2024 can’t come soon enough. You know, that’s the year when humans will set foot on the Moon again. Don’t you roll your eyes. That’s the plan. Well, unless the plan changes. But my point is, explorers going to the Moon will need to be concerned about all kinds of hazards, like dust, radiation and gigantic moon worms.
Apollo missions (NASA)
The Earth’s Magnetic Field: An Overview (British Geological Society)
Why Space Radiation Matters (NASA)
‘Seeing’ Cosmic Rays in Space (Universe Today)
BOOK: Seveneves by Neal Stephenson (Goodreads)
PDF: Lunar Regolith (NASA)
Don’t Breathe the Moondust (NASA)
The Moon Is a Hazardous Place to Live (NY Times)
PAPER: Regolith Sintering: A Solution to Lunar Dust Mitigation? (NASA)
A meteorite strike during the moon eclipse! (Earthsky.org)
Home, Space Home (NASA)
VIDEO: Do You Love Me? (Boston Dynamics)
Transcriptions provided by GMR Transcription Services
Fraser Cain: Astronomy Cast episode 590. Lunar hazards, dust, radiation, and more. Welcome to Astronomy Cast, a weekly facts-based journey through the cosmos where we help you understand not only what we know, but how we know what we know. I’m Fraser Cain, publisher of Universe Today. With me, as always, is Dr. Pamela Gay, a senior scientist for the Planetary Science Institute and the director of CosmoQuest. Hey, Pamela, how you doing?
Dr. Pamela Gay: I am doing great and I am pleased to say hello to our new audience on Houston Channel 21 where we’re on at 11:00 p.m. after the nightly news and The Daily Space. This is exciting.
Fraser Cain: This is so cool. Hello, Houston.
Dr. Pamela Gay: So if things are a little awkward, we are still learning our way around television, but don’t you fear. We’re gonna be here getting better every week as we work to bring you more and more science.
Fraser Cain: Well, to be fair, this is episode 590 of our long-running Astronomy Cast show. We have done more seasons than I think either of us can even count. There are not numbers in the universe high enough to calculate how long we’ve been doing this show, so while we may be new to television, we are definitely not new to Astronomy Cast and we will do our best to adapt Astronomy Cast to this television that you’re watching this on right now.
Dr. Pamela Gay: And –
Fraser Cain: It’s like the internet I think.
Dr. Pamela Gay: And like everyone on television right now, we are recording this from our homes. I am in Southern Illinois where I realized as we went to record, my Halloween and Christmas combined decorations are still on my wall. How about you, Fraser?
Fraser Cain: I’m on Vancouver Island, Canada. Of course, the heart of space journalism here at the headquarters of Universe Today.
Dr. Pamela Gay: And today, we’re gonna take you off of this world and bring you a story of dust, and radiation, and perhaps death.
Fraser Cain: Danger.
Fraser Cain: Danger and fear. Well, 2024 can’t come soon enough. You know that’s the year when humans will set foot on the moon again. Now, don’t you roll your eyes. That’s the plan. Well, unless the plan changes, but my point is explorers going to the moon will need to be concerned of all kinds of hazards like dust, radiation, and gigantic moon worms I believe. All right, Pamela. The moon already sounds like a scary place to me.
Dr. Pamela Gay: Well, and in general, our universe is trying to kill us.
Fraser Cain: As always. Again.
Dr. Pamela Gay: Sometimes actively.
Fraser Cain: Yeah.
Dr. Pamela Gay: Sometimes passively, but it’s full of things that, here on earth, we are protected largely by our atmosphere, so in going to the moon, as we learned from the Apollo astronauts, we need to worry about everything from dust, to radiation, to falling rocks, and even our eyes playing tricks on us.
