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Posted by baalke on September 10, 2006, 11:59 pm
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http://www.jpl.nasa.gov/news/features.cfm?feature=1166
Exploring Europa by Way of the Arctic
Written by: Annie Carone
Media contact: Carolina Martinez (818-354-9382)
Jet Propulsion Laboratory
September 08, 2006
This summer, a science team set out on a two-week expedition of Earth's
own little version of Jupiter's moon Europa -- the Borup Fiord Pass at
Ellesmere Island, a place hidden high above the rest of the world in
the
Canadian High Arctic.
The team, headed by Canadian geologists Drs. Stephen Grasby and Benoit
Beauchamp, included Dahmnait Gleeson, a grad student who works under
JPL
scientist and Europa specialist Dr. Bob Pappalardo.
Ellesmere Island's sulfur-rich springs leave large, telltale yellow
stains on the surface, comparable to those observed on Europa. The team
conducted on-site experiments, gathering samples in near-freezing
temperatures to find out what the stains on Borup Fiord could tell them
about this unique environment. To do this, they had to study the
geology, biology and chemistry of the sulfur-rich springs. While the
whole team had a part in seeing how closely Borup Fiord corresponds to
Europa, this responsibility fell mainly on Gleeson, a University of
Colorado grad student who was doing field work for her Ph.D.
"We can't figure out where exactly the sulfur is from," Gleeson said,
and until they can do further tests, the team must wait to see why this
sulfur is surfacing in such abundance. In the meantime, Gleeson and
Pappalardo have come closer to understanding this unusual environment
from what they know about sulfur. The observed forms of sulfur are "an
unusual chemical combination," says Pappalardo. If regular geology was
involved, all that should be found is gypsum, an oxidized form of
sulfur.
Gleeson explains, "Finding so much sulfur is the clue that there's a
continuous supply of it being produced, otherwise it would have become
gypsum." Pappalardo says that while scientists might expect to find
gypsum, other forms of sulfur exist there, such as hydrogen sulfide
(its
smell is often compared to that of rotten eggs) and native sulfur,
which
he describes as the plain and purest form of sulfur.
"It's out of the norm," Pappalardo says. "Biology is expected to play a
part in this. The fact that all [these forms of sulfur] were present in
close proximity suggests that life is involved." While Pappalardo
acknowledges that Europa's outer surface contains too much radiation to
ever support life, these findings could help answer the question as to
whether life could exist below the surface of Europa. Further research
can also help us to better understand how best to make future
spacecraft
observations of Europa.
Partial funding was provided by The Planetary Society, whose members
are
excited to see what this piece of Arctic land can tell us about
Jupiter's moon.
While on the excursion, which occurred earlier in the summer than it
had
in past years, the team also found the sulfur-rich springs may have
been
active during the winter. Gleeson states the sulfur layers were there
during the winter months, but were simply covered by snowfall. The team
realized that the later in the season they go, the more the spring
water
is going to be diluted when combined with melting snow. If they were to
go in spring, they now suspect that the water would be much less
diluted
and they would be able to tell if the springs were active at that
point,
as well.
On a future excursion, Pappalardo would like to bring out equipment and
instruments to detect microbial activity on the island's subsurface
similar to the types of instruments that one day might be used at
Europa.
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