Methane, strongly associated with life on Earth, was again discovered in the atmosphere of Mars, opening a new chapter in the secret of a decade ago about the presence of gas on Mars.
The latest discovery came to us from NASA's Curiosity rover, which, in addition to analyzing rocks and soil samples, studies the air of Gale crater.
A year ago, scientists reported that Curiosity suffered a fiasco after an eight-month search for methane in the atmosphere, without deciphering the unexplainable anomalies that had previously been detected with ground-based telescopes and Martian spacecraft.
"We thought we had closed the chapter in finding methane on Mars. This was a disappointment for many," said scientist Christopher Webster from NASA's Jet Propulsion Laboratory in Pasadena, California.
Then, the day after Thanksgiving in 2013, methane was detected in the Gale crater.
"It was a complete surprise," said Webster.
View from the Curiosity Mars Rover
9 weeks later, the rover using a laser spectrometer re-scanned and found a methane concentration of 1/7 billion background level, which is consistent with previous measurements of telescopes and Mars orbiters.
Methane concentrations remained at this level during the last measurement July 9, 2014.
The discovery revives two somewhat inactive investigations. The first and most difficult thing is finding methane. It is quite possible that in the past of Mars or even the present, the planet was populated with methane-forming microbes, known as methanogens. It is unlikely that Curiosity will be able to carry out chemical analysis of isotopes in methane molecules and determine whether the gas is of a biological nature or geochemical.
Methane is a chemical compound consisting of one carbon atom bound to four hydrogen atoms. On Earth, living organisms produce more than 90 percent of methane in the atmosphere. The rest is associated with geochemical processes.
Another hypothesis about the occurrence of methane in the atmosphere of Mars is that carbon-rich meteorites sometimes pierce the thin shell of atmospheric gases, temporarily replenishing the planet’s atmosphere with methane.
Such meteorites are just one of several possible geochemical sources of methane on Mars. Other possible options are: erosion of methane-enriched basalt rocks, transformation of rock-forming mineral olivine and underground methane ice.
The second secret of the re-discovery of Curiosity is the sudden disappearance of methane. On Mars, gas had to be held in the atmosphere for more than 300 years. But the testimony of Curiosity showed that it dissipates much faster.
The results of the study will be published today at the conference.
