This month, NASA’s Curiosity rover team, led by John Grotzinger ’79, Sc.D.’13, confirmed that billions of years ago, Mars was home to lakes, streams and deltas, and that low-lying depressions could have remained filled for up to 10,000 years.
Grotzinger — the lead author of the report, which appears in the journal Science — explains in the NASA press release announcing the report that “paradoxically, where there is a mountain today there was once a basin, and it was sometimes filled with water. We see evidence of about 250 feet (75 meters) of sedimentary fill, and based on mapping data from NASA’s Mars Reconnaissance Orbiter and images from Curiosity’s camera, it appears that the water-transported sedimentary deposition could have extended at least 500 to 650 feet (150 to 200 meters) above the crater floor.”
The Curiosity rover team concluded that individual lakes were stable on the ancient surface of Mars, linked through a common groundwater table. This intracrater lake system, according to the study, “probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin.”
This news comes on the heels of recent evidence from the Mars Reconnaissance Orbiter of small streams of salty, liquid water on the planet’s surface today, which are remnants, Grotzinger told NPR, of Mars’ wetter ancient climate.
The new findings from the Curiosity rover team raise further questions about the source of the water and the atmospheric and climate conditions that would have made such liquid water possible.
As Grotzinger goes on to say in the NASA press release, “we have tended to think of Mars as being simple. We once thought of the Earth as being simple too. But the more you look into it, questions come up because you’re beginning to fathom the real complexity of what we see on Mars. This is a good time to go back to reevaluate all of our assumptions. Something is missing somewhere.”
Grotzinger is the Fletcher Jones Professor of Geology at the California Institute of Technology. He is an eminent sedimentologist and stratigrapher with wide-ranging interests in sedimentary processes, geobiology, and Earth’s early history. He previously served as the Shrock Professor of Earth Sciences and director of the Earth Resources Laboratory at M.I.T. There, Grotzinger researched and investigated the spontaneous burst of life that spawned the early ancestors of all animals, otherwise known as the Cambrian Explosion, which remains one of the most debated and mysterious topics in evolutionary biology. He applied his theories of evolution to the study of Mars and developed digital mapping techniques that allow him and his colleagues to study Martian geology for signs of life.
He has been elected into the National Academy of Sciences, one of the highest honors that can be accorded a U.S. scientist. He has also been awarded the National Science Foundation Young Investigator Award, the Fred Donath Medal from the Geological Society of America, the Henno Martin Medal from the Geological Society of Namibia, and the Charles Doolittle Walcott Medal by the National Academy of Sciences. He was also awarded NASA’s Outstanding Public Leadership Medal in recognition of the Curiosity rover mission’s success, and his work on that project led Popular Mechanics to list him among its 10 Innovators Who Changed the World in 2013.
At Hobart, Grotzinger earned a B.S. in geoscience. He earned an M.S. from the University of Montana and a Ph.D. from Virginia Polytechnic Institute and State University. He returned to the Colleges as a Druid lecturer in 1996. The Colleges recognized Grotzinger with an honorary degree at the 2013 Commencement ceremony.
In his own evolution as a scientist, Grotzinger has given much credit to his time at Hobart and William Smith, and an independent research project in geology. While looking for sources of sodium entering Seneca Lake, Grotzinger found that two hypotheses led him to community sources as polluters, while a third was based on natural causes — glaciers scraping the surface down to the salt layer as they formed the lake.
“What I found most interesting was the relationship between how a social problem related to an extraordinary event in the history of the Earth,” he explained in the Pulteney St. Survey. “This experience led directly to my chosen field. I wanted to work on things for which the textbook hasn’t been written.”