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
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
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
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,
Mussels and crabs line a vent site near the Galapagos.
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.
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.