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.
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.