Astronomy Picture of the Day
September 30, 2012

Moments of Deimos
Moments of Deimos

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

These two Absolute Natural Color views of Deimos, such as the smaller of the two moons of Mars, result from imaging on February 21, 2009, by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the NASA - Mars Reconnaissance Orbiter. As it can be clearly seen here in these two frames, Deimos has an apparently really smooth Surface and this is because of the presence, almost all over it, of a (relatively thick) blanket of Fragmental Rock (also known as Regolith), which only lacks in the areas where the some recent Impact has occurred. Deimos is a dark, quite reddish object, very similar to Mars' other moon, Phobos (if you wish to make a comparison, then see the HiRISE images of Phobos taken on March 23, 2008).


These pictures of Deimos combine HiRISE exposures in Near-InfraRed, Red and Blue-Green wavelengths and, thanks to the Absolute Natural Colors additional processing, more (and really subtle) color variations of the Surface become visible - i.e.: redder in the smoothest areas and less red near the fresh Impact Craters and over Ridges of Topographic Highs (notice that these last Surface Characterizations are relative to Deimos' Center of Gravity). The color variations are also probably caused by the different exposure (and therefore the different reactions) of the Surface Material to the arsh conditions of the Space Environment, which may lead to either darkening and/or reddening of all those Rocks and Minerals which are located on the Surface of any given Atmosphere lacking Celestial Body. As a consequence of that, brighter and less-red Surface Materials must have seen less exposure to the Space Environment (for instance, because said Surface Material has been displaced - such as covered and then uncovered - due to the physical actions arising out of and/or directly connected to Recent Impacts or Downslope Movement of Regolith ---> Dust and Landslides).


Deimos is about 12 Km (such as approx. 7,5 miles) in diameter. Its Orbital Period is 1 day, 6 hours, 17' and 54" and these two images were acquired 5 hours and 35 minutes apart. The Sun was to the upper left in the smaller (right) image, and to the right in the bigger one. The viewing geometry is similar in the two images, but Surface Features appear very different due to the substantial change in illumination. With an image scale of about 20 meters (such as approx. 66 feet) per pixel, Surface Features having dimensions of about 60 meters (such as 197 feet) or larger, can be discerned. These images are products from observations catalogued by the HiRISE Team as ESP_012065_9000 and ESP_012068_9000. Other products from these observations are available at http://hirise.lpl.arizona.edu/deimos.php .


These pictures (which are the NASA - Original Mars Reconnaissance Orbiter enhanced-color frames identified by the serial n. ESP_012065_9000 and ESP_012068_9000) have been additionally processed 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 outside, towards the Martian moon Deimos), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.


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