Hi, I am Tyler Horvath and I discovered that caves on the Moon are the most habitable places (thermally) in the solar system. Ask me anything!

So what's next? Do we seal off the caves with plexiglass or something, pump in atmosphere, and make ourselves a little lunar base?

Or is there a sad but practical reason this amazing idea will never work?

So theoretically that would work, as long as the plexiglass is in the permanently shadowed reaches of the cave. If the air can pass over areas at the opening of the cave it may get too warm or too cold, not sure, but we just shouldnt worry about that haha.

Though what would be cool is as long as you have an airtight pressure suit and an oxygen source, you could wander the cave in a much smaller suit than what the Apollo astronauts did! No need for all the thermal insulation or radiation protection in the Moon caves!

Are moon rock porous? I mean, at least on caves here on earth, there are sometimes cracks and crannies where water can pass through. And are there similar rock formations on moon caves like what we find on Earth?

I think theyre porous in the same way earthly basalts are, but I'm actually not too sure, I'm not much of a geologist haha. I dont think water has made it through the cracks and crannies of the moon caves if those exist, temperatures are too high and all water sublimates/evaporates away.

I think the inside of Moon caves would look similar to Earth Lava tubes, lava drips potentially coming off the ceiling and pahoehoe/a'a' along the bottom and sides. I cant be sure though, also not my expertise 😅

I’m a geologist! The short answer is as far as rocks go, especially volcanic and igneous rocks, basalt can vary wildly for porosity and permeability. It really depends on how fast they cool and in what conditions. I don’t know too much about the moon’s geology but I’d imagine it would be similar.

I apprivate your input! Is the porosity and permeability a function of water content? Id assume water rich basalts would be more porous as theyd have increased vapor pressure while the lava is cooling!

Generally, yes, I think that’s the case. The only rocks I’ve encountered that have a porosity that is affected (or affects?) air is a highly porous sandstone but that’s also not to say igneous rocks can’t be similar. I’d also agree/imagine that the moon caves look similar to lava tubes like you said but I don’t know enough to properly verify that.

I haven’t done proper hard geology in a few years since I’m currently working in civil engineering and trying to find my way back to volcanology (still looking for PhD projects), so take my words with a grain of salt. But your research sounds super cool and I hope your PhD goes well!

Thats really cool to know! If you want to get into the planetary science game you could work on "Cryo-Volcanism" on the ocean world moons of the outer solar system! I know thats a pretty hot topic at the moment and is sort of like actual volcanology haha.

Thanks for the kind words!

Hey, hey, we're asking YOU questions here buddy.

I DO WHAT I WANT! ahahaha

Isn’t regolith just nasty for lungs? Even if you sealed off the cave entrance and filled with air, breathing in the moon dust would tear your lungs apart?

Regolith is pretty rough on the lungs and everything else for that matter, but the inside of the cave should be relatively free of regolith! Impactors, which generate the regolith from rock, can't make its way into the cave to produce it! Hopefully that is also an additional benefit of being in a cave :)

Have you found any Prothean artifacts yet?

I'm not supposed to say this, but one of the images taken with the satellite's normal cameras saw some keepers stalking around the opening. I'm not saying the Moon is a mass relay, but the Moon is a mass relay.

Male Shep or Fem Shep? And who did you romance?

Male shep, always either Tali or Liara. I've played through the games a lot of times and never strayed from them (except for xbox achievements) haha

I feel like earth is more habitable and it was in the solar system last I checked, what's that about?

Overall Earth is definitely more habitable, but in terms of temperatures alone these caves would be the most consistently comfortable! On Earth you have temperature swings, and many places that are comfortable do experience temperatures that get too hot or too cold for humans to survive indefinitely without some sort of protection. These caves would stay 63 F or 17 C essentially forever.

I am definitely not saying its easier to live there, there are plenty of other challenges, but in terms of temperature it is nearly perfect!

These caves would stay 63 F or 17 C essentially forever.

I'm wondering how humans' presence in the tunnels would affect this. The London Underground's tunnels have been slowly warming for decades and we haven't found a way to cool them yet. In London, obviously, you can just go outside, but that's not an option if you're on the Moon. Do you have any thoughts on this?

