Could microbes survive in the cryogenic temperatures of Titan?

Cassini radar imaging shows Titan to contain lakes of liquid methane:

January 03, 2007
Moon River: Titan's Polar Surface Dotted with Lakes of Methane.
By David Biello
"A missing methane sea on Titan has been replaced by a variety of
lakes, according to new radar images."
http://www.sciam.com/article.cfm?art...964C1303600942

It had been argued that life could not survive on Titan even if liquid
water existed since biological chemical reactions would not persist at
the cryogenic temperatures of Titan, down to -179 degrees C.
However, some startling research recently showed microbes metabolizing
down to -196 derees C:

1.08.2006 - Biologie
Colwellia ist echt cool
Die Mikrobe betreibt noch bei minus 200 Grad Celsius Stoffwechsel.
http://www.wissenschaft.de/wissen/news/268486

Here's the Babelfish translation:

================================================== ======
11.08.2006 - Biology
Colwellia is genuinely cool.

The microbe still operates with minus 200 degrees Celsius metabolism.

A bacterium named Colwellia gives still weak signs of life of itself at

temperatures of minus two hundred degrees Celsius. If this is made
possible by special antifreeze and enzymes, which produce the microbes
and which they protect against frost damages, researchers of the
university of Washington pointed to Seattle. This discovery does not
only show, which extreme minus degrees can bear terrestrial organisms,
they throw also a completely new light on the possibility of
extraterrestial life on icy heavenly bodies.

From a row types of bacteria it is well-known that they get along
problem-
free with temperatures of minus twenty degrees Celsius. They
live in the ice in tiny liquid vesicles, which are hardly larger than
them. The bacteria separate into these vesicles substances, which have
similarity with Xanthan. In addition, this substance is used in the
foodstuffs industry as thickener, can prevent the formation from ice
crystals to a temperature of minus two hundred degrees.

So far the scientists had assumed below a temperature of minus twenty
degrees Celsius no more metabolism is possible. But the results with
Colwellia push this border now far to the rear. So a group of
researchers could show around Karen boy of the university of Washington

for example that the microbes themselves form proteins at the
temperature of liquid nitrogen still. In addition the biologists
supplied some Colwellia cultures with the radioactively marked protein
component Leucin and examined afterwards whether in the bacteria
proteins with these marked components were. They came to the amazing
result that the bacteria insert small quantities of Leucin actually
still with minus 196 degrees Celsius into proteins.

A second researcher team of the university in Seattle examined those
scarcely 5,000 genes of the ice bacteria, in order to come the special
substances on the trace, which lend its strength to the microbes
against cold weather. The scientists encountered a whole set of
hereditary property goods, on which information for the education was
deposited by extremely effective insulation for cold proteins, explain
Jody Deming, chief of the working group.

These results demonstrated not only the extreme adaptability of
terrestrial organisms, but let also the existence of extraterrestial
life appear very many more probable than so far meant. The frozen
stores of water Mars come now likewise in principle as habitat for
micro organisms into question like the ice tank of the Jupitermonds
Europe.


New Scientist, 12 August, S. 35
================================================== ======


Jmilsom, on the Uplink.space.com site also quoted from the New
Scientist article:
------------------------------------------------------------------------------------
Psychrophiles - New possibilities for life in Solar Syst [
MeteorWayne]

That's absolutely fascinating.

This finding really is amazing and controversial. It's almost like the
martian meteorite or cold fusion announcements. If it proves true, it
really is quite a revolutionary finding about the tenacity of life.
Here is more background to the finding and process by which Colwellia
functions at very cold temperatures.

-----As the weather gets colder, Colwellia starts oozing a gloopy
concoction called exopolymer. This mixture of stringy, starch-like
molecules absorbs water and forms gels inside the ice veins. As
temperatures drop, expanding ice crystals suck water back out of the
gel, leaving the remaining water molecules isolated from one another.
"These pockets of water molecules are so small that ice nuclei can't
grow," says Christopher Krembs, a biological oceanographer at the
University of Washington. The result is a glassy state that is still
essentially liquid but resists freezing. No one knows how powerful the
exopolymer's effect is, but xanthan gum, a similar substance used in
the food industry, can prevent ice crystallisation at -200°C. Swaddled
in exopolymer, Colwellia is shielded from encroaching ice crystals that
would damage it, and from concentrated salts that would dehydrate it.

