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NAU lends expertise to NASA to check spacecraft for hitchhiking microbes

Two people wrapped in white gowns and gloves work on a Mars spacecraft
NASA
Scientists at work on a Mars rover in at the Jet Propulsion Laboratory

Scientists at Northern Arizona University have pioneered a new way to check NASA spacecraft for contamination. The goal is to ensure spacecraft don’t accidentally bring life from Earth to another planet. KNAU’s Melissa Sevigny spoke with Paul Keim, director of the Pathogen and Microbiome Institute, about how his team used DNA sequencing to hunt down hardy microbes that might try to hitch a ride.

Why is NASA worried about microbes getting on their spacecraft?

It’s clear that we’re going to be sending more and more spaceships to Mars and to other places like Europa, a moon around Jupiter, where there’s potential that there’s actually life…. And so in that exploration, looking for that life, one of the biggest fears we have is that we send along microbes from Earth. They get there, they like it, and they start to grow. First off, that would be a real shame if we showed up and discovered that the microbes that we discovered, the life that we discovered on one of these other planets, is actually from Earth. That would be devastating.

How did you and the other folks in Flagstaff get involved with this program of planetary protection?

Over the last several decades what NASA and JPL has done is monitored the cleanliness of their assembly facilities by trying to grow bacteria. The problem with that is we know 99 percent of the bacteria in the world can’t be cultured in a laboratory. We just don’t know what they need to eat, we don’t know how to do it. Using those methods is flawed, but it was all we had, until the genomic technology that we use came along. So our approach was to go in, sample the surfaces, sample the air filters in the JPL facility, and look for DNA of microbes. Sure enough, we found it.

Do you have sense, of the microbes you found in the clean rooms, how many would be capable of surviving a few years in space on a space journey?

We know microbes can survive in really harsh environments… We can pull microbes out of nuclear reactors, and they’re fine. There’s this one bacteria called Deinococcus radiodurans, we can actually give it a dose of radiation 1,000 times higher than what would kill a human, and it’s fine…. So what we do, is we go in and look at these DNA sequences and try to identify genes that are related to those phenotypes, related to that biology, of being resistant to radiation or forming spores…. So we found some of those, and those are the ones that NASA will focus upon to try to clean up their operations even more.

We’ve be sending spacecraft to Mars since the 1970s. Do you think it’s too late? Have we already maybe contaminated Mars?

I hope not. I don’t have a good, clean answer for that question. I hope not. Interplanetary ravel is harsh… If you’re not one of these super hardy radiation-resistant microbes you’re probably going to get zapped…. Luckily it’s only a small number of these extremophiles that can survive those conditions, and once they get to Mars or Europa they have to find conditions that allow them to survive and replicate. The odds are against any bacteria getting across there. But the stakes are so high we don’t want to take any chances.

Paul Keim, always a pleasure to speak with you.

Thanks, Melissa.

Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.