* Astronomy

Global Map Reveals Mineral Distribution on Mars
Scientists are getting a clearer image of mineral distribution on the surface of Mars, thanks to the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), one of six science instruments on NASAs Mars Reconnaissance Orbiter, currently circling the planet. More than 200 just-released spectral maps reveal the distribution of various minerals on the surface of Marsthe first instalment of the Global Mars Map, which will eventually cover the entire planet.
The locations and amounts of these minerals provide clues about the geological processes that created different rock formations, and will provide invaluable pointers to when and where liquid water once existed on Mars. These first maps were selected to cover many of the geologically most interesting parts of the planet and represent about 11 percent of Mars surface.
Built and operated by the Johns Hopkins University Applied Physics Laboratory (APL), CRISM detects 544 wavelengths of visible and infrared sunlight reflecting off of the planets surface. Minerals on the planet absorb some of this sunlight, leaving telltale gaps or absorptions in the spectra of the reflected light.
To create the maps, CRISM uses a multispectral survey mode of operation, collecting data from just 13 percent of the available wavelengths to highlight key mineral groups. This lower data-rate mode, coupled with other onboard data compression, decreases the data volume significantly and makes it possible for CRISM to extend its measurements beyond a few thousand targets to cover the entire planet.

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A probable active glacier has been identified for the first time on Mars.
The icy feature has been spotted in images from the European Space Agency's (Esa) Mars Express spacecraft.
Ancient glaciers, many millions of years old, have been seen before on the Red Planet, but these ones may only be several thousand years old.
The young glacier appears in the Deuteronilus Mensae region between Mars' rugged southern highlands and the flat northern lowlands.

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Mars Express has been collecting data on the Medusae Fossae Formation deposits using its Mars Advanced Radar for Subsurface and Ionospheric Sounding (Marsis).  Between March 2006 and April 2007, Mars Express flew over the Medusae Fossae Formation deposits many times, taking radar soundings as it went.

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Mars, like Earth, is a climate-fickle water planet. The main difference, of course, is that water on the frigid Red Planet is rarely liquid, preferring to spend almost all of its time traveling the world as a gas or churning up the surface as ice. That's the global picture literally and figuratively coming into much sharper focus as various Mars-orbiting cameras send back tomes of unprecedented super high-resolution imagery of ever vaster tracts of the planet's surface.
What were just a few years ago small hints about Mars' water and climate, as seen in a few "postage-stamp" high-resolution images and topography, have given way to broader theory that explains not only the features seen on the planet today, but imply a dynamic history of Martian climate change.

"When you have postage stamps, it's like studying a hair on an arm instead of the whole arm" - Mars researcher James Head III of Brown University.

Head will present the latest integrated global view of Martian surface features and how they fit with Martian climate models on Sunday, 28 October 2007, at the Geological Society of America Annual Meeting in Denver.
The pictures now reveal a range of ice-made features that show a strong preference to certain latitudes, Head explains. As on Earth, latitude-dependent features can mean only one thing: latitude-dependent climate.
The signs of water ice are obvious today at Mars' poles. But as you move towards the equator, there is plenty of evidence of water ice having shaped the surface in different ways not so long ago.
Not far from either pole, for instance, widespread bumpy polygonal patterned ground suggests the contraction and expansion of icy permafrost ground very similar to that seen in Earth's Arctic and Antarctic. Next, between 30 and 60 degrees latitude in both hemispheres, the patterned ground gives way to a pervasive pitted texture of once ice-rich dust deposits. Even closer to the equator on the flanks of Mars' equatorial volcanoes are compelling signs of large glaciers, almost exactly like those of Earth. There are also craters which seem to be filled with glacial debris and small valleys which drop precipitously into canyons which on Earth is usually a strong indicator that a glacier once filled and widened the canyon.
As for where all the ice went, much of it was sublimed away and deposited at the poles. The ice rules the more temperate latitudes only when the tilt of Mars' spin axis is far more extreme than today up to 45 degrees. That tilt, or obliquity, exposed the poles to a lot more sun during the course of a Martian year, according to climate models, evaporating the ice caps. That same water refroze on the surface in the then darker and colder equatorial and middle latitudes, hence all the evidence of ice and glaciers.

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