Dix Planetary Science Seminar
Having delivered solidly on the approach to Mars exploration in recent decades—to "follow the water" and "search for habitable environments" —the latest exploration strategy embraced by NASA is to now to "seek signs of life." In other words, the plan is to search for direct evidence of ancient life recorded in martian rocks. Identification and verification of chemical and textural biosignatures that are billions of years old will likely require comprehensive laboratory analyses of returned samples. The science community is now on a path toward Mars sample return. The decision of where to explore for biosignatures will impact the Mars exploration program for decades, as a larger fraction of exploration resources are funneled toward less frequent, higher cost "Flagship" missions. In fact, there is a high likelihood that future missions might henceforth visit and revisit the same site or sites on Mars. For example, NASA's next rover, Mars 2020, is tasked with caching a number of carefully selected samples that will remain on the martian surface to await collection by a future spacecraft. The rationale for where to explore is currently heavily rooted in our terrestrial experience, with the major emphasis placed on taphonomic potential of sedimentary environments. While understandable, this approach suffers a major epistemological problem: Mars is not Earth. In our view, the biases driven by investigation of the ancient record of life on our home planet may lead us astray on Mars. I will propose a possible course correction in our Mars exploration strategy, and explore the geology of some interesting sites on Mars that might provide clues to abiogenesis.