Fraser Cain: All right, so what – so when humans – when the humans set foot on the moon, 2024 probably. Obviously, schedules change. We’ll keep you updated, but let’s say they do. What – let’s breakdown some of these hazards. I mean, obviously, they’re gonna have some familiar things like gravity. Some gravity. They’re gonna be encased in a spacesuit, so they’ll be bringing some kind of atmosphere with them. The spacesuit will keep them warm, so they won’t freeze to death. The spacesuit will keep them cool, so they won’t boil to death, but there are some things that will be different kinds of dangers than what we face here on earth. Let’s talk about the radiation first.
Dr. Pamela Gay: So here on earth, we have a magnetic field that allows us to find our way around with compasses and generates amazing northern lights, southern lights, the aurora when solar flares interact with the magnetic field, and that magnetic field is, in general, providing brakes for any high-energy particles headed our way. These particles get their directions changed, get their velocities changed, and all together, we aren’t experiencing what’s called ionizing radiation. This is the kind of radiation that if it hits your DNA, it’s gonna snap that DNA apart and cause cancer.
It’s also, in fact, so unnerving that it will literally cause flashes to be seen in your closed eyes. This is something –
Fraser Cain: I’ve heard that.
Dr. Pamela Gay: Yeah.
Fraser Cain: Yeah. I’ve heard – I’ve heard astronauts talk about that, that they close their eyes while they’re in like the space station or when they were in the Apollo missions, and they would see these flashes and the flashes were cosmic rays busting through their retinas, which is terrifying.
Dr. Pamela Gay: Yeah, and so, you can literally see how the universe is trying to kill you passively.
Fraser Cain: So did you know that when you’re standing on the surface of the moon, you’re experiencing 200 times more radiation than when you’re on the surface of the earth? So it is a lot more radiation.
Dr. Pamela Gay: And here on the earth, our OSHA, the organization in the US government that protects people from bad work environments, had to actually change the guidelines –
Fraser Cain: Right.
Dr. Pamela Gay: – so that astronauts are exempted from the radiation levels that all other people are expected to be protected from.
Fraser Cain: Oh, that’s rich. Yeah. Yeah, it’s like there’s no way to make working on the moon a safe environment, which we’re about to continue going deeper into. Okay, so what can we do about that radiation?
Dr. Pamela Gay: Well, different kinds of radiation can be blocked in different ways, and one of the most protective barriers that we can do is just a simple layer of water. Unfortunately, putting a barrier of water between you and outer space is gonna weigh a lot. Anyone who has ever had to carry around the gallon of water knows you’re looking at a heavy amount of water. Now, imagine instead surrounding yourself with gallon upon gallon upon gallon of water. That’s a lot to carry to the moon, but we’re gonna need water anyway, so this isn’t completely unrealistic idea. It’s just awkward.
Fraser Cain: But what about dirt?
Dr. Pamela Gay: Yeah, so dirt is another option. The moon has, as we’ve discussed in past episodes that you can find on YouTube, iTunes, Google Play, and wherever you find podcasts, we have discovered that you can just become the mole man, mole woman of the moon and live in tunnels that were leftover from lava tubes and that will protect you from some of this radiation.
Fraser Cain: I don’t know if you ever read the book Seveneves –
Dr. Pamela Gay: I did.
Fraser Cain: – by Neal Stephenson. Yeah, and so, they talk about that, that when the – when people get to the moon to setup shop, they find a cavern on the moon. It’s still exposed to space and they setup their base down at the bottom of this valley, and so, that protects them from most of the radiation. It would have to be only radiation that’s coming straight down from overhead will actually impact them. Everything else is gonna come in at an angle. It’s gonna sit the sides of the valley and they’re gonna be protected from it. You can sort of play a numbers game. You don’t have to live in a tunnel.
You just have to live far enough down with steep enough walls around you that you’re gonna be able to minimize that kind of impact. I think for a lot of people if they went to the – knowing that you’re experiencing just this constant bathing radiation is unnerving, but it’s not going to – it’s the kind of problem that future you, 40 years down the road, is gonna have to face. There are more dangers that lurk more immediately, and we’ll get to that in a second after the break. This episode of Astronomy Cast is brought to you by horribly, choking, atmospheric – no, sorry. Lunar regolith dust, asbestos on another planet.
