Astronomy Picture of the Day
March 24, 2014

As Time Goes By...
As Time Goes By...

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

This pair of before (left -Sx) and after (right - Dx) images taken from the High Resolution Imaging Science Experiment (or "HiRISE", for short) Camera onboard the NASA's Mars Reconnaissance Orbiter, documents the formation of a substantial (---> remarkably well defined and visible) new Channel (---> a so-called "Gully", in fact) on a Martian Slope which must have formed between November, 5, 2010, and May 25, 2013 (the date when this picture was taken). The location of this Feature is on the Inner Wall of an Unnamed Impact Crater found at 37,45° South Latitude and 222,95° East Longitude, in the Terra Sirenum Region of the Red Planet.

Gully or Ravine Landforms are commonly found in the Mid-Latitudes of Mars, and particularly in its Southern Highlands. These Features typically have an Alcove at their upper end, feeding into a Channel and an Apron of Debris (that has been carried down from above). Planetary Researchers, using the HiRISE images, have already discovered many examples of recent Gully Activity on Mars, most likely driven (---> caused) by Sublimation of Seasonal Carbon-Dioxide Frost (---> Dry Ice) or even, pehaps, thawing of Water-Ice Frost. Observations like this show that Gullies are forming even today and, although it is not possible to pin down the exact Season (---> moment, when) this Event has occurred, the locations where HiRISE has been able to image more, often demonstrate that this sort of Events generally occur during the Martian Winter, when Liquid Water is very unlikely to erupt from the Sub-Surface.

Therefore, and despite their resemblance to Water-formed Ravines on Earth (and even though a definitive answer to this question, for the time being, cannot be given), it is likely that Carbon Dioxide Ice/Frost may actually play a key-role in the formation of these kind of Gullies. However, in this case (and just for the sake of Intellectual Honesty), we, as IPF, tend NOT to agree with the conclusions that were widely explained hereabove.

Mars Local Time: 14:18 (Early Afternoon)
Coord. (centered): 37,446° South Lat. and 222,950° East Long.
Spacecraft altitude: 252,4 Km (such as about 156,74 miles)
Original image scale range: 25,3 cm/pixel (with 1 x 1 binningso objects ~ 76 cm across are resolved
Map projected scale: 25 cm/pixel
Emission Angle: 3,4°
Phase Angle: 35,9°
Solar Incidence Angle: 39° (meaning that the Sun was about 51° above the Local Horizon at the time the picture was taken)
Solar Longitude: 324,7° (Northern Winter- Southern Summer)
Credits: NASA/JPL/University of Arizona
Additional process. and coloring: Dr Paolo C. Fienga/LXTT/IPF

This picture (which is a NASA - Original Mars Reconnaissance Orbiter False Colors and NON Map-Projected sub-frame identified by the serial n. ESP_032011_1425-1) has been additionally processed, magnified to aid the visibility of the details, 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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