

    Umass/Amherst

    You can post this to the net, but don't expect me to defend any
    of it.

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

Date: 20 May 89 03:06:00 GMT
From: [e-mail]  (Bob Gray)
Subject: Re: Giotto

In article <[e-mail]> [e-mail] (John H. Kim) writes:
>I heard some (*gag*) press reports that they were going to recover
>Giotto and check out some neat Halley's Comet samples that it got
>sandblasted with.  Is this true (eventually?)

No.

ESA currently doesn't have any way of retreiving a satellite.

Giotto isn't carrying enough fuel to slow down as it passes
the Earth (You can't just put on the brakes you know :->).

Giotto relied on the comet dust being ionised by the
impact with the first layer of the shield so that the
expanding cloud of gas gets stopped by the second layer.

And even if samples did survive the impact, there isn' any
way for them to be kept cold to preserve the more volatile
(and interesting) material.


The news yesterday was that Giotto is thought to be about
sixty percent operational, and that it still has sufficient
fuel reserves to carry out the mission to Grigg-Skellerup.

It is not expected to survive this encounter.
    Bob.

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

Date: 19 May 89 16:11:10 GMT
From: tekbspa!optilink![e-mail]  (Clayton Cramer)
Subject: Re: Asteroids and Dinosaurs (was Re: asteroid almost hits earth)

In article <[e-mail]>, [e-mail] (Nichael Cramer) writes:
> In article <[e-mail]> [e-mail] (saouter yannick) writes:
> >In article <[e-mail]>, [e-mail] (Ethan Tecumseh Vishniac) writes:
# ## It is also true that this is not the most dramatic mass extinction in the
# ## fossil record.
# #
# #Such collisions occurs about every 50 000 000 years and I've heard that others
# #species have disappeared as suddenly as the dinosaurs did, so earlier
# #collisions might be the cause for that, too.
# #
# #Does anyone knows others example of strange disappearance ?
#
# I don't remember the numbers (in species/yr) offhand, but I've read
# arguements (e.g. by S J Gould) that claim that we are *now* in the midst of
# the one of greatest (if not in fact _the_ greatest) of mass extinctions of
# all time.
#
# If I recall right, the numbers work out to ~1 species/100,000 increase in
# human population.

I've read that the current rate of extinction is about 15 species/century --
which is clearly far lower than ~1 species/100,000 increase in human
population.

Of course, we still don't know all the species on the planet, and I
very much doubt that we notice many that come and go anyway.

One of the Paleozoic extinctions involved 99% of all species then alive
being killed off.  But over what time scale?

--
Clayton E. Cramer                   {pyramid,pixar,tekbspa}!optilink!cramer
Assault rifle possession is a victimless crime.
----------------------------------------------------------------------------
Disclaimer?  You must be kidding!  No company would hold opinions like mine!

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

Date: 20 May 89 06:36:07 GMT
From: bbn.com![e-mail]  (Nichael Cramer)
Subject: Re: Asteroids and Dinosaurs (was Re: asteroid almost hits earth)

In article <[e-mail]> [e-mail] (Clayton Cramer) writes:
>In article <[e-mail]>, [e-mail] (Nichael Cramer) writes:
># #Does anyone knows others example of strange disappearance ?
>#
># I don't remember the numbers (in species/yr) offhand, but I've read
># arguements (e.g. by S J Gould) that claim that we are *now* in the midst of
># the one of greatest (if not in fact _the_ greatest) of mass extinctions of
># all time.
>#
># If I recall right, the numbers work out to ~1 species/100,000 increase in
># human population.
>
>I've read that the current rate of extinction is about 15 species/century --
>which is clearly far lower than ~1 species/100,000 increase in human
>population.

CLAYTON

I checked my source for the above after I got home last night, and he was
claiming a loss of 10,000 species/yr but he didn't cite any sources.  This
does sound very high.  But on the other hand, it seems equally difficult to
believe we've only lost 13-14 species in all of the 20th century.  (I've
also seen figures in the 1-10/yr range.)

Do you (or anyone else) have specific references for what the actual value
of this rate is?

Thanks
NICHAEL

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

Date: Sat, 20 May 1989 14:53-EDT
From: [e-mail]
Subject: explosive bolts

> Do you think that they could flip the explosive bolts that the shuttle is
> held on to the EFT with if an emergency arose?  Or would the shuttle be unable
> to do something like that?

No. SRB SEP any time before SRB burnout is nonsurvivable. The solids
would at worst burn the wings off the shuttle and at best simply tear
it apart from aerodynamic forces.

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

Date: 20 May 89 14:26:14 GMT
From: cs.utexas.edu!ut-emx![e-mail]  (Ed Nather)
Subject: Re: The late NEMESIS Theory

In article <[e-mail]>, [e-mail] (Bill Wyatt) writes:
> I had to comment on the following exchange. I find Ed's response to be
> uninformative (and even snide) despite being mostly factually correct.

I thought facts informed.  I guess I was wrong.

> The `mythical Oort cloud' is on much better theoretical and
> observational ground that this denigration would imply.