Ao thats kind of an unknown. I think these caves would actually heat up, but by how much I am not sure. It would take time, and there would definitely be ways to disappate the heat (like literal heat sinks/radiators on the surface that are open at night, closed during the day), so I dont forsee that as much of a problem. However that is a guess, actual research would need to be done ahead of time!

Are you sure that on Earth there is no place (again a cave, probably) with an even better permanent temperature, like 20 C?

Caves on earth tend to be pretty cold or pretty warm (especially mines that go down far), it is pretty rare for a cave to be stable at around 20 C as far as I am aware! Now there may be some, but I'd rather be in a spacesuit at 17 C than a likely muggy cave at 20 C, but I'm also biased haha

Speaking of mud on Earth, I imagine abrasive dust in Moon caves might be an issue, especially if some boring happens. Is moon base personnel doomed to wearing a mask even in a pressurized cave and does it make sense to pressurize one at all.

So there actually should be very minimal moon dust in the caves! The abrasive lunar regolith is produced through constant bombardment by asteroids and micrometeorites on the surface. Inside the cave, where these things arent constantly bombarding, nothing is breaking down the crusty cooled lava formations that make up the cave. Additionally, if an impactor launches regolith far away, it is very likely to stay at the opening as theres no good path for regolith grains to fly into the cave. So that additionally would be a benefit of these caves (at least relative to the rest of where you could be on the Moon)

So it may also be the only place on the Moon where you wouldnt be screwed by constant exposure to the lunar dust!

the temperature of a cave on earth is close to the average annual temperature of the area of the cave. The temperature is not completely constant - there can be small ups and downs and the deeper you go the more constant - and there can be other variable like humidity and airflow, but in general they are pretty stable.

I do agree that they will be relatively stable, just not necessarily at a comfortable temperature. Caves on the Moon that arent at the poles will basically all be at the temperature!

Earth has caves too. But I get what you're saying.

Earth caves have a huge range of climates and aren't generally comfortable. I went to one in northern California before, and although it was about 90 F out the bottom of this cave was ~40 F and there was ice at the bottom. Different physics drive the Moon ones which make them constantly nice :)

Crazy, I guess I've only spelunked caves near me and they were all usually within a few degrees of 70F all year (Missouri caves/caverns).

Thats really comfortable! That's the first I've heard that hovers around a good temperature, I see that "Fantastic Caverns" in Missouri hovers around 60 F as well in particular, its basically a Moon cave with air and high humidity! haha

Wow, Interesting. That's quite a difference!

Its honestly pretty surreal needing to put a thick jacket on at noon when its so hot in preparation for going a couple hundred feet into a cave. This was at Lava Beds National Monument, highly underrated and I highly recommend going if you get a chance, all the other caves there are really cool too as long as you aren't claustrophobic.

How did you measure the temperature inside the caves?

I used data from a thermal camera named Diviner orbiting the Moon aboard NASA's Lunar Reconnaissance Orbiter. Using this camera I was able to measure the temperatures of the floor of a collapse pit believed to be an entrance to a lava tube and compared it to computer simulations of what temperatures at the floor of the pit would be. The results were that a pit with a cave, no matter the size, would elevate the temperatures of the pit floor to the level we measured.

Fun fact - the pit/opening we were studying was less than 20% the size of a single pixel of the thermal camera. It took a lot of work to try and tease out the temperatures of the pit floor itself..

How can that be done?

So while the instrument was being made it went through a lot of calibration and testing to know exactly how temperatures are measured spatially and temporally in regards to a single detector/pixel. Knowing this and the spacecraft motion and orientation, we know for a single temperature measurement where it is receiving infrared photons from. If we know the temperature of the surface around the pit (which we measure), and we measure the temperature of the pixel containing the pit to be higher by some amount, we can infer with relatively good precisionhow hot the pit would need to be to produce the temperature we measured!

There are caves on the Moon??

Yeah! Lunar Rilles are thought to be caused by collapsed lava tubes and at the location I studied there is a cave at least 25 meters long under the surface, but could be way longer (we dont know for sure, can't image it)

I'm trying to go spelunking on the Moon, hopefully NASA will send me at some point ahaha

Does the moon have a lava core? Or did it?

