This is the Web Edition of "A Trip Into Space", a Coimbra-based electronic book on space science. Both the texts and the photos are by courtesy of National Aeronautics and Space Administration.

A Trip Into Space Mars Surface Views Mars - "Big Joe"
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See also: Mars Fact Sheet 

Mars
"Big Joe"

The following images were taken by the Viking 1 and 2 Landers. These synthetic high resolution color images were created by combining standard low resolution Viking Lander color images with standard high resolution Viking Lander black and white images, using image processing techniques. In simple terms, the colors are separated from the color image. Using the computer, those colors are then painted onto high resolution images covering the same area. The third image is about what would be seen if the Martian surface materials were on Earth. The other three images have colors balanced to approximate what a person would see on Mars. Since the Martian atmosphere carries extremely fine-grained red dust in suspension the "on Mars" images are redder

This image was acquired at the Viking Lander 1 site with camera number 1. The large rock just left of center is about 2 meters wide. This rock was named "Big Joe" by the Viking scientists. The top of the rock is covered with red soil. Those portions of the rock not covered are similar in color to basaltic rocks on Earth. Therefore, this may be a fragment of a lava flow that was ejected by an impact crater. Many of the rocks around the two Viking Lander sites were given names, both so that scientists could discuss the rocks without the need for images to point out rocks of interest, and to act as locators at the scene. For instance, to say a small landslide occurred at the base of Big Joe leaves no question as to which landing site and the approximate area at which the landslide occurred -- with no illustrations needed.

The reddish color of the rocks and soil is due to an abundance of oxidized iron in fine grained weathering products of the rocks. While the weathering of rocks is much slower on Mars than on Earth, due to the lack of abundant liquid water, atmospheric interaction with the surface (including dust storms) does cause the rocks to slowly break down. In some areas of this scene rocky plains tend to dominate, while a short distance away drifts of regolith material have formed.

Last Update: 2005-Nov-29