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.
This synthetic high resolution color image was 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 image has had its 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.
Credit: Mary A. Dale-Bannister, Washington University in St. Louis.
Last Modified: July 9, 2002
CSR/TSGC Team Web