geology of mars introduction image
  Global Properties
Dust Storms
Canyons & Caps
Viking Landers
Internal Structure

Views from the Viking Landers
During the summer of 1976, two spacecraft, The Viking I and Viking II, landed on Mars. Both landers landed on the northern lowland terrain and carried a mass-spectrometer for chemical analyses of the atmosphere and the soil. There was also a camera, together with many other scientific instruments on each lander. Figures 1.9 and Figure 1.10 are images of the Martian surface sent back by the landers.

figure 1.9
figure 1.10

The top part of the images provides a map view of the landing sites, whereas the bottom part gives the surface views. They clearly show that the surface of Mars closely resembles a desert environment on Earth. On the Viking I landing site, fine grain sands were clearly visible. There were also abundant angular rocks. The large boulder in the foreground was about 2 meters across. The gravel surface was probably formed by deflation similar to that on Earth. (Note that deflation is the removal of small particles from the surface by strong winds.) Aeolian processes obviously were operating in this area.

The Viking II landing site was a little bit different. It revealed a vast plain littered with angular blocks and low drifts of sand. These blocks might be ejecta from nearby impact craters, or they might be the weathered remnants of ancient lava or debris flows. Like those at the Viking I site, many rocks were pitted, the result of wind erosion. The horizon of the Viking II view was tilted because the lander was resting on a tilted surface. Another remarkable feature on both views was the bright sky in the background. This is very different from the surface pictures taken on the Moon where the background sky is totally black. The bright sky was a result of an atmosphere that scattered sunlight within itself.

Two decades after the Viking missions, a robotic rover called Sojourner landed on Mars in July 1997. Figure 1.11 shows the rover and the landing site. As one can see, the surface is very desert-like, similar to that observed by the Viking landers.

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figure 1.11

geology of mars