NASA

Lot 209
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Estimation :
600 - 800 EUR
NASA
Nasa. LARGE FORMAT. Approximately 1,000 Viking Orbiter violet and red filter images were processed to provide global color coverage of Mars. Individual images acquired during a single spacecraft revolution were first processed through radiometric calibration, aesthetic cleaning, geometric control, reprojection and mosaicking. These normalized mosaics were combined into global mosaics. The overall coverage is about 98% complete in the red filter mosaic and 95% complete in the violet filter mosaic. Gaps were filled by interpolation. The Viking Orbiters acquired true green filter images for about half of the Martian surface. The final mosaic was reprojected into several map projections. The orthographic view shown here is centered at 20 degrees latitude and 60 degrees longitude. The orthographic view is very similar to that seen by a distant observer looking through a telescope. The colour balance selected for these images was designed to be close to the natural colour for the bright reddish regions such as Tharsis and Arabia, but the data have been "stretched" so that the relatively dark regions appear darker and less reddish than their natural appearance. This stretching allows us to better see variations in color and brightness on Mars that are related to the composition or physical structure of surface materials, including volcanic lava flows, sedimentary rocks deposited by wind and water, and (at the poles). ice caps. The northern polar cap is visible in this projection at the top of the image, the large equatorial canyon system (Valles Marineris) below center, and four huge Tharsis volcanoes (and several smaller ones) to the left. Note also the large impact craters on the highlands (lower and right parts of this mosaic) and the younger, less heavily cratered terrain elsewhere. Photograph taken by NASA in 1998 from Viking Orbiter 1 images obtained in 1980. Numbering in the margin on the front. Legend on label on the back. 40,6 x 40,6cm with margins.
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