Apparently you know of observational evidence that I don't -- would you
please cite it, bearing in mind that the theory was devised to explain the
origin of comets, so their presence is not evidence the theory is correct?
Theoretical ground does not, of course, constitute evidence.

Note that I did not say the theory was wrong, only unproven, and totally
lacking in observational evidence other than the known evidence it was
devised to explain.  It has proved to be unprovable, hence "mythical."
I guess I would like it to be correct, since it's plausible, but my
gullibility was shattered as a child by an unplanned close encounter
with the tooth fairy ...

--
Ed Nather
Astronomy Dept, U of Texas @ Austin

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

Date: 20 May 89 22:52:07 GMT
From: agate!web-2c.berkeley.edu![e-mail]  (The Daimyo)
Subject: Re: Asteroids and Dinosaurs (was Re: asteroid almost hits earth)

In article <[e-mail]> [e-mail] (Nichael Cramer) writes:
>In article <[e-mail]> [e-mail] (Clayton Cramer) writes:
>>In article <[e-mail]>, [e-mail] (Nichael Cramer) writes:
>># #Does anyone knows others example of strange disappearance ?
>>#
>># I don't remember the numbers (in species/yr) offhand, but I've read
>># arguements (e.g. by S J Gould) that claim that we are *now* in the midst of
>># the one of greatest (if not in fact _the_ greatest) of mass extinctions of
>># all time.
>>#
>># If I recall right, the numbers work out to ~1 species/100,000 increase in
>># human population.
>>
>>I've read that the current rate of extinction is about 15 species/century --
>>which is clearly far lower than ~1 species/100,000 increase in human
>>population.
>
>I checked my source for the above after I got home last night, and he was
>claiming a loss of 10,000 species/yr but he didn't cite any sources.  This
>does sound very high.  But on the other hand, it seems equally difficult to
>believe we've only lost 13-14 species in all of the 20th century.  (I've
>also seen figures in the 1-10/yr range.)
>
>Do you (or anyone else) have specific references for what the actual value
>of this rate is?

There is a theory that was proposed by the late Dr. Luis Alvarez and Dr.
Richard Muller on the topic of mass extinctions.  In the geological
record there is evidence of mass extinctions at regular intervals thru
out earth's history.  These extinctions occurred (don't quote me on
this, I'm doing it by memory) I think every 300 million years, at a
almost frightening regular interval.  The extinctions of the dinosaurs
was one and about 300 million years later, the extinction of pre-historic
mammals another.  Before then, the geological record shows extinction
after extinction at roughly 300 million year intervals.  The theory
proposed states that our Sun may have a companion star.  For years,
astronomers and astrophysicists had assumed that our sun was different
from the rest of the stars in the universe in that it was not part of
a binary system.  This theory states that our sun may have a companion
star that at its closest point to the earth (it still looks like a normal
star from a telescope at its closest point) crosses thru the comet belt
with enough gravitational disturbance to knock about a 300,000 (I think)
or so comets out of the cloud into the inner solar system.  The odds
worked out that one would hit the earth.
    For more information consult the book "Nemesis: the Death Star"
by Dr. Richard Muller.

Extinctions on the smaller scale, aka caused by man, continue on this
planet in several key places : 1South America 2Africa ...etc. the list
goes on.  The destruction of the Amazon to make farm land is by far
one of the fastest destruction of both animal and plant species in the
world.  The uniqueness of the Amazon enviroment is such that the plant
and animal species that live there cannot be found anywhere in the world.
In fact in a recent shuttle picture, the Amazon area was nothing but
smoke as the forest is being burned down.  In Africa, the desert grows.
Man's own folly is to blame for that disaster as well.  The interference
of well meaning foreigners to help the people has led to the destruction
of thousands of acres of land.  The digging of wells in areas with lush
vegetation was not only not productive but is the direct cause of the
growing deserts.  Herd animals, wild life, and man flock for miles around
just to get to this plentiful source of water.  In their rampage, the
vegetation is stripped, trees are cut down and tender vegetation
trampled.  What's left in a matter of months is a wasteland, a addition
to already expanding desert.  Destruction of trees has had a direct
impact on the ecosystem in Africa.  In areas where there are trees it
rains.  In areas where there were trees not long ago, it will rain for
a few years more.  In areas where trees were cut down a long time ago,
there is desert.  The ecosystem is destroyed the moment the native
habitat is destroyed, and the weather adjusts accordingly.  The famine
in Africa will continue, probably and sadly, forever, unless the the
ecosystem is restored.  In the United States, coal burning plants have
destroyed forest land on the Eastern Sea Board and all over Eastern
Canada.  Lakes have so much acid content in them that the water is
poisonous.  In Europe, a similar situation exists in Germany, where
a huge portion of forest land has been labeled as doomed from the acid
rain.  In Chicago, the marble off the buildings is being dissolved by the
acid rain, of which sulfuric acid is a member.  When the habitats go,
so do the life forms that live within them.  Hopefully something can
be done to stop this.  Soon I hope.

Albert Sze-Wei Wang
------------------------------
The Daimyo                   |
[e-mail]  |
------------------------------

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

End of SPACE Digest V9 #453
*******************