Colwellia's protective coating certainly does the trick. At -7°C the
bacterium zips around as quickly as our gut bacterium Escherichia coli
swims at body temperature. At -14°C it can still grow and divide, and
in sea ice at -20°C it continues respiring (Applied Environmental
Microbiology, vol 70, p550).

Last year Deming's [Jody Deming is the marine microbiologist at the
University of Washington that led the Colwellia genome sequencing team]
colleague Karen Junge brought Colwellia into the lab to test its cold
tolerance more precisely. To get a measure of its metabolic rate, she
incubated it at various temperature's between 13°C and -20°C to see
how quickly it incorporated a radioactively labelled amino acid,
leucine, into newly manufactured protein. As a control, she also
incubated Colwellia at -80°C. At that temperature even Colwellia, she
assumed, would be dormant or probably dead.

She was wrong, Colwellia built radioactive leucine into new protein at
all temperatures including -80°C. So Junge tried harsher conditions.
She plunged a tube of bacteria into liquid nitrogen, -196°C, and left
it for 24-hours. When she read the results she could hardly believe it.
Colwellia had again incorporated a small amount of the leucine into
protein.-----

-Source: Fox, Douglas "Sub-Zero Survivors," in New Scientist, Vol 191,
no. 2564, 12 August 2006, p36.

The article then explains how over many months she tried the experiment
again and again, believeing there must be a simple explanation, but
always got the same result. They also ran an experiment to rule out
purely chemcial processes, and concluded it must be biological. Her
work is published in the journal Cryobiology Vol 52, p417.
------------------------------------------------------------------------------------

Here's the abstract to the original journal paper:

Cryobiology. 2006 Apr 26;: 16647051 [Pubmed] [Scholar]
Bacterial incorporation of leucine into protein down to -20 degrees C
with evidence for potential activity in sub-eutectic saline ice
formations.
Karen Junge , Hajo Eicken , Brian D Swanson , Jody W Deming
"Direct evidence for metabolism in a variety of frozen environments has
pushed temperature limits for bacterial activity to increasingly lower
temperatures, so far to -20 degrees C. To date, the metabolic
activities of marine psychrophilic bacteria, important components of
sea-ice communities, have not been studied in laboratory culture, not
in ice and not below -12 degrees C. We measured [(3)H]-leucine
incorporation into macromolecules (further fractionated biochemically)
by the marine psychrophilic bacterium Colwellia psychrerythraea strain
34H over a range of anticipated activity-permissive temperatures, from
+13 to -20 degrees C, including expected negative controls at -80 and
-196 degrees C. For incubation temperatures below -1 degrees C, the
cell suspensions [all in artificial seawater (ASW)] were first
quick-frozen in liquid nitrogen. We also examined the effect of added
extracellular polymeric substances (EPS) on [(3)H]-leucine
incorporation. Results showed that live cells of strain 34H
incorporated substantial amounts of [(3)H]-leucine into
TCA-precipitable material (primarily protein) down to -20 degrees C. At
temperatures from -1 to -20 degrees C, rates were enhanced by EPS. No
activity was detected in the killed controls for strain 34H (or in
Escherichia coli controls), which included TCA-killed, heat-killed, and
sodium azide- and chloramphenicol-treated samples. Surprisingly,
evidence for low but significant rates of intracellular incorporation
of [3H]-leucine into protein was observed for both ASW-only and
EPS-amended (and live only) samples incubated at -80 and -196 degrees
C. Mechanisms that could explain the latter results require further
study, but the process of vitrification promoted by rapid freezing and
the presence of salts and organic polymers may be relevant. Overall,
distinguishing between intracellular and extracellular aspects of
bacterial activity appears important to understanding behavior at
sub-freezing temperatures."
http://lib.bioinfo.pl/pmid:16647051


Bob Clark

Robert Clark wrote:
snip

It had been argued that life could not survive on Titan even if liquid
water existed since biological chemical reactions would not persist at
the cryogenic temperatures of Titan, down to -179 degrees C.
However, some startling research recently showed microbes metabolizing
down to -196 derees C:
snip

Interesting paper, but the conclusions do not point towards metabolic
activity. In fact, the authors note: (lengthy quote ahead...)

