To perform calibration and validation of surface observations made by a Mars orbiter and the instruments. This will help determine the accuracy and effectiveness of various instruments that survey
Martian geology from orbit. Also, 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. To characterize the mineralogy and textures of rocks and soils and determine the processes that created them. And, search for geological clues to the conditions that existed when liquid water was present. Finally, to assess whether those environments were conducive to life. As you can see, there are many different reasons why NASA sent
Opportunity and Spirit to Mars. The main reason was to look for water, which they succeeded in doing, thanks to Curiosity, another NASA rover. There is water on
Mars, but it is frozen under the north and south polar ice caps. Mars has a lot of flood and river channels making it seem that a long time ago water flowed on Mars during a time when Mars was a warm and wet planet with a thicker atmosphere, kind of like Earth. That is what the spirit rover