At the American Geophysical Union Meeting held in San Francisco, NASA scientists revealed that the Mars Rover Curiosity found methane concentrations ten times higher than earlier and later measurements in the Martian atmosphere. It’s a very interesting result but despite the optimism of some sources of information it’s not evidence of the presence of life forms on Mars.
The presence of methane on Mars isn’t new. In 2004, ESA announced that its Mars Express space probe detected it in the Martian atmosphere. The measured concentration was minimal, 10 parts per billion by volume. For comparison, the Earth’s atmosphere contains about 1,800 parts per billion by volume of methane. Moreover, the Earth’s atmosphere is tens of times more dense than the Martian one.
Over the following years, new measurements were made with various instruments but this recente one made by the Mars Rover Curiosity gave the most interesting results as the methane concentration was much higher for a certain period of time. For its analysis, Curiosity used its Sample Analysis at Mars (SAM), a small but sophisticated chemical laboratory. It includes various instruments and in this case in particular the Tunable Laser Spectrometer (TLS) was used.
Since the beginning of its mission, the Mars Rover Curiosity has carried out a series of measurements of the levels of methane in the Gale Crater where is traveling and analyzing the atmosphere and soil samples. The basic level of methane detected is 0.7 parts per billion, really low. Between late 2013 and early 2014, Curiosity detected a concentration ten times higher.
There are various possible sources for methane. Biological activity is the most intriguing possibility, also thinking about the recent announcement that Gale Crater used to be a lake, but there are others. There are geological activities that can lead to the creation of methane and other possible sources. The methane recently detected might have been imprisoned underground for millions of years.
NASA scientists have carefully analyzed the measurements taken by the Mars Rover Curiosity to try to identify the cause of the methane spike. The most likely hypothesis is that it came from some area of Gale Crater. The problem is to understand its origin. The optimists see that concentration as an indication of the existence of life on Mars but there are many other possibilities so it’s necessary to continue the research.
In addition to methane, the Mars Rover Curiosity found other organic molecules in a sample of a rock called Cumberland. SAM analyzed the sample finding materials such as chlorobenzene. Again, those are compounds that can be created by biological activities but also from other phenomena such as certain geological activities.
NASA will keep on analyzing the data from the Mars Rover Curiosity but also from its space probe Maven and will work with the Indian space agency to compare the results with those obtained by its probe MOM. The instruments available may be not enough to solve the mystery. In this case we may need to wait for new missions to get different kind of measurements.