The Best Frames from Viking Orbiter 1 and 2
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MarsColors01-Viking.jpgVolcanic Outgassing from Arsia Mons? (CTX Frame)118 visiteDURING THE FINAL APPROACH to Mars, just before going into orbit, the Viking Orbiters took a series of pictures of the Planet with different color filters. As the Planet rotated, different parts were photographed until almost the entire surface was covered.
The pictures taken with the various filters were then compared, and the color at each point on the surface was determined by means of a variety of sophisticated computer processing techniques. The results are displayed in frame (2) as Mercator Maps of the Equatorial Regions (the approach trajectory prevented good visibility of the Polar Regions, and they are not shown).
Although Mars has very distinct light and dark areas, differences in color are quite subtle. The appearance of the Planet is dominated by variations in brightness or albedo that cause the classical markings known from telescopic observations.
The color of the surface is a fairly uniform rusty brown and differences are so small that they can barely be seen.
NOTA Lunexit: nel frame in questione si vede BENISSIMO (anche se nessuno - neppure noi, sino a circa 5 minuti fa (ore 18:00 dell'AD 2011, Novembre, 6 - sembra averci MAI fatto caso) una "fumata vulcanica" di notevolissime dimensioni che potrebbe provenire sempre da Arsia Mons (diciamo che SEMBRA Arsia, ma non possiamo esserne sicuri al 100%). A questo punto, la recente "fumata" di Arsia (ripresa dalla Sonda ESA Mars Express) a noi non pare più il solo e semplice prodotto di una svista o di una interpretazione eccessivamente immaginifica dei dati. Molto probabilmente, anche se potrebbe trattarsi di mero vulcanismo residuale (ossìa di fenomenologie, si, vulcaniche, ma del tutto estemporanee e di entità minima), i Grandi Vulcani di Tharsis non sono ancora - e comunque non del tutto... - morti. E su questga riflessione, ci si dovrebbe fermare per un pò...
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MarsColors02-Viking.jpgThe Colors of Mars (2)53 visiteTo see the color differences, they must be artificially enhanced through computer processing at the same time, differences in brightness must be suppressed.
Two color maps are shown here, one that approximates the natural color (frame 3) and another in which the color differences arc artificially emphasized (frames 2 and 4).
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MarsColors02-Viking.jpgVolcanic Outgassing from Arsia Mons? (EDM)2461 visitenessun commentoMareKromium
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MarsColors03-Viking.jpgThe Colors of Mars (3)55 visiteColor is of considerable geologic interest because it allows remote detection of chemical and mineralogical differences. Only the upper few millimeters of the surface contribute to the color and on Mars this layer may be mostly wind blown debris. The bright materials that dominate the north equatorial zone are apparently aeolian deposits. Two units have been recognized. The upper unit is discontinuous, very red, and among the brightest of materials exposed at the planet's surface. The lower unit is darker and less red. The boundary between the two is generally serrated and has no relief. In the southern e equatorial belt, the color variations are apparently related to local bedrock and not to randomly dispersed aeolian debris. The dark highland region (0° to 40° S and 60° W to 30° E) is divided into (a) dark red ancient crater rims, rugged plateaus, mostly riddled with small channels , and graben; and (b) dark "blue" volcanic flows intermediate in age, and show very few channel networks. The large volcanic constructs in the Tharsis region and volcanic centers in the southern highlands northeast of Hellas are both very dark and very red.
In this image, all three color components have received the same contrast e enhancement, which approaches saturation in the brightest areas. Because Mars is by a factor of two to three more reflective in the red than in the violet, the red component is predominant-giving the planet its classic rusty appearance. Some artifacts of the processing remain in the image, for example, diagonal streaks running from upper left to lower right.
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MarsColors04-Viking.jpgThe Colors of Mars (4)54 visiteAtmospheric phenomena and surface frost affect the Planet's appearance. South of approximately 40° Lat., the scene is dominated by the annual South Polar CO2 fee cap. Near-surface condensate clouds arc abundant in this Region, especially in Hellas. Because some of the data in the bright areas were saturated, the color balance is distorted; no attempt was made to correct this problem. North of about 20° Lat., condensate clouds are especially noticeable along the northernmost edge where emission angles were extreme. Other clouds are scattered locally throughout the Equatorial Region South and South-West of Valles Marineris.
This image dramatically enhances subtle color variations The violet/green ratio is used as the blue component of the final image, the albedo at the are en wavelength as the green component, and the red/green n ratio as the red component. Hence, the amount of red or blue is controlled primarily by the slope of the spectral reflectance curve: areas with high albedo are also green. Thus, high albedo blue areas (ice, fog, clouds) are blue-green in color, and high albedo red areas are orange and yellow; bright areas of average color are green. Green is absent in dark areas, so the colors represent the slope from violet to red; red areas have a steeper slope, increasing from violet to blue; blue areas have a shallower slope.
