Possibilities for the detection of hydrogen peroxide–water-based life on Mars by the Phoenix Lander

Abstract

The Phoenix Lander landed on Mars on 25 May 2008. It has instruments on board to explore the geology and climate of subpolar Mars and to explore if life ever arose on Mars. Although the Phoenix mission is not a life detection mission per se, it will look for the presence of organic compounds and other evidence to support or discredit the notion of past or present life. The possibility of extant life on Mars has been raised by a reinterpretation of the Viking biology experiments [Houtkooper, J. M., Schulze-Makuch, D., 2007. A possible biogenic origin for hydrogen peroxide on Mars: the Viking results reinterpreted. International Journal of Astrobiology 6, 147–152]. The results of these experiments are in accordance with life based on a mixture of water and hydrogen peroxide instead of water. The near-surface conditions on Mars would give an evolutionary advantage to organisms employing a mixture of H 2O 2 and H 2O in their intracellular fluid: the mixture has a low freezing point, is hygroscopic and provides a source of oxygen. The H 2O 2–H 2O hypothesis also explains the Viking results in a logically consistent way. With regard to its compatibility with cellular contents, H 2O 2 is used for a variety of purposes in terran biochemistry. The ability of the anticipated organisms to withstand low temperatures and the relatively high water vapor content of the atmosphere in the Martian arctic, means that Phoenix will land in an area not inimical to H 2O 2–H 2O-based life. Phoenix has a suite of instruments which may be able to detect the signatures of such putative organisms.