Mariner, Viking & MGS's Maps & Mars in the '70s
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ZE-I-Viking1-12h051-1.jpgFrom the "Viking Archive" - Viking 1: daylight167 visiteComposizione a colori dei Viking Lander 1 frames n. 12h051.red, 12h051.grn and 12h051.blu.
"Breve Storia della Conquista di Marte"
Era l'Estate del 1976 e, per i Planetologi (gli Esperti di Scienze Planetarie) si trattò, senza dubbi, di un'Estate indimenticabile: l'Estate del "soft landing" delle Sonde Viking 1 e 2, le prime 2 Sonde capaci di scendere dolcemente su Marte e quindi eseguire un grande numero di operazioni, trasmettendo i dati a Terra. Prima dei Viking (prodotti USA-NASA), però, anche l'Agenzia Spaziale Sovietica aveva tentato la discesa morbida sul Pianeta Rosso ma.... la Sonda Mars 2 si schiantò sulla superficie di Marte; Mars 3 riuscì a compiere l'atterraggio ma il segnale si interruppe dopo soli 20" di trasmissioni. Il Mars 6 Lander riuscì a trasmettere qualche dato sull'atmosfera Marziana, ma andò in crisi durante la discesa (non sappiamo cosa accadde, ma supponiamo che si schiantò anch'esso).
Il Mars 7 Lander, infine, 'scivolò' sull'atmosfera di Marte e si perse nello spazio.
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ZE-I-Viking1-Oppy-2.jpgMartian Clouds, from Viking 1 until "Oppy" (an Image-Mosaic by Dr M. Faccin)56 visitenessun commentoMareKromium
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ZE-I-Viking1-PIA10738.jpgMars Surface near Viking Lander 1 Footpad (MULTISPECTRUM; credits: Lunexit)73 visiteCaption NASA:"This image, which has been flipped horizontally, was taken by Viking Lander 1 on August 1st, 1976, 12 Soles after the landing. Much like images that have returned from Phoenix, the soil beneath Viking 1 has been exposed due to exhaust from thruster engines during descent.
This is visible to the right of the struts of Viking's surface-sampler arm housing, seen on the left".MareKromium
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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)
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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)
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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".
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ZE-I-Viking1-p135a.jpgColor snap-shots from Viking 1 (4)74 visitenessun commento
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ZE-I-Viking1-p135b.jpgColor snap-shots from Viking 1 (5)67 visitenessun commento
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ZE-I-Viking1-p136a.jpgColor snap-shots from Viking 1 (6)86 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...".
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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".
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ZE-I-Viking1-p137c.jpgFrost on the Surface (Natural Colors; credits: Dr M. Faccin - Lunexit Team)56 visitenessun commentoMareKromium
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ZE-I-Viking1-p138a.jpgColor snap-shots from Viking 1 (8)96 visitenessun commento
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