NASA examined its first patch of soil in a small crater where the Opportunity rover landed on Mars. In the patch of soil, scientists found strikingly spherical pebbles among the mix of particles on the planet. The particles, which vary in shape, appear in new photos taken from Opportunity’s microscopic imager. Scientists say the different shapes and colors of the particles indicate they have been brought to the area from a variety of sources.

Due to the different types of particles on Mars’ surface, scientists are examining different alternatives as to where they came from. They include accretion under a body of water or volcanic eruptions.

What scientists are most interested in is the finding of hematite, which usually forms in association with liquid water. The mineral map of Opportunity’s surroundings showed that concentrations of course-grained hematite vary in different areas of the crater. The soil patch photos showed a low concentration of hematite, while higher concentrations were found inside the crater in a layer above an outcrop of bedrock and on the slope just under the outcrop.

This holds special interest because they are trying to determine if Mars ever had watery environments that could be sustaining for life. Along with this finding, Opportunity’s Moessbauer spectrometer, an instrument on the rover's robotic arm designed to identify the types of iron-bearing minerals in a target, found a strong signal in the soil patch for the ingredient Olivine, commonly found in volcanic rocks.

To get a better understanding of the soil on Mars, NASA’s mission controllers plan to use Opportunity’s wheels to scoop a trench to expose deeper material.

• Small Picture NASA February 5, 2004
• Large Picture NASA February 5, 2004

NASA February 5, 2004