Department of Chemistry
Office: P-108B || Phone:617-627-3124
Professor of Chemistry, Department of Chemistry, Tufts University
Visiting Professor, Department of Earth Science & Engr, Imperial College London, UK
Postdoctoral Fellow, 1987-88, Harvard University, Cambridge, MA
The presence of perchlorate as Ca(ClO4)2 suggests that Mars' surface (at least around the Phoenix landing site) may have been severely arid for at least the past ~600 million years. The ClO4- may also be responsible for brines & gullies due to its depression of the H2O freezing point to -78ºC, the control of planet-wide soil and atmospheric water content, and the dificulty of instruments to detect organics (VL/GCMS; Phx/TEGA; & MSL/SAM). It could also act as an electron doner/energy source for any indigenous subsurface microbes, and is both good & bad for human explorers (can provide energy, fuel, and oxygen, but is human health hazard). The group's recent discovery, that ClO4- may form on any Cl-bearing mineral surface that is exposed to UV and that the process generates intermediary oxychlorines and highly oxidizing radicals, has implications not only for the production of ClO4- and the alteration/destruction of organics on Mars, but also on Earth and perhaps throughout the solar system and beyond.
The discovery of perchlorate on Mars led the group to investigate the same possibility in the Antarctic Dry Valleys. The study provided the first unambiguous discovery and clear evidence of the ubiquitous natural formation of perchlorate on Earth, with accumulation in arid environments and global atmospheric production. The discovery also suggests the hypothesis that the perchlorate reducing bacteria and arachea may be a remnant of a significant pre-oxygen Earth perchlorate ecosystem. The group has also recently confirmed ClO4-, ClO3-, and NO3-, in the Mars meteorites EETA79001 & Tissent, and also in lunar and chondrite meteorites.
In addition to the current investigations exploring Mars' geochemistry and its potential for supporting past or present microbial life in surface or subsurface environments, their research (funded by NASA and NSF) includes understanding the geochemical and environmental history as recorded by the chemistry of planetary surface materials, and the geobiochemistry in extreme environments on Earth in places such as the Antarctic Dry Valleys, Death Valley, the Atacama Desert (Chile), and deep-ocean thermal vents. They are also interested in applying similar techniques to investigate the surface and sub-glacial oceans on icy moons such as Europa and Enceladus. The group's research in astrobiology is focused on exploring concepts and analytical techniques for unambiguous detection of microbial life in extraterrestrial settings, and the survivability of organics on Mars' surface.
Selected Recent Publications
The Origins of Perchlorate in the Martian Soil, B. L. Carrier and S. P. Kounaves, Geophys. Res. Lett.,
Identification of the Perchlorate Parent Salts at the Phoenix Mars Landing Site and Possible Implications,
Evidence of Martian Perchlorate, Chlorate, and Nitrate in Mars Meteorite EETA79001: Implications for Oxidants and Organics, S. P. Kounaves, B. L. Carrier, G. D. O'Neil, S. T. Stroble, and M. W. Clair, Icarus, 2014, 229, 206-213. doi:10.1016/j.icarus.2013.11.012
Electrochemistry of Aqueous Colloidal Graphene Oxide on Pt Electrodes, G. D. O'Neil, A.W. Weber, R. Buiculescu, N. A. Chaniotakis, and S. P. Kounaves, Langmuir, 2014, 30, 9599-9606. doi:10.1021/la502053m
An Electrochemically Based Total Organic Carbon Analyzer for Planetary and Terrestrial On-Site Applications, S. T. Stroble and S. P. Kounaves, Anal. Chem., 2012, 84, 6271–6276. doi:10.1021/ac301704m
Effects of Extreme Cold and Aridity on Soils and Habitability: McMurdo Dry Valleys as an Analog for the Mars Phoenix Landing Site, L. K. Tamppari, R. M. Anderson, P. D. Archer Jr., S. Douglas, S. P. Kounaves, C. P. McKay, D. W. Ming, Q. Moore, J. E. Quinn, P. H. Smith, S. Stroble, A. P. Zent, Antarctic Science, 2012, 24, 211-228. doi:10.1017/S0954102011000800
Soluble Sulfate in the Martian Soil at the Phoenix Landing Site, S. P. Kounaves, M. H. Hecht, J. Kapit, R. C. Quinn, D. C. Catling, B. C. Clark, D. W. Ming, K. Gospodinova, P. Hredzak, K. McElhoney, and J. Shusterman, Geophys. Res. Lett., 2010, 37, L09201. doi:10.1029/2010GL042613
Discovery of Natural Perchlorate in the Antarctic
Dry Valleys and its Global Implications,
Wet Chemistry Experiments on the 2007 Phoenix Mars
Scout Lander: Data Analysis and Results
Detection of Perchlorate and the Soluble Chemistry
of Martian Soil at the Phoenix Lander Site, M. H. Hecht,
H2O at the Phoenix Landing Site, P. H. Smith, L.
K. Tamppari, R. E. Arvidson, D. Bass, D. Blaney, W. V. Boynton, A. Carswell, D.
C. Catling, B. C. Clark, T. Duck, E. DeJong, D. Fisher, W. Goetz, H. P.
Gunnlaugsson, M. H. Hecht, V. Hipkin, J. Hoffman, S. F. Hviid, H. U. Keller, S.
P. Kounaves, et al.,
Complete list of publications can be found HERE.
Selected Media & E/PO Links
- AAAS Annual Meeting News "Perchlorate on Mars" February 2013
- The Analytical Scientist "Quantitative Analysis and the Essence of Doing Good Science" January 2013
- NECN TV "Curiosity Rover Lands on Mars" August 2012
- WGBH 7 One Guest Interview May 2009
- NOVA ScienceNOW "Phoenix Lander Wet Chemistry with PBS/Tyson" July 2008