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N-Deimos.jpgDeimos (Natural Colors; credits: NASA/JPL)54 visiteCaption NASA originale:"Color pictures of the two Martian moons have confirmed Earth-based spectra by also showing both satellites to be gray. The Viking imaging data showed the surfaces to be uniformly gray over the complete surface to a resolution of a few hundred meters. No significant color differences were seen on either surface, including areas around craters and those within the bright albedo features on Deimos.
The color indicates composition is of a carbonaceous chondritic material. Deimos, here, is at a range of 2100 km from the Viking 1 Orbiter. In these pictures, color differences have be en exaggerated; most of the color differences are due to noise or are artifacts of the processing, especially around craters and the limb".
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PHOBOS-451A06.pngPhobos over Iani Chaos (frame Viking: 34553639)111 visiteImage Id: 451A06
Center Latitude: -1.945031°
Center Longitude: 341.82642°
Solar Longitude: 331.55576°
Local Solar Time: 18.7825
Sample Resolution: 0.349275 km
Solar Incidence Angle: 65.52523°
Emission Angle: 17.508633°
Orbit: 451
Image Time: 1977-09-11 T16:09:49Z
Spacecraft: VIKING_ORBITER_1
Image Number: 34553639
Filter Name: CLEAR
Exposure Duration: 0.01697s
Line Resolution: 0.366696 km
Aspect Ratio: 1.049878
Phase Angle: 83.01045°
Slant Distance: 13711.231 km
Sun Azimuth: 90.210976°
Gain Mode ID: HIGH
Flood Mode ID: ON
Offset Mode ID: ON
Target Name: MARS
Mission Phase: EXTENDED_MISSION
Note: PHOBOS TRANSIT SEQUENCE
North Azimuth Angle: 191.46452°
Instrument: VISUAL_IMAGING_SUBSYSTEM_CAMERA_BMareKromium
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Phobos-03.jpgStereo views of Phobos56 visiteCaption NASA originale:"The upper pair shows the side facing away from Mars at a range of 500 Km from the Viking 1 Orbiter. The large craters near the limb are about 4 Km across and a few hundred meters deep. The lower pair shows the side facing Mars at a range of 300 Km.
The grooves are radiating from Stickney and are tens of kilometers long, hundreds of meters wide and can be tens of meters deep".
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Phobos-05.jpgFractures radiating from Stickney Crater54 visiteCaption NASA originale:"Viking Orbiter 1 flew within 300 Km of Phobos in May 1977 to obtain this photomosaic. Raw pictures are at the top and computer-enhanced pictures, to show small surface detail, are at the bottom. The Northern Hemisphere of Phobos is visible from about 30° above the Equator (Phobos' orbit plane), with the side of Phobos facing Mars at the lower right. Phobos presents an illuminated area of about 17 Km from top to bottom and 23 Km across. The rim of Stickney, the largest crater on Phobos, is seen at the lower left, with a large network of grooves radiating from it.
A large, 2-km diameter crater with a slumped wall is seen just below the middle of the picture".
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Phobos.jpgPhobos, in natural colors55 visiteCaption NASA originale:"Color pictures of the two Martian moons have confirmed Earth-based spectra by also showing both satellites to be gray. The Viking imaging data showed the surfaces to be uniformly gray over the complete surface to a resolution of a few hundred meters. No significant color differences were seen on either surface, including areas around craters and those within the bright albedo features on Deimos. The color indicates composition is of a carbonaceous chondritic material. Phobos, here, is at a range of 4200 Km from the Viking 1 Orbiter.
In this picture, color differences have be en exaggerated.
Most of the color differences are due to noise or are artifacts of the processing, especially around craters and the limb".
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Volcanic_Features-Apollinaris_Patera-PCF-LXTT.jpgApollinaris Patera (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)54 visiteThis Martian Volcano is found along the border between the ancient Martian Highlands and the younger Northern Lowlands.
It is characterized by a large caldera (~60 Km diameter), a basal scarp, and a large fan that emanates from the caldera and covers the Southern Flanks. Like other martian volcanoes it appears to have undergone episodes of both explosive and effusive eruptions. The color information in this mosaic of Apollinaris Patera comes from a series of color frames acquired by Viking 1 during orbit 468S (~350 m/pixel).
To sharpen details of morphology, the color mosaic was merged with a higher resolution (~180 mt/pixel) series of images acquired during orbit 088A.
For more information on Apollinaris Patera see:
- Robinson et al., Chronology, Eruption Duration, and Atmospheric Contribution of the Martian Volcano Apollinaris Patera, Icarus, 104, pp. 301-323, 1993.
- Scott, D.H., J.M. Dohm, D.J. Applebee, Geologic Map of Science Study Area 8, Apollinaris Patera Region of Mars, (Special MTM-10186 Quadrangle), USGS Misc. Investigations Series, MAP-I-2351, 1993.MareKromium
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vo1-PIA00300-PCF-LXTT.jpgOlympus Mons (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)54 visitenessun commentoMareKromium
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