AFAIK it did once.

I think this is correct, the Moon being much smaller than Earth means it has lost its heat much faster/didnt have as much heat to lose, to the point that I believe the core is no longer molten!

How confident are you in the data? Any chance of confirming it via other instruments in orbit? How was this not seen before? Are there any indications the Artemis program will pivot to take advantage of these findings?

I'm very confident, the only other thing that would cause an increase in temperatures we see with the thermal camera is a high abundance of rocks, but from visible images the small amount of rocks there arent enough to maintain the temperature we see throughout the Lunar night.

We are currently the only thermal camera in orbit, and ours is pretty good, and none of the other types of instruments would be sensitive to this kind of feature. So probably no more followup with what we currently have.

Initially nobody saw a thermal signal at the location of the pit we studied, but I actually also found out that our camera had pointing errors, so when you combined a bunch of images from the thermal camera, the signal became suppressed and blurry. After I figured out how to correct the offsets it lit up like a beacon (metaphorically speaking). We're actually working on another research paper showing the effects of having corrected this, the results are pretty cool and we can show much more with our thermal data now!

I doubt Artemis will pivot, their main goal is to go to the South pole and try to find water ice. I do think, however, that it will come in the future, it will take some time but probably within the next couple decades!

Hey Tyler - what makes the moon’s caves more habitable than the likes of Europa or potentially Ganymede? Is it just the temperature?

Also (something I like to ask scientific folk) - what are you’re favorite sci fi books/tv/movies?

Hello! So there's more things that do make these caves super habitable beyond what I found with temperatures. If there's a cave at, for instance, the Tranquillitatis pit that I primarily studied, it is buried under 60 meters of rock. With all of that material you're also protected from micrometeorites solar radiation and flares, and cosmic rays. Plus our research found that the caves would be 63 F (or 17C essentially forever, no matter the time of day.

On europa and Ganymede there are a few more hazards or difficulties, youre under a multi-kilometer thick ice shell which is difficult to get through, and the pressures youd experience in the subsurface ocean would be pretty high. Its easier (and safer) in a vacuum than it would be in a liquid with much higher pressures. Temperature wise it could be just as nice in places, though i suspect the liquid water would be hotter with since it is at increased pressure!

Favorite Book: The Martian (has to be!) Favorite Movies: Martian, Interstellar, Blade Runner (original and 2049) Favorite TV: Altered Carbon, For All Mankind, and The Expanse!

Hail Mary....give it a go. Weir did a number with that one. I found the audio book better than the read for unknown reasons.

I think I enjoyed reading it more, but all of the forms definitely have my seal of approval (for whatever that is worth) haha

What makes the moons caves safer than other rocky planets. Or do we just lack the research on caves in other planets?

So the Moon's caves arent necessarily safer than the caves on other rocky bodies, but its definitely better thermally. A cave on earth is likely cooler due to humidity and warm air rising. On mercury or venus a cave would be hotter, and a cave on mars or anywhere further would be colder. A cave on the Moon being 1 AU from the sun and not having an atmosphere directly correlates to being 63 degrees F. its in the goldilocks zone for caves!

Hey Tyler, Are Aliens real?

Yes, though unfortunately I'm pretty confident any intelligent ones are nowhere near us, and that makes me sad. Crossing my fingers someone creates faster than light travel in my lifetime so we can go to them!

Have we mapped any lunar cave systems, entrances, or general locations?

So we have found a few potential entrances, three with a strong possibility to lead into caves located in Mare Tranquillitatis, Mare Ingenii, and Marius hills. There are ~13 other collapse pits that could also be excavated to expose potential caves! Unfortunately beyond that we have not mapped actual cave systems, they're essentially invisible with all of the different instruments we've used from orbit. We'll have to go in person or with a rover to truly map them!

Are any of these caves or potential caves near known water sources?

The ones we know of are unfortunately not near the water we believe is on the Moon, which we believe is all tied up in craters near the lunar poles (primarily the South pole). There could be caves at the poles but we have yet to discover any that may be there!

