College of Science News
NASA taps Dasgupta to build ion chromatograph for Mars
Purnendu “Sandy” Dasgupta, a professor of Chemistry and Biochemistry renowned for his innovations in the field of ion chromatography, has been awarded a nearly $1.2 million grant from NASA to develop technology that could help pave the way for future human missions to Mars and beyond.
Dasgupta will use the funds to develop “An Ion Chromatograph for Extraterrestrial Explorations.” The goal is to create a new system for testing the chemical composition of extraterrestrial soil. Dasgupta’s project was one of eight nationwide to be funded recently by the Astrobiology Science and Technology for Instrument Development grant program of the NASA Astrobiology Program.
During past lander missions, examinations of Martian soil have been limited by technology that used ion selective electrodes to probe for specific materials, Dasgupta said. An ion chromatograph, on the other hand, separates and detects ions, which are molecules bearing an electrical charge. The device can look at a broad suite of ions sensitively and identify them with some confidence.
“By creating an easily portable and robustly-designed ion chromatograph, we’re hoping to rapidly expand scientists’ knowledge of extraterrestrial geology and geochemistry,” Dasgupta said. Proving organic ions exist in Martian soil could be a first step to identifying organic compounds, the building blocks of life.
Past Mars missions have heated soils to look for organic vapors coming from samples. None have been detected. But if the recent finding of large amounts of perchlorate in Martian soil proves correct, that discovery would explain why heating soil never shows any organics - the perchlorate would oxidize them.
“Although we cannot address the issue of neutral organics,” Dasgupta said, “with this machine, we should be able to unequivocally answer if organic ions are present”.
Dasgupta plans to use low-pressure open tubular columns in the design of his chromatograph for NASA, making it uniquely designed for storage in the subfreezing temperatures of space when not in use. The columns typically used for ion chromatography are packed with polymer or silica beads and filled with an aqueous solution. They cannot withstand such freeze-thaw cycles.
The new device would enable researchers to search for organic compounds in a way that is compatible with the chemistry of the Martian soil and would provide answers to questions about organic compounds on Mars, said Alfonso Davila, principal investigator at the California-based Carl Sagan Center for the Study of Life in the Universe and a collaborator on the project.
“If that answer was positive, then the possibility of life on Mars would gain new strength,” Davila said.
An ion chromatograph could also detect ions such as nitrate and phosphate in extraterrestrial soil. These are also very important for life and strategically, for human exploration beyond Earth, Davila said.
Researchers are particularly interested in learning more about the presence of perchlorate in Martian soil, an inferential discovery made by the Phoenix lander in 2008. Perchlorate is a naturally occurring and manmade chemical used in rocket fuel and explosives. It is also considered a contaminant that is harmful to human health.
Dasgupta also notes that perchlorate can be both a producer of oxygen and an energy source. So, its presence on Mars could benefit future human exploration.
Dasgupta is the Jenkins Garrett Professor of Chemistry at UT Arlington and the recipient of the American Chemical Society’s 2011 Award for Chromatography. He invented the electrodialytic eluent generator used in modern ion chromatographs as a way to electrically generate high purity alkali hydroxides, thereby making results more reliable.
As a first step in the four-year project, Dasgupta will design and build an open tubular ion chromatograph system for Earth-based exploration that weighs three kilograms or less. Researchers from his lab and the labs of his collaborators, including students, will then test the device in the challenging environment of the Atacama Desert in Chile. After that, they’ll refine the machine for use on Mars and other extraterrestrial bodies.
Additional collaborators on the project include: W. Andrew Jackson, associate professor of civil and environmental engineering at Texas Tech University; Samuel Kounaves, a professor at Tufts University; and Christopher McKay, a research scientist at NASA’s Ames Research Center in Moffett, Calif.