All right, before we went into the break, I was preparing people to wrap their minds around another fearful danger on the surface of the moon, and that’s dust.
Dr. Pamela Gay: So here on earth, our dust is, as creepy as it may sound, majority made of things like skin, flex deteriorating from the plaster in your room, bits of dirt thrown up into the air.
Fraser Cain: When you’re sweeping your house, you’re just sweeping your pieces of your family and dog up. Yeah.
Dr. Pamela Gay: And then there’s all the dust mites that live off the dust.
Fraser Cain: Gross, but not that dangerous. Yeah.
Dr. Pamela Gay: So our dust is of the soft and squishy variety that is gross, but won’t generally kill you.
Fraser Cain: You’re just like haunting my dreams now, right? Our dust is skin cells, bits of hair, fluff, and dust mites. That’s like – dust on earth and dust on the moon could not be any different.
Dr. Pamela Gay: No, so on the moon, what we’re dealing with is small pieces of essentially glass. The surface of the moon is covered in what’s called regolith. This is various lunar minerals that have been broken down into the size of dust by impact after impact after impact of asteroids and meteorites falling from space. There’s no rain to round the edges on these little tiny shards. There is no buffering of them against each other to round them down. Instead, you just have itty bitty little tiny shards that are small enough to be breathed and smell like gunpowder according to the Apollo astronauts, and after exposure of just 22 hours, Astronaut Harrison Schmidt declared he had a version of hay fever due to moon dust irritating his lungs and sinuses.
Fraser Cain: And we don’t know what the long-term effects of this are going to be. I don’t think any of the astronauts when they came back to earth experienced any increased incidents of like lung cancer or things like that, which you see with things like asbestos, but asbestos is a really close analog to what we’re looking at; tiny pieces of little glass shards with almost like hooks in it that really want to dig into your lung tissue and stick around for a while, literally.
Dr. Pamela Gay: And this is one of those things where we don’t have a lot of experience with how dust acts in this kind of environment. The 12 Apollo astronauts that were on the moon, altogether, were only there for 80 hours, and during that time, it was long enough for them to be miserable, but not so long as to generate these permanent health hazards. There was an increased risk of cancer that we have seen with the astronauts from the radiation.
Fraser Cain: Mm-hmm.
Dr. Pamela Gay: But –
Fraser Cain: Which we mentioned earlier, yeah.
Dr. Pamela Gay: Right, but the dust – this is a problem that’s new and it’s new not just because of the sharpness that we’re having to deal with, but also, the ability of dust to stay in the air. Here on earth, when you’re sweeping, the dust that gets tossed up that you can see in sunbeams, it is getting slowed with its interactions with the atmosphere, so it doesn’t go very far.
Fraser Cain: Right, right.
Dr. Pamela Gay: There’s no atmosphere on the moon.
Fraser Cain: Well, I do want to talk about that, but I feel like we’re not quite finished talking about that dust because we talked about the dust getting into your lungs.
Dr. Pamela Gay: Yeah.
Fraser Cain: But it actually gets everywhere. Like it’s not just going to be a problem for your lungs. It’s gonna be a problem for machinery, for equipment, things that connect together, things that turn and move. You’ve got – like imagine you’re taking – you’re just dumping just glass into everything. This stuff’s like electrostatically charged, and so, it stays around.
Dr. Pamela Gay: It wrecked the seals on some of the moon rock containers that were brought back by the Apollo astronauts because they couldn’t get the dust to not be in the seals, and if you’ve ever seen dirt buildup on the seals to your refrigerator, and then looked at your electric bill, you know that having grime in the seal makes it less effective. Well, with moon rocks, it doesn’t just pack in there. It also wrecks the surface like sandpaper while it gets in there. This means it gets really, really hard to have a perfect seal between something exposed to the outer environment of the moon and the inside of your spacecraft and the containment vessels for any samples we bring back to earth.