What kind of special preparations would you need to make for spelunking caves on the moon vs on earth? Aside from regular astronaut stuff, of course.

Honestly not much. it would actually be very similar once youre in there if you had the same equipment that you would on Earth! If you had a base in there you'd need nothing more than a pressure suit and oxygen to survive outside of the habitat, no need for a bulky EVA suit! just dont poke a hole in it..

Would the gravity make it harder or easier to spelunk?

Easier! But that doesnt necessarily mean it will be easy overall. The pit I studied is 100 meters deep, climbing a rope or building an elevator capable of lowering things down would be a lot easier in lower gravity than it would be otherwise!

What did you think about the movie Contact?

I remember enjoying the movie, but admittedly it has been a long time since I have seen it and don't remember many of the details haha. I do like when people theorize how we would interact/speak to aliens upon first contact that isn't just warfare (but those are cool to think about as well!)

I, for one, like to think we might finally communicate by wiggling our toes in complex signing. But humans have too short of toes. Which leads us to train an orangutan named Randall to wiggle his toes for us and be the sole earthly communication point to all aliens which of course leads to many hilarious hijinks like way too much macaroni and the eventual destruction of earth and all life on it.

I actually see this as the only way to communicate with aliens, should the opportunity arise. I hope the experience will be accompanied by a laugh track.

Where dem aliens at bruv?

I'm tellin you bro theyre in the caves 👽👽👽

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Very little, which makes me very happy haha. We had an in person outreach event pre-covid and somebody walked up with his kid and was basically like "moon landing was fake prove me wrong". It was a polite enough conversation and he was happy i didnt just trash on him, didnt change his mind either though so it was basically a waste of time lol

Good, I’ve checked and no one has asked yet:

Would you rather fight one horse-sized duck, or a hundred duck-sized horses?

Important follow up: would your answer change if you were in one of the thermally stable lunar caves and all wearing the appropriate gear to survive in that environment?

Thats easy, one-hundred duck-sized horses. Horses are nothing if not for their size. Ducks can be relentless and vicious with their small stature, one could only imagine the terror they would bring with a horses stature.

And no, because tiny horses in spacesuits would be much more cute.

I need a scientific answer:

Are you the most intelligent cave man known to man?

The answer is both yes and no. I may be the most intelligent caveman, but i know many cave people way smarter than I am. Take your pick.

Would you say that if humans began building habitats on the Moon and other planets we would have the potential to live for billions of years?

How probable and practical would it be to mine the rare metals found in asteroids?

Are you into theoretical bigger picture universe philosophy and paradoxes? I have a few questions pertaining to that as well but didn't want to overwhelm you.

Its really hard to say, the key is if we can find ways to sustain crops for an indefinite amount of time. I believe we will be able to grow crops to some capacity, but nutrients have to be replenished and who knows if we can find a good reliable way to do that. I think we can overcome most other things.

I dont think its terribly impractical, getting the cost of space travel down will be really important because the energy required to get to an astroid and transport it back isnt minimal. May be a while before we can do that with more pros than cons.

Im down to talk about them, I cant say I've got big brain thoughts on those topics but I'm happy to ponder them!

Couldn’t we dig our own caves?

Also we could use mirrors for heat, lighting, and solar power.

We could, but setting up the ability to dig huge holes would be hard on another celestial body, also, it takes time for the surfaces of a cave to equilibrate to the comfortable levels. The reason why using mirrors and heat, lighting, and solar power is an issue is because a lunar night lasts 15 days (as does the day time), so we'd probably need a massive amount of batteries or a lot of insulation to keep people alive, inside these caves we would need a lot less of both!

Do we have much information on the interior qualities beyond their stable temp? Size of the individual caverns, extent of the network,what the surfaces are like, etc?

There has been some research done on the theoretical structural stability of caves on the Moon, and the results are that they can be quite large and is dependent on how deep they are underground. At the Tranquillitatis pit, where there is evidence for such a cave, it would be stable up to 750 m wide! If a cave is deep enough, the Moon could possibly support up to 4 kilometer wide caves (which is insaaaane).

