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ZQ-Mercury-PIA10942.jpgShield-Volcano on Mercury54 visiteAs reported in the July 4, 2008 issue of Science magazine, volcanoes have been discovered on Mercury’s Surface from images acquired during MESSENGER’s first Mercury flyby. This image shows the largest feature identified as a volcano in the upper center of the scene. The volcano has a central kidney-shaped depression, which is the vent, and a broad smooth dome surrounding the vent. The volcano is located just inside the rim of the Caloris Impact Basin. The rim of the Basin is marked with hills and mountains, as visible in this image. The role of volcanism in Mercury’s history had been previously debated, but MESSENGER’s discovery of the first identified volcanoes on Mercury’s surface shows that volcanism was active in the distant past on the innermost Planet.
Date Acquired: January 14, 2008
Image Mission Elapsed Time (MET:108826877
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 270 meters/pixel (0,17 miles/pixel)
Scale: This image is about 270 Km across (approx. 170 miles)
Spacecraft Altitude: approx. 10.500 Km (about 6500 miles)MareKromium
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ZQ-Mercury-PIA10984.jpgCraters "Deformed" and "Shortened" on Mercury54 visiteNumerous examples of craters that have been deformed and shortened by younger faults have been identified on images returned from MESSENGER’s first flyby of Mercury. In three cases shown here (arrows), portions of the floor and rim of a crater were buried when a large block of crust was thrust over the crater during the formation of a prominent fault scarp or cliff. By comparing the estimated size and shape of the original, undeformed crater with the crater’s current geometry, scientists can infer the amount of movement between the two crustal blocks on either side of the fault. This figure was recently published in Science magazine.
For each of the three examples of deformed and shortened craters shown here, movement on the faults buried at least a kilometer of the original crater. A: 17-Km (11-mile) diameter crater (arrows) shortened by Beagle Rupes. B: 5-Km (3-mile) diameter crater deformed near the rim of an older, larger crater, shown enlarged in the box on the lower left. C: 11-Km (7-mile) diameter crater (arrows) shortened by a North/West-South/East-trending fault scarp.MareKromium
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ZQ-Mercury-PIA11025.jpgWrinkle-Ridge Rings on Mercury and Mars54 visitePlanetary scientists commonly compare and contrast the geologic features found on different planetary bodies, to learn about the similar processes that operated throughout the Solar System and to understand how each planet is different and unique. This figure, recently published in Science magazine, shows wrinkle-ridge rings on both Mercury (upper image) and Mars (lower image) that look quite similar. Wrinkle ridges arrayed in such a ring are interpreted to trace the rim of an impact crater that was nearly or completely flooded by lavas prior to ridge formation. Wrinkle ridges are created by forces that compress the crust horizontally.
A buried crater rim can concentrate the near-surface forces and cause the wrinkle ridges to form a ring. The presence of wrinkle-ridge rings is thus good evidence that volcanism helped to shape the surfaces of both Mars and Mercury.
Date Acquired: January 14, 2008
Image Mission Elapsed Time (MET): A: 108826972
Instrument: A: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Mars Image: B: Mars Express High-Resolution Stereo Camera nadir image h2660_0001
MareKromium
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ZS-Mercury-PIA11077.jpgFaults in Caloris Basin54 visiteAs the youngest large impact basin known on Mercury, the Caloris Basin has landforms that are better preserved than in older basins, which have been more modified by impact cratering.
This figure, recently published in Science magazine, shows a map of many linear features within Caloris Basin that formed when the near-surface rocks were subjected to large horizontal forces. The Caloris Basin contains hundreds of extensional troughs, mapped as black lines, where the surface has been pulled apart and faulted.
