Scientists have begun an experiment aimed at solving one of the most intriguing enigmas of astronomy: the great mystery of Martian methane.
In the coming months they hope to determine if tempting tics of the gas that have been detected on the red planet in recent years are of geological origin or are produced by living organisms.
On Earth, methane is produced mainly by microbes, although gas can also be generated by relatively simple geological processes underground. The ExoMars Trace Gas Orbiter, which has been maneuvering over Mars for more than a year, has been designed to determine which of these sources is responsible for the planet's methane. Last week, sensors were deployed on the spacecraft and they began making their first measurements of the planet's atmosphere.
"If we find traces of methane that mix with more complex organic molecules, it will be a strong signal that methane on Mars has a biological source and that it is being produced – or was once produced – by living organisms," he said. Mark McCaughrean, Senior Advisor on Science and Exploration of the European Space Agency.
"However, if we find that it is mixed with gases such as sulfur dioxide, which will suggest that its source is geological, not biological." In addition, biologically methane tends to contain lighter isotopes of the carbon element than methane. Geologically generated. "
The ExoMars trace gas Orbiter was launched to Mars in a proton rocket from the Baikonur cosmodrome in Kazakhstan in March 2016. The robot spacecraft, a joint European-Russian mission, reached its goal seven months later and launched a small landing module, called Schiaparelli, which was designed to test heat shields and parachutes in preparation for future landings. However, the lander was destroyed when it crashed after its retro-propelled rockets went out too early.
At the same time, the main orbiter entered a highly elliptical route around Mars, as planned.
Space engineers have been altering that orbit ever since, repeatedly touching the Martian atmosphere, so that now the ship is circling the planet 250 miles above the surface. A few days ago, engineers pointed their instruments to the planet and began to take action.
Scientists hope that it will take more than a year to complete a complete study of the planet's methane pockets, but they hope that within a month or two they will have a good idea if their source is of biological or geological origin.
Astronomers have found evidence of methane on Mars on several previous occasions. In 2004, Europe's Mars Express orbiter detected atmospheric methane levels of approximately 10 parts per billion. Ten years later, NASA's Curiosity rover recorded the presence of gas on the surface. Fundamentally, atmospheric methane breaks down quickly in the presence of ultraviolet solar radiation. Its continued presence on Mars suggests that it is being replenished from a source somewhere on the planet.
"We will observe sunlight as it passes through the Martian atmosphere and we will study how it is absorbed by methane molecules," said Håkan Svedhem. , the scientist of the orbiter project. "We should be able to detect the presence of gas with an accuracy of one molecule in every 10 billion molecules."
If methane has a biological origin, two scenarios have to be considered: extinct microbes, which disappeared millions of years ago, have allowed methane to slowly seep to the surface, or some very resistant methane producing organisms still survive underground. "Life may still be clinging to the Martian surface," Svedhem said.
However, if it is discovered that the gas has a geological origin, the discovery could have important implications. On Earth, methane is produced -geologically- by a process known as "serpentinization" that occurs when olivine, a mineral present on Mars, reacts with water.
"If we discover that methane is produced by geochemical processes on Mars, that will at least indicate that there must be liquid water below the surface of the planet, and since water is crucial to life as we know it, that would be Good news for those of us who hope to find living organisms on Mars some day, "he said. McCaughrean.