| Piú votate - Mercury |
ZZ-Mercury-Craters-Xiao_Zhao_Crater-PIA10668.jpgXiao Zhao's Rays paint Mercury's Surface73 visiteRecently named after the 12th century Chinese artist, Xiao Zhao crater on the central left side of this image is small in comparison with many other craters on Mercury and even with many other craters in this scene. However, Xiao Zhao's long bright rays make it a readily visible feature. The fresh, bright rays, which were created by material ejected outward during the impact event that formed the crater, indicate that Xiao Zhao is a relatively young crater on Mercury's surface.
Date Acquired: January 14, 2008
Image Mission Elapsed Time (MET): 108828473
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 500 meter/pixel (0.3 miles/pixel)
Scale: Xiao Zhao crater is 23 kilometers (14 miles) in diameter
Spacecraft Altitude: 19,760 kilometers (12,280 miles)
MareKromium
(4 voti)
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ZO-Mercury20_Messenger-PIA10171.jpgRendez-Vous with Mercury76 visiteAs the MESSENGER spacecraft approached Mercury for its first flyby, the Narrow Angle Camera, part of the Mercury Dual Imaging System (MDIS) instrument, acquired a series of images of the Planet in support of spacecraft navigation.
The 9 images shown here were taken from January 9 to 13, 2008, as MESSENGER closed to between 2,7 MKM and 760.000 Km (1,7 MMs and 470.000 miles) from Mercury. (...)
At the beginning of the image sequence, Mercury was no more than a bright crescent in the blackness of space. As MESSENGER drew closer, surface features began to be resolved. The image from January 13 (bottom right) has the highest spatial resolution of this sequence (20 Km/pixel, such as about 12 miles/pixel).
In this image, bright markings are visible, and impact craters can be seen near the Terminator.MareKromium
(4 voti)
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ZZ-Mercury-Global_View_of_the_Surface-Cratered_Surface-209516.jpgHow many craters do you see?63 visiteOne of many investigations underway includes identifying and measuring the impact craters on Mercury's previously unseen Regions. The density of craters on the surface of a planet can be used to indicate the relative age of different places on the surface; the more craters the surface has accumulated, the older the surface.
By counting craters on different areas of Mercury's Surface, a relative geologic history of the Planet can be constructed, indicating which surfaces formed first and which formed later. However, this process is also time consuming; Mercury has a lot of craters!
This image shows just a portion (276 Km, or 172 miles, wide) of 1 frame taken with the Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS). In this image alone, 763 craters have been identified and measured (shown in green) along with 189 hills (shown in yellow).
Altogether, 491 frames were taken by the NAC to create HR mosaics of Mercury's surface.
Of course, simply counting the craters is not enough. Each crater has to be measured and classified to fully interpret the differences in crater density.
Many small craters form as "secondaries," as clumps of material ejected from a "primary" crater re-impact the surface in the regions surrounding the primary.
In order to learn about the history of asteroid and comet impacts on Mercury, scientists have to distinguish between the primary and secondary craters. Once many more craters are measured, MESSENGER researchers will have new insights into the geological history of Mercury.
Image Mission Elapsed Time (MET): 108826672
MareKromium
(4 voti)
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ZZ-Mercury-Craters-Unnamed_Rayed_Crater-209510.jpgRayed Crater on Mercury62 visiteJust above and to the left of center of this image is a small crater with a pronounced set of bright rays extending across Mercury's surface away from the crater. Bright rays are commonly made in a crater-forming explosion when an asteroid strikes the surface of an airless body like the Moon or Mercury. But rays fade with time as tiny meteoroids and particles from the Solar Wind strike the surface and darken the rays. The prominence of these rays implies that the small crater at the center of the ray pattern formed comparatively recently.
This image is 1 in a planned set of 99. Nine different views of Mercury were snapped in this set to create a mosaic pattern with images in 3 rows and 3 columns. The WAC is equipped with 11 narrow-band color filters, and each of the 9 different views was acquired through all 11 filters. This image was taken in filter 7, which is sensitive to light near the red end of the visible spectrum (750 nm), and shows features as small as about 6 Km (about 4 miles) in size.
The MESSENGER team is studying this previously unseen side of Mercury in detail to map and identify new geologic features and to construct the Planet’s geological history.
Mission Elapsed Time (MET) of image: 108827618MareKromium
(4 voti)
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ZZ-Mercury-Cliffs-209522.jpgMercury's Long Cliffs66 visiteAs the MESSENGER team continues to study the HR images taken during the Mercury flyby encounter on January 14, 2008, scarps (cliffs) that extend for long distances are discovered. This frame, taken by the Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS), shows a Region of Mercury's surface previously unseen by spacecraft and a large scarp crossing vertically through the scene, on the far right of the image. This scarp is the northern continuation of the one seen in the NAC image released on January 16. The width of this image is about 200 Km (approx. 125 miles), showing that these scarps can be hundreds of kilometers long on Mercury.
The presence of many long and high scarps, as discovered from pictures from the Mariner 10 Mission in 1974 and 1975, suggests a history for Mercury that is unlike that of any of the other Planets in the Solar System. These giant scarps are believed to have formed when Mercury’s interior cooled and the entire Planet shrank slightly as a result.
However, Mariner 10 was able to view less than half the planet, so the global extent of these scarps has been unknown. MESSENGER images, like this one, are providing the first high-resolution looks at many areas on Mercury's surface, and science team members are busy mapping these newly discovered scarps to see whether they are common everywhere on the planet.
