John P. Grotzinger is the Fletcher Jones Professor of Geology at California Institute of Technology and chair of 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.
Academic history
B.S., Hobart College, 1979
M.S., University of Montana, 1981
Ph.D., Virginia Polytechnic Institute and State University, 1985
Post-doc, Columbia University, 1985-1987
Professor, Massachusetts Institute of Technology, 1987-2005
Jones Professor, California Institute of Technology, 2005–present
Studies on Mars
John Grotzinger is involved in several planetary missions. He was Project Scientist for the Mars Science Laboratory (MSL) Curiosity rover mission, a Participating Scientist for the Mars Exploration Rover (MER) mission, and a Participating Scientist for the High Resolution Science Experiment (HiRISE) camera, on board the Mars Reconnaissance Orbiter (MRO).
Grotzinger has made significant contributions to understanding the early environmental history of Mars, as preserved within its record of sedimentary rocks. 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 an indicator of potential habitability as well as of formerly different climatic conditions. Prior to in situ investigations by the Mars Exploration Rovers, most studies of water-related processes had been based on orbiter analysis of geomorphic and spectroscopic attributes. However, we can now directly 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 was 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 fine-grained sedimentary rocks of basaltic composition that represent an ancient lake and preserve evidence of an environment that would have been suited to support a Martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. C, H, N, O, S, and P were measured directly as key biogenic elements. The environment likely had a minimum duration of hundreds to tens of thousands of years, and could have existed for millions of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars.
Co-evolution of Earth's early environment and biosphere
Grotzinger has made major contributions to the fields of Geobiology and Paleontology. Beginning in 1993, Grotzinger and his colleagues began a research program aimed at understanding the chronology of major biological and environmental events leading up to, and perhaps driving early Cambrian radiation of metazoans. The so-called Cambrian explosion of biodiversity was shown to have been much more rapid than previously understood. It also may have followed an extinction event of earlier organisms that pioneered and experimented with calcification. More recent research over the past decade has been based on understanding carbon and sulfur isotope ratios in carbonate sediments of Ediacaran age. This work proposed that vertical circulation of ocean water led to oxygenation of the deep ocean shortly before the end of the Proterozoic time, which may also have contributed to the rise in biodiversity in early Cambrian time.