response 1 of 127:

Aug 8 00:23 UTC 1996

   The URL for this is http://www.jsc.nasa.gov; there is a link entitled
something like "Is there life on Mars?".

   Basically, a team of researchers at NASA (jsc) and Stanford
have found strong (but not absolute) evidence of organic molecules
in a meteorite.  This meteorite is believed to have come from Mars,
when another meteorite hit Mars and debris from the impact went into
space, drifted for however long and finally was captured by Earth's
gravity.

   The soon-to-be-famous rock is called ALH84001.  The JSC site has
pictures of it, and electron microscope pictures of fossil-like evidence
of the organic substances involved.

response 3 of 127:

Aug 8 01:31 UTC 1996

There are some unique chemical characteristics of Mars which set
it apart from Earth.  I do not know exactly what was used to determine
the origin of AHL84001, but I do know that the concentration of
deuterium on Mars (measured by Viking, I would guess) is about 3
times that on Earth.  That's one possible smoking gun.  FYI, AHL84001
was known to be of likely Martian origin for quite a while.  It was
only recently that the tests which could detect traces of life-like
chemistry and such were developed and applied to it.

I've been getting e-mail about this all day.  Makes fascinating reading.

response 5 of 127:

Aug 8 01:57 UTC 1996

From the various things I've read, this is what pointed the researchers
to conclude that they had something which had once been alive:

1.)  Filling the cracks in a rock of another type, they found carbonates.
Terrestrial life often deposits carbonates.  It indicates liquid water also.

2.)  In the veins of carbonate, they found microscopic inclusions, some
egg- and some rod-shaped.  While these could be mineral grains swept into
the cracks, they also look much like bacterial microfossils from Earth.

3.)  Also in the neighborhood, they found grains of magnetite.  There
are huge deposits of magnetite iron ore on earth thought to have been
laid down by bacteria oxidizing dissolved iron for energy, and bacteria
which create magnetite grains even today.

4.)  In the immediate vicinity of the fossiloid inclusions, there were
polycyclic aromatic hydrocarbons.  PAH's are one of the breakdown products
of organic matter under heat and lack of oxygen.

They knew that the rock wasn't from Earth due to its chemistry.  They
also knew that the organics had not come from earth for two reasons:
they were most abundant in the center rather than the edges as they
would be if they had leached in, and other meteorites from the same
area did not have any thing similar.  It was only in the carbonate
stone.  All of these things can occur inorganically, but when you put
all of the signs together, it's extremely suggestive of life.

As for how the meteorite got to Earth, and why Antarctica:   big meteor
impacts can splash material for long distances, a la the rays pointing
back to craters on the Moon.  Mars is much smaller and lighter than Earth
and it is much easier to escape its gravity; a big meteor or comet
impact could throw some material away at escape velocity, never to
return.  Once off Mars, orbital perturbations can nudge it to Earth.
And there are valleys in Antarctica which are "dry"; glaciers flow in
and evaporate.  The dry, cold climate preserves everything against
weathering, and anything sitting on top of a glacier that's too big
to be lifted by the wind had to have fallen from the sky.  (Where
else could something sit in the weather for 13,000 years and still
be in pristine shape?  Not in Michigan.  And meteorites look a lot
like any other piece of rock, unless you see it fall.  This is rare.)

response 7 of 127:

Aug 8 08:26 UTC 1996

Well, organic molecules travelling planetary distances is not an old idea.
In fact I have heard of a theory that said human life originated on Earth that
way.
If the Martian existence is proved then that theory will gain weight.

response 9 of 127:

Aug 8 14:30 UTC 1996

I, too, have always thought it probably that there was/is life outside of
earth.  Something like this is not surprising at all.  Very fascinating, tho.

response 11 of 127:

Aug 8 18:15 UTC 1996

  Indeed.  That's amazing, and the fact that extraterrestrial life
may have been sitting in our "back yard," astronomically speaking.
If it's confirmed that there was even the simplest of life forms on
Mars, it will affect the probability estimates of intelligent life
in the universe, by boosting one of the intitial assumptions of the
probability of life forming on a given hospitable planet.  Unless
that interplanetary organic molecule theory that vedagiri mentioned
gains weight, which would imply that our neighboring planets have
life because of our proximity, not by random chance on each planet.