"We hypothesize that the leucine tracer entered the bacterial cells not
at the sub-eutectic incubation temperature but during the Wrst seconds
of the freezing process, when liquid water was still present to
facilitate cross-membrane transport and the leucine concentration
gradient would have favored entry. (Some leucine incorporation also
occurred in these seconds, but time zero controls fully accounted for
it, as discussed above.) EPS produced by the test strain (whether
added or already present as a natural cell coating) would have
facilitated enzyme-mediated leucine transport and enhanced vitriWcation
[27]. As temperature dropped below the eutectic, diVusion-based
processes would no longer be infuential. Although leucine diffusivity
at ¡80°C would be orders of magnitude higher than at ¡196°C, the drop in
diVusivity is sharp below ¡120°C [33]; the similarity in measured
incorporation rates at ¡80 and ¡196°C argues against a diVusionlimited
incorporation process. Instead, only the leucine molecules that had
reached enzyme–ribosome–energy complexes in the Wrst seconds of freezing
would have been incorporated into protein, according to peptidyltransfer
activity within the ribosome reaction center that proceeds via subtle
conformational changes, reactions and electron transfers [5,32] still
possible in the glassy state [37]. In fact, only a small number of
leucine molecules were incorporated at sub-eutectic temperatures
(e.g., »2moleculesbacterium¡1h¡1 at ¡196°C for a total of »400 molecules
incorporated after 24h). Given the typical ribosome content of cultured
marine bacteria (many thousands per cell [22]) and average incorporation
frequency for leucine (one in six amino acids incorporated [24]), only a
small fraction of the ribosomes needed to be active to account for the
observed incorporation rates. This hypothetical scenario for
sub-eutectic activity deWnes new territory for further study."

So the interesting thing is low-temp protein dynamics, not low
teperature metabolic processes.


--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University

On Jan 12, 4:00 pm, Andy Resnick wrote:
RobertClarkwrote:

snip

It had been argued that life could not survive on Titan even if liquid
water existed since biological chemical reactions would not persist at
thecryogenictemperatures of Titan, down to -179 degrees C.
However, some startling research recently showed microbes metabolizing
down to -196 derees C:

snip
Interesting paper, but the conclusions do not point towards metabolic
activity. In fact, the authors note: (lengthy quote ahead...)

"We hypothesize that the leucine tracer entered the bacterial cells not
at the sub-eutectic incubation temperature but during the Wrst seconds
of the freezing process, when liquid water was still present to
facilitate cross-membrane transport and the leucine concentration
gradient would have favored entry. (Some leucine incorporation also
occurred in these seconds, but time zero controls fully accounted for
it, as discussed above.) EPS produced by the test strain (whether
added or already present as a natural cell coating) would have
facilitated enzyme-mediated leucine transport and enhanced vitriWcation
[27]. As temperature dropped below the eutectic, diVusion-based
processes would no longer be infuential. Although leucine diffusivity
at ¡80°C would be orders of magnitude higher than at ¡196°C, the drop in
diVusivity is sharp below ¡120°C [33]; the similarity in measured
incorporation rates at ¡80 and ¡196°C argues against a diVusionlimited
incorporation process. Instead, only the leucine molecules that had
reached enzyme-ribosome-energy complexes in the Wrst seconds of freezing
would have been incorporated into protein, according to peptidyltransfer
activity within the ribosome reaction center that proceeds via subtle
conformational changes, reactions and electron transfers [5,32] still
possible in the glassy state [37]. In fact, only a small number of
leucine molecules were incorporated at sub-eutectic temperatures
(e.g., »2moleculesbacterium¡1h¡1 at ¡196°C for a total of »400 molecules
incorporated after 24h). Given the typical ribosome content of cultured
marine bacteria (many thousands per cell [22]) and average incorporation
frequency for leucine (one in six amino acids incorporated [24]), only a
small fraction of the ribosomes needed to be active to account for the
observed incorporation rates. This hypothetical scenario for
sub-eutectic activity deWnes new territory for further study."

So the interesting thing is low-temp protein dynamics, not low
teperature metabolic processes.

