Astronomy Picture of the Day
November 3, 2013

North Polar Spring (CTX Frame)
North Polar Spring (CTX Frame)

Credits: NASA/JPL/University of Arizona - Credits for the additional process. and color.: Dr Paolo C. Fienga/LXTT/IPF

The North Polar Regions of Mars are capped with Layers basically made of Water Ice and Dust, which are called "North Polar Layered Deposits". This Permanent North Polar Ice Cap is also covered, during the long and extremely dark Martian Winter, with a Layer of Seasonal CO2 (such as Carbon Dioxide) Ice (also known as "Dry Ice") or just CO2 Frost. When the Sun rises higher in the Sky and then start (sometimes, in a remarkable and very fast way) to warm-up the whole frozen environment - and, as you know, this phenomenon happens during the Martian Spring and Summer -, the steep Edges of these North Polar Layered Deposits get quickly warmer. When this happens, the Dry Ice begins to sublime (meaning that it goes directly from a solid state to a gaseus state), and this physical process destabilizes each and every loose Chunks of (Icy or even Rocky) Material that was perched in/on the Steep Cliffs and Slopes that characterize the Edge of the Martian North Polar Regions. The loose Material that is contained in the weaker Layers of Ice, therefore, gets quickly dislodged and then cascades (---> falls) down along said Steep Cliffls and Slopes.


Here, in today's APOD, we can see a Dark Streak that marked the path of some (obviously, already fallen) loose Material, and which is approximately 1 Km (such as 0,621 miles) wide. As a matter of fact, many NASA - Mars Reconnaissance Orbiter - HiRISE images have already shown Ice and Dust Avalanches (always occurring during the North Polar Springtime) while they were falling down along the Edges of several North Polar Layered Deposits that are located in this area.


Mars Local Time: 12:41 (Early Afternoon)
Coord. (centered): 85,061° North Lat. and 239,038° East Long.
Spacecraft altitude: 318,9 Km (such as about 198,036 miles)
Original image scale range: 63,8 cm/pixel (with 2 x 2 binningso objects ~ 1 mt and 91 cm across are resolved
Map projected scale: 50 cm/pixel
Map projection: POLAR STEREOGRAPHIC
Emission Angle: 4,7°
Phase Angle: 73,4°
Solar Incidence Angle: 76° (meaning that the Sun was about 14° above the Local Horizon at the time the picture was taken)
Solar Longitude: 21,3° (Northern Spring - Southern Fall)
Credits: NASA/JPL/University of Arizona
Additional process. and coloring: Lunar Explorer Italia


This picture (which is a NASA - Original Mars Reconnaissance Orbiter False Colors and NON-Map Projected Sub-frame identified by the serial n. ESP_033433_2650) has been additionally processed, magnified, contrast enhanced, Gamma corrected, and then re-colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Mars Reconnaissance Orbiter and then looked down, towards the Surface of Mars), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.



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