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The surfaces are probably similar to lava tubes on earth, I'd guess solidified magma drips coming off the ceiling and pahoehoe structures elsewhere all with little to no weathering (theres no liquid water or wind going through these caves!)

As for the extent, or exact size, we have no clue, and there really isnt a good way to know until with go there in person or with a rover. Check out the proposed NASA mission "Moon Diver" for a cool idea about how we would do that! (disclaimer: I was part of this science team for Moon Diver)

Ty!

I wonder if one could design a seismic mapping type of mission. The 'bomb the moon' headlines would be fun, but I personally have no idea about the resolution or practically of something like that.

I'm actually getting ready to take my masters exam, for it I have to propose two science projects I can do and defend their validity. One of them is *Literally* to do that hahah. Well I am proposing to do it at the south pole to help find ice, but it could work exactly the same way to find lava tubes!

So you are trying to get funding to send Dune thumpers to the moon? 😁

I mean kind of ahaha. But also trying to get money to send myself ro the Moon!

so how will humans defeat the ant people who live in those caves?

You ever seen Starship Troopers? Something like that.

How far out of the city do you need to go to see these caves clearly? For reference I did my phd in microbiology so I know NOTHING about things this large

So to see the caves you'd need to go to the Moon, so ~240,000 miles away (give or take) from the city! If you want to see generally where these caves would be, if you look at the Moon tonight, even within a city, you will be able to see Mare Tranquillitatis just above the equator and just right of the Middle of the Moon. Its the bottom part dark circle of the two that are touching on the right!

Howver, all of the dark regions of the Moon you can see, known as the Lunar Maria, probably have lava tubes/caves running through them, we just haven't discovered them yet!

Thank you! And I guess a better wording for my question would be "how far is your observation point/telescope from the city?"

We used a thermal camera currently in orbit around the Moon, so still about that far haha. Our data was taken from around 50 kilometers to 100 kilometers away directly above the entrance to the potential cave.

People who went into space (forgot how they are called) said that it smells like rusted metal, because they most likely smelled the space craft.

But my high school teacher said if you smell something in space it means you’ll die soon.

Who should I believe?

I would say people who went to space, your teacher was making a bad dad joke haha. You can still smell stuff in a space suit or space station :P I've heard that it smells like burnt steak!

Hello. I only have one question: Do you have Hungarian ancestry?

As far as I know I do not, I believe my great great grandparents were Jewish and moved to Germany pre-WWII and changed their last name to blend in more!

How soon will I be able to leave this godforsaken planet and live in a Moon hole?

I give it 20 years. May have to work hard to get a spot to go there though! Hopefully this will be a good bump toward that happening for me!! Haha

Have you checked caves on Earth? I think they might be pretty good too

There are comfy caves on earth, but most are either too cold or too hot, and often very muggy. Overall Earth caves are great, air is unbeatable. But caves on the Moon are pretty cool too, and their temps are great for not being on Earth!

What is your favorite celestial body besides the moon?

Gotta be Enceladus. Absolutely the best looking thing in the solar systemits blue tiger stripe fractures,its got an insanely high albedo/reflectance, and its surprisingly small. Plus its got a subsurface ocean that could have fish!! All of that stuff makes it really cool and exciting!!

What are your ideas on what the potential fish on Enceladus look like? Would they look like any fish that we know of here on Earth?

I have absolutely no idea haha. Everything on Earth is biologically related, because of that essentially every subclass of fish has very similar features and work the same way give or take. Whatever life is (or is not) on Enceladus took its completely own evolutionary path to become what it is, which could literally be anything. Like I want to say I would expect the fish to have at least a tailfin to propel themselves through the water but what if their evolution came up with some crazy other way? I honestly don't know but the amount of possibilities is super cool!

Star Wars or Star Trek?

Television and Movies - Star Trek

Overall Universe and Video Games - Star Wars

I think the universe of Star Wars is more unique and creative as a whole, and I really appreciate it a lot when you feel like youre a part of it through a video game or generally in the extended universe. However, I personally enjoy the Star Trek movies and TV shows more than that of star wars, despite it being a slightly less creative than star wars as a whole. I'm not saying Star Trek isn't innovative at all though, it absolutely is/was!

