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Why we can't go to Mars (yet)



 
 
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  #11  
Old January 12th 04, 01:22 PM
Mike Miller
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Default Why we can't go to Mars (yet)

"R F L Henley" wrote in message .. .

unless and until we have robotically established conclusively that there is
or is not life on Mars, we can't put humans on the planet because they will
inevitably bio-contaminate it.


Anyone agree?


No. Mars has already been biocontaminated. I think the Russians didn't
bother to decontaminate their 1971 lander and I don't think the
Vikings were held to exacting standards of decontamination, either.

Considering how inhospitable Mars is to terrestrial life, I say let
the astronauts go. If the microbes on their suits and in any dumped
turds and pee can prosper on Mars...go Earthlife!

Mike Miller, Materials Engineer
  #12  
Old January 12th 04, 02:41 PM
Poliisi
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Default Why we can't go to Mars (yet)

No. But I suspect that the first men going to Mars might
well stay in orbit and direct rovers more quickly; with a
time lag of seconds instead of many minutes, they can do
a lot more.


I think not, the current rovers will find their own path, mission
controllers just tell the general directions. If i remember correctly, the
Sojourner (or what was it) almost flipped over because the mission
controllers wanted to manually control its moves and ended up rotating over
huge (2x rover size) rock. After that they switched back to AI.

I bet the Spirit could drive to distant rock with single command.
  #13  
Old January 12th 04, 08:36 PM
Henry Spencer
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Default Why we can't go to Mars (yet)

In article ,
Mike Miller wrote:
No. Mars has already been biocontaminated. I think the Russians didn't
bother to decontaminate their 1971 lander and I don't think the
Vikings were held to exacting standards of decontamination, either.


Sorry, wrong: the Viking landers were quite carefully sterilized, and if
memory serves, the Russians made at least some attempt to sterilize their
landers too.

More recent landers, e.g. Mars Pathfinder, generally have *not* been
sterilized, because it is now fairly certain that conditions on the
Martian surface are so hostile that it's virtually impossible for Earth
organisms to survive and spread. Attempts are still made to reduce the
"biological load" carried, e.g. by careful cleaning, to minimize possible
interference with future life-detection experiments. (And of course, any
probe which carries life-detection experiments -- as Beagle 2 did -- must
be sterilized to avoid false alarms.)
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |
  #14  
Old January 12th 04, 09:22 PM
Raven
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Default Why we can't go to Mars (yet)

"Steen Eiler Jørgensen" skrev i en meddelelse
. ..

Should human activity on Mars bio-contaminate the surface, it should be no
problem for a trained biologist to spot the difference between terrestrial
microbes and organisms never encountered before.


Not necessarily. If Terran microorganisms are introduced to Mars, and
some of them survive and actually grow, they will be subject to an enormous
selection pressure. A few decades might change them beyond easy
recognition. Do microorganisms have enough junk DNA, which is not subject
to selection pressure, to establish kinship?
Also, there is the possibility that Earthlife has already been introduced
to Mars, a very long time ago. Imagine a large meteorite strike on Earth;
some of the ejecta somehow reaches Earth escape without being cooked, and
Terran microorganisms survive in hibernation, well protected within the
rock. Then this rock impacts Mars, in such a way that the central parts of
the rock is not cooked. Discovering Mars-life with this particular kinship
to Earthlife would be a considerable scientific find.

Jon Lennart Beck.

  #15  
Old January 13th 04, 11:40 AM
Steen Eiler Jørgensen
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Default Why we can't go to Mars (yet)

Raven wrote:

Not necessarily. If Terran microorganisms are introduced to Mars,
and some of them survive and actually grow, they will be subject to
an enormous selection pressure. A few decades might change them
beyond easy recognition.


"A few decades" - most certainly. I don't see it as a problem for the first
handful of human missions. Besides, you wouldn't start looking for Martian
life right below the habitation module. You'd probably go hundreds - perhaps
thousands - of meters away from the base. Considering that the Martian
surface is very hostile to organic life (oxidizing agents in soil, strong UV
radiation), the probability for terrestrial germs to blow around in the wind
AND for us to discover these germs is very small.

Also, there is the possibility that Earthlife has already been
introduced to Mars, a very long time ago. Imagine a large meteorite
strike on Earth; some of the ejecta somehow reaches Earth escape
without being cooked, and Terran microorganisms survive in
hibernation, well protected within the rock. Then this rock impacts
Mars, in such a way that the central parts of the rock is not cooked.
Discovering Mars-life with this particular kinship to Earthlife would
be a considerable scientific find.


Absolutely. But I see it this way: If Mars is - or was ever - capable of
sustaining life - and that's what we're trying to figure out - traces of
this life should be present all over the planet. The idea of Mars as overall
frigid and sterile, *apart* from unmistakeable signs, only found in e.g. the
Hellas Basin, that Mars supported life long enough for it to develop, is -
as I see it - extremely improbable. If life ever evolved on Mars, we should
be able to find traces of it over most of the planet.

Of course, if we find only small traces of what could appear to be
terrestrial life brought to Mars billions of years ago, we'd probably find
it only in specific locations.

--
Steen Eiler Jørgensen
"Time has resumed its shape. All is as it was before.
Many such journeys are possible. Let me be your gateway."


  #16  
Old January 13th 04, 12:45 PM
Simon Laub
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Default Why we can't go to Mars (yet)

"Raven" ro.com wrote in
message ...
"Steen Eiler Jørgensen" skrev i en

meddelelse
. ..

Should human activity on Mars bio-contaminate the surface, it should be

no
problem for a trained biologist to spot the difference between

terrestrial
microbes and organisms never encountered before.


Not necessarily. If Terran microorganisms are introduced to Mars, and
some of them survive and actually grow, they will be subject to an

enormous
selection pressure. A few decades might change them beyond easy
recognition. Do microorganisms have enough junk DNA,


I wish people would stop calling the "non protein coding" part of DNA for
junk.
See e.g. Scientific American, nov 2003 for the latest on this.

which is not subject
to selection pressure, to establish kinship?


hmmm, again I think you are assuming junk here. As it is not (junk), it must
be fair to argue that there is selection pressure on these parts as well.

Also, there is the possibility that Earthlife has already been

introduced
to Mars, a very long time ago.


And hopefully more to come! Ok, lets scan Mars for life, but surely it
shouldn't hold back exploration of the planet.

-Simon



  #19  
Old January 15th 04, 05:05 PM
Henry Spencer
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Default Why we can't go to Mars (yet)

In article ,
Mike Miller wrote:
More recent landers, e.g. Mars Pathfinder, generally have *not* been
sterilized, because it is now fairly certain that conditions on the
Martian surface are so hostile that it's virtually impossible for Earth
organisms to survive and spread.


Well, you learn something every day.
Old: clean. New: sloppy.


I should have added that there's a *reason* for this: sterilizing a
spacecraft is difficult. It's hard to make chemical sterilization work
well enough, and heat sterilization is terribly hard on electronics.
(Sterilization-induced failures are thought to have been a contributing
factor in the dismal early history of the Ranger program; the reforms that
got Ranger out of its mess included discontinuing sterilization.)
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |
 




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