SP-425 The Martian Landscape


Surveying the Landscape


[36] Figure 26 shows the first segment of a 300° low resolution panorama, the second picture acquired from the surface of Mars. For the location of the picture refer to figure 19.

This image was initiated 6 min after touchdown. The camera continued to scan the landscape for 9 min, at which time it automatically returned to the stowed position. As we viewed the picture, building from left to right, our attention was first drawn to successful deployment of the meteorology boom seen at the upper left. Drifts of sediment are visible in the midfield. A succession of ridges and depressions lead to the distant horizon.

The bright sky was a surprise. Most scientists had expected that, because the martian atmosphere is very thin, there would be little scattering of light, and that the sky would be deep blue to black. What we failed to anticipate was a constant pall of fine grained soil particles suspended in the lower atmosphere. These particles scatter incoming light, a large amount of which is directed toward the viewer. The general effect has been described, not very romantically, as similar to a smoggy day in Los Angeles.

The brightness bands in the sky are a camera effect. In fact, the sky continuously darkens at higher elevations, but the camera separates this continuum into a series of sampling intervals (gray levels).

Bright patches and horizontal filaments appear in the upper left of figure 26, and are more prominent in figures 27 and 28. They superficially look like clouds. However, they are actually the result of spurious reflections of light from the outer camera housing onto the mirror. We confirmed this theory by producing the same effect in tests on Earth.

As remarkable as the first panorama was, the most dramatic part of the scene was contained in the 60° not covered. Only when we took an equivalent panorama with the other camera three days after touchdown (fig. 27), did we realize what we had missed on the first day-an impressive array large, distinctive boulder.

Figure 28 is a picture taken with the "blue" diode, recording brightness at the shorter wavelengths in the visible range. The meterology boom appears in the foreground. The bright lower atmosphere is dramatically accentuated.


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Figure 26

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Figure 27

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Figure 28