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June
21, 2007
EXPLORERS
USE ROBOTS
TO HUNT FOR LIFE ON ARCTIC SEAFLOOR
Scientists
and engineers from the Woods Hole
Oceanographic Institution (WHOI) have just completed a successful test
of new
robotic vehicles designed for use beneath the ice of the Arctic Ocean.
The
multidisciplinary research team will now use those vehicles to conduct
the
first search for life on the seafloor of the world’s most
isolated ocean.
WHOI
researchers have built two new autonomous
underwater vehicles (AUVs) and a new tethered, remote controlled
sampling
system specifically for the difficult challenges of operations in the
Arctic
ice. They hope to discover exotic seafloor life and submarine hot
springs in a
region of the ocean that has been mostly cut off from other ecosystems
for at
least 26 million years.
The
30-member research team will depart on
July 1 from Longyearbyen, Svalbard, for a rare expedition to study the
Gakkel
Ridge, the extension of the mid-ocean ridge system which separates the
North
American tectonic plate from the Eurasian plate beneath the Arctic
Ocean.
The 40-day cruise on the Oden—a 108-meter
long (354-foot) icebreaker
operated by the Swedish Maritime Administration—will take
researchers close to
the geographic North Pole.
The research team for the Arctic Gakkel Vents Expedition (AGAVE)
includes
specialists in each field of deep-sea exploration, with scientists and
engineers from the United States, Norway, Germany, Japan, and Sweden.
WHOI geophysicist Robert Reves-Sohn will serve as chief scientist. Fellow principal
investigators
include: Tim Shank, a hydrothermal vent biologist from WHOI; Hanumant Singh, a WHOI engineer and
vehicle developer; marine
chemist Henrietta Edmonds of the University of Texas at Austin, who
sailed on
the last research expedition to the Gakkel Ridge in 2001; Susan
Humphris, a
WHOI geochemist who has surveyed dozens of hydrothermal vent sites
around the
world; and Peter Winsor, a WHOI oceanographer who studies Arctic Ocean
circulation and its implications for climate.
Major funding for the expedition and for vehicle development was
provided by
the National Science Foundation (NSF) and the National Aeronautics and
Space
Administration (NASA).
“This is an exciting opportunity to explore and study a
portion of Earth’s
surface that has been largely inaccessible to science,” said
Reves-Sohn. “Any
biological habitats at hydrothermal vent fields along the Gakkel Ridge
have likely
evolved in isolation for tens of millions of years. We may have the
opportunity
to lay eyes on completely new life forms that have been living in the
abyss
beneath the Arctic ice pack.”
Most of the instrumentation that researchers would normally use to
study deep
sea environments and organisms—such as the human occupied
submersible Alvin or
tethered vehicles—cannot be safely operated in the Arctic
ice, which can easily
crush most small vehicles. So researchers asked Singh and colleagues to
design
and develop three new vehicles from scratch.
During the July expedition, researchers will use the Puma
AUV, or “plume
mapper,” to sniff out the chemical and temperature signals of
hot, mineral-rich
fluids venting out of the ocean floor. Once Puma
finds the source of
venting, Singh and colleagues will send down the Jaguar
AUV, which will
use cameras and bottom-mapping sonar systems to image the seafloor.
Finally,
the CAMPER towed vehicle will be lowered to the seafloor to scoop or
vacuum up
rocks, sediments, and living creatures.
During a 10-day engineering trial in May and June 2007, all three
vehicles were
lowered through the Arctic ice and driven underwater, while engineers
simultaneously tested acoustic communications techniques. The
researchers were
able to recover their vehicles from beneath the ice, which can be risky
in the
midst of moving floes that can quickly close the leads around an
icebreaker.
“Anyone can deploy an AUV in the Arctic; the trick is getting
it back,” said
Singh, who will send his vehicles to the seafloor for 10 to 24 hours at
a time
during the Gakkel expedition. “In order to have a good day
with autonomous
vehicles, the number of recoveries must equal the number of
launches.”
