ARI SHAPIRO, HOST:
It's time for some science news from our friends at NPR's Short Wave podcast. Emily Kwong and Regina Barber are the hosts, and they are here for our science roundup. Good to have you both back.
EMILY KWONG, BYLINE: It's so fantastic to be here, Ari.
REGINA BARBER, BYLINE: Yeah, it's good to be back, Ari.
SHAPIRO: What have you got for us this week?
BARBER: We've got three stories that let us all hang out in space together.
KWONG: It's true. We are leaving Planet Earth for a little bit to check out a newly discovered asteroid, a new finding on a distant moon and deepen our understanding of what spaceflight even does to the human brain.
SHAPIRO: I got to say, space has always kind of scared me, but I'm - I trust you to keep me safe. Let's go into orbit. Emily, what's first?
KWONG: Aw, you're in good hands. You're in good hands. OK. This first story is how spaceflight affects the brain. And it's a big topic of interest because if you think about it, commercial spaceflight is totally on the rise, right?
SHAPIRO: And it's not just like these short hops where people float around without gravity for a few minutes. They're actually visiting the International Space Station.
KWONG: Yes. The future of spaceflight is looking expansive. We know what long-term spaceflight does to the body. There's the increased radiation, the social isolation, the weakening of your muscles and bones from the microgravity. But it turns out that spaceflight also changes your brain. Rachael Seidler studies this at the University of Florida.
RACHAEL SEIDLER: In the absence of gravity, the brain is actually sitting higher in the skull, and the top of the brain is a little bit compressed against the skull. There's also headward fluid shifts that happen in the absence of gravity.
KWONG: Gray matter shifts - the cerebral spinal fluid in your body moves around too. A lot of first-time astronauts, Ari, report fluid buildup in the face - what they call puffy head, bird legs. And we don't know how this affects someone's health long term. Rachael made me think about how this issue is colliding with our very evolution.
SHAPIRO: Yeah, because we evolved with gravity. Emily, you're not making space any less scary for me right now.
KWONG: Yeah, I mean, we got to deal with the facts in front of us. You know, our bodies were designed for fluid to travel up, and without gravity, there's nothing to pull it down. So Rachael's study, published in Scientific Reports last week, looked at 30 astronauts. Those in space for two weeks saw minimal brain changes. But at six months, their brain saw a lot more changes. And astronauts who went for a year or more, there was no further change, kind of like a plateau suggesting the brain was trying to adapt to space.
SHAPIRO: And after people come back to Earth, did the brain changes reverse?
KWONG: Not really - at least not for a long time. One of the most typical things researchers see among astronauts post-flight is these cavities called ventricles deep in our brains expanding. They're trying to accommodate all of that fluid shift from living in a weightless environment. And interestingly enough, the earthbound astronauts, whose last spaceflight was less than three years ago, demonstrated less adaptation to all that fluid, less expansion in their brains. And that actually worries Rachael because if these pockets of the brain aren't expanding to take up all that fluid, the brain itself may be getting compressed. We're not totally sure of the health risks of any of this. But she worries that the potential pressure on the brain from too little time back on Earth might not be a good thing.
SHAPIRO: So what's the solution, apart from just don't go to space?
KWONG: Or spending more time on Earth between space flights to...
SHAPIRO: OK.
KWONG: ...Allow the body to kind of recalibrate. I mean, this is the kind of research and data we need - right? - to figure out what to do. It's a new area of study - space flight in the brain. It only began less than a decade ago. And if we're going to go to space, which we clearly want to do, work like this could help inform...
SHAPIRO: (Laughter) Speak for yourself.
KWONG: Fair. Some private citizens and a lot of space companies want to do - work like this could help inform more thoughtful policies about what would be healthy when it comes to the humans spending time in space.
SHAPIRO: OK. Our second space story comes from you, Regina, and this is about water on one of Saturn's moons. Paint a picture for us.
BARBER: Yeah, I actually love the icy moons in our solar system. It's one of the reasons I got into astronomy. And also, a few of those icy moons show evidence of possible oceans underneath - like Enceladus that orbits Saturn.
