TEACHING CRITICAL THINKING BY COMPARING TERRAN AND MARTIAN GEOLOGY

Photographs of the Martian surface taken by Mars orbiters and surface rovers provide an opportunity to develop critical thinking skills in both K-12 and college-level students. Interpreting the geology shown in the photographs requires analytical skills such as analogy, deduction, induction, and the use of multiple working hypotheses. Typically the first step in analyzing Martian geology is that of analogy, the transferring of information from a particular subject (Earth example) to another particular subject (Mars image). Because similar features may arise from different processes, having students use multiple working hypotheses allows them to explore several lines of evidence in order to confirm or reject individual hypotheses. Another aspect of interpretation is that of resolution. Images from Mars orbiters typically have resolution of 1.4-2.0 meters per pixel. By comparison, the human eye in the field has a resolving power 2,000,000 times finer. From orbit, Gusev crater, landing site of the Spirit rover, was thought to be covered by lakebed sediment. Instead, the rover's cameras revealed a landscape of impact pulverized lava. The “face on Mars” provides an excellent opportunity for students to develop hypotheses as to its origin. Natural geologic processes have formed many “organic” shapes on Earth (faces, animals, etc.); there is no reason to doubt that similar process did the same things to Mars some time in its past. Persons lacking a knowledge how geology works are more likely to be taken in by more suspect hypotheses and theories as to how these patterns came to exist.