The Gakkel Ridge extends roughly 1,800 kilometers (1,100 miles) from
north of
Greenland toward Siberia. It is both the deepest ocean
ridge—ranging from 3 to
5 kilometers (1.8 to 3 miles) beneath the ice cap—and the
slowest spreading
tectonic plate boundary anywhere on Earth. The ridge moves roughly one
centimeter
(1/3 inch) per year, about 20 times slower than most other ridges.
At most mid-ocean ridges, Earth’s crust spreads apart,
allowing hot magma from
the mantle to come up and form new ocean crust. The enormous heat
sparks
chemical reactions between crustal rocks and the seawater that seeps
down into
them.
These chemical reactions produce hot, mineral-rich fluids that spew
like
geysers from seafloor vents, as well as massive deposits of minerals,
such as
copper and zinc. These hydrothermal fluids also contain chemicals that
sustain
rich communities of unusual life forms, which thrive via
chemosynthesis, rather
than photosynthesis.
Many geologists believed the Gakkel Ridge region would be too
geologically cold
to produce hydrothermal vents. And yet during a 2001 expedition,
researchers
found signs of such venting in the Arctic. Where there are vents, there
may be
unusual seafloor life forms.
“A few years ago, mid-ocean ridge and hydrothermal vent
biologists came
together and asked: ‘Where are the key places in the world to
go to make big
leaps in understanding biodiversity?’ The Gakkel Ridge was
one of the top
places,” said Shank, who plans to study the genetics of
animals found during
the expedition.
“The region has been mostly separated from the Atlantic and
Pacific oceans for
millions of years, so whatever lives there has since been evolving in
relative
isolation—much the way animals in Australia did," Shank
added. "We
know that deep-sea Arctic fauna found away from vents are more than 70
percent
different from all others around the world. So at hydrothermal vents we
are
likely to find completely new suites of species with never-before seen
adaptations.”
Some scientists—including program managers and scientists
from the NASA
Astrobiology Program—have been keenly interested in the
possibility that Gakkel
Ridge may harbor life forms and environmental conditions consistent
with
primordial Earth or other watery planets.
“The origin of life discussion comes up because the rocks
that are exposed on
this very slow spreading ridge are not volcanic, but instead come
directly from
Earth’s mantle,” said Humphris. “The
chemistry is very much like the volcanism
that occurred on the primordial Earth. If you are thinking about
origins of
life, you’d like to have an area that is the closest analog
to what was
happening on the early Earth.”
In July 2001, WHOI researchers were part of the Arctic Mid-Ocean Ridge
Expedition (AMORE) that produced the first detailed maps of the Gakkel
Ridge
and made the unexpected discovery that the ridge is volcanically
active.
Scientists also found that large sections of Earth’s mantle
appear to be
deposited directly onto the seafloor along the Gakkel Ridge.
The Gakkel Ridge expedition will be covered live on the web, allowing
students,
educators, and the general public to follow along with daily dispatches
from
the Arctic Ocean. The Dive
and Discover web site
brings students and
teachers along on research field trips to read about science in action,
while
the Polar
Discovery project
uses photos and live phone calls from the Oden to
allow museum visitors
and the public to see the Arctic through the eyes of the explorers.
Support for the Gakkel Ridge expedition
and for underwater vehicle development has been provided by the
National
Science Foundation’s Office of Polar Programs and Division of
Ocean Sciences;
the NASA Astrobiology Program; the WHOI Deep Ocean Exploration
Institute; and
the Gordon Center for Subsurface Sensing and Imaging Systems, an NSF
Engineering Research Center.
The Woods Hole Oceanographic Institution is a private, independent
organization
in Falmouth, Mass., dedicated to marine research, engineering, and
higher
education. Established in 1930 on a recommendation from the National
Academy of
Sciences, its primary mission is to understand the oceans and their
interaction
with the Earth as a whole, and to communicate a basic understanding of
the
ocean's role in the changing global environment.
##
Contact: Media
Relations Office
media@whoi.edu
508-289-3340
Woods Hole
Oceanographic Institution
This
text derived from:
http://www.whoi.edu/page.do?pid=7545&tid=282&cid=28811&ct=162
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