Sigma Xi Lecture: The Mars Science Laboratory Experience

Hear about the Mars Science Laboratory (MSL) experience. The MSL began its journey to Mars in November 2011 and landed in Gale Crater on the night of August 5, 2012. Gale Crater is occupied by Mt. Sharp at the center, three times higher than the Grand Canyon is deep. MSL carries 10 instruments on or inside the Curiosity rover, including a variety of cameras as well as radiation, weather, and chemistry analyzers. The rover also includes a device for analyzing gases in the Mars atmosphere and in soils and rocks (the SAM instrument) and an X-ray diffraction (XRD) instrument for detecting the minerals in soils and rocks using CheMin. XRD is a well established technique on Earth using large laboratory instruments and it can provide more accurate identifications of minerals than any method previously used on Mars. The MSL experience involved working on “Mars time” with a 24-hour, 39-minute solar day (sol); if you went to work at 8:00 a.m. today, you would go to work at 8:00 p.m. in about two weeks. Work with Curiosity involves sending commands (~14 minutes from Earth to Mars) and receiving data, every day. The first photos from MSL showed a variety of volcanic rocks along with apparent sedimentary rocks that support the past existence of flowing water. Contrary to previous results, analyses of the atmosphere have not found compelling evidence of methane gas. Methane can have a variety of origins, including volcanic and biological, and its absence has important implications in the search for life. The CheMin instrument first analyzed a Martian soil from a dune and found that it is very similar to soils on the flanks of Mauna Kea Volcano in Hawaii. Unlike some several-billion-year-old conglomerates that Curiosity investigated, which are consistent with flowing water, the soil is representative of more modern processes on Mars. Subsequent XRD analyses of drilled rocks revealed the presence of phyllosilicates, which are consistent with formation in water. To date, the materials analyzed by Curiosity are consistent with our ideas of the deposits in Gale Crater recording a transition through time from a wet to dry environment. The ancient rocks, such as the conglomerates and drill cores, suggest the past presence of liquid water, whereas minerals in the younger soil are consistent with little or no interaction with water. Curiosity will spend the next two years traveling across the surface of Gale Crater to Mt. Sharp in search of evidence for past water and environments that may have once been habitable.

About the speaker

David Bish is the Haydn Murray Chair of Applied Clay Mineralogy in the Department of Geological Sciences at Indiana University. His research centers on clay and zeolite mineralogy and X-ray powder diffraction. More recently he has focused on the behavior of hydrous minerals under Martian surface conditions. Bish is a co-investigator on the CheMin XRD instrument on the Curiosity rover, which has given him the opportunity to analyze the first X-ray diffraction data from Mars. He is the author or co-author of more than 220 publications, is a fellow of the Mineralogical Society of America, and has been president of the Mineralogical Society of America and The Clay Minerals Society.