The rover, Sojourner, noses up to the rock, Barnacle Bill. Using an Alpha-Particle-X-Ray Spectrometer, the rover was able to determine that Barnacle Bill contains high amounts of silica and is andesitic in composition.

The rover, Sojourner, noses up to the rock, Barnacle Bill. Using an Alpha-Particle-X-Ray Spectrometer, the rover was able to determine that Barnacle Bill contains high amounts of silica and is andesitic in composition.

The rover, Sojourner, noses up to the rock, Barnacle Bill. Using an Alpha-Particle-X-Ray Spectrometer, the rover was able to determine that Barnacle Bill contains high amounts of silica and is andesitic in composition.

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