Matthew Bettino 2/6/13
Block C Davies
The Antarctic ice sheet is the largest
single piece of ice on the planet. Recently, the National Science Foundation of
America invested $10 million into ice drilling in the Antarctic. The goal of
these drilling expeditions is to locate and drill to lakes under the thick
sheet of ice. About half a mile under the surface of the ice sheet is a system
around one hundred lakes. These lakes are wedged in between the continental
crust and the ice sheet on top. Lake Whillans was one of these lakes. Lake
Whillans spans about 23 square miles and is about 5 feet deep. When the US
drills finally reached this lake, scientists discovered mind-changing things.
Half a mile below a pure sheet of ice lives bacteria. The inhabitants of Lake
Whillans were chemically tested and were found to be fully alive. This
discovery changes the way scientists understand the possibility of
extraterrestrial life forms. Down in these deep, cold conditions, the bacteria
have no access to light. Therefore, to obtain the necessary energy to metabolize,
the bacteria are forced to rely on another source. Scientists determined that
these bacteria were consuming the decaying remains of microbes found in the
receding glaciers. However, Chris McKay of NASA said the bacteria would be of
even more interest if they were consuming another body of energy. One clue of
life that led to the discovery was the location of DNA in cells they observed.
The DNA that has been collected is still to be analyzed. Scientists are hopeful
that the DNA testing will shed even more light on the topic of sub-ice
creatures and their relationship with extraterrestrial life.
This
discovery is important to science because it gives scientists more evidence
that life can thrive under extreme conditions and without sunlight. An example
similar to this discovery was one made under the ocean. On our trip to the
Museum of Natural History in Earth Science, we came across an exhibit about
black smokers or underwater sea vents. These vents are located so deep in the
ocean, scientists believed that the pressure, temperature, and lack of light
would not allow for life to survive. However, a whole ecosystem was discovered
around the smokers. The life living down there used chemosynthesis, a process
of using the chemicals produced by the black smokers to create necessary
energy. This discovery showed scientists how life could survive without access
to things humans and other surface organisms need to survive. This discovery of
bacteria living deep under ice depicts another way life can survive under
extreme conditions. The ability of life to adapt and survive based on its
environment has led scientists to believe that life could survive on other
planets in or solar system or beyond. I chose this article because I am very
interested in astronomy and the possibility of life beyond our knowledge. This
topic has limited information available to use as proof. It is exciting when I
hear that scientists took another step in the direction of determining how
extraterrestrial life could survive.
I
thought that this article was well written. The author explained details in
understandable terms and clearly showed how the discovery was important to
science. However, the article was written in a way that the facts and data
collected were presented first, while the actual process came second. I think that the details about funding
and set-up of the operation should have followed the brief summary of what was
discovered. The more pinpoint details should have followed. Also, the
description of the DNA found in the lake was jammed in at the end of the
article. This information seemed to be relevant and interesting. I wish the
author would have spent more time discussing the discovery and possible
importance of the DNA collected in Lake Whillans. Overall, I really enjoyed
reading this article. It enriched the knowledge I already possess on a topic I
really enjoy.
Bibliography:
Gorman, James. "Bacteria Found
Deep Under Antarctic Ice, Scientists Say." The New York Times. The
New York Times, 07 Feb. 2013. Web. 06 Feb. 2013.
Bacteria Found Deep Under Ice, Scientists
Say, Opening New Antarctic World
Published: February 6, 2013
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For the first time, scientists report, they have
found bacteria living in the cold and dark deep under the Antarctic ice, a discovery that
might advance knowledge of how life could survive on other planets or moons and
that offers the first glimpse of a vast ecosystem of microscopic life in
underground lakes in Antarctica.
Dr. Alberto Behar, JPL/ASU; underwater camera funded by
NSF and NASA
The first view of
the bottom of subglacial Lake Whillans in Antarctica.
A network of hundreds of
lakes lies sandwiched between the continent’s land and the ice that covers it,
and scientists had thought that it could harbor life. The discovery is the
first confirmation.
