The methane emission on Mars detected in 2013 by NASA's Curiosity rover was confirmed, completely independently, by an international team of researchers led by Marco Giuranna of the National Institute of Astrophysics (INAF) and in which researchers from the 'National Institute of Geophysics and Volcanology (INGV) and the Italian Space Agency (ASI), thanks to the measurements of the Italian PFS (Planetary Fourier Spectrometer) instrument on board the ESA Mars Express probe. The team also identified the possible emission zone, in a region of the planet located about 500 kilometers east of the Gale crater.
The search for methane on Mars is of fundamental importance since the molecule could have a biological origin and therefore serve as a tracer for the presence of life on the red planet. However, to date, no detections have been confirmed with independent measurements.
"Finally now we have the first simultaneous observation of methane on Mars, in the same place and at the same time, by two independent and very different instruments: a rover on the surface and a spectrometer in orbit around the planet", explains Marco Giuranna , first author of the article describing the discovery, published in the journal Nature Geoscience (“Independent confirmation of a methane spike on Mars and a source region east of Gale Crater”).
The Fourier spectrometer PFS first detected traces of methane in the Martian atmosphere in 2004. Today, 15 years later, the same instrument reports the presence of a peak of methane in the atmosphere above Gale Crater. The PFS observations are from June 16, 2013. The previous day, the Curiosity rover had observed similar amounts of methane within the same crater.
But the team didn't stop there. Indeed, these results provided a unique opportunity to identify the area of the planet from which the gas was probably released.
“We have adopted a synergistic approach to integrate PFS observations with atmospheric simulations and with geological factors, and to be able to trace the source of the methane. The most important result is that two completely independent studies suggest the same place of origin,” explains Giuranna. In fact, all the available observational constraints have been supplied to a theoretical model of the global circulation of the Martian atmosphere to identify the most plausible areas of origin of the gas. The simulations were performed considering realistic gas emission scenarios, such as typical gas release patterns from rocks observed on Earth. The results of the model, developed by the Royal Belgian Institute for Space Aeronomy (BIRA-IASB), indicate that a region located approximately 500 km east of Gale Crater has a high probability of being the source site of the observed methane. A geological analysis, completely independent of the atmospheric model, indicated the same region of origin.
"We studied the Martian geological context in a large region around the gas detection point, looking for structures that could be associated with the release of methane", explains researcher Giuseppe Etiope of INGV, "The most interesting region from the from a geological point of view it is exactly the same indicated by global circulation models. This vast area includes the fractured terrain of Aeolis Mensae which hosts, in a sector called the Medusae Fossae Formation (MFF), numerous faults and a subsoil rich in ice, such as the permafrost widespread in cold areas of the Earth. Since the permafrost can contain methane or provide an impermeable cover for the rising gas", concludes Etiope, "it is possible that the methane is released along the fractures in an episodic manner, by partial melting of the ice, by overpressure of the gas which accumulates in the underground, due to seismic events or the impact of meteorites”.
These results constitute an important first step in understanding the origin of methane on Mars. “Italy has been contributing to missions to the planet Mars for years”, explains Barbara Negri, ASI head of the Exploration and Observation of the Universe Unit, “and has gained an important European scientific and industrial leadership. ASI has created the scientific instrumentation on various ESA and NASA missions to Mars, which allow the Italian scientific community to produce important results based on the interpretation of the data r
welcomed".
“We have not discovered the ultimate origin of methane” concludes Giuranna. “Many abiotic and biotic processes can generate methane on Mars. However, the first step in understanding the origin of methane on Mars is to determine where it is released. Detailed analysis of these locations will ultimately help us reveal the origin and significance of the methane detected."
Link to publication: https://www.nature.com/articles/s41561-019-0331-9
Rome, April 1st 2019
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