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Birth of an Expedition
by Peter Tyson
Imagine taking a chain saw to a stalagmite. Imagine that
stalagmite is not in a cave but on the seafloor a mile and a
half down, and it is spewing toxic, scalding fluid, like a
garden hose from hell. There is not the faintest glimmer of
light, the surrounding seawater is a degree or two above
freezing, and the pressure is enough to squeeze you into a
stick figure faster than you can say boo.
Luckily, you're not there. You're 7,000 feet up in a research
ship bobbing lazily in the northeast Pacific. Your hands grip
joysticks and your eyes are fixed on a video screen before
you. There, on the monitor, you can see the "black smoker"
chimney, as that stalagmite-like geyser is known. It is being
filmed live from a video camera mounted on a remotely operated
vehicle, which you're controlling from the other end of a long
tether. You can also see the business end of the chain saw,
which is also mounted on the robot.
Your name, by the way, is
Keith Shepherd,
and you're about to try what no one has ever tried before: saw
down a black smoker and have it lifted to the surface.
Shepherd, a submersible pilot from the Canadian Scientific
Submersible Facility in Sidney, British Columbia, is one
member of an ambitious oceanographic expedition to retrieve
one or more black smokers from the Juan de Fuca, an undersea
ridge about 200 miles west of Seattle, Washington. Scientists
want to study a black smoker in the comfort of their own labs,
because these unassuming towers of rock may just hold clues to
how volcanoes can support life, how life got started on Earth,
and even how it could exist on other planets.
Brave new world
In a way, this expedition had its genesis in 1977. That year,
geologists made a series of astonishing discoveries during
dives in a submersible to the seabed near the Galapagos
Islands. They were looking for hydrothermal vents, cracks in
the seafloor where seawater that has seeped into the ocean
floor and come into contact with superheated rock rushes back
up at scalding temperatures. Before this dive, scientists
could only hypothesize that such vents existed, and that they
were the place where new planetary crust was formed.
The scientists found the vents, lending support to the notions
of seafloor spreading, plate tectonics, and continental drift.
But the researchers also stumbled upon something wholly
unexpected: life forms living in the pitch dark,
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Mussels and crabs line a vent site near the
Galapagos.
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crushing pressures, and severe temperature extremes at vents.
These animals superficially resembled creatures already known,
including mussels, clams, crabs, and tubeworms. But they
proved to be radically different. They relied for energy not
on sunlight, as all other life does, but on chemicals bursting
forth from the Earth's interior.
Not long after that historic dive, other scientists came upon
their first black smoker chimneys. They are called black
smokers because they belch particle-laden, superheated water
that looks like black smoke. The particles, composed primarily
of sulfides, precipitate in a constant rain to form, directly
below the belching smoke, an ever-growing chimney of stone.
Black smokers look like miniature volcanoes in a constant
state of eruption. Besides the particles, the eruptive
material includes hydrogen sulfide, a chemical that
heat-loving bacteria help convert into food for creatures
higher up the food chain. Black smokers, which are a form of
hydrothermal vent, make ideal homes for that strange community
of life first seen in 1977.
Black smoker erupting on the Juan de Fuca Ridge.
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These oases in the deep sea (see
Living at Extremes) led some scientists to wonder whether life itself might
have begun at hydrothermal vents, or at least in an
environment much like it. Taking that notion and running with
it, other researchers began to speculate whether other planets
that have similar conditions might also harbor such life; one
candidate is Jupiter's moon Europa. They were getting into big
questions, questions whose answers could only be approached
through intense study of the geology and biology of black
smokers. But studying black smokers in their natural habitat
is as daunting a task as studying rocks on Mars.
Continue: An expedition is born
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