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127 responses total.

   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.

I'd like to know how they have determined that a meteorite they found at the
south pole originated on Mars.

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.

Thanks.  I knew that it wasn't contested that it was from Mars, but I had
never heard how they knew.

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.)

I always thought that Extra Treerstrial life was statistically probable. But
I will be surprised if it turned out to be in our own neighbourhood :)
<er  Terrestrial>

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.

Is panspemia next? Drink a beer, smell a rose and think about aromatic
hydrocarbons on Mars!

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.

What amazes me is that out of a handful of rocks which have made it from
Mars to Earth, through cataclysmic collisions, life was apparently *so*
common there that we have strong indications about its presence.

  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.  :)

Well, 

        Those "grubs" could have broken down and decayed.. All sorta'
possibilities, but I'm always minded of the Galaxy Serial called "Venus On
The Half Shell" - poor story, but the idea that life on earth was derived
from "Bug Shit" from an alien outpost was rather amusing, and no less
valid than any other logic..


        If they found bacterial evidence of Mars life, then there is more
evidence to obtain - this is a basic fact. I wonder when we'll get an
international effort to obtain the info?

        Anyone been to the 'stroids lately? Last I heard, there are
exactly two theories:

        A) The Asteroid belt is a planet that "Never got it's shit
           together" (hard to believe, since everything else collided);

        B) There was a planet there and SOMETHING rather sseriously
           damaged it (read "blew it to hell")


        Leaning towards the second theory.. I am always suprised that
nothing ever seems to be launched out there to inspect one or more of the
masses.. We already KNOW it's gotta' have ores in easily refinable
quantities that make all the mining of Man seem miniscule.

        Anyone have a spare Singleship? I need to get away for awhile
anyway ;-)

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.

        'Scuse me Russ?


        These are _theory_, right? They ain't sent a probe I missed, have
        they?

        Seems to me that the line between a planet and "protoplanet" is
        pretty thin when they have no facts..

        I guess what yer saying is that "they" are siding with my first
        theory: it never got it's shit together.

        I seem to recall from some silly-assed physics course that, based
        on the solar "belch" theory of planetary composition, there is a 
        pretty damn large piece of Real Estate missing precisely where the
        Belt spins around in ever smaller chunks..

        Still, this does nothing to probe the biomatter or evidence which
        might be drifting thru there..

        I reiterate, did I miss a probe-shot or has NASA not bothered to
        wend it's way thru the Belt?

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.

Perhaps this is a test of the faithful...

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?

        Quite a non-linear piece of thinking by rowyn. Yes it could be the
result of one of God's dice games ( with apology to Prof. Einstein )

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.

Re 14: No, I don't think you missed a prob shot.  The Voyagers went bast the
belt, er, past, but I don't think they got a close look.  However the "large
piece of Real Estate missing" could be missing for other reasons that having
been blowed up.  The aforementioned Jupitor, for example, could have kept the
Real Estate from forming completely.  Again, these are all thoeries.  The
problem with mining the belt is that it's more expensive to get the materials
into and out of Earth's gravity well than could *possibly* be made mining
unless a new form of propulsion is developed.

Re: 17  I understand that the meteor is chemically determine4d to br from mars
and not earth.  However, if life can come from mars to earth, why not from
earth to mars?  That seems more likely...

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 ;-)

I wanted to write a response to pfv and dadroc, but I'm out of time.

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).

re 23:  You're probably right about it being harder to knock a metor off of
earth, but I'd say it's harder more because of atmosphere than because of
gravity.  And I agree that itt would be much more interesting if life
origionated independantly on mars and earth.  either way, tho, life elsewhere
is a very very exciting proposition.  I read one time in a sci fi book about
life developing on one planet and then spoors drifting out through space for
billions of years and starting life all over.  How's that for a "common
ancestor"?

Nothing sez that the microbial life couldn't transit the "void" either,
guys...

Even if the "space seed" turned out to be true, it raises the distinct
possibility that life could be all OVER, just varied and evolved
differently.... Shades of Star Trek!

The step from bacteria surviving interplanetary travel alive, to bacteria
surviving interstellar travel alive is one hell of a huge leap.  I'm willing
to believe the first could happen in the natural course of things, but the
second really requires little green men to tote them around on purpose to be
very plausible.

Re #20:
    Certainly it would be a huge investment to get a shipload of miners and
mining equipment out to the Belt. But once there, it should be fairly easy
to slow the rocks, that they fall toward Earth. Takes maybe three years
for a delivery, even on a Hohmann course. But no reason not to send a rock
every month or so. Aerobraking could take care of most of the slow-down
delta-V, though some of the material would be lost in the process.

