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John P. Grotzinger is the Fletcher Jones Professor of Geology at California Institute of Technology under the Division of Geological and Planetary Sciences. His works primarily focus on chemical and physical interactions between life and the environment. In addition to biogeological studies done on Earth, Grotzinger is also active in research into the geology of Mars and has made contributions to NASA's Mars Exploration Program.
John Grotzinger is involved in several planetary missions. He is project scientist for the Mars Science Laboratory (MSL) Curiosity rover mission, a participating scientist for the Mars Exploration Rovers (MER), and a participating scientist for the High Resolution Science Experiment (HiRISE) camera, onboard the Mars Reconnaissance Orbiter (MRO).
A long-standing goal of Mars environmental studies has been to understand the role of water throughout its geologic history. The presence of water is a strong indicator of potential habitability as well as of formerly different climatic conditions. Prior to studies by the Mars Exploration Rovers, most studies of water-related processes had been based on analysis of geomorphic attributes. However, we can now examine the record of past surface processes, including the role of water, through sedimentologic studies of the stratigraphic record of Mars. Many processes that operate at a planetary surface have the potential to create a record of sedimentary rocks. Sedimentary rocks can provide clues that allow past environmental conditions to be reconstructed. Therefore, the detection of sediment transport by water and wind in ancient sedimentary layers is important, because it provides insight into past climatic regimes and potential habitability.
The Mars Science Laboratory Curiosity rover launched on Saturday, November 26, 2011 on-board an Atlas V-541 rocket from Cape Canaveral, Florida. The rover landed in Gale Crater on August 5, 2012. Curiosity’s mission is to determine the planet’s habitability and has been doing this using a suite of sophisticated instruments including cameras, spectrometers, environmental sensors, sample collection tools, and laboratory-quality geochemical instruments. Curiosity landed at the foot of Mt. Sharp – Gale Crater’s central mound – near the end of an ancient alluvial fan that formed by sediments transported by streams from the crater rim. In the first year of its mission, Curiosity discovered evidence of a past aqueous environment characterized by low salinity and neutral pH. By exploring these materials, scientists on the rover team hope to discover what types of rocks are favorable for preserving evidence of ancient habitable environments.
Grotzinger has made major contributions to the field of paleontology. In 2003, Grotzinger and his colleagues researched the idea that the so-called Cambrian explosion of biodiversity may have followed an extinction event of earlier organisms. Furthermore, his recent research based on carbon and sulfur isotope ratios has shown that vertical circulation of ocean water led to oxygenation of the deep ocean shortly before the end of the Proterozoic, which may also have contributed to the rise in biodiversity.
Combining his expertise in sedimentology and biogeology, Grotzinger’s research on stromatolites reveal that these structures could form from both biological accretion and physical deposition, asserting that early Proterozoic stromatolites may not all have had biological origins. Since stromatolites are vital tools in understanding the Precambrian biota, this proves to be an important consideration when studying ancient microbial evolution.
In 2007, Grotzinger received the Charles Doolittle Walcott Medal from the National Academy of Sciences "for the insightful elucidation of ancient carbonates and the stromatolites they contain, and for meticulous field research that has established the timing of early animal evolution".