Pantheon Fossae (located inside the white box of the top map and shown in detail in the bottom image) has over 200 such troughs in a radiating pattern, but near the outer edges of the basin interior troughs are seen in patterns broadly concentric to Caloris Basin. The Caloris Basin interior also has been deformed by many wrinkle ridges, mapped as red lines, formed when the surface was compressed or shortened horizontally. Relationships between the extensional troughs and contractional wrinkle ridges provide information about the evolution of the Caloris basin and Mercury's interior.
Date Acquired: January 14, 2008
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Scale: Caloris Basin is about 1550 Km (approx. 960 miles) in diameter. The crater Apollodorus near the center of Pantheon Fossae is about 41 Km (approx. 25 miles) in diameter. MareKromium
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ZT-Mercury-WAC_1x1_color.pngThe "True Colors" of Mercury?53 visite...Ed alla fine, anche la NASA (almeno per quanto riguarda la Missione MESSENGER) si è "arresa" alla Logica Generale dei Colori adottata - tempo fa - da Lunexit.
Citiamo (come da nostro Sondaggio) "I colori di un Mondo dipendono (o, se volete, stanno) dagli (negli) occhi di chi lo guarda".
Una considerazione che potrà anche sembrarVi stupida e scontata ma che, va detto per Onestà Intellettuale, è stata oggettivata e fatta propria da Lunar Explorer Italia da tempo ed attraverso l'articolo "True Colors", che potete trovare nell'archivio del nostro blog TrePlanets.
A nostro avviso, questa considerazione NASA (che riprende Lunexit) deve farci ancora una volta sentire fieri del Lavoro che svolgiamo e dei risultati che otteniamo.
Anche se, a parte Voi Lettori e noi STAFF, non sembra essersene accorto nessun altro (specie in Italia)...
Caption NASA:
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131775256, 131775260, 131775264, 131775268
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 5 Km/pixel (about 3 miles/pixel)
Scale: Mercury’s diameter is roughly 4880 Km (approx. 3030 miles)
Spacecraft Altitude: about 27.000 Km (approx. 17.000 miles)
Of Interest: Given the WAC’s ability to take images through 11 narrow-band color filters, it is natural to wonder what does Mercury look like in “true” color such as would be seen by the human eye. However, creating such a natural color view is not as simple as it may seem. Shown here are four images of Mercury. The image in the top left is the previously released grayscale monochrome single WAC filter (430-nanometer) image; the remaining three images are three-color composites, produced by placing the same three WAC filter images with peak sensitivities at 480, 560, and 630 nanometers in the blue, green, and red channels, respectively. The differences between the color representations result from how the brightness and contrast of each individual WAC filter image was adjusted before it was combined into a color picture. In the top right view, all of the three filter images were stretched using the same brightness and contrast settings. In the bottom left picture, the brightness and contrast of each of the three filter images were determined independent of the others. In the bottom right, the brightness and contrast settings used in the upper right version were slightly adjusted to make each of the three filter images span a similar range of brightness and contrast values.
So which color representation is “correct” for Mercury? The answer to that would indeed DEPEND ON THE EYES OF THE BEHOLDER. Every individual sees color differently; the human eye has a range of sensitivities that vary from person to person, resulting in different perceptions of “true” color. In addition, the three MDIS filter bands are narrow, and light at wavelengths between their peaks is not detected, unlike the human eye. In general, in light visible to the human eye, Mercury’s surface shows only very subtle color variations, as seen in the three images here. However, when images from all 11 WAC filters are statistically compared and contrasted, these subtle color variations can be greatly enhanced, resulting in extremely colorful representations of Mercury’s surface.MareKromium
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ZU-PIA12038.jpgIn search of the "Vulcanoids"53 visiteIn mid-February 2009, before and after MESSENGER's latest Perihelion (such as the closest approach to the Sun), an imaging campaign was conducted to search for "Vulcanoids": small rocky bodies that have been postulated to exist in orbits between Mercury and the Sun. Those images are still waiting to be transmitted to Earth.