“It transforms the way we
view the Antarctic continent,” said John C. Priscu of Montana State University,
a leader of the scientific expedition.
After drilling through a
half-mile of ice into the 23-square-mile, 5-foot-deep Lake Whillans, the
expedition scientists recovered water and sediment samples that showed clear
signs of life, Dr. Priscu said, speaking from McMurdo Station in Antarctica on
Tuesday. They saw cells under a microscope, and chemical tests showed that the
cells were alive and metabolizing energy.
Dr. Priscu said that every
precaution had been taken to prevent contamination of the lake with bacteria
from the surface or the overlying ice. In addition, he said, the concentrations
of life were higher in the lake than in the borehole, and there were signs of
life in the lake bottom’s sediment, which would be sealed off from
contamination.
Much more study, including
DNA analysis, is needed to determine what kinds of bacteria have been found and
how they live, Dr. Priscu said. There is no sunlight, so the bacteria must
depend on organic material that has drifted into the lake from other sources —
for instance, decaying microbes from melting glaciers — or on minerals in the
rock of the Antarctic continent.
Chris McKay, a NASA senior
scientist, said in an e-mail that such analysis could determine if the bacteria
in Lake Whillans have implications for the possible discovery of
extraterrestrial life. “If it was using a local energy source, it would be
interesting,” he said. “If it’s just consuming organics carried in from
elsewhere, it is of much less interest.” The reason, he said, is that elsewhere
in the solar system where there is good evidence of liquid water under thick
ice sheets, life would have to depend on minerals alone. “There is not going to
be oxygen on other worlds,” Mr. McKay said.
Slawek Tulaczyk of the
University of California, Santa Cruz, another leader of the science expedition,
said that samples were drawn from as deep as four feet in the sediment, and
that oxygen decreased with the depth of the sample.
The scientific project,
called Wissard, for Whillans Ice Stream
Subglacial Access Research Drilling, was years in the planning and is one of
three efforts to investigate the lakes that lie under the Antarctic ice.
A year ago, a Russian expedition penetrated the surface of Lake Vostok, under two miles of ice.
They found hints of life on samples from the drill bit, but contamination from
the kerosene drilling fluid was a possibility. This year they recovered samples
of frozen lake water that are yet to be analyzed.
A British effort to reach
Lake Ellsworth, under a mile of ice, was called off in December because of
equipment problems.
The American effort,
supported by $10 million from the National Science Foundation and other grants,
focused on Lake Whillans, which is quite different from the other two lakes. It
lies under a half-mile of ice, less than the others, and its water is
replenished in about a decade, scientists believe, with meltwater from
overlying ice. Lake Vostok is much more sealed off from the surface and is
thought to take 10,000 years for its waters to renew. Lake Ellsworth may turn
over in about 700 years.
Although Lake Whillans may
be more reachable than the other two, doing anything in Antarctica is
enormously difficult. It took a tractor convoy 12 days to take the drill and
other equipment more than 500 miles over the Ross Ice Shelf to the drilling
site from the American research station at McMurdo.
The scientists had four
days to collect samples and obtain images of the lake. Several lines of
evidence convinced them that they had found microbial life in the lake. First, they
saw cells under the microscope and confirmed that DNA was present.
Then they measured evidence
of an enzyme that is important in metabolism and a chemical called ATP, for
adenosine triphosphate. Molecules of ATP are essentially packets of energy, and
their presence was a further indication that the bacteria were living. Further,
they found that concentrations of ATP were higher in the lake water than in the
water in the borehole, which, Dr. Priscu said, meant that there was more life
in the lake and argued against any contamination.
Much further study will be
done before scientific results are published and other scientists can look at
all the data. Dr. Priscu said that new tests were being done each day, but that
DNA tests would have to wait until the scientists returned to the United
States.
“Our stateside DNA sequence
work will tell us who they are,” he said of the microbes, “and, together with
other experiments, tell us how they make a living.”
But he said he was confident that the
researchers had achieved the first glimpse of an ecosystem that had been
completely unknown. “It’s the world’s largest wetland,” Dr. Priscu said.