Now having discovered this information, what now? What ultimately would you like to see your research from this mission used for?

Ideally I would see Earth moving away from me while blasting toward the Moon in a rocket so I can go live there and help set up the base!

But truthfully, there is a lot we can learn a lot about the Moon's geologic history in the walls of the pit openings, which could then inform us about its formation and how the Moon came to be. I would also like to see this as a target for future exploration to be set up as a base, I think it would make for the perfect place for one as you could expand rapidly with little to no hazards (relative to elsewhere on the Moon)!

This is not related to your discovery, but this is an amA so...are you closely related to Nick Horvath? 20 years ago, he was a basketball player for Duke University and a physics major.

Haha no, as far as I know nobody in my family has done anything prominent outside of being in the military for long periods of time lmao.

Given the ambient temp and the protective nature of the cave it seems like a custom fit for habitation. Do you see boring machines as a solution. Could we use smaller more manageable autonomous drone drillers to core out living spaces? Do you think it would be solid enough to seal without secondary applications to "coat" the surfaces? What is the water ratio in the stone/regolith to aggregate for cooling applications, consumption, cutting? Is moon regolith going to cause serious issues with any of that I seem to remember reading somewhere that it is very non-uniform and abrasive.

I have so many questions, but I will stop there. Thanks for taking the time to swing in.

It depends on the nature of the cave. It is likely that a cave (especially at the location I studied) would be quite large, at the bare minimum its 40 meters tall and 150 meters wide. With the kind of size you actually wouldnt need to carve anything out if its sufficiently long! Assuming the cave wasn't that deep, carving into the walls and extending the cave wouldn't be out of the option. It may be possible to hermetically seal the cave, even without a coating, but I'd personally want to run tests on if that would be safe or not.

So in the cave there wouldn't be a need for cooling, and the heating of normal operations would probably help maintain just the right temperatures in the habitats. This is good, because water is extremely hard to come by at the locations where we have evidence for caves (near the equator), the Moon is incredibly dry and there's definitely not enough to get in appreciable amounts with a lot of energy expenditure.

Lunar Regolith shouldnt be a problem inside of the cave itself, theres no reason for regolith to be down there as the interior of a cave cannot get constantly pulverize the rock to produce the regolith! Theres also no mechanism to transport the regolith into the cave if its there.

So as a moon researcher, what’s your theory moonquakes and their effect on habitability?There is always much speculation regarding the intense moonquakes that occur; could a habitat in a cave survive these quakes, especially a lunar impact larger than the Apollo Impacts?

Would sympathetic resonance destroy it if we used lunar regolith as a construction material? What sort of compounds could we form with our increased knowledge of regolith (mooncrete?) that would withstand seismic effects and be possible to produce?

I believe that Bigelow aerospace currently has an inflatable space station design, not gonna lie, moon bouncy castle in a crate sounds pretty amazing!

Moon quakes usually arent too strong, I think the strongest they ever measured was about a magnitude 5-6, and if the habitats are made out of or were supported by strong rigid metal and not that tall, they shouldnt be affected too much!

Im not sure what the progress is for using regolith as a building material, and im not a civil engineer so im not sure how using it would work seismically given the surrounding material is the same, but I have a hunch it may be okay. But I definitely am not sure!

Where are your ancestors from? Hungary, Croatia, Slovakia or Slovenia?
You said "anything" :)

PS: Congratulations on your success!

As far as I know, Poland! They were Jewish, changed their name to Horvath and emigrated to germany pre-WWII, they made a good choice if you ask me!

a good choice if you ask me

Pre-WW2? Now that's a somewhat controversial statement, hehe. But, I get it, their decision led to the present you know and love.

Hmm, you don't usually find the surname 'Horvath' so far up north, in Poland. Mine is basically the same, just spelled differently. Did you know it translates to 'Croat'?

Anyway, sorry for the major off-topic. I was only being curious.

hey that's pure survival haha, and it led to me being born so I can't be too mad at them lol.

Thats pretty cool though, I've known it is a surname from that region, but I didn't know that's what it translated it to. Thanks for sharing that bit of knowledge!

