The case for the presence of methane in Mars’ atmosphere expanded, but the theories about its abundance and source floated in different directions as Vladimir A. Krasnopolsky, of Catholic University of America, and Michael J. Mumma, of NASA, updated their previous findings at the American Astronomical Society’s Division for Planetary Sciences (DPS) annual meeting held in Louisville, Kentucky last week. Using Earth as the analogue, Krasnopolsky maintained that the methane is uniformly distributed in the atmosphere of Mars, and took the hypothetical leap that living bacteria under the surface are “a plausible source” of the odorless and colorless gas. Mumma, on the other hand, reported the methane to be significantly “enhanced” in some areas, and veered out of the (Earth) box, suggesting that distinctly Martian processes may be in play.