A crater of image on
Mars could hold evidence of how temperature evolves on the planet, variable considerably
due to changes in the orientation of its axis of rotation. On June 19,
2011, Mars Express said its high-resolution stereo camera to the Arabia Terra
region of Mars, photographed the craters Danielson and Kalocsa. The first is
called the George E. Danielson, a key player in the development of several
satellite cameras shipped in exploring the Red Planet. In this image from Mars
Express, Danielson is the crater of the right (north), about 60 km in diameter.
The Kalocsa crater in
the center of the image has a diameter of about 33 km and is a kilometer
shallower than its neighbor. It is named after a Hungarian town, famous for its
astronomical observatory.
Danielson
craters environment and Kalocsa
Danielson, like many
craters in the Arabia Terra region, is full of sediment that, in this case, has
suffered serious erosion over time. Inside you can distinguish rocky formations
with very peculiar stratification, known as yardangs. A yardang hill is a kind
of stylized, carved into the bedrock of any material or semi-consolidated or
consolidated by the abrasive action of particles of dust or windblown sand.
Here on Earth we find
yardangs in desert regions, with clear examples in North Africa, Central Asia
and in the Arizona desert in the United States.
In the case of
Danielson crater, sediments may have been cemented by water from an underground
aquifer before being eroded by the wind at a later stage of the geological
history of the planet. The direction of the yardangs suggested to scientists
that strong winds from north-northeast (in this picture, the bottom right
corner) were responsible for both the original sediment deposition and its
subsequent erosion, when the climate became driest. The image can also be seen
a field of dunes, darker in color, about 30 kilometers long, which crosses the
region yardangs. It is thought that this training had its origin in a much
later stage.
Danielson
Surveying and Kalocsa
In the bottom of the crater
can distinguish a series of layers, separated and fairly uniform thickness that
alternate their orientation. Some scientists think that these formations may
indicate periodic fluctuations in the atmosphere of Mars caused by regular
changes in the orientation of the axis of rotation of the planet. So, would have been different strata deposited
at different times of the planet's history.In this second crater layered
deposits are not appreciated. It is thought that this could be due to the
higher elevation of its base, which would have prevented that come into contact
with the hypothetical aquifer sediments cemented underground Danielson crater.
Another hypothesis
suggests that this crater is younger than its neighbor, having formed when
there was no water in the region.
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