Mars long has been considered a cold, dead planet. However, recent reports of methane in the Martian atmosphere [Formisano et al., 2004; Krasnopolsky et al., 2004; Mumma et al., 2004] suggest that methane currently is being produced, since its calculated atmospheric lifetime of 400 years or less [Nair et al., 2005] requires a constant resupply. Possible subsurface sources for this resupply are geological, or even microbiological, in nature. So the question is: Is Mars alive, biologically or geologically speaking?
If either geological or microbiological sources of methane on Mars can be confirmed, there will be profound implications for astrobiology and the U.S. space program. If the existence of active microbiology were established, it would not be surprising if NASA reorganized its mission plan to follow-up on such a discovery. Additionally, current geological processes that result in the formation of methane would be in locations that are warm and wet, and thus likely habitable. If key nutrients such as nitrogen and phosphorus—in addition to liquid water—also were available, such locations could support life, and not necessarily just methane-producing organisms.