--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University


Cryobiology. 2006 Apr 26;: 16647051
Bacterial incorporation of leucine into protein down to -20 degrees C
with evidence for potential activity in sub-eutectic saline ice
formations.
Karen Junge , Hajo Eicken , Brian D Swanson , Jody W Deming
http://lib.bioinfo.pl/pmid:16647051

This is a great paper if the results are valid. I
would even call it a revolutionary paper, if
confirmed. The paper also gives some very nice
references to life surviving in subfreezing
temperatures.
In their Discussion section, the authors do examine
some possible explanations for the observations but
their primary conclusion is that there is some
metabolic activity going on even down to -196C (!)
They note that the low rates of incorporation of the
radiolabeled leucine at the low subfreezing
temperatures were in keeping with the results of Price
and Sowers that metabolic activity at subfreezing
temperatures is sufficient only for maintenance
activities (such as DNA repair) but not growth
(reproduction):

Temperature dependence of metabolic rates for
microbial growth, maintenance, and survival.
P. Buford Price and Todd Sowers
PNAS|March 30, 2004|vol. 101|no. 13|4631-4636
http://www.pnas.org/cgi/content/full/101/13/4631

As explanation of how metabolic activity could have
occurred even down to liquid nitrogen temperatures,
Junge et.al. note that at rapid freezing rather than
water turning to ice it can convert to a semi-liquid
glassy form. This is referred to vitrification. They
hypothesize that metabolism can still take place with
water in this glassy state.

However, another possibility is suggested by another
recent startling research finding: water can remain
liquid inside carbon nanotubes down to -265C, only 8
degrees above absolute zero!

Nanotube Water Doesn't Freeze -- Even At Hundreds Of
Degrees Below Zero.
Science Daily - ARGONNE, Ill. (May 13, 2005) -- "A new
form of water has been discovered by physicists in
Argonne's Intense Pulsed Neutron Source (IPNS)
Division. Called nanotube water, these molecules
contain two hydrogen atoms and one oxygen atom but do
not turn into ice -- even at temperatures near
absolute zero."
http://www.sciencedaily.com/releases...0605183843.htm

Since this unusual capability of water is due to its
structure in its liquid compared to its solid forms,
this would probably also be true of other thin,
tubular macromolecules. The researchers note also that
some proteins have the function of conducting water
through the cell wall into the cell:

"Researchers ranging from biologists to geologists and
materials scientists are interested in water's
behavior in tightly confined spaces controlled by
hydrophobic -- water repulsing -- materials because
this situation is found in nature, for example when
tiny roots carry water to plants. Some membrane
proteins also face this challenge, including
aquaporin, which controls water flow through cell
walls."

Then conceivably some cellular proteins could have
the necessary structure to maintain the water in
liquid form down to cryogenic temperatures.
The nanotubes in this study were less than 2 nm
across however. Similar results though may hold at
larger diameters, though still at the nanoscale, at
higher cryogenic temperatures.
One type of protein to test this capability on for example
might be microtubules:

Microtubule.
http://en.wikipedia.org/wiki/Microtubule

These are 24 nanometers across. So there is some question
if the structural restrictions for the water phase change would
remain for water trapped in tubes at this larger diameter.
Even if it is shown that some biomolecules have the capability
to retain water in liquid form at cryogenic temperatures though,
there still would be the question of whether the radiotracer uptake
observed was due to metabolic activity at these temperatures.
In order to test this further I suggest a method devised by Lin Chao
as a test of astrobiology be used.

Defining Life
by Bruce Moomaw
Cameron Park - April 28, 2000
http://spacedaily.com/news/life-00w4.html

The Meaning of Life.
by Lin Chao
BioScience, March 2000, Vol. 50, No. 3, p. 245-250.

Chao notes that life has the ability to evolve when exposed to new
environments. He suggests successively transferring the putative life
forms to a new nutrient batch and observing whether or not they
become more efficient at utilizing the nutrients, in essence a test
to
see if they undergo natural selection and Darwinian evolution.
However, it appears in the Junge et.al. experiments that at the very
lowest temperatures, the microbes were only undergoing maintenance
activity; they weren't reproducing, which is required for the Lin
Chao
test.
The specific psychrophilic (cold-loving) bacteria used though can
reproduce at higher subfreezing temperatures. Then what might
work would be to perform the Lin Chao test at the lowest temperature
at which growth occurs. Then the strain selected (developed) by the
Lin Chao method would be better evolved to grow at this temperature,
and presumably it would show greater metabolic activity at the
cryogenic temperatures as well.



Bob Clark

On Jan 12, 3:00 pm, Andy Resnick wrote:
Robert Clark wrote:

snip

It had been argued that life could not survive on Titan even if liquid
water existed since biological chemical reactions would not persist at
the cryogenic temperatures of Titan, down to -179 degrees C.
However, some startling research recently showed microbes metabolizing
down to -196 derees C:

snip

Interesting paper, but the conclusions do not point towards metabolic
activity. In fact, the authors note: (lengthy quote ahead...)

