AILSA CHANG, HOST:
So a science experiment aboard NASA's Curiosity Rover has found tantalizing traces of possible past life on Mars.
DANIEL GLAVIN: We're really living kind of a science fiction film, if you will, here. It's just amazing that we can even do this.
CHANG: Daniel Glavin is an astrobiologist with NASA - cool job - and he's part of the team that has detected the largest organic molecules ever found on the red planet.
JUANA SUMMERS, HOST:
The molecules came from a sample of 3.7 billion-year-old Martian mudstone dug up in Gale Crater, the site of an ancient lake. Glavin says the compounds could be the remnants of what's called fatty acids.
GLAVIN: Well, what's a fatty acid? These are components of cells. The cell membrane includes fatty acids. So these are really important and critical building blocks of life.
CHANG: But before you get too excited, there could be other explanations for where these things came.
GLAVIN: They could have been delivered to Gale Crater by meteorites. They can also be formed by kind of natural geological processes. And then the third possibility is that we're looking at the ancient chemical remnants of life, that biology actually built these fatty acids.
CHANG: He says there's only one way to know for sure.
GLAVIN: A next logical step here is to bring back samples from Mars, bring them home, so we can finally get at this age-old question about whether or not there was ever life on Mars.
SUMMERS: Doing so will be a journey, but that's nothing new for Glavin. This new discovery took more than a decade to come to fruition.
GLAVIN: We first drilled this ancient Martian mudstone sample in May of 2013, and here we are now almost 13 years later, where we're finally able to report the discovery.
SUMMERS: Their findings appear in the proceedings of the National Academy of Sciences.
CHANG: So what's next? Well, the first part of that sample return mission - it's already underway. A different Mars rover called Perseverance landed on the planet back in 2021, and it's been collecting tubes of dust and rock and packing them in its belly.
SUMMERS: Sometime in the future, another spacecraft will land on Mars, take those tubes and blast into Martian orbit. Then a second spacecraft will rendezvous in orbit, bring the samples back to earth and drop them in Utah. Well, that's the plan, at least.
GLAVIN: If everything goes perfectly, this would happen in the mid-2030s, 2035. But again, a lot has to go right. The only thing that we've done here is we've demonstrated we can land on Mars. So launching off the surface of Mars, orbiting with a sample in Mars orbit, rendezvousing, capturing it - all of that is basically the first time we would ever have demonstrated that.
CHANG: So it may be a while before scientists on Earth have Mars dust in their hands. But the fact that these molecules endured billions of years on Mars - that indicates any traces of past life can probably wait a few more years - right? - until Earthlings figure out how to bring these samples home.
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