Mission Elapsed Time (MET) of image: 108826206
MareKromium
(4 voti)
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ZZ-Mercury-Craters-Matisse_Crater-209136.jpgMatisse Crater (HR)63 visiteAs NASA’s MESSENGER approached Mercury on January 14, 2008, the Spacecraft took this image of the Crater Matisse. Named for the French artist Henri Matisse, Matisse crater was imaged during the Mariner 10 Mission and is about 130 miles in diameter. Matisse crater is in the Southern Hemisphere and can be seen near the Terminator of the Planet (the line between the sunlit, day side and the dark, night side).
On Mercury, craters are named for people, now deceased, who have made contributions to the Humanities, such as Artists, Musicians, Painters and Authors. The International Astronomical Union (IAU) oversees the official process of naming new craters and other new features discovered on bodies throughout the Solar System. Scientists studying and mapping unnamed features can suggest names for consideration by the IAU. The 1213 images taken by MESSENGER during its first flyby encounter with Mercury cover a large region of Mercury's surface previously unseen by spacecraft, revealing many new craters and other features that will need to be named.
MareKromium
(4 voti)
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ZZ-Mercury-Limb-208698.jpgMercury's Horizon (HR)63 visiteAs NASA’s MESSENGER drew closer to Mercury for its historic first flyby, the Spacecraft acquired this image showing a variety of surface textures, including smooth plains at the center of the image, numerous impact craters and rough material that appears to have been ejected from the large crater to the lower right.
MESSENGER has acquired over 1200 images of Mercury. These types of images will assist scientists to study, as never before, details to help them learn about the history and evolution of the innermost Planet.MareKromium
(4 voti)
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ZZ-Mercury-Craters-Unnamed_Double-Ring_Crater-208672.jpgDouble-Ringed Crater (HR)62 visiteNASA’s MESSENGER Spacecraft’s closest approach to Mercury on January 14, 2008, acquired this image as part of a mosaic that covers much of the sunlit portion of a hemisphere not view by previous spacecraft. Images such as this can be read in terms of a sequence of geological events and provide insight into the relative timing of processes that have acted on Mercury's surface in the past.
The double-ringed crater pictured in the upper right of this image appears to be filled with smooth plains material, perhaps volcanic in nature.
This crater was subsequently disrupted by the formation of a prominent cliff, the surface expression of a major crustal fault system that runs alongside part of its southern rim. This may have led to the uplift seen across a portion of the crater’s floor. A smaller crater in the upper left of the image also has been cut by the cliff, showing that the fault beneath the cliff was active after both of these craters had formed.MareKromium
(4 voti)
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ZZ-Mercury-Scarp-208630.jpgDeep Scarp on Mercury (HR)71 visiteNASA’s MESSENGER Spacecraft captured this image on January 14, 2008, during its closest approach to Mercury. The image reveals a variety of intriguing surface features, including craters as small as 300 yards across.
The image also shows landscapes near Mercury’s Equator on the side of the Planet never before imaged by spacecraft. These highly detailed close-ups enable planetary geologists to study the processes that have shaped Mercury’s surface over the past 4 Billion Years. One of the highest and longest scarps cliffs yet seen on Mercury curves from the top center down across the right side of this image. Great forces in Mercury’s crust have thrust the terrain occupying the left two-thirds of the picture up and over the terrain to the right. An impact crater has subsequently destroyed a small part of the scarp near the top of the image.
This image was taken from a distance of 3600 miles from surface of the Planet and shows a region approximately 100 miles across. MareKromium
(4 voti)
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ZO-Mercury02_Messenger.jpgMessenger's First Look at Mercury's Previously Unseen Side76 visiteCaption NASA:"This image was taken on January 14, 2008, by NASA's MESSENGER Spacecraft at a distance of approx. 17.000 miles following the Spacecraft's closest approach to Mercury. The image shows features as small as 6 miles in size.
Similar to previously mapped portions of Mercury, this Hemisphere appears heavily cratered. It also reveals some unique and distinctive features.
On the upper right is the giant Caloris basin, including its western portions never before seen by spacecraft. Formed by the impact of a large asteroid or comet, Caloris Basin is one of the largest, and perhaps one of the youngest basins in the Solar System". MareKromium
(4 voti)
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B-Mercury-PIA02948.jpgOld Basin Filled with by Smooth Plains (natural colors - elab. Lunexit)67 visiteCaption NASA:"Old basin, 190 km in diameter, filled by smooth plains at 43° South Latitude and 55° West Longitude. The basin's hummocky rim is partly degraded and cratered by later events. Mariner 10 frame 166607".MareKromium
(4 voti)
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C-Mercury-HR-PIA02416.jpgA slice" of Mercury... (HR)60 visiteCaption NASA originale:"A limping Mariner 10 spacecraft was coaxed into a third and final encounter with Mercury in March of 1975. Due to several problems with the aging spacecraft, only ~450 useful images of the planet were acquired, though many are at significantly higher resolution than previous encounters. This is one of the highest resolution images of Mercury acquired by Mariner 10: Frame 528922, ~90 m/pixel.
The vertical (tall narrow) format of the third encounter images resulted from problems with the tape recorder and transmitter on the spacecraft. Only the middle quarter of each frame could be sent back".
(4 voti)
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