SHAPIRO: An ocean on Enceladus - why do scientists think there's water there in the first place?
BARBER: Yeah, there was this really cool mission called the Cassini mission, and it flew by Enceladus numerous times, like, between 2004 and 2017. And it collected data from a plume shooting liquid into space from Enceladus' surface. It was recently analyzed, and it was published in the journal Nature. And the researchers detected amounts of phosphorus at higher levels than our oceans on Earth.
KWONG: And phosphorus may sound familiar. It's a macronutrient that makes pools become overrun with algae, right?
BARBER: You're totally right, Em. It's a basic ingredient in fertilizer.
SHAPIRO: Look, I'm a gardener. Water plus fertilizer...
BARBER: Yeah. Nice.
SHAPIRO: ...Equals plant growth. Does that mean anything is growing on this moon of Saturn?
BARBER: I mean, we always need to be careful when talking about life on other worlds. But phosphates in water can point to possible - possible - habitability in an ocean that most likely exists under that ice. And I talked to a planetary geochemist, Mikhail Zolotov, at Arizona State University. And he was not associated with the study, but he says it's a positive sign. If there is life there, they wouldn't have to struggle like ocean organisms do in our oceans that don't have enough phosphorus.
SHAPIRO: OK, I'm really into this. How are they going to find out if there is actually life on this moon of Saturn?
BARBER: Yeah, that's for future missions, ones that look at these icy moons. There's one actually in the works. It's called Jupiter Icy Moon Explorer or JUICE. But yeah, as for Enceladus, I mean, we can't rule it out, right? So that's pretty fun.
SHAPIRO: Totally. OK, third and final space story is about a newly discovered asteroid. Tell me it's not hurtling towards Earth.
BARBER: No, it's not too close. So we tend to think of asteroids as, like, these random objects hurling, like, throughout space, throughout the solar system. But they actually have very predictable flight patterns. Many have these large orbits around the sun, and scientists recently detected one. And it's called 2023 FW13. It's orbiting the sun along a path very similar to Earth's orbit, and that's what's unofficially known as a quasi moon.
SHAPIRO: As in, like, our Earth has a moon and also a quasi moon?
BARBER: Yes, yes. But we shouldn't go thinking we have two moons. This asteroid, it's not orbiting Earth. It's only slightly influenced by our planet's gravitational pull. So it's more like a fellow passenger driving a similar highway as us as we lap around the sun. And it's much smaller than our moon. It's the size of a camper van, like a quasi moon Winnebago. Quasi moons like this one have been discovered before, and they tend to come and go.
KWONG: And this one might be one of the oldest quasi moons ever found. Like, some estimate, it's been circling the sun since 100 BC and will likely do that until 3700 AD. And at that point, its orbit will kind of break down, and it'll probably, like, just amble off to wherever its velocity takes it.
SHAPIRO: Amazing to me that astronomers can not only detect this thing but figure out its age. OK, so if it does wander off at some point, could it potentially be dangerous to, you know, those of us on Earth?
KWONG: No. No. So the quasi moon's orbit doesn't come close to Earth at all. Plus, its orbit is so stable that we'd probably know about any dangers, like, decades in advance. That's what one astronomer told Sky and Telescope magazine, which reported on this discovery.
BARBER: Yeah, that article mentioned too, Ari, how one of the most remarkable things about this quasi moon was that it was even discovered at all. It was a total accident. Scientists weren't looking for it. They just noticed it. And it took data from multiple observations in Hawaii and Arizona to confirm the finding. But it's all just a reminder that space is a big place. We know only a fraction of a fraction of what's going on out there. Hopefully this makes you understand it a little better, though.
SHAPIRO: Yeah, I mean, in a space that big, it's easy to miss a quasi moon the size of a Winnebago.
(LAUGHTER)
SHAPIRO: Emily Kwong and Regina Barber host NPR's science podcast Short Wave, where you can learn about new discoveries, everyday mysteries and the science behind the headlines. Emily, Regina, this has been a delight. Thank you.
KWONG: Thank you, Ari.
BARBER: You're welcome. Thank you.
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