| Ultimi arrivi - Mariner, Viking & MGS's Maps & Mars in the '70s |
ZE-I-Viking1-p138a.jpgColor snap-shots from Viking 1 (8)96 visitenessun commentoSet 03, 2006
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ZE-I-Viking1-p137b.jpgColor snap-shots from Viking 1 (7)69 visite"...In the course of the Martian Year an important surface change was observed at the Viking 1 site. During the Winter months a thin layer of frost formed. This is documented by comparing two black and white pictures, the first taken early in the mission in late Martian Summer and the second taken months later in late Martian Winter.
Patches of receding frost were visible in the 2nd picture. During the height of Winter, frost probably covered the entire surface.
This picture is a color image of the frost, looking across the spacecraft. The colors purposely have been distorted slightly to enhance color contrast.
The frost persists at temperatures higher than those required for frozen Carbon Dioxide (dry ice).
It may be Water Ice or a Carbon Dioxide clathrate, a crystalline mixture of H2O and CO2".
Set 03, 2006
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ZE-I-Viking1-p136a.jpgColor snap-shots from Viking 1 (6)87 visite"...Taken early in the Viking 1 Mission, was nicknamed "The American Flag Picture". During the final months of preparation before the landing NASA managers took exception to our decision to feature only the Mars Surface in the first few color pictures. In particular, they emphasized the popular appeal of a color picture looking back across the spacecraft, the American Flag in the foreground and the Martian Horizon in the distance. We temporized; they insisted. Frame (6) composite was the result. The photograph is both pictorially attractive and scientifically useful. The bright ridge in the distance, part of the crater rim catches the morning Sun. Difficulties in precisely balancing the colors are indicated by the violet hue of the blue color chip on the test chart. The relative differences in reflectance that yield a color image are illustrated by the 3 constituent images taken in blue light, green light and red light...".Set 03, 2006
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ZE-I-Viking1-p135b.jpgColor snap-shots from Viking 1 (5)67 visitenessun commentoSet 03, 2006
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ZE-I-Viking1-p135a.jpgColor snap-shots from Viking 1 (4)74 visitenessun commentoSet 03, 2006
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ZE-I-Viking1-p133c.jpgColor snap-shots from Viking 1 (3)65 visite"...The scene has a reddish or orangeish cast. Figure (2) is constructed by incorporating data from an accompanying IR picture and using the spacecraft's test charts, in this way accounting for out of band contributions and atmospheric colorations.
The scene is shown as it might appear "on Earth". For example, if you could pick up one of the boulders and transport it to your back yard, this is the color you would observe. Note that, relative to figure (1), the reddish tint is subdued, replaced with a brown hue.
Figure (3) shows the scene as it would appear "on Mars". The yellowish cast of Sunlight filtering through the atmospheric dust imparts a similar yellowish hue to the entire scene".Set 03, 2006
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ZE-I-Viking1-p133b.jpgColor snap-shots from Viking 1 (2)80 visite"...Even for pictures where we have both visible and IR information, two possible types of color can be created. The character of the Sunlight reaching the Martian Surface is significantly different than that reaching Earth's surface, primarily because of scattering and absorption by suspended dust particles. In addition, a certain amount of light reflected from the yellowish brown surface finds its way back as reflected sky light.
Figures (1), (2), and (3) illustrate the range of possible color reconstructions. All three pictures are based on the same camera data. The sampling area at the Viking 1 Site is shown. Two trenches in the Sandy Flats site, the first to be dug are shown at the far left.
Figure (1) is produced by using only visible color information, making no allowance for IR leaks..." (continua)
Set 03, 2006
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ZE-I-Viking1-p133a.jpgColor snap-shots from Viking 1 (1)70 visite"...As it has been already discussed in the past, the problems in reconstructing the (true) colors of the Martian Surface and Atmosphere are formidable.
It would be nice to present a folio of color pictures with the unqualified comment that these are the (Real) "Colors of Mars". But, after more than a year (many more, now) of analysis, it becomes clear that the situation will never become so simple.
In order to correct for the out of band spectral leaks in the color filters within the camera it is necessary to have access to both a color and an infrared (JR) picture taken at the same time. Only in that way can the IR contributions to the visible color, a result of camera filter design, be assessed.
For the many color pictures taken without an IR companion detailed calibration is not possible. Instead, the three visible channels-blue, green, and red-are balanced on the assumption that there are no out of band contributions..." (continua)Set 03, 2006
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P-Phobos-M09_mtvs4109_09.jpgPhobos, from Mariner 9 (HR)82 visiteDi immagini controverse di Phobos (e non necessariamente connesse all'incidente della Sonda Phobos-2) ce ne sono tante - anche nella nostra Sez. "Mars and His Moons" - ma un'immagine spettacolare, nitida e così profondamente diversa dalle altre (tutte le altre, specie le più recenti!) non è comune sulla Rete.
