The space colonists
Reproduced from panspermia.org
“On April 20, 1967, the
unmanned lunar lander Surveyor 3 landed near Oceanus Procellarum on the surface
of the moon. One of the things aboard was a television camera. Two-and-a-half
years later, on November 20, 1969, Apollo 12 astronauts Pete Conrad and Alan L.
Bean recovered the camera. When NASA scientists examined it back on Earth they
were surprised to find specimens of Streptococcus mitis that were
still alive. Because of the precautions the astronauts had taken, NASA
determined that the germs were inside the camera when it was retrieved, so they
must have been there before the Surveyor 3 was launched. Apparently, these
bacteria had survived for 31 months in the vacuum of the moon's atmosphere.
Perhaps NASA shouldn't have been surprised, because there are other bacteria
that thrive under near-vacuum pressure on the earth today. Anyway, we now know
that the vacuum of space is not a fatal problem for bacteria.
What about the low
temperature and the possible lack of liquid water in space? The bacteria in the
camera recovered from the moon would have suffered huge monthly temperature
swings and the complete lack of water. Freezing and drying, in the presence of
the right protectants, are actually two ways normal bacteria can enter a state
of suspended animation. And interestingly, if the right protectants aren't
supplied originally, the bacteria that die first supply them for the benefit of
the surviving ones! English
microbiologist John Postgate discusses this fact in The Outer Reaches of
Life:
"When a population
of bacteria dries out without a protectant, many of the cells break open and
release their internal contents. Among these contents are proteins, gums and
sugars, all of which are protective. If the population is sufficiently dense,
so that significant amounts of protectant are released, material released from
the majority which died first can protect a few of their surviving fellows.
"Comparable
considerations apply to death from freezing.... Protective substances such as
glycerol are well known and widely used; they are called cryoprotectants. Bacteria
frozen without such chemicals leak internal contents, among which are many
substances that are cryoprotective."
Postgate says that
bacteria have apparently survived for 4,800 years in the brickwork of Peruvian
pyramids, and maybe even 300 million years in coal, using the drying strategy.
He also describes bacteria that apparently survived for 11,000 years in the gut
of a well-preserved mastodon, although in this case the colony may have
continued to live and multiply using nutrients available in the carcass.
Postgate gives several other examples of long-surviving bacteria, and he is
careful to mention the possibility that some of the bacterial cultures may have
been contaminated, so not all of the reports are necessarily reliable.
Some bacteria have
another even more effective survival strategy: they form spores. Spores are
bacterial cells in complete dormancy, with thick protective coats. In terms of
our computer analogy, a bacterial spore is like a handheld calculator that has
repackaged itself into its original protective shipping carton and turned
itself off.
"The resistance of
some bacterial cells to environmental destruction is impressive. Some bacteria
form resistant cells called endospores. The original cell replicates its
chromosome, and one copy becomes surrounded by a durable wall. The outer cell
disintegrates, but the endospore it contains survives all sorts of trauma,
including lack of nutrients and water, extreme heat or cold, and most poisons.
Unfortunately, boiling water is not hot enough to kill most endospores in a
reasonable length of time.... Endospores
may remain dormant for centuries".
Postgate concludes his chapter on spores, entitled "Immortality and
the Big Sleep," by saying, "There may be much older spores out there,
waiting for energetic microbiologists to revive them." And
there were.”
No comments:
Post a Comment