    Ion drives, if memory serves, *have already been built*; they just have
not been tested in an environment where they would actually be useful (deep
space). I could be wrong on this point.

My parents World Book Encyclopedia has a project to build an ion drive with
a car pattery and some wire and copper rod.  The problem with ion drive is
that the output is so low it's good only if you don't mind taking a couple
hundred years to get up to speed.

Ion Drives are "old tech" - they are guarenteed to function, and the
velocity is a function of output power.. Stick in a lousy Fission plant
and let it get as "hot" as it wants... Not gonn'a hurt a soul, and it
could easily be dumped into the Sun at any point it becamse too unreliable
or dysfunctional.. (Good place for politicians and repeat criminals, too
;-)


Never suggested we crew the things, drew.. In fact, If I ain't goin',
neither is anyone else! ;-)

Surely we have sufficient computer expertise to automate the silly-assed
thing AND get tons of data AND make a profit... The olny thing is it could
be 20 or so years before the first dime of return... Plenty of time to
build a Catchers-mitt, too..

Re #28:
    Once you're off the ground, you don't need all that much thrust to
change orbits. The delta-V needed to get on a Hohmann course to just about
anywhere further out that Earth is less than 12000 meters per second, which
is not much more than Earth escape speed. So from Earth orbit, the ship
must boost for:

                20 minutes at 1 gravity; or
                3 hours and 20 minutes at 0.1 gravity; or
                1.4 days at a hundreth of a gravity; or
                2 weeks at a thousandth of a gravity.

The coasting part will take a couple of years, but this would be true even
if high acceleration cryogenic rockets were used. What makes the trip take
so long is the limit on available delta-V.

Re: the martian meteor.  In order to conclude life on mars you have to
eliminate martian meteor picking up terrestrial biological material on
way to earth surface.  You need to go to mars and find life on mars
that was not brought to mars via poor control on the part of US or USSR
satelite manufacturers.

Hmm. it's pretty clear that there's a lot of interest here in many different
aspects of space science. I want to focus in the exobiology, though, and maybe
come back to issues of mining, etc. later.

Jan made a good point back in #26, but there's a typo there that confused me
for a while. The Mars rock that started this thread brought with it *evidence*
of life on Mars, but it did not bring life. At least there is no evidence that
it did.

While I would not argue that it could not have brought life through a journey
in which it spent perhaps hundreds of millions of years in a vacuum, I would
think that we just have no good reason to believe that.

It will be most interesting to see how much detail can be obtained from the
evidence of past life on Mars in the rock. What biologists will be looking
for is the degree of similarity of biological mechanisms that operate at the
lowest levels. It is not clear that this Mars rock will have those answers.

For example, all life on earth relies on a mapping from sequences on
nucleotides too peptide chains. This mappping, carried out by RNA is rather
arbitrary, yet it is shared by all life on earth. It is referred to today
as a "universal code".

If we could study extraterrestrial life, we would be interested in finding
out what is similar and what is different. It mnight be so different that it
doesn't use DNA at all, but has a completely different genetic code.

But even if it did use DNA, there is no guarantee that it would translate
nucleotides to peptides using the same code as terrestrial life. It is
believed that the "universal code" developed as a chance occurrence.
It is so engrained in the way life forms repsroduce, that it is not possible
for it to mutate. No competing life forms have ever been successful using a
different mapping. This goes way back to the origin of life on Earth,and it
would be of enormous interest to see what life that developed on another
planet might tell us. It is pretty safe to say that not much is understood
about how this came about. (not yet, anyway)

I think it's a pretty good bet that if we found a live cell on Mars we could
decide if it had common ancestory with terrestrial cells, using things similar
to what srw describes.  If they have common ancestory, you might well be able
to make a fair estimate of when the two lines diverged.

Common ancestory or not, you may well learn *alot* about how living systems
work and how life evolved if you could find such live cells.  We aren't likely
to learn a awful lot if all we find are fossil cells.

As I understand it, the rock is evidence of *past* life - 3.5 billion
years ago.  Basically, what we're looking at is a fossil, and a very old
one at that.

There is a very good chance that even if we find life elsewhere that
evolved independently of us, it's likely to have many astonishing
similarities.  Chemistry & evolution are universal, after all, and even
here on earth, we can find many examples of parallel evolution.