The image here is from the first set of 240 MDIS images taken to look for vulcanoids, acquired in June 2008. It is a 10" exposure taken through the WAC's clear filter. Jupiter is bright and visible in the image. The camera field of view is nearly large enough to capture the entire width of Sagittarius, a constellation of the Zodiac visible low and to the South in Summer from temperate latitudes in the Northern Hemisphere. The Greek letters identify some of the brighter stars in Sagittarius.
During the Vulcanoid search campaign, 4-5 images of the same scene are taken back to back. This procedure allows Cosmic Ray strikes on the camera's detector to be identified and enables fainter objects to be detected. One such Cosmic Ray strike is labeled on this image. In this single image, the Cosmic Ray strike appears similar to the stars, but in the 4 images taken immediately after this one, the Cosmic Ray strike is gone whereas the stars remain. Images are also taken hours and days apart, so the motion of objects in the sky can be determined. If a Vulcanoid were imaged, its motion through the sky would appear very different from motions of the background stars and known Solar System objects.
No Vulcanoids have been found yet, but the latest set of acquired images will expand the volume of the search region examined so far.
Date Acquired: June 4, 2008
Image Mission Elapsed Time (MET): 121050477
Instrument: Wide Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
WAC Filter: 2 (clear filter)
Field of View: The WAC has a 10,5° field of viewMareKromium
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ZU-PIA12051.jpgGlobal Map of Mercury53 visiteMESSENGER's two flybys of Mercury in 2008 have greatly increased the portion of the Planet's Surface that has been imaged by spacecraft, from approximately 45% coverage obtained by Mariner 10 to about 90% coverage following the second flyby.
This significant increase in imaging coverage is enabling global studies of Mercury's Surface for the first time. MESSENGER team members recently published an article in the 1st of May issue of the "Science" Magazine that utilizes this new global view to examine the evolution of Mercury's crust. This recent work was also featured in a NASA media teleconference, and the top image shown here was presented during that teleconference.
Both images are orthographic map projections of Mercury created with WAC enhanced-color images. The orthographic projection produces a view that has the perspective that one would see from deep space. The WAC enhanced color uses a statistical analysis of images from all 11 WAC filters to highlight subtle differences in the crustal rocks on Mercury's Surface. For other examples and discussion of enhanced color images, see previous releases of the departure view from Mercury flyby 2, Rudaki Plains, Thakur Crater and Caloris Basin.
The top view uses images from Mercury flyby 1, with the thin crescent of Mercury imaged during approach forming the right portion of the globe and the fuller departure view showing Caloris Basin forming the left side and majority of the view.
The black strip between the approach and departure images is a portion of Mercury's Surface not viewed by MESSENGER during the flybys. Similarly, the approach and departure images obtained during Mercury flyby 2 yielded the bottom view.
The top and bottom projections are centered on 180° and 0° Longitude, respectively.
Date Acquired: January 14, 2008, and October 6, 2008
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Scale: Mercury’s diameter is about 4880 Km (approx. 3030 miles)MareKromium
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ZU-PIA12135.jpgGood-bye Mercury!54 visiteThese images were taken by MESSENGER as the spacecraft departed Mercury after completing its 2nd flyby on October 6, 2008. During this sequence, images were taken every 5 minutes.
A portion of the same sequence, totaling 198 images in all, has also been made into a movie (see PIA11412). MESSENGER will make its third and final flyby of Mercury on September 29, 2009, and will become the first Spacecraft ever to orbit Mercury in March 2011.
