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| Ultimi arrivi - Mercury |
ZZ-Mercury-Craters-Tiziano_Vecellio_Crater-PIA11765-2.jpgTiziano Vecellio Crater (Natural Colors; credits: Lunar Explorer Italia)86 visitenessun commentoMareKromiumGen 27, 2009
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ZZ-Mercury-Craters-Unnamed_Southern_Rayed_Crater-PIA11371.jpgSpectacular "Rayed-Crater" (Enhanced Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)72 visiteThis NAC image shows a bright crater with an extensive system of impact ejecta rays; the crater is also clearly visible on the Southern portion of Mercury near the Limb of the Planet in the departure full-planet image (see PIA11245).
This impact crater and its associated system of rays were originally detected in 1969 as a “bright feature” in radar images at 12,5-centimeter wavelength obtained by the Goldstone Observatory in California. Subsequently, about a decade ago, radar images acquired by the Arecibo Observatory in Puerto Rico clearly revealed this feature to be a crater with a fresh system of rays of rough material radiating outward from it. This feature has been referred to simply as Feature “A”.
MESSENGER’s recent Mercury flyby provided the first Spacecraft images of Feature “A”, enabling this relatively young crater with its impressive set of rays to be seen here in close-up detail.
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131773947
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 530 meters/pixel (0,33 miles/pixel)
Scale: The bright rayed crater is approx. 80 Km (about 50 miles) in diameter
Spacecraft Altitude: approx. 20.600 Km (about 12.800 miles)MareKromiumNov 09, 2008
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ZZ-Mercury-Terminator-PIA11372.jpgDawn on Mercury (HR - possible True Colors; credits: Lunexit)64 visiteThe first image taken following MESSENGER’s closest distance to Mercury (PIA11352) during the mission’s recent flyby was a Wide Angle Camera (WAC) image. The image shown here is the first NAC image acquired after closest approach, and since the resolution of the NAC is a factor of seven higher than that of the WAC, this image is the highest-resolution image obtained during MESSENGER’s second Mercury flyby.
The image was taken near local dawn, so the shadows are long and many features are shrouded in darkness. The right side of this image overlaps with the left side of the previously released close-up view of Machaut crater (see PIA11249), which was taken just 5" later than this image. This portion of Mercury’s Surface is heavily cratered, with small craters visible down to the limits of even this highest-resolution image.
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131770803
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 100 meters/pixel (0,06 miles/pixel)
Scale: This image is about 100 Km (approx. 63 miles) across
Spacecraft Altitude: approx. 3800 Km (about 2400 miles)MareKromiumNov 09, 2008
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ZZ-Mercury-Limb-PIA11374-0.jpgA View to the South…from the Other Side of Mercury (Extremely Enhanced Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)60 visiteMESSENGER’s 2nd Mercury flyby passed over the opposite side of the Planet from that seen during the Mission’s 1st Mercury encounter. Thus, if one could follow this view obtained by the NAC during the 2nd flyby toward the South, beyond Mercury’s South Pole, it would lead to the Surface seen in an image from MESSENGER’s 1st Mercury flyby (see PIA10187).
Visible in the recently obtained image shown here are many features also seen by Mariner 10: Shevchenko crater named for the 19th century Ukrainian poet, Khansa for the Arabic poet of the 7th century, Rabelais for the Renaissance French writer, Holberg for the Norwegian-Danish writer of the 18th century, Spitteler for the Swiss epic poet who won the Nobel Prize for Literature in 1919, Rameau for the Baroque-era French composer, Puccini for the Italian composer of the late 1800s and early 1900s, and Horace for the ancient Roman poet. Discovery Rupes cuts through Rameau and is named for the ship of English explorer Captain James Cook.
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131773823
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 510 meters/pixel (0,32 miles/pixel) at the top of the image
Scale: Shevchenko crater is approx. 137 Km (about 85 miles) in diameter
Spacecraft Altitude: approx. 20.000 Km (about 12.400 miles)MareKromiumNov 09, 2008
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ZZ-Mercury-Craters-Machaut_Crater-CN0131770808M_web.pngMachaut Crater (natural colors; credits: Lunexit)86 visiteDate Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131770808
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 100 meters/pixel (0,06 miles/pixel)
Scale: This image is about 100 Km across (approx. 60 miles)
Spacecraft Altitude: about 3900 Km (approx. 2400 miles)
Of Interest: Machaut is the name of a crater, approx. 106 Km (about 66 miles) in diameter, first seen under high-Sun conditions by Mariner 10 in the 1970s. The crater is named for the medieval French composer and poet Guillaume de Machaut.
