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| Ultimi arrivi - Mercury |
ZZ-Mercury-Volcanic_Features-Vent-PIA12370.jpgIrregular Rimless Depression - Candidate for an Explosive Volcanic Vent on Mercury (Natural Colors; credits: Lunexit)63 visiteThis Region of high reflectance was just barely seen on the limb during MESSENGER's 2nd flyby, but without enough detail to characterize it as anything other than a bright spot.
A more favorable viewing angle reveals this bright spot to be an irregular rimless depression approx. 30 Km across surrounded by highly reflective material. Its features are distinctly different from those of impact craters and, though its origin remains ambiguous, it is suspected to be volcanic, possibly the site of an explosive Volcanic Vent. The high-reflectance halo surrounding this enigmatic feature is distinct in color and may represent a pyroclastic deposit greater than 150 Km in diameter.
Date Acquired: September 29, 2009
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Scale: The irregular rimless depression in the center of the image is approx. 30 Km (about 19 miles) acrossMareKromiumNov 17, 2009
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ZZ-Mercury-Limb-PIA12306.jpgBehind the Sun64 visiteAs MESSENGER approached Mercury during the Spacecraft's 3rd Mercury flyby, the Solar System's innermost Planet appeared to the imaging system as a sunlit crescent against the blackness of space. About 78 minutes prior to closest approach, the NAC captured this striking high-resolution image of the northernmost Region of Mercury's surface that was visible to the camera and illuminated by sunlight. The brightly lit North-Eastern walls of large impact craters can be seen near the horizon, catching the grazing rays of the Sun. The high Sun angle also accentuates wrinkle ridges winding across the smooth plains. In the foreground, features cast long shadows and the Terminator separates day from night.
Date Acquired: September 29, 2009
Image Mission Elapsed Time (MET): 162744006
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Scale: The crater near the middle of the left edge of the image is approximately 100 Km (about 60 miles) in diameter
Spacecraft Altitude: about 16.200 Km (approx. 10.100 miles)MareKromiumOtt 18, 2009
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ZZ-Mercury-Terminator-PIA12279.jpgStrange Neighbors73 visiteThe MESSENGER Spacecraft was flying toward Mercury at 3,7 Km/second (8300 miles/hour) when it captured this image. The Sun was just above the horizon, and the deep shadows it cast emphasized the texture and topography of the terrain along the Terminator (day/night boundary). The large crater at upper left has a rough rim and walls, and the floor of this crater has a sunken inner circular area. At the center of the sunken floor section is an irregular depression (or pit) that is entirely in shadow in this view. Just to the South-South/West is the right half of another large crater whose rim intersects that of the crater with the sunken floor. The southern crater is about the same diameter as its northern neighbor, but instead of exhibiting a sunken floor with a pit, it has been filled nearly to its rim with smooth material likely of volcanic origin. These two close neighbors, one empty and one full, attest to the surprisingly complicated geological history of the little planet closest to the Sun.
Date Acquired: September 29, 2009
Image Mission Elapsed Time (MET): 162744138
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 400 meters/pixel (0,25 miles/pixel)
Scale: This image is about 220 Km (approx. 140 miles) wide
Spacecraft Altitude: about 15.700 Km (approx. 9800 miles)MareKromiumOtt 18, 2009
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ZZ-Mercury-Volcanic_Regions-PIA12284.jpgEvidence of Volcanism on Mercury73 visiteSome impact craters on Mercury have non-circular, irregularly shaped depressions or pits on their floors. Such craters have been termed "Pit-Floor Craters", and MESSENGER team members have suggested that such Pits formed by the collapse of subsurface magma chambers. If this suggestion is correct, the pits are evidence of volcanic processes at work on the Solar System's innermost Planet. With high-resolution images from MESSENGER's 3rd Mercury flyby, more pit-floor craters are being identified on Mercury's Surface.
This NAC image shows a good view of a Pit-Floor Crater imaged last week prior to closest approach. The large crater near the center of the image contains an elongated bean-shaped depression on its floor and is a Pit-Floor Crater. The slightly smaller crater to the South also contains a pair of depressions on its floor, though from this image alone it cannot be determined if the depressions are pits or overlapping impact craters. Other examples of pit-floor craters discovered in MESSENGER images include Beckett, Gibran, and another newly imaged crater from Mercury flyby 3.
