Geologic Analysis Combining Remote Sensing Data with Field Investigation: Learning to Interpret Planetary Data in Real-World Environments

Field experience comparing remotely sensed data with real world geology is essential to properly interpret the complex geology from another planet using only data returned from orbiter and rover missions. There is a vast amount of information in a multi- or hyperspectral image. However, the interpretation formed from analyzing these data is only an approximation for the true geology, and experience is required to gain an appreciation for the limitations of these approximations. The Granite Wash Mountains, Arizona provide an excellent training ground, having a remarkably complex geology that is condensed within a small (several square mile) area, with excellent rock exposures and excellent data sets. The site consists of a pre-Cambrian sedimentary sequence of widely varying composition with overlying Jurassic volcanic sediments that provide an excellent diversity of remote sensing targets. Subtle compositional and textural differences that affect the remote sensing signatures are present throughout. The sequence has been dramatically deformed, and numerous structural elements are revealed in the remote data. This site clearly demonstrates the advantages, and limitations, of compositional mapping from multi-spectral data. Another key instructional benefit of the site is use of the remote data to plan field traverses and sites for detailed field investigation. This experience – both the correct and the incorrect choices made based on the remote data – is essential for selecting planetary landing sites and planning rover traverses through those sites. We have collected infrared spectra of over 20 unique units that simulate a robotic field spectrometer. These data illustrate the interplay between remote image data that provide excellent geologic context and detailed compositional information from in situ sampling. The ultimate goal of these training exercises is to illustrate the tremendous advantages obtained from remote “orbital” data, while instilling a healthy respect for the complexity of a real planetary surface.