Fraser Cain: But I mean imagine like a lunar rover or some kind of machine that’s designed to go. It’s gonna have bearings and turn-y parts, and there’s going to be hose clamps. They’re gonna be attaching, and removing batteries and electrical equipment, and all this kind of stuff again and again, all the time, and it’s just gonna be – this dust apparently really gets around. It gets into all of it. It’s so tiny and so abrasive that it’s going to almost instantly wear down everything, so what can we do about this dust?
Dr. Pamela Gay: So we’re still trying to figure this out. One of the first things that they’re working to do is in designing the new spacesuits that will be used on the moon. They’re making it so that you don’t put them on inside, and then, go in and out and in the air lock. Instead, they’re making it so you slide down into your spacesuit, pull your arms down, latch up your head, and now, the only thing that is between you, your spacecraft and the outside world is a single seal that’s part of your spacesuit, part of how you close up your helmet.
When you get out, you basically have to pull your arms back in, and then reach up and pull yourself out, but with lower gravity, this isn’t that terrible, and they’ve actually been practicing this out in the Nevada desert and would-be astronauts have been able to do this even under earth gravity, so changing how we get in and out of the lunar environment is one of the first things that we’re looking at. The second thing that’s being looked at is when spacecraft are landing or anyone is tearing around on the surface of the moon, just like a galloping horse will stir up dust here on earth, a landing rocket or a dune buggy on full speed ahead is going to stir up dust.
We’re trying to figure out technology will allow us to not necessarily melt, but to what’s called sinter the moon dust and the moon rocks, so that it forms a compact surface that doesn’t throw up dust. So instead of the effects of a dune buggy going across sand, it will be more like just a car going down the highway without throwing material up into the air. This is actually work that’s being done by one of our friends, Phil Metzger, down at Central Florida University.
Fraser Cain: And the good news is that the dust that’s on the moon has taken billions of years to get there, and so, if you do sinter some, I don’t know, like imagine like creating a big concrete pad that you have – that have you made out of lunar dust that is now dust-free. You’re not gonna get any new dust falling on this region very rapidly, and so, it’s not gonna be – so you’re gonna essentially clear a region of the moon that is safe to work within. You’re gonna minimize all the dust.
Literally, a broom will be your friend to keep this area clean, and then as long as you’re working within this space, you won’t be able to – you won’t have to deal with the lunar dust, but also, it’s – you know the fact that it is electrostatically charged is a benefit, as well, because you can run an electrical field and try to make this stuff get repelled.
Dr. Pamela Gay: So this is our new way forward. We have to mitigate dust by kind of, sort of, almost melting it.
Fraser Cain: Melting it, and then charging it.
Dr. Pamela Gay: But there are still more ways the moon is going to try and kill us and we’ll talk about those when we’re right back.
Fraser Cain: So we talked about the dust that’s collecting on the surface, but there are hazards in space, and actually, that dust is still a problem in space itself. When a rocket is going to be landing on the moon, it’s gonna be kicking up so much dust that it will cause a problem for future missions going to the moon. Can you talk about this?
Dr. Pamela Gay: You had hinted earlier that the dust on the moon is electrostatically charged, and what this means is these particles have either extra electrons or too few electrons on them, and when they go to come together, they get repelled, and this is enough force that gravity isn’t nearly as effective as you would expect at causing the dust to fall back down to the lunar surface, and since the gravity’s already significantly less than we have here on earth, that dust is able to stay suspended for a long time. And because there’s no atmosphere to slow it down when it’s accelerated, it gets lofted to great distances above the surface.
This is something we’ve actually been able to see with some spacecraft, the LADEE mission. It was able to see how dust got stirred up in the atmosphere from impacts of meteorites, so we’re getting dust at spacecraft orbital elevations.
