The scientific objectives of the Mars Exploration Rover mission are to:

1. Search for and characterize a variety of rocks and soils that hold clues to past water activity. In particular, samples sought will include those that have minerals deposited by water-related processes such as precipitation, evaporation, sedimentary cementation, or hydrothermal activity.

2. Determine the distribution and composition of minerals, rocks, and soils surrounding the landing sites.

3. Determine what geologic processes have shaped the local terrain and influenced the chemistry. Such processes could include water or wind erosion, sedimentation, hydrothermal mechanisms, volcanism, and cratering.

4. Perform "ground truth" -- calibration and validation -- of surface observations made by Mars orbiter instruments. This will help determine the accuracy and effectiveness of various instruments that survey Martian geology from orbit.

5. Search for iron-containing minerals, identify and quantify relative amounts of specific mineral types that contain water or were formed in water, such as iron-bearing carbonates.

6. Characterize the mineralogy and textures of rocks and soils and determine the processes that created them.

7. Search for geological clues to the environmental conditions that existed when liquid water was present. Assess whether those environments were conducive to life.