NASA announced Thursday it has discovered organic molecules on the surface of Mars that suggest the conditions for life existed on the planet.
The molecules, containing carbon and hydrogen, are locked in rocks that are 3 billion years old. Scientists also discovered that the amount of methane gas in the Martian atmosphere changes with the seasons, although the cause of these fluctuations was not clear.
“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.
The findings were published in the journal Science.
Organic molecules, which can also include elements like oxygen and nitrogen, are often associated with the rise of life on Earth, although they can exist on planets devoid of life as well. Earlier research has led scientists to believe that liquid water pooled on the ancient surface of Mars, meaning that Earth’s planetary neighbor had some very similar ingredients for life billions of years ago.
“The Martian surface is exposed to radiation from space. Both radiation and harsh chemicals break down organic matter,” said Jen Eigenbrode, a NASA scientists who was the lead author of two papers detailing the latest findings, in a statement.
“Finding ancient organic molecules in the top five centimeters of rock that was deposited when Mars may have been habitable, bodes well for us to learn the story of organic molecules on Mars with future missions that will drill deeper.”
The studies were conducted using evidence collected by NASA's Curiosity rover, which is currently rolling around the Martian surface.
Curiosity observed that the amount of methane gas in the planet’s atmosphere increased in the summer and decreased in the summer. Although no direct signs of life have been found on Mars, NASA researchers said that the changing methane content could be caused by microbes living somewhere on Mars.