Nasa says it's found new evidence which suggests Mars could have supported ancient life.
The Curiosity Rover - which is a robot that Nasa has sent to explore Mars - has discovered three different types of organic compounds.
The compounds were found after Curiosity dug just five centimetres down into 3-billion-year-old rock on an ancient lake bed.
It's also found a source of a gas called methane.
This isn't the first time the gas has been found on Mars but it's definitely interesting because here on Earth, 95% of it comes from living things.
Scientists are investigating but say it's too early to say where the molecules have come from.
Although they're often linked to life, they can also be created in other ways, so they're not evidence for life themselves.
But scientists say it's all very promising for future missions!