Guardate il Phobos ripreso da Mars Express (liscio e piatto) o quello di Mars Global Surveyor (un pò più accidentato, ma sempre liscio e piatto per un ampia percentuale della sua superficie) e poi osservate questo splendido frame Mariner 9: Vi sembra che state guardando lo stesso oggetto?
Certo, la forma "a patata", nelle sue linee essenziali, è rimasta ma...la superficie della misteriosa Luna Marziana che vediamo in questo frame ormai "preistorico" è radicalmente differente da quella che vediamo nei frames "moderni".
E allora? E allora la domanda è: Phobos è cambiato in 30 anni oppure le Grandi Agenzie Spaziali ci stanno - ahinoi, costantemente - prendendo in giro?
Guardate, e poi decidete Voi stessi (anche se, purtroppo, c'è davvero poco da decidere)...Ago 29, 2006
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QB-VikingOne-PIA08616-02.jpgViking One: the Landing Site, 30 years after the landing... (3)65 visiteCaption NASA originale:"The MOC image of that location, acquired in 2003, showed additional near-field features (rocks associated with a nearby crater) that closely matched the Viking 1 images (frames 2 and 3, where "B" denotes "Volkswagen Rock"). The inset (upper right of frame 3) is an enlargement that shows the location of the Viking 1 Lander.
The MOC image of the Viking 1 Lander Site (3) was acquired during a test of the MGS Pitch and Roll Observation (PROTO) technique conducted on May 11, 2003. (Following initial tests, the "c" part of "cPROTO" was begun by adding compensation for the motion of the Planet to the technique). The PROTO or cPROTO approach allows MOC to obtain images with better than its nominal 1,5 mt (5 ft) per pixel resolution.
The image shown here (3) was map projected at 50 cm (~20") per pixel. The full 11 May 2003 image can be viewed in the MOC Gallery, it is image R05-00966.
In addition to celebrating the 30th anniversary of the first U.S. robotic Mars landing, we note that 20 July is also the 37th anniversary of the first human landing on the Moon, on 20 July 1969. There are two dates that are most sacred in the space business (three, if you count the 4 October 1957 launch of Sputnik 1). The other date is 12 April, which celebrates the 1961 launch of the first human in space, and the 1981 launch of the first space shuttle orbiter".Lug 21, 2006
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QB-VikingOne-PIA08616-01.jpgViking One: the Landing Site, 30 years after the landing... (2)79 visiteCaption NASA originale:"The suite of pictures shown here describes the best MOC view of the Landing Site. These were previously released in May 2005, but the MOC team felt that 20 July 2006 is an appropriate time to review this story.
The 1st figure (1) visually tells how the Lander was found. The initial observations of the location of Viking 1, as originally determined by members of the Viking science team based on sightlines to various crater rims seen in the Lander images (black lines), did not show the detailed features we knew from the Lander pictures (2) to be in the area.
Using geodetic measurements, the late Merton Davies of the RAND Corporation, a MGS-MOC Co-Investigator, suggested that we should image areas to the East and North of where Viking 1 was thought to be. Timothy J. Parker of the JPL (Pasadena, California), using sightlines to crater rims seen in the Lander images (white lines), deduced a location very close to that suggested by Davies".Lug 21, 2006
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QB-VikingOne-PIA08616-00.jpgViking One: the Landing Site, 30 years after the landing... (1)82 visiteCaption NASA originale:"Viking 1 landed 30 years ago, on July 20, 1976. It was the first U.S. landing on Mars and a very exciting time for Mars Exploration. Since that time, 4 additional Spacecrafts have successfully landed on Mars and conducted their science investigations. Today, new missions to the Martian Surface are in the works, with landings expected in 2008 (Phoenix) and 2010 (Mars Science Laboratory).
The Viking 1 Lander is difficult to see in MGS-MOC images. The Western Chryse Planitia Landing Site is often obscured by dust hazes and occasional storms, especially during Northern Winter, which would otherwise be the best time to look for the Lander from orbit because the Sun casts longer shadows in Winter.
When the atmosphere is clearest, in portions of the Spring and Summer, the Sun is higher in the sky as seen from MGS's orbit. The spacecraft always passes over the Landing Site Region around 2 p.m. in the afternoon".Lug 21, 2006
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