SP-425 The Martian Landscape

 

Tilt

 

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Figure 82

 

[78-79] Figure 82 is the second picture taken by Lander 2, a low resolution panorama that was completed about 20 min after touchdown. The most striking feature is the sloping horizon. Recall that the picture is assembled from left to right. As we looked at the first few lines all we could tell was that the horizon dipped to the right. Although it was possible that this was an actual feature within the scene, we suspected otherwise. As the image continued and we watched the horizon regularly descend and then climb back up our suspicions were confirmed. The horizon was, in fact, very nearly level but the spacecraft was tilted approximately 8° toward the northwest. The effective result is that in the middle of the panorama, looking toward the southeast, the camera is tilted up and the horizon appears near the bottom of the image. Pointing in the opposite direction, northwest, the camera's field of view is tilted downward and the horizon appears near the top of the image.

Since the tilted spacecraft is situated on a nearly level plain, the obvious conclusion was that we were perched on one of the thousands of boulders that littered the plains as far as our camera could see. Initially, the health of the spacecraft was in doubt. If a boulder had penetrated the Lander underbelly, then the internal components might have been destroyed by cold during the martian night. Fortunately this was not the case. When the Orbiter passed overhead 24 hours later, the Lander telemetered data indicating it was alive and well.

During landing, sediment collected in the dish shaped S band antenna which was stowed in a concave up position.

When the antenna was rotated 90° the sediment slid to the lower edge. However, interpretation of the image was difficult. Some viewers thought they saw a ragged crack in the antenna.

Note the bright streak in the sky. The fact that it is horizontal, even though the horizon is tilted, indicates that it is not an atmospheric effect but is due to spurious camera reflections, as described in figure 24. This interpretation is further confirmed by the fact that the "cloud" passes in front of the S band antenna.


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