Curiosity Finds No Methane on Mars

NASA’s Mars Curiosity rover has not yet found signs of methane on Mars, the agency reports.  Methane is of interest to scientists because it may be a sign of life.

The lack of methane came as a surprise to some scientists, since in the past decade several reported observing signatures of methane through observations using Earth-based telescopes and instruments on spacecraft orbiting Mars.

Curiosity, however, is analyzing samples in-situ—on the surface of Mars.  Given the sensitivity of the instrument that the rover used to analyze six samples of the Martian atmosphere at surface level, the lack of detection means that the concentration of methane in the atmosphere is no more than 1.3 parts per billion. This is nearly six times less than recent measurements made by other scientists, and 50 million times less than the amount of methane on Earth.

The finding greatly reduces the probability that there are methane-producing microbes on Mars, but does not mean there is no chance for life there.  Many types of microbes do not produce methane.

More than 90 percent of the methane on Earth is produced biologically as living organisms digest nutrients.  Although the Mars environment is much harsher than that of Earth, it has been postulated that microbial life may exist under the Martian surface, shielded from the cold, dry, and radiation-bathed surface.  Methane can also be produced by geologic processes such as volcanoes or even impacts from comets and meteorites laced with methane.  Methane has been found on several other planets in our solar system, as well as some of their moons.  It has even been observed at a planet outside of our solar system.

The Mars Atmosphere and Volatile Evolution Mission, or MAVEN, a NASA mission that is scheduled to launch in November, will analyze how the atmosphere of Mars has changed with time, but will not be equipped to specifically search for methane. However, a European satellite with the objective to search for gases such as methane is anticipated to arrive at Mars in 2016.  The ExoMars Trace Gas Orbiter (TGO) was initially part of a long-term collaboration between NASA and ESA involving a suite of Mars spacecraft for launch in 2016, 2018 and 2020.  NASA had to withdraw from that collaboration for budgetary reasons, but is providing Electra communications relay and navigation equipment for the TGO mission.