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Endeavour Crater is an ancient Impact Crater located in the Martian Region of Meridiani Planum; it is about 22 Km (approx. 14 miles) in diameter and, from a Mineralogical point of view, we have found out, using data obtained by the NASA - Mars Reconnaissance Orbiter, that several Phyllosillicate-bearing Rocky Outcrops are present in many locations situated along its Outer Rim. These Minerals, according to our knowledge, should have formed under so-called "Wet Conditions" and in a Low-Acidic Environment, probably (but we CANNOT in any way be sure about this) during the Early History of Mars. On the other hand, and as far as the Geomorphology of Endeavour Crater is concerned, we can say that it shows "Raised Rim Segments" (also called "Capes") towards the North, East, and South/West. In general, however, the Rim of Endeavour has become worn, rounded and degraded, with infilling of material coming from the Surrounding Plains, in a manner that appears quite similar to what we have seen at Victoria Crater.

When compared to the Surrounding Plains, the Floor of Endeavour Crater shows an enhanced Spectral Signature of (meaning the presence, inside it, of Minerals like) Basalt and Hematite. In the large interior of the Crater there are also two groups of relatively wide Dunefields. Images taken from the orbit since the AD 2008 show evidence of changes in both the Dunefields as well as in the surrounding (and, perhaps, associated) Rocky Formations: a fact, this one, that proves the existence of a still ongoing (and, obviously, quite powerful) Aeolian (such as "Wind-related/caused/induced") Erosional Process, which took place and showed obvious results in this area over a period of only 2 (two) to 3 (three) years. Furthermore, the Plains surrounding the Rim of Endeavour Crater also show some clear evidence of the presence of Polyhydrated Sulfate.

As you know, the NASA - Mars Exploration Rover-B Opportunity began its course (surrounded by a general skepticism about the final result of the march) toward Endeavour Crater in August 2008, with the Rim coming into sight on March 7, 2009, and the arrival at the Edge of the Crater (that we can see now, in today's APOD) on August 9, 2011. In December 2011, the NASA - Mars Exploration Rover-B Opportunity discovered a Mineral Vein sticking out of the Soil near the Rim of Endeavour Crater and some testing that was carried out on it confirmed that the Vein contained Calcium and Sulphur. The conclusion that made the best match for the collected data was that the Vein (nicknamed "Homestake") must have been made of a Mineral known as Gypsum. As far as its formation is concerned, The Homestake Mineral Vein likely formed from some Mineral-rich Water that must have been flowing (for a VERY LONG time!...) through a Crack in the Rock that now contains it. The Vein, Scientists said, should have been created in conditions way more "Neutral" than the severe Acidic Conditions that now characterize this Region and which are well indicated by the presence, here and there, of several Sulfate Deposits; as a consequence of such a reasoning, this specific environment, in the past (probably a very distant one), may/should have been more hospitable for a large variety of Earth-like Living Organisms. The Homestake Vein (that we shall show you in a future APOD) is located in a zone where the Sulfate-rich Sedimentary Bedrock of the Plains of Meridiani (such as the so-called "Martian Paving") meets older, Volcanic Bedrock that is now exposed in the proximities, as well as at the Rim, of Endeavour Crater.

This frame has been colorized in Absolute Natural Colors (such as the colors that a normal human eye would actually perceive if someone were on the Surface of Mars, near the NASA - Mars Exploration Rover-B Opportunity, and then looked towards the Rocky Outcrop located near the Outer Rim of Endeavour Crater), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.