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131788060-131840260
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Scale: Mercury’s diameter is 4880 Km (approx. 3030 miles)
Spacecraft Distange from Target: from 95.000 up to 370.000 Km (such as from about 59.000 up to 230.000 miles)MareKromium
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ZW-Mercury-PIA12365.jpgRising Mercury (Natural Colors; credits: NASA and Lunexit)53 visiteAs MESSENGER approached Mercury for the mission's 3rd and final flyby of the Solar System's innermost planet, the WAC acquired images through all 11 of its narrow-band color filters. The 1000, 700, and 430 nanometer filters were combined in red, green, and blue to create this color image, the last close-up color view that will be acquired until MESSENGER goes into orbit around Mercury in March of 2011. Only 6% of Mercury's Surface in this image had not been viewed previously by spacecraft, and most of the measurements made by MESSENGER's other instruments during this flyby were made prior to closest approach. The observations from MESSENGER's third flyby of Mercury nonetheless revealed fresh surprises. Check out the NASA Science Update Telecon held today for details about some of these new surprises.
Date Acquired: September 29, 2009
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC Filter: 9, 1, 6 (1000, 700, and 430 nanometers)
Resolution: 5 Km/pixel (about 3 miles/pixel)
Scale: Mercury's diameter is approx. 4880 Km (about 3030 miles) MareKromium
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ZW-Mercury-PIA12397.jpgMercury53 visiteToday (December, 15th, 2009), the first High-Resolution Global Map of Mercury was made publicly available. Members of the MESSENGER team and experts from the U. S. Geological Survey (USGS) used images from MESSENGER's three Mercury flybys and from the Mariner 10 Mission in 1974-75 to create a Global Mosaic that covers 97,7% of Mercury's Surface at a resolution of 500 meters/pixel (0,31 miles/pixel).
The above image shows the full global Mercury mosaic but at a greatly reduced scale of only 5% of the HR version. The full HR mosaic by can be seen at the USGS Map-a-Planet website.
Date Mercury Fly-By 1: January 14, 2008
Date of Mercury Fly-By 2: October 6, 2008
Date of Mercury Fly-By 3: September 29, 2009
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Scale: Mercury's diameter is approx. 4880 Km (such as about 3030 miles)MareKromium
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ZW-Mercury-PIA12842-1.jpgThe Eastern Limb of Mercury (possible Natural Colors; add. process. and color.: Dr Paolo C. Fienga - Lunexit Team)135 visiteDate Acquired: January, 14th, 2008
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 2,8 Km/pixel (such as about 1,7 miles/pixel) at the Equator
Scale: Caloris Basin (which is the round, light-brown colored Surface Feature visible on the top right of Mercury) is about 1550 Km (approx. 960 miles) in diameter
Spacecraft Altitude: about 13.000 Km (approx. 8000 miles)MareKromium
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ZW-Mercury-PIA13508-PCF-LXTT.jpgHokusai Crater (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)113 visiteThis mosaic of NAC images shows the Impact Crater Hokusai, located on Mercury at a latitude of approx. 58° North. The Crater has an impressive System of Rays, which extend as much as a thousand kilometers (more than 600 miles) across the Planet and are the longest that have yet been identified on Mercury.
Such Rays are formed when an impact excavates material from beneath the Surface and throws that material outward from the Crater. These bright Rays, consisting of both Ejecta and Secondary Craters (that form when the ejected material re-impacts the Surface), slowly begin to fade as they are exposed to the harsh Space Environment. Mercury and other airless Planetary Bodies are being constantly bombarded with Micrometeoroids and Energetic Ions, both concurring to produce an effect known as "Space Weathering".
Craters with Bright Rays are thought to be relatively young because the Rays are still visible, indicating that they have had less exposure to such weathering processes than craters that lack rays.
Although the extent of some of Hokusai's Rays have been determined, images acquired during MESSENGER's three Mercury fly-bys have not yet shown all of them.
During MESSENGER's orbital observations, which will begin in March 2011, MDIS will acquire high-resolution color images of Mercury's entire Surface.
This Global Color Map will allow the better understand the extent of the extensive Systems of Rays emanating from Hokusai and other young Craters, to be mapped for the first time.
Date Acquired: October, 6th, 2008
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Scale: The diameter of Mercury is of about 4880 Km (3030,48 miles) and Hokusai Crater has a diameter of approx. 95 Km (58,995 miles)MareKromium
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