Protecting Other Planets From Earth’s Germs

11:30 minutes

nasa scientists in white sanitation gowns and masks assess and test a mars rover in a lab
In the clean room of the Spacecraft Assembly Facility at NASA’s Jet Propulsion Laboratory, scientists wear suits and masks while working on the Mars 2020 rover to avoid contamination. Credit: NASA/JPL-Caltech

For decades, people have been trying to figure out how to avoid contaminating other planets as they explore them—an idea called planetary protection. As missions venture forth to places such as Mars or Jupiter’s moon, Europa, the need to protect worlds that could support life becomes more critical. And at the same time, as space programs begin to bring samples back to Earth from places like Mars or asteroids, planetary protection becomes a concern in another way—the need to protect Earth from potential unknown life forms from the cosmos. 

Sending humans to another world raises the stakes even more. NASA has a limit of no more than 300,000 spores (single-celled organisms) allowed on board robotic Mars landers. But human bodies contain trillions of microorganisms, making it impossible for human missions to achieve the same level of microbial cleanliness as robotic landers. 

Dr. Nick Benardini is a NASA official responsible for ensuring that the proper precautions are made to prevent humans from contaminating outer space. Ira Flatow spoke to him about how to avoid spreading microbes between planets. 

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Segment Guests

Nick Benardini

Dr. Nick Benardini is the Planetary Protection Officer in the Office of Safety and Mission Assurance at NASA HQ in Washington, DC.

Segment Transcript

IRA FLATOW: Remember the Orson Welles radio drama, and then the movie, War of the Worlds, where the Martians tried to conquer the Earth? They actually start winning, and then, mysteriously, they die. And it turns out they die from, what, the common cold, to which they have no immunity– science fiction.

Yeah, well, what about reality? What’s to prevent just the opposite from happening– I mean, a space probe returning from space to Earth, bringing foreign microbes to our planet. I bring this up because next month, NASA’s OSIRIS-REx probe will bring the first sample of an asteroid back to Earth.

The capsule is projected to land in Utah’s desert, and scientists hope the sample of asteroid dust on board will help them get a snapshot of our solar system maybe 4 billion years ago. But is there any risk to bringing back material from space to Earth when we don’t entirely know what’s in it?

Well, let me give you the flip side. What about when we send missions to other planets or moons like Mars or Europa? Could we accidentally contaminate them with Earth microbes?

Here with me now is someone who thinks a lot about this question and questions like this. Dr. Nick Bernardini is NASA’s planetary protection officer based at NASA’s headquarters in Washington, DC. Welcome to Science Friday.

DR. NICK BERNARDINI: Thanks for having me, Ira.

IRA FLATOW: Thank you for coming. Let’s talk about OSIRIS-REx projected to return to Earth next month. As far as we know, there’s no life there, but how do we ensure that anything from that asteroid does not contaminate us?

DR. NICK BERNARDINI: Yeah, that’s an excellent question. So for planetary protection, we have a whole series of international scientists and engineers that think about this on a regular basis called Committee of Space Research. And so they put forth international guidelines and current understandings together and frameworks for what exactly is the type of potential science that can be conducted on these target bodies as well as the type of potential for life on these target bodies as we go explore the solar system.

And so we know that OSIRIS-REx we refer to as an unrestricted Earth return sample. So this is of lowest likelihood of life or harboring life. And so we actually don’t have any restrictions for bringing that asteroid material back much like our comets and other asteroids that we would bring back.

IRA FLATOW: How do we know, Dr. Bernardini, what to look for if it’s something we’re not used to?

DR. NICK BERNARDINI: So this is exactly one of the conversations we have all the time. What is life? What do what do we think about life and the unknown space? And so we have a lot of conversations in the science community and international community about sample safety assessment. Really, what would we look for with life? And that gets down to understanding what life looks like from a physical or molecular perspective, what it looks like from an organic perspective. And so we use all of these clues that we can about life as we know it to infer about potential of life on other planets.

And so on Mars, for example, we see those signs. But on other asteroids, such as OSIRIS-REx and Bennu, we don’t see that. And so we’re able to make those guidelines more unrestricted versus having a more restricted like we would for a Mars sample return mission.

IRA FLATOW: We have been exploring space since, what, the 1950s. Have we improved in our space exploration techniques so that our spacecraft do not unintentionally bring back alien microbes such as on OSIRIS-REx?

DR. NICK BERNARDINI: So we’ve definitely improved both in our, obviously, engineering capabilities as well as our science knowledge. And all of those directly feed into our policies, a lot of our approaches that we take, for example, our understanding of clean room technologies and how we make sure that we can leverage these clean rooms which control particulates and organic molecules so when we go to life on other planets, we don’t inadvertently detect our own life because we built the spacecraft dirtier than what we thought. That’s just one of the examples of the types of advancements that we’re using nowadays.

