This month’s biggest science news.

PLUS: Hawking’s last hurrah

Organic molecules found preserved in rocks on the surface of Mars have raised hopes that the Red Planet may once have been home to life.

NASA’s Curiosity Rover has found the most compelling evidence for the existence of life on Mars yet – complex organic molecules preserved in three-billion-year-old sedimentary rock.

Although the surface of Mars is inhospitable today, there’s clear evidence that in the distant past the Martian climate was such that it allowed for the existence of pools of liquid water on the surface – an essential ingredient for life as we know it. Now, new data from Curiosity reveals that a water lake that existed billions of years ago inside Gale Crater held the ingredients necessary for life, including chemical building blocks and energy sources.

“With these new findings, Mars is telling us to stay the course and keep searching for evidence of life,” said

Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate. “I’m confident that our ongoing and planned missions will unlock even more breathtaking discoveries on the Red Planet.”

Curiosity found the organic material by drilling into an area of sedimentary rocks, known as mudstone, on Mars’s surface. This material formed billions of years

“THE MOST COMPELLING EVIDENCE FOR LIFE ON MARS”

ago as silt accumulated at the bottom of an ancient lake. The rock samples were then analysed using Curiosity’s Sample Analysis at Mars instrument, which uses an oven to heat samples to 500°C to release any organic molecules trapped within. All organic compounds contain carbon – a key component of all known life on Earth. Key to this is carbon atoms’ unique ability to link together to form long chains, allowing them to create millions compounds with different properties. For example, our own DNA is made up of many carbon chains linked together and twisted into a double helix. Some of the molecules identified include benzene, an important constituent of crude oil consisting of six carbon atoms and six hydrogen atoms, and propane, a natural gas made from three carbon atoms linked to eight hydrogen atoms used in everything from heaters to barbecues.

If these simple compounds were able to form on the planet’s surface it means it is also possible that more complex compounds, and maybe even life, were able to form too, the researchers say. “Finding ancient organic molecules in the 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,” said Jen Eigenbrode of NASA’s Goddard Space Flight Center.