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South_Polar_Features-Fans-PIA08658.jpgSouth Polar Fans (Original NASA/MGS/MSSS b/w Frames)58 visiteCaption NASA originale:"Dark spots (left) and 'Fans' appear to scribble dusty hieroglyphics on top of the Martian South Polar Cap in two High-Resolution MGS-MOC images taken in Southern Spring. Each image is about 3-Km wide".
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APOLLO 17 AS 17-149-22838.jpgAS 17-49-22838 - Crater Chain (Far-Side)58 visiteThis oblique view taken with the Hasselblad camera shows a crater chain on the Far-Side, about 500 Km North of Tsiolkovsky. For an idea of the scale, the large crater near the upper left corner is about 26 Km wide. The origin of this chain is controversial. To some geologists, the irregular shape of many of the craters suggests that the chain was formed by the impact of a stream of ejecta from a large primary crater. The presence of herringbone ridges would have strengthened this interpretation, but none are visible; perhaps the high Sun angle and the oblique viewing angle of this scene have obscured them. To others the simple geometry of the chain suggests a volcanic origin. However, there is an apparent lack of faulting to control the alinement of the craters and an apparent absence of a blanket of volcanic ejecta.
The origin of this chain may not be decipherable until, and unless, additional photography becomes available.
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APOLLO 17 AS 17-3107.jpgAS 17-3107/3105/3103 - Euler Crater (HR)58 visiteParts of 3 frames from the Apollo 17 PanCam were mosaicked to form this HR view of the crater Euler, in South-Western Mare Imbrium (an exceptionally fine example of a young mediumsized crater). 27-Km in diameter, Euler has most of the features that typify young craters in this size range. Its sharp rim shows little evidence of rounding. A solid blanket of ejecta is visible for approximately 1/2 crater diameter outside the rim and the radial pattern of secondary craters, crater clusters, ridges and grooves is visible outward to a full crater diameter.
Terraces formed by slumping of the steep crater walls, probably contemporaneously with the formation of the crater, are clearly evident. The steepness of the walls and the fact that the crater floor is below the level of the surrounding mare surface indicate that relatively little erosion and infilling have occurred. Other features typical of medium-sized craters are the central peak and the level floor surrounding the central peak. The pattern of ejecta around Euler is notably asymmetric because the area was later flooded by mare lavas that inundated parts of the ejecta blanket and other ejecta features.
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APOLLO 15 AS 15-0274.jpgAS 15-0274 - Euler Crater58 visiteIn this oblique view of Euler, some details are shown that are not visible in other pictures. Note, for example, the ledges (L) of bedrock cropping out along the South Wall and the low terraces (T) at the points of contact between the slump masses and the floor. They may be aprons of debris or "bathtub rings" of lava. This oblique viewing angle also enhances the polygonal outline of Euler's rim crest and the size and ruggedness of the huge masses that have slumped from the walls.
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APOLLO 17 AS 17-3072.jpgAS 17-3062 - Timocharis Crater58 visiteThis oblique view of the crater Timocharis in Southe-Eastern Mare Imbrium illustrates how the original diameter of a crater is enlarged by slumping of its walls. Its present diameter is about 35 Km. The sparsity of small superposed craters on the walls of Timocharis - in contrast to their density on its floor and rim - is caused by the erosive effect of downslope movement of material on the steep walls. Timocharis, like many other young impact craters of similar size, possesses a well-defined central peak complex. Such structures are believed to result from elastic rebound of the bedrock immediately after the impacting event. However, the central peak of Timocharis apparently has been substantially modified by a large superimposed crater.
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APOLLO 15 AS 15-9866.jpgAS 15-9866 - Jansen "B" Crater58 visiteHigh Sun views such as this often show fascinating dark and bright patterns that would be overwhelmed by highlights or shadows if the Sun were lower in the sky. This view of the 17-Km-wide crater Jansen "B" shows numerous bright avalanche deposits on the steep crater walls, apparently originating at outcrop ledges near the top of the wall. Most avalanches stop in a moat at the base of the wall, but a few in the foreground extend out onto the irregular, inward- sloping floor.
The floor is a jumble of slump blocks.
Avalanching appears to be a major means of erosion on steep lunar slopes.