  It makes me wonder if we're not all ultimately descended from
Martian grubs, rather than terrestrial "primordial soup" cells.  :)

response 13 of 127:

Aug 8 22:28 UTC 1996

It is known that the asteroid belt was once home to proto-planets,
or planetesimals.  Some of these were big enough, and hot enough
from the decay of short-lived radioactives born in the supernova
which precipitated our solar system's collapse, to melt internally
and separate into heavy fractions in the center and lighter outside.
(The frozen cores, smashed into pieces by subsequent collisions,
are the source of nickel-iron meteorites.)

The best I can recall is that current models of orbital disturbance
show that Jupiter makes it less likely that small bodies in that
region will coalesce, but instead will hit each other at such high
speeds that they fragment.  Jupiter does this by kicking bodies
into highly elliptical orbits which cross at greater angles.

response 15 of 127:

Aug 9 02:08 UTC 1996

Some sceintists believe that antartica was once a liveable continenet
and that human life may have even started there.  Buried under the
ice there could be links betweenb earth and mars...

A find like this would certainly
disp[orve creationism...unless god created mars first
and mae it so lousy that he had to start over.

response 17 of 127:

Aug 9 03:20 UTC 1996

re #15:
NOw (and I mean this sincerely) correct me if I'm wrong, but the meteor
bearing signs of life from mars was thought to be kicked up from another
meteor striking mars. On the flip side, could it not be also possible that
a meteor hitting Earth kicked up something that made escape velocity? I mean,
we know that some fairly major meteors have hit our own planet in prehistory.
Isn't it even remotely possible that a big enough chunk got annexed to our
neighbor? Tried to adapt, failed?

response 19 of 127:

Aug 9 16:11 UTC 1996

I agree with Scott, this is a real test of the faithful. They have problems
with radiocarbon dating, and fossil records. A validated rock from Mars
could be a real affront. We have a 3.15 billion year record of life without
a god or anything remotely resembling man. Did trilobites have a god? This
will be a big strech for all who do not love Babylon 5.

response 21 of 127:

Aug 9 20:03 UTC 1996

hmm...

        Drives and automation... A good computer system, hardened.. An Ion
        Drive, even a Fission Drive.. Lightsails... Long lags between
        "deliveries".. 

        Taking along some H-bombs and simple-minded Guidance Systems: kick
        the ore toward the Moon/Earth Orbit and let the GS finetune the
        flight.. Flying "Catchers Mitts" (the design is old L5 related).

        The problem was, is and remains, that the Federal Govs of the
        world are pretty adamant in denying Corporate bodies access to the
        sky, let alone the technologies required..

        "The Man Who Corrupted Earth" covers a lot of the socio-economic
        horrors, too.. What happens when someone parks an asteroid
        in orbit containing more nickel-iron than Man has ever even mined?

        OTOH, those resources have a tendency to make arguments against L5
        colonies a bit moot.. Yeah, there are other problems, but the
        costs suddenly drop like a mofo ;-)

response 23 of 127:

Aug 9 20:18 UTC 1996

Supposing life on Earth and Mars had a common origin, the more likely scenario
is *not* that it started on Earth, as dang says in #20.  Earth has more
gravity than Mars, so it is a lot easier to knock rocks off of Mars and get
them to land on the Earth than vice versa.

Actually, I'd be disappointed if it turned out that Mars and Earth life had
a common origin.  If life evolved separately on Earth and Mars, then that
means the universe has to be just *full* of life.  That's much more exciting
than discovering that microbes from Mars colonized Earth and we are their
decendents (which is pretty danged exciting too).