Do you think it'd be possible to hermetically seal off one of these caves and establish an atmosphere inside? Or will we be limited to structures within the caves for the forseeable technological future?

I think it would be possible to seal off the caves, though I am not sure we would do that as it could have unknown effects on the rock that has never been exposed to air. I think we'd first have normal base/building structures there and do tests before trying to hermetically seal off the whole cave. The sooner we go there the faster we would be able to try!

Hi Tyler! With your education and profession, whats your thoughts on Interstellar? (The movie from 2014).

Hello! I thought the movie was fantastic, both from a scientific and storytelling point of view. The message was very clear that we're really just messing up earth and we may end up pushing it to such an extreme that we just have to leave.

Scientifically, the only issues that arise are:

1) The existence of a wormhole in our solar system and their experiences they go through when travelling through it.

2) the 4th demension being a combination of time and love (lmao)

3) And potentially some tidal effects being ignored near Gargantua, I cant be sure and I havent done the math, but the tidal forces may do more than just cause ocean sized tsunamis haha, planets alone can pull things apart gravitationally, so I'd expect some more extreme stuff with the crew when they're near it.

Those things to me are also non-issues, they were either story telling elements, so far in the weeds that it was kind of unnecessary, or I'm just flat out wrong about that 3rd point. In any case, great movie, 9.5/10.

Does the moon have many caves and cave complexes? How were they formed? And how do we know about them. Thank you. Also is the center of the moon hot like the center of earth is?

So we don't know how many cave's their may be nor there extent, there could be very little or they could be everywhere. Based on the amount of Rilles and pit-crater chains there are on the Moon there could be quite a lot, but there could be a lot under the surface we have zero clue about.

They're formed due to massive flood volcanism, the same events that create the large lunar Maria. These were cataclysmic events that were pumping out lava like crazy and filling huge basins with lava. The surface of these lava flows cool faster because theyre exposed to space, and the lava underneath it can still be flowing. In some cases the conditions will be right that a channel will be formed and all or most of the lava will leave exit the channel before cooling, leaving behind a lava tube!

As I had mentioned, we know they exist because of rilles and pit-crater chains, as well as the features such as those I was studying for my research, they all show that lava tubes/caves exist!

The center of the Moon is definitely warm, but it as cooled down a lot faster because it is smaller. I believe the estimates are 1500-1800 Celcius for the Moon's core, while Earth's is ~5200 C!

Is it safe to say the deeper the cave goes the more habitable it will be? Could there be large cave systems underneath the surface we can use?

Anything 50m or so from the opening will have very stable temperatures, ~10 C variation through the day, 200 m back the variation is less than 1 C. So maybe it would be technically, but there's diminishing returns or no change after you go so far! There indeed could be large cave systems, I'm really hoping we go there soon to find out!! (Check out the proposed mission Moon Diver, we had a pretty cool idea for exploring these caves!)

There’s a couple of planets with other moons in our solar system that I’m very curious about. Could those have life?

Its hard to say, we don't know how difficult it is to start and maintain life for long periods of time. If there is life in our solar system, the most likely places would be Europa, Ganymede, Enceladus, Callisto, or Triton. These are thought to have subsurface oceans which would probably be the most likely place for things to surface further out in the solar system. the other rocky planets are unfortunately not that nice to life were it to be on the surface..

Would the Tube Caves on Mars with a matching depth be as warm as the ones on Earth's moon?

Probably not, and for a similar reason why caves on Earth can have very different climates than their surroundings. On the Moon there is (essentially) no atmosphere, so the only thing that controls the temperature of things is solar radiation, thermal emission of radiation, and conduction. Conduction at the surface of the Moon is very poor, so its essentially all radiation based which allows it to stay at 63 F constantly. On Mars you still have an atmosphere to help take heat out of the cave, (because hot air rises). So, I think, caves on Mars would likely be colder. Additionally, Mars is further away so it receives less solar energy and is generally colder overall.

All of that to say the Moon is at a good distance relative to the Sun and the lack of atmosphere actually helps!

Was this something you people were particularly looking out for, as in did you suspect the moon caves to probably be habitable, or did you all just came across it somehow?

