Mars Pathfinder The Little Robot that Could

http://marsprogram.jpl.nasa.gov/missions/past/pathfinder.html

The first myth to dispel is that Pathfinder was sent to Mars to look for signs of life. Wrong. It was largely an engineering project, designed to test new technologies. The main part of the project was the lander, since re-named the Carl Sagan Memorial Station in honor of one of the great proponents of Mars exploration, and perhaps the best-known popularizer of science in the previous century. The rover, Sojourner, was almost (but not quite) an add-on that stole the show. The lander returned 16,500 images, and the rover 550.

Landing was on July 4, 1997, using a new method airbags instead of retro-rockets for the final touchdown. The site chosen was Ares Vallis, near the mouth of an outflow channel where it was believed a variety of rock from different sources would be deposited. The landing area is within the ellipse in the picture.

Sojourner’s view of the Carl Sagan Memorial Station

The science results are available on-line at the pathfinder web site. http://marsprogram.jpl.nasa.gov/MPF/science/science-index.html

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The pathfinder site displayed a variety of rock morphologies. The red arrows point to rocks believed to be rounded by the action or water in a flood. Blue arrows indicate rocks with sharp points thought to come from impact craters or volcanic eruptions. White arrows seem to be deposits left by evaporating water.

The nearby rocks in the “rock garden” were given somewhat whimsical names by the project scientists.

The rock called “Yogi” is two-toned. The reason is unknown, but might result from the preferential accumulation of dust on one side, or from fracturing off of a larger boulder.

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“Moe” shows definite signs of “fluting” indicative of the action of windblown dust (essentially sandblasting).

The rover could get a close look at rock textures that would have been invisible from the main lander. This rock shows “sockets” where pebbles have apparently been dislodged by weathering.

Reflectance spectroscopy provided information about the color of the rocks and sand. These aid in determining basic rock minerality. Generally, the greater the curvature in the visible, the more ferric the rock is and usually more weathered.

Example of a spectral map.

The Alpha Proton X-ray Spectrometer (APXS) on the rover was used to determine the atomic composition of the rocks and soil.

In general, the rocks on Mars are somewhat different from terrestrial basalts. However, the soil samples at the Pathfinder and Viking sites are similar to many of the Martian meteorites (red squares).