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10/20/2004
Microbes Hitching Rides to Mars
Last week we discussed equipment malfunction in the Genesis
capsule, which failed to deploy its parachutes and crashed to
earth. Now I see that an AP news report by John Antczak posted
on AOL News says that backward engineering drawings may
have caused the failure! Gemini was equipped with two pairs of
gravity switches; each pair was to activate one parachute. With
the backward drawings, the switches were placed in the wrong
positions. Whether this mistake is responsible for the parachutes
not deploying is uncertain and the investigation continues.
In contrast, the Martian rovers Opportunity and Spirit are both
performing admirably well beyond the expected times for their
demises. The August 6 issue of Science contains 12 papers on
the findings of the Spirit rover in the Gusev Crater on Mars. The
papers deal with topics such as evidence of water in Mars’ past,
wind directions on the planet, erosion of the rocks, compositions
and magnetic properties of rocks and dust, etc. We’ll probably
end up knowing more about Gusev Crater than we know about
most craters here on Earth. One uncontrollable factor that will
bring the rovers to a halt will be a buildup of dust on the solar
panels that will block the Sun’s feeble rays and power will be
lost. Meanwhile, they’re still roaming around supplying mission
scientists with data for many more papers in the future.
Genesis’ mission was to sample bits of the Sun via the solar
wind, providing clues on the formation of our solar system.
Opportunity and Spirit are charged with finding evidence of what
happened on one planet well after the solar system formed. Of
course, the Holy Grail of any planetary mission would be to find
existing life or evidence of life in the planet’s past.
But there are serious questions that must be answered. If there is
life on other planets, would we be able to recognize it as life?
Are we contaminating Mars with life carried there by our rovers
and our orbiters? We’ll see shortly the answer to this question is
quite likely to be yes! If this happens, are we seeding life on the
planet and could it evolve into something quite different from
life here on Earth?
Kasthuri Venkateswaran, of NASA’s biotechnology and
planetary protection group, is asking such questions in NASA’s
Spacecraft Assembly Facility (SAF) located in the foothills of
Pasadena, California. Venkat, as he’s called, looks for bugs,
microbes that live on or in the spacecraft being assembled in
SAF. I learned of his work in an article by Alan Burdick titled
“Seeding the Universe” in the October Discover magazine and
found more about the work on the NASA Web site.
It shouldn’t be surprising to find bugs in the SAF. After all, we
humans assemble the spacecraft and we’re loaded with all kinds
of critters. In spite of all the clean rooms and special gowns and
hats and shoes and gloves, we can’t help shedding stuff off our
skin, our hair, even off our eyeballs! Efforts are made to sterilize
the components of the spacecraft by heating and by chemical
treatments but some items, such as printed circuits and electronic
devices, don’t take too well to being heated.
Venkat has been surprised by some of the bugs that he and his
colleagues have found on their spacecraft. Most are microbes
known to thrive in harsh, dry environments found in the nearby
deserts but some are new to the biological community. In fact,
the speculation is that some of these microbes may have evolved
specifically to thrive in the SAF. For example, there’s Bacillus
pumilis, which was found on the Mars Odyssey orbiter and on
Spirit and Opportunity. B. pumilis actually thrives on traces of
aluminum and titanium on the surfaces of the spacecraft! And
three strains of B. pumilis have survived treatments in a sterilizer
containing hydrogen peroxide vapor.
B. pumilis also resists desiccation by forming spores that
aggregate together to form what look like little macaroons. Cut
open the macaroons and there’s no evidence of B. pumilis; the
microbe just seems to have dissolved into its surroundings. But,
add a tad of moisture and B. pumilis is back in business. If life
on Mars resembles this microbe, it will take one clever robot to
know it’s alive! It isn’t as though the biological community
wasn’t aware of B. pumilis. It’s been widely studied for years
but Venkat suspects that the SAF version is a new substrain that
has evolved to live in the hostile conditions it found in the SAF.
There’s also Bacillus safensis (named for its SAF environment),
which appears to be an offspring of B. pumilis. B. safensis is
resistant to gamma rays, high doses of which can kill most
microbes and can kill us humans. Without the protective
atmosphere we have on Earth, Mars is a hotbed of gamma
radiation. Bacillus odesseyi is a microbe with a double spore
layer that offers it super protection from gamma rays and it’s
named after the Mars orbiter Odyssey. B. odesseyi has been
circling Mars on its habitat, the Odyssey orbiter, for three years
now. Is it still alive? How about B. pumilis on the rovers?
These microbes obviously are hardy critters, with a will to
survive under very harsh conditions. Will they manage to
clamber down off their rovers or drift down from their orbiters
onto the Mars surface? If so, what happens then? Can they
evolve to flourish on Mars, perhaps searching out some of that
moisture that’s been found either in frost or in hydrated chemical
compounds? We’re back where we started. If these microbes
we’ve brought along to Mars do evolve and we later find them,
will we be able to recognize the evolved microbes as ours or will
we be tricked into thinking we’ve found native Martian life?
Hey, if we find any life, even if we’re fooled, it would be life
thriving on a world bombarded by radiation, probably devoid of
liquid water and with a hostile tenuous atmosphere. To my
mind, such a discovery would demonstrate forcefully that some
form of life is likely on other planets in other solar systems
throughout the universe.
The thought just occurred to me that we should really go back to
the Moon to check out the areas where we’ve been. With all the
traipsing around that we’ve done on our satellite, we must have
shed zillions of microbes. If we revisit those sites, we may find
some still living or even evolving to exist in a truly hostile
environment. Just a thought.
Allen F. Bortrum
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