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APOLLO 14 AS 14-70-9671.jpgAS 14-70-9671 - The "Bright One"59 visiteThis crater on the Lunar Far-Side is similar in age and size to the near- side crater Euler. It is located midway between the craters Becvar and Langemak. About 36 Km in diameter, it was informally called the "Bright One" by the Apollo 14 Astronauts because of its bright ejecta and ray pattern. The bright halo that surrounds the crater is about 150 Km in diameter. Its brightness is not evident in this view because the picture was taken when the Sun angle was low. The radial pattern of dunelike ejecta around the crater is most apparent where the Sun's rays are perpendicular to the direction of ejecta flow, as in the lower part of the picture. The hummocky or bumpy floor of the crater is caused largely by material that has slumped from the walls. Stuart A. Roosa, the Apollo 14 CMP, used a handheld camera with an 80-mm lens for this photograph. Later, using a 500-mm lens, he photographed in much more detail that part of the floor of the crater outlined in this photograph and shown in AS 14-9975.
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APOLLO 14 AS 14-72-9975.jpgAS 14-72-9975 - The "Bright One" (detail mgnf)59 visiteWhen photographed with the 500-mm lens, the abundance of blocks (bright spots with shadows extending to the right) attests to the freshness of the materials on the floor of the "Bright One". Material that has flowed and in some instances formed smooth-surfaced "pools" is evident in much of the area. Arrows mark the edge of a major flow distinguished by its surface texture, color (in the original negative), location in a topographic low, and clearly defined border. Note that the abundance of boulders in the flow is much less than in nearby areas, presumably because the flow has buried most of the boulders in its path. Scientists generally agree that material has flowed here, and on the floors and flanks of many other craters, but the nature of the material that has flowed is a matter of debate.
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APOLLO 16 AS 16-120-19295~0.jpgAS 16-120-19295 - Gassendi59 visiteThis view into the shallow crater Gassendi shows another strongly fractured crater floor. Gassendi is about 110 Km wide. Dark mare lavas in the distance embay the rim and a little of the interior of Gassendi. They may have entered the crater through the narrow gap partly in shadow below the arrow. Most craters that have fractured floors are near areas of mare flooding. This suggests that the fracturing is a consequence of volcanic activity. An area next to the central peaks of Gassendi was the runnerup choice for a landing site for Apollo 17.
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APOLLO 15 AS 15-2510.jpgAS 15-2510 - Humboldt Crater59 visiteThe crater Humboldt, on the east limb of the Moon, as seen from Earth, is 200 km across, a little larger than Tsiolkovsky. This view by the Apollo 15 mapping camera looks southward across Humboldt's ejecta blanket and into the crater. Irregular secondary craters partly covered by the ejecta are in the foreground and a long chain of secondaries extends from Humboldt's rim to the foreground. Humboldt is one of the largest craters known to have a prominent central peak. If the crater is like terrestrial impact structures, the peak may expose rock uplifted about 10% of the crater's width, on the order of 20 Km from beneath the crater floor. This would be an exciting find for future Astronauts. A spider web of cracks on the crater floor suggested to R. B. Baldwin (1968) that the floor was bowed up in the middle. Later, dark mare lavas flooded low areas in the outer part of the floor and covered the cracks. A peculiar "bull's eye" double crater on the crater floor has several counterparts elsewhere on the Moon. The origin of these double craters is a continuing puzzle.
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APOLLO 16 AS 16-4511.jpgAS 16-4511 - Crater "Rays"59 visiteThis picture shows the striking bilateral symmetry of the rays of a small (2-Km diameter) crater in the floor of the large crater Daguerre in Mare Nectaris. Continuous areas and narrow filaments of light-gray ejecta extend from the crater across the dark mare surface through 270°, but are entirely absent in the southern 90° sector. Within the crater, dark material occurs on the southern crater wall while the remaining walls are bright. (The reader may wonder about the material whose reflectivity cannot be observed because it lies in shadow on the East wall of this crater. Until the area is observed under high Sun conditions, we are forced to make the simplifying assumption that it is bright because most of the materials visible elsewhere in the walls are bright).
This crater probably resulted from the impact of a projectile traveling from South to North along an oblique trajectory.
Its pattern of ejecta distribution is similar to that of small craters produced by the impact of missiles along oblique trajectories at the White Sands Missile Range, N. Mex. Some observers postulate that the dark material is a talus deposit of mare material that has fallen into the crater.
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APOLLO 15 AS 15-9287.jpgAS 15-9287 - A "Middle-aged" Crater59 visiteRemarkable detail is shown in this enlargement of a small part of a panoramic camera frame. In most respects, the crater itself is typical of a great many craters its size-about 1,2 Km. Because it does not have rays, it is believed to be older than most other Lunar craters. Its rounded rim crest and slightly raised rim (extending outward to the arrow, on the West side) also point to its greater age. On the other hand, it is young enough that some of the original dunelike texture of the ejecta blanket is preserved (especially to the West), a great many large blocks of ejecta are still visible, and the original depth of the crater has not been greatly lessened by infalling debris. The largest blocks, which are about 30 mt in size, occur near the rim. The terrace (T) extending partly around the wall about 100 mt below the surface probably marks the top of a resistant rock layer. However, if there were other signs of bedrock stratification within this crater, they have been obscured by the movement of debris down the walls. The very smooth floor is the only unusual feature of this crater. It may consist of a solidified pool of rock melted by heat generated from the impact.
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South_Polar_Features-Fans-PIA08658.jpgSouth Polar Fans (Original NASA/MGS/MSSS b/w Frames)59 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)59 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 16 AS 16-4530.jpgAS 16-4530 - Seconday impact craters, faults and rifles59 visiteLinear features of external and internal origin are contrasted in this area of Southernmost Mare Tranquillitatis.
The North-trending line of overlapping, very irregular craters along the East edge of the picture is clearly a chain of secondary impact craters. Its trend is radial to Theophilus, a large crater of early Copernican age that lies about 105 Km south of this area. The flaring shapes of some of the craters and their state of preservation also suggest that Theophilus is the primary crater. The narrow, straight rifle or graben that extends westward across the picture is clearly of internal origin. It formed when tensional forces ruptured the crust, causing the floor of the rifle to subside along faults.
Straight rifles are commonly the sites of volcanic cones or of blankets of volcanic ejecta; however, there are no signs of volcanism here that can be related to this rifle.
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APOLLO 15 AS 15-0274.jpgAS 15-0274 - Euler Crater59 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 15 AS 15-9866.jpgAS 15-9866 - Jansen "B" Crater59 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 15-9874.jpgAS 15-9874 - Dawes Crater59 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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