Fraser Cain: Right.
Dr. Pamela Gay: From falling rocks.
Fraser Cain: Right. From falling rocks, not to mention when powerful rock is – like when, for example, when the Artemis missions happened and the lander comes down to the surface of the moon, it’s gonna be firing its rockets. It’s going to be propulsively slowing itself down. The blast from those rockets is gonna be kicking up dust into orbital trajectories, and so, now you’ve kicked up this glass debris and it’s now orbiting around the moon, and any future rockets are gonna have a problem because they’re gonna now get impacted by this literally sandpaper that they’re moving through. And you mentioned Phil Metzger.
He talked about it down near the surface, and also, he’s calculated the danger that future rockets will have, and so, literally, until they sinter that landscape, until they make safe landing pads, just landing on the surface of the moon, like the Apollo missions did, will mean that nobody else will be able to follow you for a certain amount of time until that dust all impacts the surface again and gets cleared out again. There will – there’s a practical limit to how many spacecraft can go to the surface of the moon while this dust is being kicked up.
Dr. Pamela Gay: And again, we are looking at ways to mitigate this. One of the easiest ways to mitigate this is to essentially take an entire crater, sinter the surface of the crater, and land inside the crater. Now, the reason you do this in a crater is twofold. On one hand, you have the walls of the crater act as a shield for any dust you don’t successfully sinter to the surface and the other is it just gives you a nice, easy to surface to aim for with your rocket, so you like that flat bottom that it exists and you like the walls that prevent things from going too far away.
Fraser Cain: Right, right, right, and so, you’ve got this situation. You’ve got your – the first like one of the top priorities is to build a landing pad and to bring a broom in a crater, and then build your landing pad, keep it clean, and then future rockets won’t be kicking up this dust. We’ve talked about dust coming from the surface that you brought there. Let’s talk about falling rocks after this break. When you look at the surface of the moon you can see that it has been through some rough times. There are a lot of craters, big and small. When you think that there are meters and meters of this churned up lunar regolith that was caused by rocks falling from the sky, is that a serious threat to people on the surface of the moon?
Dr. Pamela Gay: It is and for the most part, when we’re looking at the moon, we’re seeing a history of impacts that have occurred over the past four some-odd billion years, but craters are still getting formed, and in fact, there were everyday people who back in January of 2019, during a lunar eclipse, saw in that darkened part of the moon a bright flash of light.
Fraser Cain: We saw it. We captured it during our live stream of the eclipse.
Dr. Pamela Gay: And this was bright enough that we could see the energy of impact here on earth, and while the astronaut’s spacesuits are designed to withstand a nine millimeter round, which is pretty big, the problem we run into is micrometeorites can come both at higher velocities than those bullets and in larger masses than those bullets, and in both those scenarios, you’re gonna have a whole lot more energy than that bullet might have, and that can go through a spacesuit, which is bad. It can also potentially go through your habitat.
We’re going to have to figure out not just how to shield the astronauts from radiation, which has a different kind of high energy, but also from the impact of rocks, and also, our own debris. The more we’re going to and from the moon, the more junk we’re gonna end up accidently throwing at ourselves, as we currently do with the international space station.
Fraser Cain: But when you think about the international space station, a lot of that debris is earth caused. It’s our space junk.
Dr. Pamela Gay: Yes.
Fraser Cain: It’s little bits of flex of paint. It’s little pieces of – it’s gloves that were left outside and hammers and things like that, and there are – I mean you can absolutely see. When you look at the – you can see the pictures of the screen of the space shuttle and you can see all the nicks and dents from it going through space debris, and there are puncture holes in the international space stations solar panels that show that it is still a very active environment. It’s actually not as bad out at the moon because there isn’t all that human debris in that same region.
Dr. Pamela Gay: Yet.
