Mars Photo of the Day - Mar 29 2012

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Today's Image of Mars shows the North Polar Region in late spring, as taken by HiRISE. Earlier in the year the ground was covered in ice, but now most of it has sublimated. The ice that remains is located in areas shadowed from the sun or in places where the ice built up and will take longer to sublimate. The easiest way to imagine those is by thinking of snow drifts on Earth, which may survive for weeks after all the other snow has disappeared.

Clicking on this image will take you to the original captioned and larger image from HiRISE.

 

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Mars Photo of the Day - Jan 11 2012

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Today's Image of Mars shows the Martian equivalent of terrestrial barchan dunes, which are usually crescent shaped and formed by winds blowing in one uniform direction. These dunes are located in the North Polar region of Mars.

Dunes like these are useful in determining the direction of the wind in this region of Mars because the side facing the wind becomes more eroded, resulting in a sheer, less rounded face. The wind also creates horn-like features oriented in the direction the wind predominantly blows. 

In this image the carbon dioxide ice on the dunes is just beginning to sublimate, revealing the dark basaltic sand underneath. The north polar Martian winter is just ending so most of the ground is still covered in the carbon dioxide ice, but by the time summer arrives it will have fully thawed, leaving the ground as dark as the patches in this image.

Clicking on this image will take you to the original, captioned HiRISE image.

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Mars Photo of the Day - Dec 30 2011

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Today's Image of Mars show the South polar cap in early Spring as taken in May 2005. This image is a mosaic of images taken by the Mars Global Surveyor. A lot of this ice is carbon dioxide ice, but with an underlying layer of water ice. By this time the carbon dioxide ice has likely begun sublimating, since the temperatures have begun rising and carbon dioxide ice begins sublimating at temperatures greater than -78.5°C (197.5 K, −104.2 °F).

Clicking on this image will take you to the original Mars Global Surveyor gallery where this image is located.

Source: NASA/JPL/Malin Space Science Systems

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Mars Photo of the Day - Dec 25 2011

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Today's Image of Mars shows 'swiss cheese' terrain in the South Polar residual caps on Mars. Just like on Earth, Mars has water ice at its poles, but because Mars is much colder carbon dioxide ice is deposited during the winter and sublimates when the climate gets warmer come Spring. This is similar to water ice snow on Earth which typically appears during the winter season and melts during the Spring. 

In this image the carbon dioxide ice has already begun sublimating, but only in patches, thus the 'swiss cheese' like terrain. The reason why the exposed terrain is so flat is likely due to a layer of water ice that exists under the carbon dioxide ice. Because water ice has a higher freezing point than carbon dioxide ice it remains solid when the temperatures increase in the spring.

Today is Christmas for those that take part, so here is to hoping that your Christmas is as white as this image on Mars!

Clicking on this image will take you to the original, captioned HiRISE image.

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If you like the HiRISE images showcased in the Mars Photo of the Day posts I encourage you to enter for a free 2012 HiRISE Calendar