[meteorite-list] Did Life Arrive Before the Solar SystemEvenFormed?

From: Sterling K. Webb <kelly_at_meteoritecentral.com>
Date: Thu May 5 01:57:37 2005
Message-ID: <4279B5AD.B2D22E35_at_bhil.com>

Hi,

    Just a sort of footnote to my previous post on this topic. I forgot the most
obvious example of critters in space.
    On April 20, 1967, the Surveyor 3 spacecraft landed on the moon. Unknown to us,
it was carrying some uninvited passengers. When Surveyor 3 was being prepared for
launch, somebody apparently coughed on it, and a colony of a common bacteria,
Streptococcus mitis, was established on a piece of foam insulation that covered one
of Surveyor's circuit boards.
    The bacteria was discovered in 1969 when Apollo 12 astronauts Pete Conrad and
Alan Bean visited the wreck of Surveyor and saw something odd growing on the
insulation and brought back a piece of it. The bacteria had struggled along,
multiplying and growing for a while before they went dormant and were freeze-dried.
Once back on Earth, they were revived in a normal agar culture and started growing
again, while waiting for their chance to get back into a warm wet human throat and
give it a cough...
    For someone whose natural habitat was that warm wet human throat, I'd say they
handled life in a vacuum with a temperature range of +300 degrees C. to -250 degrees
C. every month pretty well.
    I also remember experiments done in the 1950's in which tiny creatures called
Tardigrades (also known as "water bears") were put into Mars Jars, meaning
simulations of the Martian evironment kept at the correct Martian temperatures,
pressures, atmospheres, near-waterlessness, and so forth. They thrived and
multiplied (although more slowly than on Earth). Although Tardigrades are tiny
(about 200 microns long!), they like us are complex multicellular organisms with
feet, guts, heads, eyes, and lots of other movable parts. (Although, they don't
have jaws because they have evolved a specialized "spear mouth" that doesn't need a
jaw -- they don't bite; they stab!)
    I quote: "Some tardigrades can survive in temperatures as low as minus 200
degrees Celsius (minus 328 F). Others can survive temperatures as high as 151
degrees C (304 F). Tardigrades can survive the process of freezing or thawing, as
well as changes in salinity, extreme vacuum pressure conditions, and a lack of
oxygen. Tardigrades also are resistant to levels of X-ray radiation that are
hundreds of times more lethal to humans and other organisms. This resilience stems
from the tardigrade's ability to survive without water."
    The quote is from NASA's ASTROBIOLOGY magazine, which had a nice article about
the "water bears" (with pictures). They look more like Gummi Bears, with the same
silly faces...
<http://www.astrobio.net/cgi-bin/h2p.cgi?sid=261&ext=.pdf>
    Now, what would happen if you snuck a tiny little capsule with about
100,000,000,000 Tardigrades onto the next Mars probe scheduled to land on the
surface? Instant Martians? I love a good experiment...


Sterling K. Webb
Received on Thu 05 May 2005 01:57:01 AM PDT