Research confirms Mars once had conditions to support life
Indiana University scientists contribute to papers that help characterize geological history
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BLOOMINGTON, Ind. -- Researchers with NASA's Mars Science Lab found what they were looking for when the Curiosity rover drilled two holes and collected samples of rock from the planet's Yellowknife Bay: evidence that, in the distant past, Mars possessed conditions needed to support life.
The latest results from the Curiosity expedition are included in six papers today by Science Express. David Bish, an Indiana University Bloomington geologist and a member of the Mars team, is a co-author on several of the papers, which discuss the mineralogy and chemistry of the rock samples.
"The exciting thing about the mineralogy is that we found clay minerals in both the drill holes," Bish said. "And the mineral assemblage in these holes is consistent with their having been formed in water."
Researchers say the evidence indicates the clay minerals would have formed in a shallow lake less than 4 billion years ago, around the time primitive life appeared on Earth. Bish said the clay minerals, of which smectite is the dominant type, would have formed in water that was relatively benign, with temperatures and pH moderate enough to support life.
Bish, the Haydn Murray Chair of Applied Clay Mineralogy in the Department of Geological Sciences in the College of Arts and Sciences, is co-investigator for the CheMin experiment, which uses a portable X-ray diffraction device to identify minerals on Mars. Juergen Schieber, a professor in the IU Bloomington Department of Geological Sciences, analyzes images from the Mars Hand Lens Imager, a camera on Curiosity's robotic arm. Schieber is co-author of a paper that examines the physical characteristics of rock layers near Yellowknife Bay and estimates the era when it may have been habitable.
David Vaniman, senior scientist at the Planetary Institute in Tucson, Ariz., is lead author of the mineralogy paper, "Mineralogy of a Mudstone at Yellowknife Bay, Gale Crater, Mars." It provides the first detailed examination of clay mineralogy in its original setting on Mars, offering new insights on the planet’s past habitability.
Finding evidence of habitability on Mars, even if in the distant past, is a key goal of the Curiosity mission.
Other Mars research results published today include an unprecedented measurement of the age of a rock on Mars and the first readings of radiation hazards on the planet’s surface, an important piece for planning future Mars exploration. The papers were discussed today at a news conference at the American Geophysical Union’s fall meeting in San Francisco.
Curiosity landed in Gale Crater on Mars in August 2012 and began making its way toward Mount Sharp, which rises 3 miles above the crater floor. But along the way, researchers spotted an area that looked geologically interesting, and the rover detoured there to collect samples.
Papers analyzing results for a sample of loose soil from a site called Rocknest, published in September, found the soil included basaltic minerals similar to those found at Mauna Kea volcano in Hawaii. But somewhat to researchers' surprise, it didn't contain clay minerals.
But Curiosity also drilled two holes -- dubbed John Klein and Cumberland -- in soft mudstone nearby. The rover scooped up rock powder produced by the drilling and took the powder onboard for analysis. The CheMin X-ray diffraction device showed the rock contained clay minerals along with calcium sulfate minerals, and other minerals similar to those found in the Rocknest sample. The Sample Analysis at Mars, or SAM, instrument also recorded concentrations of oxygen, hydrogen, sulfur, carbon and nitrogen compounds released as the samples were heated.
The two drill holes were only about 3 meters apart, but they produced different clay minerals, Bish said.
The John Klein and Cumberland samples were drilled in February and March 2013, and since then, Curiosity has been driving, recording numerous high-resolution images and using an ionizing laser to analyze rock materials. It is expected to reach Mount Sharp and collect more samples early in 2014.