More organic compounds and a seasonal methane cycle discovered on Mars

The Mars Rover Curiosity and two elements found (Image NASA/GSFC)
The Mars Rover Curiosity and two elements found (Image NASA/GSFC)

In a press conference, NASA announced the latest discoveries on the planet Mars obtained thanks to the analyzes carried out by the Mars Rover Curiosity. In some new samples taken at two sites of Gale Crater, various organic compounds were detected. The methane measurements in Mars atmosphere indicate a seasonal cycle in which its amount varies. These findings have been described in detail in two articles published in the journal “Science”.

The discoveries announced are not completely new and are only partially surprising. Those is in fact information that got added to those already collected in previous years and of analyzes of information collected in previous years that help to better understand what’s happening on Mars.

A team led by Jennifer Eigenbrode of NASA’s Goddard Space Flight Center found organic compounds in sedimentary rocks close to the surface that have an estimated age of about 3 billion years. These are molecules similar to those found in Earth’s sedimentary rocks and include thiophene, 2- and 3-methylthiophene, methanethiol and dimethyl sulfide. In some cases they’re likely fragments of bigger molecules.

Among the interesting elements found in the fragments there’s sulfur, which may have contributed to their conservation. Another indication is the carbon concentration in the order of 10 parts per million or more. It’s an amount close to that observed in Martian meteorites and about 100 times greater than previous measurements of organic carbon on Mars surface.

Another team led by Christopher Webster of NASA’s JPL analyzed data collected by the Mars Rover Curiosity’s Sample Analysis at Mars (SAM) instrument suite during nearly three Martian years, almost six Earth years. Methane detections have been at the center of researchers’ interest since the beginning of the mission to try to understand the origin of that compound, given that on Earth it’s also produced by biological activities.

The Mars Rover Curiosity’s detections indicate that in Gale Crater methane levels in the atmosphere peaked during the summer months to drop when winter comes. This cycle is illustrated graphically in the bottom image (NASA / JPL-Caltech).

Christopher Webster explained that this is the first time that researchers have seen something repeatable in the studies on Martian methane and it’s a step forward in understanding its origin. This was possible thanks to the fact that Curiosity keeps on working and long-term research shows the seasonal patterns.

These discoveries are interesting but there’s a great deal of caution about whether they’re traces of life forms on Mars, either existing now or that existed in the past. Michael Meyer, head scientist of NASA’s Mars Exploration Program, admitted that they don’t know it, so any very enthusiastic statement is based on pure speculation. Those data tell researchers that they’re on the right track to understand the origin of organic molecules and methane and in 2020 the next missions by NASA and ESA will bring new investigative tools to Mars.

Methane seasonal cycle
Methane seasonal cycle

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