Mars is full of the organic molecules that life needs to thrive. Two studies from the Curiosity rover found methane that seeps up from the ground in summer, and more complex organic molecules that have been preserved in the clay for 3.5 billion years.

Most molecules that contain carbon are classed as organic. We’ve found some organic molecules on Mars before, but none as complex as the ones that Curiosity found in a dried lake bed.

“These are complex organic molecules that we think …