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Springtime at Mars' southern polar cap |
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Mars has seasons, just as Earth does. Using the Mars orbiter camera on
Surveyor, scientists are now able to monitor the red planet's weather
changes from one martian year (about twice as long as an Earth year) to
the next. One of their discoveries has been that the southern polar ice
cap, long thought to be permanent, isn't so permanent.
"What we're finding is just short of incredible," said
Edgett. "For most of the Mars year, the weather patterns are very
predictable. Last year, in late June, we had global dust storms that
obscured the planet for three months - an event that did not fit the
patterns we'd otherwise seen. We found that there were lots of storms
going on at once, not that there was one gigantic global dust storm, as
was thought during previous events."
Thorpe said, "The weather reports are very important, since
weather will affect future spacecraft landings and operations on the
surface of Mars, including the 2003 Mars Exploration Rovers."
Weekly Mars weather reports are available by going to the Mars
Exploration page at http://marsprogram.jpl.nasa.gov
and clicking on the How's the Weather on Mars box.
Students interested in exploring Mars further can go to
http://marsprogram.jpl.nasa.gov/classroom/students.html
for more information on the red planet.
Extensions Lead to Discoveries
"One of the reasons I'm so very excited about the
second extension is because every week there is something
new and surprising in our data," said Mars scientist Ken
Edgett. "And what's really cool is that every four to six
months we discover something totally amazing. Last year, we
were flabbergasted to find that the southern polar
"permanent" ice cap isn't so permanent. We're
now tracking changes to the cap on shorter time scales."
Each winter, frost forms a seasonal polar cap covering
everything from 60 degrees latitude to 90 degrees latitude;
it retreats in spring. The permanent ice cap, which is mostly
carbon dioxide, remains through the entire summer and was
previously thought to be permanent.
"We now know that even in summer the ice is
subliming (converting directly from solid to vapor) at a rate that
suggests the entire cap could disappear in a few thousand to
tens of thousands of years," said Edgett. "There's
a lot of carbon dioxide in the permanent cap, but we're finding
that it is going away on a larger time scale
[than the seasonal frost], independent of season."
For more information and images, please see
http://www.msss.com/mars_images/moc/CO2_Science_rel/ .
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