IRA FLATOW: I started off mentioning a science fiction movie. And in sci-fi movies, we see extreme examples of what could happen when an alien pathogen infects Earth. People think this is not real because it’s just something they see in the movies. But you think of this every day.

DR. NICK BERNARDINI: Absolutely– we don’t think of it in terms of Hollywood or the sci-fi angle, but really more of it a scientific- and evidence-driven perspective in that on Mars itself, we know that, for example, the samples that we’re collecting right now are going to be lower likelihood to harbor life than a deeper depth- or cave-type of sample. So we have these scientific inferences that allow us to help develop that risk posture for thinking about what we need to do to ensure that the public is safe and that our spacecraft are clean when we go to visit other planets.

IRA FLATOW: Let’s talk about that, visiting other planets, because one planet we visited a lot is Mars. And I remember going way back into the ’70s, Viking, were these probes pristine when they landed on the planet?

DR. NICK BERNARDINI: So that’s a common misnomer is that we send sterile or clean spacecraft. Matter of fact, we can’t given the fact that we humans have life, and the rooms that we assemble and test and launch operations all have some bit of biological presence, although that’s not saying that it’s completely dirty. We highly control these. We’re talking our spacecraft are less than half a million organisms per spacecraft. That’s compared to– think about perhaps a probiotic that you might take on a regular basis. That probiotic has 40 times more organisms than what we allow on our spacecraft to go to Mars.

IRA FLATOW: But when we went to the moon, the Apollo astronauts left an enormous amount of human poop on the moon, didn’t they?

DR. NICK BERNARDINI: So that’s certainly something that we have to mitigate in thinking about when we introduce humans is what we do with human waste streams and what the microbial transport could be just because of those humans being present.

IRA FLATOW: And let’s imagine an astronaut gets sick in space. Just sky with me [LAUGHS] now. How do they determine if someone who gets sick in space, it’s because of in-flight sickness, a pathogen from Earth, or maybe a planet– some other pathogen that snuck in? How would you know that?

DR. NICK BERNARDINI: So that’s exactly the type of work that we’re doing right now with our knowledge gaps and planning for moon to Mars. And so we have the luxury right now on the International Space Station that if an astronaut gets sick, we have several days we can get that astronaut back down to Earth for medical attention.

Once we start talking about lunar surface missions in the upcoming years, some of that may be upwards of a week before we can get that astronaut back to Earth. And even Mars is particularly more time-consuming from an orbital dynamics perspective. We’re talking upwards of 600-plus days depending on when that astronaut were to get sick. And so we have to think about that a little bit different than what we do currently with our International Space station astronauts.

IRA FLATOW: And do you have special testing kits that would quickly diagnose that?

DR. NICK BERNARDINI: So that’s what we’re looking at developing with the Office of Chief Health and Medical at NASA. And so we need to work through from a planetary protection perspective and a built environments perspective if it’s a human-associated organism, or if it’s something from Mars. And so we’re working to fill those knowledge gaps and to develop a framework for that kind of decision making within this next decade.

IRA FLATOW: One question that I always get– and I’ve been talking about this for quite some time– is from people who do not think we should be exploring other planets. They think we should be focusing on the problems here on Earth. It’s a good point given all of our problems with climate change. Why do you think we should explore other planets. Why should we be so concerned about bringing our environment over there?

DR. NICK BERNARDINI: Well, I think from a perspective of going and exploring, I think, obviously, it’s human nature to go explore. And I think from having other planets and being able to have that curiosity, I think that’s essentially inherent in our human DNA. There also is a lot of potential spin-offs that we’ve seen throughout the years with NASA products that we might need for space that put it into our daily lives and impact Earth. I’m thinking VELCRO, also, perhaps a lot of our environmental life support systems that we have for water cleaning coming up.

So I think there’s a lot of cross-pollination and cross-potential for the technologies to be fed forward into improving our Earth life that we see on a regular basis.

IRA FLATOW: Do you think we need a better technology for sterilizing– to use a better word– the craft we send out, especially for going to Europa or some other place?

DR. NICK BERNARDINI: So don’t think it’s necessarily the sterilization. I think it’s more along the lines of how do we keep it clean? That’s really the hardest job that we have. So whether that’s thinking about different types of bio-barriers or protective shields after we keep it clean. Perhaps, it’s more stringent types of clean processing. And we’re leveraging heavy right now on the medical-sterilization industry with high heat, vapor hydrogen peroxide, solvent types of cleaning methods very similar to med device, for example, or pharmaceuticals.

IRA FLATOW: We look forward to talking more with you and learning more about this. Thank you, Dr. Bernardini, for being with us.

DR. NICK BERNARDINI: You’re welcome. Thank you.

IRA FLATOW: Nick Bernardini is the planetary protection officer at NASA.

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