News broke this week that NASA's Curiosity rover has found organic matter on Mars in soil samples taken from a 3 billion-year-old mudstone in the Gale crater. Curiosity has already indicated that water flowed in Gale crater which is the same place that the rover traced the organic matter billions of years ago.
The exploration of the Curiosity robot, which already discovered in 2013 the first signs of water on the planet Mars, also determined that the concentration of methane in the atmosphere of that planet changes with the seasons.
The rover also collected information about the varying levels of methane in the atmosphere of Mars. At this point, researchers are unable to determine whether this discovery come from life on Mars or from a less exciting geological process.
"While not necessarily evidence of life itself, these findings are a good sign for future missions exploring the planet's surface and subsurface", NASA said in the announcement.
Launched in 2011, Curiosity was created to assess whether Mars ever had an environment able to support small life forms called microbes. Methane levels were measured over a period of 4.5 years, which showed an increase of methane during late winter in the southern hemisphere and late summer in the northern hemisphere.
Additionally, the molecular observations by Curiosity do not reveal the specific source of the organic compounds in the Gale Crater.
The scientists were surprised to find organic compounds, especially in the amounts detected, considering the harsh conditions, including bombardment of solar radiation on the Martian surface. According to ten Kate, the recent findings leaves so many questions unanswered and calls for better equipment and extensive measurement hours.
"We know that on Earth microorganisms eat all kinds of organic products, it is a source of valuable food for them", said Eigenbrode.
"We have no proof that the methane is formed biologically, but we can not rule it out, even with this new data set", Webster said.
Humayun has done extensive work analyzing a Martian meteorite known as Black Beauty and has been published in prestigious journals such as Nature, Science, Meteoritics & Planetary Science and Earth & Planetary Science Letters.
"This is the first time we've seen something repeatable in the methane story, so it offers us a handle in understanding it", said Chris Webster of NASA's Jet Propulsion Laboratory in Pasadena, California, lead author of the second paper.
He and his colleagues think the methane is coming from underground.
Organic molecules contain carbon and hydrogen, and also may include oxygen, nitrogen and other elements.
On Thursday, NASA announced that its robotic explorers on Mars have identified several complex organic molecules on the red planet's surface.