Date Acquired: September 29, 2009
Image Mission Elapsed Time (MET): 162744290
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 390 meters/pixel (0.24 miles/pixel)
Scale: this image is about 400 Km (approx. 250 miles) from top to bottom
Spacecraft Altitude: about 15.200 Km (approx. 9400 miles)MareKromiumOtt 18, 2009
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ZZ-Mercury-Craters-Unnamed_Double-Ring_Basin.jpgDouble "Concentric" Basin on Mercury (Natural Colors; credits: Lunexit)63 visiteCaption NASA, da "NASA - Picture of the Day" del giorno 7 Ottobre 2009:"What created the internal second ring of this Double Ringed Basin on Mercury?
No one is sure.
The unusual feature spans approx. 160 Km and was imaged during the robotic MESSENGER Spacecraft's swing past our Solar System's innermost planet. Double and Multiple Ringed Basins, although rare, have also been imaged in years past on Mars, Venus, Earth and Earth's Moon.
Mercury itself has several doubles, including huge Caloris Basin, Rembrandt Basin and enigmatic Raditladi Basin. Most large circular features on planets and moons are caused initially by a forceful impact by a single asteroid or comet fragment. Since it is unlikely that a second impact would occur right in the center of the first, large double rings are usually attributed to a subsequent volcanic lava flow inside the impact crater.
Possibly, though, a second ring could be caused by the melting and flowing of material upon impact. One clue to the origin of the above-imaged double ring is that the basin center appears much smoother than the region between the rings. MESSENGER has now completed its last flyby of Mercury but will return and attempt to enter orbit in March 2011".MareKromiumOtt 08, 2009
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ZU-PIA12135.jpgGood-bye Mercury!74 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)MareKromiumLug 20, 2009
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ZZ-Mercury-Craters-Tiziano_Crater-PIA12079.jpgTitian Crater (extremely enhanced Natural Colors; credits: NASA and Lunar Explorer Italia)62 visiteThis enhanced-color image shows Titian Crater (center) and is similar to an image that recently appeared in the 1st of May 2009 issue of Science magazine.
The enhanced-color view was created by using high-resolution images taken in all 11 WAC filers (one of which is shown in a previously released image, see PIA11765) and comparing and contrasting them to accentuate differences on Mercury’s Surface. Such color differences can be used to learn about the history of Mercury’s Surface in this area. In the enhanced color, the smooth floor of Titian is a brighter orange color than the surrounding area, likely due to being filled with volcanic material. Ejecta from Titian appear blueish and cover much of the Surface surrounding the Crater. This material was excavated from depth during the Crater’s formation.
Later impacts, such as the one that produced the small crater that appears yellowish in the upper center of the image, excavated material from below the Titian ejecta. This yellow-appearing material was present at or near the surface before the impact that created Titian and is a different composition (and thus, color) from its surroundings. Impacts make it possible to assess how Mercury’s Crust varies with depth and ultimately how the crust evolved through time.
Date Acquired: October 6, 2008
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 462 meters/pixel (0,29 miles/pixel)
Scale: Titian crater is about 121 Km (approx. 75 miles) in diameter
Nota Lunexit: curiosa la "chiazza violacea" visibile ad ore 01:00 del Cratere "Tiziano". La NASA, ovviamente, ha commentato tutto, tranne il dettaglio più intrigante. Noi, purtroppo, non possiamo aggiungere nulla, se non ribadire un concetto già espresso dalla NASA più volte, e cioè che "a colore diverso, nei frames colorizzati in natural enhanced colors, corrisponde un materiale diverso". Nulla di più.MareKromiumLug 14, 2009
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ZZ-Mercury-Craters-Lermontov_Crater-PIA12116.jpgLermontov Crater (possible Natural Colors; credits: Lunar Explorer Italia)62 visiteLermontov Crater was first observed by Mariner 10 and seen more recently by MESSENGER during its second flyby of Mercury. The Crater fFloor is somewhat brighter than the exterior surface and is smooth with several irregularly shaped depressions.
Such features, similar to those found on the floor of Praxiteles Crater (see PIA12040), may be evidence of past explosive volcanic activity on the Crater Floor. Lermontov appears reddish in enhanced-color views (see PIA11411), suggesting that it has a different composition from the surrounding surface.
Lermontov is named for Mikhail Yurevich Lermontov, a nineteenth-century Russian poet and painter who died from a gunshot suffered in a duel.
