Astronomy Picture of the Day
March 26, 2014

Small Lobate Scarp
Small Lobate Scarp

Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington and Dr Paolo C. Fienga/LXTT/IPF for the additional process. and color.

Some of the new images obtained during the so-called "low-altitude opportunities" (such as when the NASA - MESSENGER Spacecraft is closest to the Mercurian Surface), have revealed a small Lobate Scarp, identified here with white arrows. The cooling of Mercury's interior, as it has happened over a period of several billions of years, must has caused the Planet to "contract", thus forming a network of large Landforms called "Lobate Scarps".

Many of them are over a kilometer in height, and hundreds of kilometers long. One of the goals for the NASA - MESSENGER Spacecraft current Extended Mission, is to determine if there is evidence of (relatively speaking) more young Fault Scarps, which might indicate the occurrence of (relatively, from a Geological point of view) recent contractions of the Planet Mercury, possibly due to its (still ongoing) interior cooling and the subsequent ongoing solidification of its Core.

This specific Lobate Scarp is only 2 Km (such as about 1,242 miles) long, and it is the shortest Fault Scarp yet found on Mercury. It has to be said that Landforms of such a small scale must be (always relatively speaking) young, because - in general - small Surface Features could not survive for billions of years under a constant Meteoroid Bombardment. As a matter of fact, some Lobate Scarps of the same scale of this one, but found on the Moon, are thought to be no more than 800 Million Years old, and they could even be less than 50 Million Years old! Thus, this small Scarp - and others like it -, all likely to be discovered duirng some further low-altitude imaging of Mercury's Surface, could provide Planetary Scientists with a tangible evidence that some (very) recent contractions have actually occurred on the Mercurian Surface.

Date acquired: February, 9th, 2014
Images Mission Elapsed Time (MET): 34263837, 34263839
Images ID: 5729947, 5729948
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 65,80° North
Center Longitude: 64,80° East
Solar Incidence Angle: 79,7° (meaning that the Sun, at the time that the picture was taken, was about 10,3° above the imaged Local Mercurian Horizon)
Emission Angle: 33,5°
Sun-Mercury-Messenger (or "Phase") Angle: 113,3°

This picture (which is an Original NASA - MESSENGER Spacecraft's b/w and NON Map-Projected image-mosaic published on the NASA - Planetary Photojournal with the ID n. PIA 18124) has been additionally processed, contrast enhanced, Gamma corrected, magnified to aid the visibility of the details and then colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - MESSENGER Spacecraft and then looked outside, towards the Surface of Mercury), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team. Different colors, as well as different shades of the same color, mean, among other things, the existence of different Elements (Minerals) present on the Surface of Mercury, each having a different Albedo (---> Reflectivity) and Chemical Composition.

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