Astronomy Picture of the Day
November 26, 2012

Recent Crater Cluster on Mars
Recent Crater Cluster on Mars

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

This NASA - Mars Reconnaissance Orbiter observation shows a Close Cluster of small Impact Craters that must have formed sometime between August 2005 and November 2010, and that was first discovered in the Context Camera (CTX) image n. G05_020035_1699_XN_10S064W_101104. What is interesting (and somehow unusual) about this Impact Site, is that it is not as Dusty as most places where new Impacts are discovered. Often the airblast disturbs the Dust and "forces" it to create a Dark Spot that is much much larger than the Crater itself and its Ejecta: it is clear that this circumstance makes the new impacts way more visible, and therefore relatively easy to discover over Dusty Terrains.


The dark Ejecta Blanket, here, is quite obvious, while the larger Dark Spot is subtle, but still easily detectable, even in the Context (CTX) image. But if you pay attention, when you look at the EDM, you shall notice that what appeared to be just a single Impact is, in fact, a tight cluster of extremely small Impact Craters, and this fact is due to the circumstance that Rocky Bolides often break-up in the Martian Atmosphere. When the break-up occurs just before the impact on the Surface, the Bolide creates a "Close Crater Cluster", with all the Craters concentrated in a relatively small area. If the break-up occurs, instead, while the Rocky Bolide is still far from the Surface, then it is going to be very likely that the Impact Site will be characterized by an "Open Crater Cluster", with all the Craters derived from the fragmentation of what originally was just a single Rocky Bolide, spread over a relatively large area.


Mars Local Time: 15:39 (Middle Afternoon)
Coord. (centered): 9,246° South Lat. and 295,828° East Long.
Spacecraft altitude: 257,0 Km (such as about 160,6 miles)
Original image scale range: 25,7 cm/pixel (with 1 x 1 binning) so objects ~ 77 cm across are resolved
Map projected scale: 25 cm/pixel
Map projection: EQUIRECTANGULAR
Emission Angle: 1,2°
Sun-Mars MRT (or "Phase") Angle: 56,4°
Solar Incidence Angle: 55° (meaning that the Sun was about 35° above the Local Horizon at the time the picture was taken)
Solar Longitude: 182,7° (Northern Fall - Southern Spring)
Credits: NASA/JPL/University of Arizona
Additional process. and coloring: Lunar Explorer Italia


This picture (which is a NASA - Original Mars Reconnaissance Orbiter b/w frame, identified by the serial n. ESP_029015_1705) has been additionally processed and then 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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