Little
did Bucknell University geology professors Craig Kochel and Jeffrey Trop know,
as they were working in Alaska, that they would soon predict one of the most
important planetary observations ever made.
The
pair was in Alaska for an eight-day trip in July 2006, studying geological
features and the processes that create them. As they studied photographs taken
of the surrounding area, some features caught Kochel's eye. He thought they
were strangely familiar, and then realized they reminded him of images he'd
seen when working on the Viking
missions to Mars in the 1970s.
Kochel
and Trop trekked to where the shots were taken overlooking a glacier. Spotting
triangle-shaped landforms called "fans" sealed the deal: They looked
strikingly similar to photographs taken of features on Mars.
Mystery solved
Although
geologists can usually tell what shapes the landscape around us, it was a
mystery what formed the Mars-like features found in Alaska.
The
conditions on Mars are quite different than anything experienced on Earth. For
example, Mars is much colder than even the Arctic — the
average martian temperature is -81 degrees F (-63 degrees C) — and the
planet's atmospheric pressure is lower than Earth's. Still, for the same
features to be present on Earth and Mars, the two professors suspected similar
processes would have made them.
They
had just over a week in Alaska to discover what created the glaciers and fans.
During
this time they managed to see an impressive 289 events, including rock falls
and floods. The vast majority of these events were snow and ice avalanches. The
frequency of these avalanches astounded the scientists, who reasoned that
climate change was the most likely culprit. As temperatures rise, the glaciers
pull back, creating large areas where ice has been separated. Material can fall
down these cracks and lead to avalanches. This was creating the features seen
in Alaska, and perhaps the same thing had happened on Mars.
An astounding prediction
Realizing
the importance of this discovery, Kochel and Trop presented their findings to a
NASA lunar and planetary science meeting. Their comparisons were based on older
photographs of Mars, but the HiRISE
camera aboard NASA's Mars Reconnaissance Orbiter was sending back new
pictures which further confirmed the idea of avalanches on Mars.
Kochel
and Trop explained that with a bit of luck and good timing, it would be
possible to snap photographs of martian avalanches.
Amazingly,
soon afterwards the orbiter sent back images of an ice flow avalanche in action
on Mars. Pieces of ice, dust and possibly rocks crashed down from high, steep
areas, sending clouds of fine material billowing upwards. The cloud itself was
about 590 feet (180 meters) across. The exact cause of the avalanche isn't
known with certainty, but it could be because the sun warmed layers of ice.
This
was the first time an avalanche had been observed on another world, and was the
perfect confirmation of Kochel and Trop's ideas.
Valuable research
Studies
like this help us understand the changes that take place during periods of
climate variation. They also show that although planets like the Earth and Mars
are very different places, in many ways they can be astoundingly similar.
The
details of this paper will also be of interest to astrobiologists. Searching
for water
on other worlds is thought to be a key step toward finding life, and
understanding how the water cycle takes place on Mars will help scientists make
more accurate predictions. Couple water with a dynamic world experiencing changes
to its landscape, and Mars looks all the more promising for life.
Kochel
and Trop's research paper was published in the July issue of the journal Icarus.
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