Mars Simulation Measurements (MSM)
A ubiqutous oxidant has long been proposed as being responsible for destruction of organic compounds on Mars, and the inability of Viking, Phoenix, and Curiosity, to detect organics. The discovery of perchlorate (ClO4-) in 2008 by the Wet Chemistry Lab (WCL) on Phoenix, and its recent confirmation by the Sample Analysis at Mars (SAM) instruments on the Curiosity rover, provides a possible mechanism by which the detection of organics may have been thwarted. Although perchlorate salts are stable at ambient Mars conditions, when heated to the high temperatures required for thermal detection techniques, they becomes powerful oxidizers and would destroy any organics.
The presence of perchlorate in the martian soil also strongly points to the existence of oxidizing intermediary oxychlorines (ClOx-) and radicals that would likely be produced during the UV oxidation of chloride to perchlorate in the martian environment [1,2]. For example, intermediary species such as chlorite (ClO2-) and hypochlorite (ClO-) can oxidze simple organic molecules, however, radicals such as ClO-, O2-, •OCl, •Cl, and •OH can oxidize and destroy organic compounds to form H2O and O2. On Earth production of perchlorate occurs photochemically in the atmosphere and possibly on mineral surfaces. On Mars, the depleted levels of chlorine precursors in the present atmosphere leads to the hypothesis that perchlorate may instead be primarily produced on chloride containing mineral surfaces including rocks, regolith, and dust particles. Such an on-going formation of oxychlorines on a global scale in the past and present , could lead to surface materials on Mars depleted or even devoid of organics. Understanding the formation of perchlorate on the surface of Mars and the processes by which it and/or its intermediates destroy or alter organic compounds is key to understanding the preservation of fossils, modern organics, life detection, and the safety of future human explorers.
 "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 Full Text
 "The Origins of Perchlorate in the Martian Soil" B. L. Carrier and S. P. Kounaves, Geophys. Res. Lett., 2015, 42, 3746-3754, doi:10.1002/2015GL064290 Full Text
 "Evidence for the Distribution of Perchlorates on Mars" B. C. Clark and S. P. Kounaves, Int. J. Astrobiol., 2015, doi:10.1017/S1473550415000385 Full Text