This NAC image shows an amazing new view of Machaut taken during MESSENGER’s second flyby of Mercury. The slanting rays of the Sun cast shadows that reveal numerous small craters and intricate features.
The largest crater within Machaut appears to have been inundated by lava flows similar to those that have filled most of the floor of the larger feature. The adjacent, slightly smaller crater was formed at a later time and excavated material below the lava-formed surface.
MESSENGER science team members will also be studying the shallow ridges that crisscross Machaut’s floor.MareKromiumOtt 19, 2008
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ZT-Mercury-WAC_1x1_color.pngThe "True Colors" of Mercury?88 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.MareKromiumOtt 17, 2008
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ZZ-Mercury-Craters-Crater_Field.jpgChangings...87 visiteDate Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131774145
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 550 meters/pixel (0,34 miles/pixel)
Scale: Asvaghosa crater is approx. 90 Km in diameter (about 56 miles)
Spacecraft Altitude: about 21.000 Km (approx. 13.000 miles)
Of Interest: This pair of images illustrates the dramatic effect that illumination and viewing geometry (i.e., the angle at which Sunlight strikes the surface, and the angle from which the spacecraft views the surface) has on the appearance of terrain on Mercury. The image on the right is a frame captured by MESSENGER’s NAC as the spacecraft was departing the planet after its second Mercury flyby. On the left is a portion of a mosaic made from Mariner 10 clear-filter images, obtained by that mission in 1974. The yellow arrows point to the 90-Km- (56-mile-) diameter crater Asvaghosa (named for the first century AD Indian philosopher and poet), and the purple arrows indicate a smaller crater to the southwest. A bright ray, prominently visible in the high-Sun MESSENGER frame, crosses both craters. The stripe of high-reflectance material may have originated at Kuiper crater (to the southwest) or may come from a newly imaged crater to the northeast that has an extensive ray system. This ray and others seen in the NAC image were mostly invisible to Mariner 10, because low-Sun illumination emphasizes topography instead of differences in reflectance. As another example, the curving scarp (cliff) named Santa Maria Rupes (white arrows in the left image) is visible in the Mariner 10 image by the shadow it casts, but this rupes disappears in the MESSENGER image when the Sun is high overhead. Images collected under both high- and low-Sun conditions are needed for geologists to develop a complete understanding of the features on a planetary surface.MareKromiumOtt 17, 2008
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ZZ-Mercury-Limb-CN0131766454M.pngSigns of Aging... (natural colors; credits: Lunexit)88 visiteDate Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131766454
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 420 meters/pixel (0,26 miles/pixel) on the right side of the image
Scale: The small crater superimposed on the long cliff is about 30 Km (approx. 19 miles) in diameter
Spacecraft Altitude: about 16.500 kilometers (approx. 10.300 miles)
Of Interest: This dramatic NAC image was acquired about 56 minutes prior to MESSENGER’s closest approach during the mission’s recent Mercury flyby, as the spacecraft approached the Planet's illuminated crescent. Prominent toward the horizon in this view of newly imaged terrain is a long cliff face. A small impact crater (about 30 Km, or approx. 19 miles, in diameter) overlies this lengthy scarp. The scarp extends for over 400 Km (about 250 miles) and likely represents a sign of aging unique to Mercury among the planets in the Solar System.