"We hypothesize that the leucine tracer entered the bacterial cells not
at the sub-eutectic incubation temperature but during the Wrst seconds
of the freezing process, when liquid water was still present to
facilitate cross-membrane transport and the leucine concentration
gradient would have favored entry. (Some leucine incorporation also
occurred in these seconds, but time zero controls fully accounted for
it, as discussed above.)

I don't understand that. They first suggest leucine tracer entered
the cells during a given time period, then say some leucine
incorporation also occured during this period but was "fully accounted
for". Since "incorporation" and "entered the cells" ought to mean the
same thing, that doesn't make any sense, unless there is a difference
between "leucine tracer" and "leucine".

EPS produced by the test strain (whether
added or already present as a natural cell coating) would have
facilitated enzyme-mediated leucine transport and enhanced vitriWcation
[27]. As temperature dropped below the eutectic, diVusion-based
processes would no longer be infuential. Although leucine diffusivity
at ¡80°C would be orders of magnitude higher than at ¡196°C, the drop in
diVusivity is sharp below ¡120°C [33]; the similarity in measured
incorporation rates at ¡80 and ¡196°C argues against a diVusionlimited
incorporation process. Instead, only the leucine molecules that had
reached enzyme-ribosome-energy complexes in the Wrst seconds of freezing
would have been incorporated into protein,

They seem to be suggesting that diffusion has essentially shut down,
but that the ribosomes are still functioning somewhat, incorporating
nearby leucine molecules into protein. That sounds metabolic to me.

according to peptidyltransfer
activity within the ribosome reaction center that proceeds via subtle
conformational changes, reactions and electron transfers [5,32] still
possible in the glassy state [37]. In fact, only a small number of
leucine molecules were incorporated at sub-eutectic temperatures
(e.g., »2moleculesbacterium¡1h¡1 at ¡196°C for a total of »400 molecules
incorporated after 24h). Given the typical ribosome content of cultured
marine bacteria (many thousands per cell [22]) and average incorporation
frequency for leucine (one in six amino acids incorporated [24]), only a
small fraction of the ribosomes needed to be active to account for the
observed incorporation rates. This hypothetical scenario for
sub-eutectic activity deWnes new territory for further study."

So the interesting thing is low-temp protein dynamics, not low
teperature metabolic processes.

I'm not sure why you say this. Well... maybe. If there are
"thousands of ribosomes", and, and a given snapshot in time, roughly
one six were are the threshold of incorporating a leucine, then, if
one rapid freezing, the amino acid already in the assembly line just
pops into place as things come to a halt, that would account for 400
molcules incorporated.

A very delicate measurement, and made difficult by the necessity of
controlling for what happened during rapid cool down as opposed to
what happened after. It sounds like their methods are so sensitive
that they can catch the last creaking of the machinery as it comes to
a halt.

Anyway... I don't undersand the original thesis: is it necessary for
bacteria to metabolize at -179 degrees C, or merely survive? Is it
always that cold on Titan, or is that a cold day in February? And how
can there be liquid water present?

Edward Green wrote:
snip

Anyway... I don't undersand the original thesis: is it necessary for
bacteria to metabolize at -179 degrees C, or merely survive? Is it
always that cold on Titan, or is that a cold day in February? And how
can there be liquid water present?

Survival= metabolism. Otherwise, nothing happens, which is equivalent to
death. As for the other questions above, good points all.

As for all the snipped stuff, I was pointing out that it was important
to distiguish between metabolic processes initiated before and occuring
at the moment(s) of freezing, versus metabolic processes initiated and
occuring *after* freezing. The paper indicated that all of the results
could be explained by biochemical processes which were initated during
the freezing, not by reactions occuring after everything was cooled
down. If the enzymes have no substrate available, there is no action.
And no substate became available *after* freezing.


--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University

On Feb 16, 11:51 am, Andy Resnick wrote:
Edward Green wrote:

snip



Anyway... I don't undersand the original thesis: is it necessary for
bacteria to metabolize at -179 degrees C, or merely survive? Is it
always that cold on Titan, or is that a cold day in February? And how
can there be liquid water present?

Survival= metabolism. Otherwise, nothing happens, which is equivalent to
death.

Well, yes: but there might be a niche for organisms which could
survive bouts of cryogenic freezing with suspended metabolism
interspersed with relatively warmer periods, when they did their 3
F's. Isn't that the life cycle of some creatures in Antarctica
(albeit not quite so cryogenic... but cold enough)? On Titan, I take
it the warm periods would correspond to tidal vulcanism.