I imagine what scientists will be hoping to find are examples of
"coin-flips" in the chemistry that went the other way.  For instance,
here on earth, d-glucose occurs in most living organisms.  There is a
chemically identical "mirror-image" form, l-glucose, that is almost
never found.  So far as we can tell, nature "flipped a coin", and
decided to use d-glucose.  If we found a blue-green algae on mars that
happened to use l-glucose, that would be very good evidence of
extraterrestrial origins.

Yes, but even if all things were equal, you would spot life as
extraterrestrial only 50% of the time with that test.

It is not clear that the mapping from nucleotides to peptides is anything more
than a much more elaborate sequence of coin flips, though. However, now the
probability of independently developing the same mapping is nearly zero.

Yes, you're all quite right, THe Mars Rock won't answer these questions, as
it only contains fossils of ancient life (if that). That's why I was
poo-pooing much of the speculation about life traveling from planet to planet
through  the vacuum of space, by virtue of ejected rocks. We're not looking
at anything that amazing here.

l-glucose is manufactured, as a dietary artificial sweetener, I think.

Re #14:  I think this item would be better served with a bit less
sarcasm, but to address your points:

>       These are _theory_, right? They ain't sent a probe I missed, have
>       they?

Thousands of probes, Pete.  Thousands of samples from the Belt to Earth.

Which is basically what every fallen meteorite *is*.  It's a sample
of something that's out there.  Spectrographic evidence shows that
what falls on Earth has counterparts in orbit.

>       Seems to me that the line between a planet and "protoplanet" is
>       pretty thin when they have no facts..

There are plenty of facts.  The composition of every meteorite is
another set of facts, filling in a piece of a puzzle.  Taken together,
they tell a consistent story.

>       I guess what yer saying is that "they" are siding with my first
>       theory: it never got it's shit together.  ....  there is a 
>       pretty damn large piece of Real Estate missing precisely where the
>       Belt spins around in ever smaller chunks..

Possibly, but not quite as likely.  There isn't enough mass in the
Belt to make a planet, and lots of the planetesimals have been reduced
to fragments (shown by the firm evidence that many meterorites and
smaller bodies have been chemically fractionated by some process,
and had to have come from a larger parent body).  How much mass was
originally in the Belt region is anybody's guess, AFAIK.

My best guess is that the same orbital processes which kick rocks out
of the Belt now, removed lots of mass from it very early on.  It
wound up on the inner planets, in the middle of Jupiter, or on
escape trajectories out of the solar system.  What was left wasn't
enough for a planet.

>       I reiterate, did I miss a probe-shot or has NASA not bothered to
>       wend it's way thru the Belt?

Well, there was the Galileo encounter with the asteroid Gaspra (?)
on the journey to Jupiter, plus the evidence from all the free
samples that Nature has dumped here.  What would satisfy you?

Re #17:  Yes, something hitting Earth could kick something up to
escape velocity.  However, escape velocity for Earth is 11 km/sec,
compared to Mars' 5 km/sec.  That's 4.8 times as much energy, and
Earth has more of an atmosphere to contend with.  Getting something
off Earth is far more difficult than getting off Mars.  It would,
I agree, be very interesting to look for Earth and Luna samples
on the ice caps of Mars.

Re #19:  What do you mean, "problems with radiocarbon dating?"
You wouldn't use radiocarbon dating on anything that old, or anything
which did not come from Earth.  If you want to go into the reasons
in another item, I'll be happy to.

As I'm a lover of Babylon 5, I guess I'm implicitly in the class
you think will not have to make "a big stretch" to accept it.

Responses to items entered since Friday afternoon will come later.

It is great to know so many things about MARS.I realy appreciate your 
collections on "THE LIFE ON MARS" .Was there any CANAL existing?
I want to know much more details regarding th present atmospheric conditions
can people land on Mars on present conditions?.

  From what I have read on the subject, I would ascertain that this life on
Mars thing is a load straight from the farm. I base my opinions on what I have
learned from Carl Sagan's book "Cosmos" in which he states that there are no
canals (that was Lowell's theory). I'll have to find my copy to state the
exact wording, but he does make a pretty good case for the no-life theory.
  I would further guesstimate that NASA is behind this looking for additional
funding for the future trips to Mars and beyond. I personally think that the
money in NASA's budget could feed, house and clothe a lot of people who really
need it. If Dole gets to be president, he should eliminate NASA and the 
Dept of Defense instead of balancing the budget on the backs of the people
who are the most at risk, and the least able to speak for themselves.

  We have no need to explore Mars. We need to take care of the people on Earth
first.

- Backtalk version 1.3.30 - Copyright 1996-2006, Jan Wolter and Steve Weiss