As time passes, the interior of a planet cools. However, the relative size of Mercury's central metallic core is larger than that of the other planets and hence has significantly affected the planet’s geologic evolution. The numerous long scarps on Mercury are believed to be the surface expression of faults formed in the rocks of Mercury's crust as the interior of the planet cooled and contracted. This contraction compressed the surface and thrust some sections of crust over others, creating long curving cliffs like the one shown here.MareKromiumOtt 17, 2008
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ZZ-Mercury-Limb-CW0131772818A_web.jpgMercury, during MESSENGER's 2nd Fly-By (natural, but enhanced colors; credits: Lunexit)77 visiteDate Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131772818
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC Filter: 1 (700 nanometers)
Resolution: 2,6 Km/pixel (about 1,6 miles/pixel)
Scale: The left side of the image is about 2700 Km tall (approx. 1700 miles)
Spacecraft Altitude: about 15.000 Km (approx. 9300 miles)
Of Interest: One week ago, no spacecraft had ever seen the majority of the surface visible in this image. Today, one week after MESSENGER’s successful second Mercury flyby, about 95% of Mercury’s surface has been viewed by spacecraft, resulting in nearly global spacecraft imaging coverage of Mercury’s surface for the first time. This WAC image is just one of 99 in a set of 3 columns by 3 rows by 11 color filters that is being combined into a color mosaic of the departing planet. Kuiper crater, with its bright ejecta rays, is visible on the left edge of the image and was seen by Mariner 10, but most of the terrain east of Kuiper was not. A newly imaged crater with an unusual halo of dark material is visible at about the same latitude but toward Mercury’s limb. The long, bright rays that can be seen extending across the surface emanate from a crater just north of this image.MareKromiumOtt 17, 2008
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ZZ-Mercury-Limb-CN0131766564M.pngA Small Crater Makes a Bright Impact (natural colors; credits: Lunexit)77 visiteDate Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131766564
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 410 meters/pixel (0,25 miles/pixel) in the lower right corner of the image
Scale: The bright crater is about 30 Km in diameter (approx. 19 miles)
Spacecraft Altitude: about 16.000 Km (about 9900 miles)
Of Interest: In both the optical navigation images and the full-planet Wide Angle Camera (WAC) approach frame, a bright feature is clearly visible in the northern portion of the crescent-shaped Mercury. This NAC image resolves details of this bright feature, showing that it surrounds a small crater about 30 Km (approx. 19 miles) in diameter, seen nearly edge-on. Presumably, the bright material was ejected from this small crater, which apparently formed relatively recently in Mercury’s past, because Mercury’s surface materials tend to darken with time. The brilliant ejecta are so bright compared with the neighboring surface that Earth-based telescopic observations also detected this feature, despite its being associated with such a small crater.MareKromiumOtt 17, 2008
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ZZ-Mercury-Rupes-CN0131773865_web.pngAstrolabe Rupes (natural colors; credits: Lunexit)89 visiteDate Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131774936
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 660 meters/pixel (0,41 miles/pixel)
Scale: Ghiberti crater is approx. 123 Km in diameter (about 76 miles)
Spacecraft Altitude: about 26.000 Km (approx. 16.000 miles)
Of Interest: This NAC image, taken about 85 minutes after MESSENGER’s closest approach during the mission’s second Mercury flyby, shows a view of Astrolabe Rupes, named for the ship of the French explorer Jules Dumont d’Urville. Rupes is the Latin word for cliff. Mercury’s day/night transition (the Terminator) is located on the left side of the image, and the Sun is striking the cliff face of Astrolabe Rupes in the upper right of the image. Also visible in the image are additional unnamed rupes, whose cliff faces are casting dark shadows. One of these rupes intersects the crater Ghiberti, named for the Italian Renaissance sculptor. Rupes on Mercury are thought to have formed as the interior of Mercury cooled and the planet consequently contracted slightly. Determining the number and extent of rupes on Mercury can thus be used to understand the thermal history of the Planet.MareKromiumOtt 17, 2008
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ZO-Mercury-Flyby2_Messenger_big.jpgMercury as Revealed by MESSENGER (Enhanced Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)66 visiteCaption NASA:"The Planet Mercury has been known since history has been recorded, but parts of the Solar System's Innermost Planet have never been seen like this before. Two days ago the robotic MESSENGER Spacecraft buzzed past Mercury for the second time and imaged terrain mapped previously only by comparatively crude radar.
The above image was recorded as MESSENGER looked back 90 minutes after passing, from an altitude of about 27.000 Km. Visible in the above image, among many other newly imaged features, are unusually long rays that appear to run like meridians of longitude out from a young crater near the northern limb.
MESSENGER is scheduled to fly past Mercury once more before firing its thrusters to enter orbit in 2011".MareKromiumOtt 08, 2008
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