Or perhaps you are saying that even in Antarctica, some basal
maintenance metabolism continues even at the coldest temperatures, and
if that stops, the organism isn't coming back?

As for the other questions above, good points all.

As for all the snipped stuff, I was pointing out that it was important
to distiguish between metabolic processes initiated before and occuring
at the moment(s) of freezing, versus metabolic processes initiated and
occuring *after* freezing. The paper indicated that all of the results
could be explained by biochemical processes which were initated during
the freezing, not by reactions occuring after everything was cooled
down.

Well, that wasn't clear to me from the quoted passages.

If the enzymes have no substrate available, there is no action.
And no substate became available *after* freezing.

Though that was... it sounded like the last few substrate molecules
near the ribosome were picked up, though it was not 100% clear if they
could distinguish whether that happened during freezing, or after.

As for "death", I suppose the question would be if metabolism picked
up again on warm up, or if the molecular machinery had broken, the
elan vital fled (elan vital is scientifically known to reside in giant
coherent quantum wavefunctions :-).

Maybe the question for the far future could be,
would genetically engineered DNA and proteins
be able to metabolize at Titanic temperatures
if it were able to be made to function in an ethane
or propane solvent, or would some other complex
organic-like structures useing weaker bonding
be needed?

Probably Earth's water-solvent creatures could
be cryo-preserved on Titan but it is doubtful that
they would be able to function if all of their
molecules were prohibited from interacting,
because they would be encased in something
close to rock at those temperatures.

In article , Andy Resnick wrote:
Survival= metabolism. Otherwise, nothing happens, which is equivalent to
death. As for the other questions above, good points all.

Because of numerous examples of the apparently-dead being
resuscitated if "worked on" for long enough, the working definition of
death that I've been taught with respect to hypothermic victims is "death
is a failure to revive after return to normal body temperatures". By this
definition "nothing happens" is NOT equivalent to death (if the appropriate
environmental conditions of the organism is different to the conditions
under which you collect your sample).
Perfectly reasonable suggestions in this vein are that "really
interesting chemistry" (up to and possibly including what might be
described as "life") could happen only intermittently on Titan, for example
in the ice-lava lakes that follow on from medium-sized meteor impacts and
could persist for decades or even centuries.

[Relevant footnote : nylon and it's chemical precursors become
common chemicals about 1940 ; bacteria that can live using these decidedly
un-natural substrates for energy and carbon supply had appeared by the
early 1970s. "Really interesting chemistry" could happen in a few decades.]

--
Aidan Karley, FGS,
Aberdeen, Scotland
A light wave is more like a crime wave than a water wave.

My prediction is that if life is found elsewhere in the solar system,
it will have the same biochemistry as on earth. Thats because the
chances of interplanetary "infection" are much higher than multiple
origins. Two facts- many meteors from the Moon and Mars on earth have
been identified so far. These are probably a minscule number of those
that have reached Earth. Second, microbes have been found five miles
deep in earth in rocks that were buried hundreds of millions of years
ago. So there is a chance life can hitchhike on meteor rides between
planets and moons lasting hundreds of thousands of years.

Note I am not stating which planet life first orginated in this solar
system. I have a slight preference for Mars which because of its
smaller size may have had a stable environment for life a few hundred
million years before Earth stablized.

In article .com,
"rick++" wrote:

My prediction is that if life is found elsewhere in the solar system,
it will have the same biochemistry as on earth. Thats because the
chances of interplanetary "infection" are much higher than multiple
origins.

How do you know this?

Two facts- many meteors from the Moon and Mars on earth have
been identified so far. These are probably a minscule number of those
that have reached Earth. Second, microbes have been found five miles
deep in earth in rocks that were buried hundreds of millions of years
ago. So there is a chance life can hitchhike on meteor rides between
planets and moons lasting hundreds of thousands of years.

Hmmm. I'm not certain how you get from here to there.

Note I am not stating which planet life first orginated in this solar
system. I have a slight preference for Mars which because of its
smaller size may have had a stable environment for life a few hundred
million years before Earth stablized.

How long do you think it took Earth and mars to stabilize?

What does any of what you wrote have to do with the subject line?

--
Timberwoof me at timberwoof dot com http://www.timberwoof.com
"Like this cup," the master daid, "you are full of your own opinions and
speculations. How can I show you anything unless you first empty your cup?"