One of the rover’s main tasks while operating on the surface is to determine the habitability of the ancient Martian environment.
To do this, the rover operators have to steer the rover towards outcrops and image key rocks which can yield important information about the ancient surface conditions. Information held within the rocks can include whether the rocks were deposited by wind or water, the strength of these flows, and the direction these flows transported sediment. Additionally, the chemical composition of the rocks can yield insights into the chemistry, diagenetic processes (how loose sediments becomes rocks) and the potential for preservation of the signature of habitability, if it existed within the past environment.
While a real Mars rover cannot be accompanied to the Martian surface by a geologist (much to the dismay of most geologists), the Mars analogue rover can be accompanied to the surface of Utah (much to the joy of the mission geologists).
The role of the field geologists is to characterise the geology of the landing site, identify and map key features, which can be used to understand surface processes and build a model of the environment responsible for the deposition of the rocks. These observations and model created by the geologists can then be used to compare and validate rover observations, and the model created by the Mission Operations Centre.
Once operations cease, the mission operations team can compare their observations with those of the field geologists, to better understand the strengths and limitations of rover observations. By comparing human and rover observation techniques, mission planners can alter protocols and improve observation methods to better resolve key features, or to weight rover observations at particular levels within the strata most likely to yield important information about the past environment.