Fraser Cain: Yeah. Yet. Right. Oh, we victims of our own success, but like the chances are really low of you actually getting hit by a piece of rock from space, right? Like that’s bad luck.
Dr. Pamela Gay: The chances are exceedingly low, but this is one of those things where you have to build it into your system. There are certain things that probability is low and you design for it, so for instance, one thing I learned prepping for this show is there are earthquakes as strong as fifth magnitude on the moon. When they’re building space habitats, they’re going to have to design them to survive earthquakes even though the probability of that large an earthquake happening in the exact location where the astronauts are is extremely low, but low is not zero, and killing people is a bad thing.
Fraser Cain: Mm-hmm.
Dr. Pamela Gay: Usually.
Fraser Cain: Yeah. Can confirm. Yeah.
Dr. Pamela Gay: We are trying to build to keep people safe. We’re trying to build to keep equipment, technology, experiments, and most of all, people safe, so this means we design for falling rocks and earthquakes.
Fraser Cain: Right, but I mean isn’t just – like there is no design for falling rock. There’s no design for a chunk of space rock or metal flying at you at ten thousand kilometers an hour. There’s no mitigation of that.
Dr. Pamela Gay: To a certain point. There –
Fraser Cain: Yeah.
Dr. Pamela Gay: There’s ways to make things less harmful, and we see this with the international space station and with plans by companies like Bigelow, and what they do is instead of building a single thick wall where you have to worry about punching through, worrying about cracks in this one structure, things are instead made in layer, upon layer, upon layer, so that a rock coming through, meteorite, it will puncture through the different layers and each time gets slowed down, and hopefully, leave enough layers completely undamaged that you can just go out and patch the part that was a problem.
Duct tape is actually an important thing in outer space, and the other layers are there keeping you safe, and so, by using this kind of a baffling system, we can build smarter, build better. Other ways are, again, build underground and make sure that what above you includes sandy soils that are better at absorbing impacts instead of collapsing on top of you.
Fraser Cain: Right, but you’re just gonna go with blind luck while you’re out on the surface of the moon, but I mean for the radiation purposes and the dust purposes, you’re gonna want to minimize the amount of time that you spend out on the surface anyway, so just get used to being underground.
Dr. Pamela Gay: And robots. Robots are our new arms, eyes, hands, and there’s actually now a Boston Dynamics dog being trained for future exploration in space, so our robot rovers are going to be our investigators digging up the surfaces of other worlds, safe from the things that would kill us.
Fraser Cain: Yeah, when you saw those dancing Boston Dynamics robots, you kind of imagine them being tele-operated by human beings and being able to explore around on the surface of the moon, largely safe from the radiation; although, still I guess a meteorite strike would be a bad day for a robot. All right. Well, thank you Pamela. Do you have some names for us this week?
Dr. Pamela Gay: I do, so we are, as always, supported through Patreon. You and your generous donations allow us to hire our audio and video editors, to pay our server costs, to not have to do our own budgeting. Everything goes through the Planetary Science Institute, and this allows us to focus on just bringing you the science, which is really what we want to do. So many thanks to all of you, and today, I would like to specifically thank Catherine McCabe, Jordan Young, Burry Gowen, Birko Roland, Andrew Poelstra, Brian Cagle, David Truog, Jeanette Wink, Aurora Lipper, Joe Hook, David, ACUT-Patron, Venkatesh Chary, TheGiantNothing , Dan Litman, Laura Kittleson, Robert Palsma, William, Joe Hollstein, Jos Cunningham, Les Howard, Paul Jarman, Adam Annis-Brown, Emily Patterson, Ed loves science, cacoseraph, Just Joe, Helge Bjørkhaug, Frank Tippin, William Baker and Gordon Dewis. Thank you all so much and I just want to say we were trying to find 60 new Patreons across all of our Cosmic Quest projects, and because of you, we succeeded in doing that and this is going to allow so much science to be done. Thank you.
Fraser Cain: Thank you everybody.