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APOLLO 15 AS 15-9328.jpgAS 15-9328 - Bessel Crater58 visiteOutcrops of layered rock are strikingly evident in the upper part of the far wall of the crater Bessel (17- Km diameter) in South-Central Mare Serenitatis. The outcrop is most evident where it forms shadows; however, the dark debris that streams downslope from the layered rock is visible even on parts of the crater wall where the Sun has washed out all details of relief. The outcrop is at a uniform distance below the crater rim, indicating that the strata are horizontal. Thus, Bessel furnishes convincing evidence that mare surfaces are underlain by dark layered rock. The dark rock is now known to be basalt that accumulated as successive flows or layers of lava.
Bessel is youthful enough that boulders are abundant on its rim and floor.
An anomalously high number of boulders is visible in and around the 750-m diameter crater (arrow) on the floor.
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APOLLO 15 AS 15-9874.jpgAS 15-9874 - Dawes Crater58 visiteThis is a near vertical view of the crater Dawes, 18 Km in diameter. Morphologically it is typical of many lunar craters in the 15- to 20-Km size range. It lacks terraced walls and distinct central peaks but has an extremely rough floor. Small terracelike structures on the crater floor (upper left, lower right) occur where the wall is bowed outward and probably represent slump deposits where portions of the crater wall have collapsed into the crater. Local stratigraphy is revealed in the walls of the crater, and material of different albedo is seen streaming down into the crater from various levels. The dark layer clearly visible in the upper part of the crater wall represents the thin mare deposits in this part of Northern Mare Tranquillitatis. The lighter gray material below it is a combination of underlying submare material and talus from units higher on the crater wall. The highest unit (white and gray) probably represents the ejecta blanket and may consist primarily of lighter lunar crustal material excavated from beneath the mare.
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APOLLO 17 AS 17-2265.jpgAS 17-2265 - Proclus Crater58 visiteThis oblique view looks South over the 26-Km-diameter crater Proclus in the highlands at the Western edge of Mare Crisium. Proclus is a young rayed crater that is distinctive because of the marked asymmetry of its ray system-a characteristic visible even in Earth-based telescopic views. The excluded zone is along the South-West edge (top of photograph) but is visible in this moderate Sun photo only as a slight albedo change. Laboratory experiments suggest that a low trajectory angle might account for the asymmetry. A number of large blocks can be seen at the edge of the crater rim. The exceptionally large block (arrow) is about 200 mt wide and, judging from the length of the shadow it casts, nearly as high. As in several other craters shown in this chapter, a darker layer is present in the upper part of the crater wall.
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Rhea-N00064799-A.jpgMoments of Rhea (1) - context image58 visitenessun commento
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M-008-3.jpgM 8 - The "Lagoon" Nebula58 visite"...But now we are...dead to that which held us captive, so that we are slaves not under the old written Code, but in the new Life of the Spirit..."
Romans - 7:6
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APOLLO 15 AS 15-9299.jpgAS 15-9299 - Le Monnier Crater58 visiteOn January 16, 1973, the Soviet unmanned roving vehicle Lunokhod 2 was landed by Luna 21 in or near this area in the South-Eastern part of the crater Le Monnier. This crater is a large (61 Km) pre-Imbrian crater cut into terra at the Eastern edge of Mare Serenitatis before Serenitatis was flooded by mare laves. Part of Le Monnier's Southern wall fills the lower part of the picture. A conspicuous chain of elongate depressions has formed in the lava-filled floor of the crater. The chain trends 22 Km northward and its pattern is quite surely controlled by an underlying fracture system. Regionally, the inferred fracture system is concentric to the grossly circular Serenitatis Basin and in this area trends Northward. No comparably young structural features having the same trend cut the terrae surrounding Le Monnier. However, older structures having this trend occur in the southern and northern walls and rims of Le Monnier. The aligned depressions on the mare are mostly 300 to 400 mt wide and 30 to 60 mt deep. The three deepest stretches are 1 to 2 km long and about 50 to 65 m deep. These depressions probably were the locus of fissure eruptions of mare basalt. Withdrawal of the last lava back into the fissure may have created subsurface voids into which collapse took place, causing the depressions and accounting for the absence of raised rims on the depressions.
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