The article is based on a study of analysis of data from one of the instruments on board the rover Curiosity that has been on Mars for two years.The instrument, called SAM (Sample Analysis at Mars), have discovered an episodic increase in methane concentration in the atmosphere of Mars. The collection of data has been going on for 605 sols, that is 605 Martian days (one March day corresponds to 24 hours, 39 minutes and 35 seconds).
The fact that the Martian atmosphere contains methane was detected already a decade ago. However, previous research, including ground-based telescopes and orbiters, has shown conflicting results and has not been able to explain how and where methane occurs and how it disappears.
Methane can occur as a by-product of biological activity. For example, most of the methane in our atmosphere derives from this. One issue that attracted considerable research interest is whether biological activity also resulted in the presence of methane in the Martian atmosphere.
The instrument SAM has been able to measure background levels of methane concentrations of about 0.7 ppbv (parts per billion in volume) and has also measured an episodic increase up to ten times as much, 7 ppbv, for a period of 60 sols. As a complement to the measured values, data from SAM has been compared to reference data from the meteorological station REMS (Rover Environmental Monitoring Station), that is also located on Curiosity. REMS measures, among other things, air and ground temperature, relative humidity, pressure and ultraviolet radiation. Thus, researchers have been able to examine the possibility of interaction with the parameters from the surrounding environment.
– Possibly it may be that there is a seasonal variation in the methane concentration's relation to environmental variables. This could be confirmed by further continuous measurements, says Javier Martín-Torres, who along with María Paz Zorzano Mier, PhD in physics at the Centro de Astrobiología, is responsible for the scientific part of the REMS instrument.
Biological life on Mars
The research results that are now published in Science magazine, definitively determine that there is methane in the Martian atmosphere. However, several questions remain. Among other things, finding an explanation for the origin of the gas. Hence, it is still unknown what mechanisms underlie methane production and destruction.
– The knowledge of methane in the Martian atmosphere rises several hypotheses about why the methane behaves as it does. It evokes ideas of climate change on Mars, volcanism, or even the presence of microorganisms, says Javier Martín Torres.
The authors of the article published in Science all belongs to the research team Mars Science Laboratory, MSL.