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131771953
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 250 meters/pixel (0,16 miles/pixel)
Scale: Lermontov’s diameter is about 152 Km (approx. 94 miles)
Spacecraft Altitude: about 10.000 Km (approx. 6200 miles)
Nota Lunexit: curiosamente, dopo il nostro Color Processing, non è Lermontov ad apparire "rossiccio", a fronte di terreni circostanti grigiastri, bensì l'esatto contrario! Curioso...MareKromiumLug 14, 2009
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ZZ-Mercury-Craters-Unnamed_Rayed_Crater-PIA12068.jpgRayed Crater Cluster (possible Natural Colors; credits: Lunar Explorer Italia)73 visiteThis NAC image from MESSENGER’s second Mercury flyby shows a crater with a set of light-colored rays radiating outward from it. Such rays are formed when an impact excavates material from below the surface and throws it outward from the crater.
These bright rays, consisting both of ejecta and the 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 constantly being bombarded with Micrometeorites and Energetic Ions, an effect known as "Space Weathering".
Craters with bright rays are thought to be relatively young because the rays are still visible, suggesting that they have had less exposure to Weathering processes. The crater in the center of this image has rays that have already begun to fade, implying that it is older than some other rayed craters on Mercury’s surface. Images of younger craters with much brighter and more striking rays have been previously released (see PIA11355).
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131771863
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 240 meters/pixel (0,15 miles/pixel)
Scale: Image is approximately 240 Km (about 150 miles) wide
Spacecraft Altitude: about 9500 Km (approx. 5900 miles)MareKromiumLug 14, 2009
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ZZ-Mercury-Craters-Cratered_Plains-PIA12050.jpgRudaki Plains and Crater75 visiteLast week (April 2009), MESSENGER team members presented the results from 4 papers published in the 1st of May issue of the "Science" magazine at a NASA media teleconference. The color views shown here of the Plains near Rudaki Crater was just one of the graphics presented at that teleconference (nota: NO. La versione che vedete su queste pagine è quella ottenuta da Lunar Explorer Italia, applicando la metodologia Multispettrale).
The left image was created by combining WAC images from three narrow-band color filters to approximate Mercury's color as it would be seen by the human eye. The right image used a statistical analysis of all 11 WAC filters to highlight subtle color differences on the surface, as has been used for many previous releases, such as ones focused on Thakur Crater and Caloris Basin.
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131770571-131770621
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS).
WAC Filters: Left image: 3, 4, 5 (480, 560, 630 nanometers). Right Image: statistical analysis involving all 11 WAC filters
Scale: The crater in the center of the image is approx. 68 Km (about 42 miles) in diameter
Spacecraft Altitude: about 2800 Km (approx. 1700 miles)MareKromiumGiu 23, 2009
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ZZ-Mercury-Craters-Moody_Crater-PIA12044_fig1.jpgMoody Crater70 visiteThe crater identified in this NAC image was named in November 2008 for Ronald Moody, a 20th century Jamaican sculptor and painter (see PIA11762). Moody features a Central Peak or Peak-Ring structure and an Annulus of dark material on its Outer Floor (green arrows). The area inward of the dark ring appears reddish in enhanced color WAC images (see PIA11219), indicating the presence of material different in composition from that of either the dark material or the Crater's immediate surroundings. Dark material has been found associated with other craters on Mercury, including Munch and Poe (see PIA12034). Moody is somewhat unusual for having its dark ring confined to the Crater Floor, rather than forming the crater rim as at Munch and Poe.
Date Acquired: January 14, 2008
Image Mission Elapsed Time (MET): 108829034
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 590 meters/pixel (0,37 miles)
Scale: Moody is about 80 Km (approx. 50 miles) in diameter
Spacecraft Altitude: about 23.100 kilometers (approx. 14.300 miles)MareKromiumGiu 23, 2009
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ZZ-Mercury-Craters-Vyasa_and_Stravinsky_Crater-PIA12035_fig1.jpgLow-Sun over Mercury...62 visiteThis NAC image shows a close-up view of the craters Vyasa and Stravinsky (see PIA11360). Stravinsky is the smooth-floored crater partially seen on the right side of the image that overlies the rim of the larger, rougher crater Vyasa in the center and left. The low-Sun lighting angle casts distinctive shadows that show Mercury's rough surface, pockmarked by craters of all sizes. Small craters are visible on the smooth-floor of Stravinsky because of the high resolution of this image.
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131771118
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 140 meters/pixel (0,09 miles/pixel) near the bottom of the image
Scale: Stravinsky crater is about 190 Km in diameter (120 miles)MareKromiumGiu 23, 2009
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