If you had suspected the moon caves to be habitable, what reasons were there for such a suspicion?

We actually started researching the thermal environment of the pits that could lead to the caves to help a NASA group of scientists and engineers that were designing a rover to be sent there. We were trying to help them determine what the rover should be able to withstand and what the opwrations would look like from a thermal standpoint. We didnt really become interested in these features from a thermal standpoint until we noticed in the thermal camera data that it was warmer than its surroundings!

We didn't expect it, though looking back we probably ahould have as its a good example of a physics concept known as a blackbody cavity!

That is very interesting to know. Congratulations to you all and I hope you are able to keep up the good work.

Thank you for the response. Have a blessed day.

Thank you very much! You as well :)

Most habitable in the solar system but are they ever actually habitable? And if so, how?

Theyre the most havitable temperature wise, a constant 63 F day-in day-out! Theyre able to be that temperature because theyre 1 AU from the Sun which means the equilibrium temperature of surfaces is about 70 degrees, and the material on the sirface has very low thermal conductivity, so it behaves like a blackbody cavity. If the moon were closer, say at the orbit of venus, it would be too hot, and at mars it would be too cold! Its the same reason why the average temperature of Earth is just right for us!

Have you ever read the book "The Moon is a Harsh Mistress" by Robert A. Heinlein?

If so, what did you think of it?

I havent read it, but reading a quick synopsis has a lot of similar ideas to that of the Expanse, to a point that it looks like it was likely a strong influence! I'll add it to my list :)

As another PhD student (albeit in a different field), I’m curious how you landed roles at NASA and made such notable discoveries before even having your doctorate? We’re these things early in your career, did you work on them as a “student”, or have you just had an extremely productive few years?

Similarly, what did you study in undergrad and did you do any volunteer work to secure your spot at UCLA?

Thanks!

So I went to CU Boulder for undergrad and they have a really cool Lab affiliated with them named LASP, or the Laboratory for Atmospheric and Space Physics. They had opportunities for undergraduates to work in satellite operations, actively sending commands and monitoring telemetry of the spacecraft! Thats how I got involved with some of those missions.

With the rest it was because I had taught myself how to code in Python and Matlab and went to professors in the Astrophysical and Space Sciences department there to ask for work I can do, even if it was unpaid. I worked on a bit of exoplanet stuff with Kepler and TESS with one Professor there, and started this particluar project with another who hired me to be an undergraduate research assistant. His advisor was the principle investigator for the thermal camera we used for this study, and he is actually now my advisor for the PhD at UCLA. He is also Deputy Principle Investigator for an instrument on the Perserverence rover which is how i got involved with that. I basically just put myself out there and got lucky with the path it led me on!

I also wouldnt say I've worked particularly hard, I definitely know people around me who have worked harder and probably seen less for it which is really unfortunate. Thats why I think I was lucky to have done the things I've done.

I will say I also went into Boulder a little bit older and have taken a bunch of courses already at a community college, so I think it was a breath of fresh air to hire a 22 year old thats got a few more skills than try to toss it at a freshman or sophmore. That probably helped make me more desirable from a hiring/working standpoint.

Would we still have the problem with regolith as you got deeper into the cave structure as you do on the surface? Hearing that it's a really hostile environment to try and build structures in...

I dont think you would, regolith production relies on impacts which arent happening 50 meters betond the opening and further at all, there may be a small amount thats been blown into the cave from the floor of the opening, but i expect that to be pretty minimal. Either way we it would be waaaayyyy more manageable than regolith on the surface!

What would be the main advantages of a moon-base compared with a space station?

I assume the main disadvantage of a moon base would be the fuel cost for landing and return flights.

So that may technically be a disadvantage, but the fuel cost for landing and return is a lot less than you may think. The lack of atmosphere means less fuel to take off into orbit, and the energy to go from Moon orbit to earth is pretty small. Plus we can use aerobraking on Earth to slow down. Look at rhe Saturn V rocket to get them to the Moon, and look at how small the lander+command module were to get them back! To be fair, they needed to haul the thing there, but I think the benefits of the science you can do and having some amount of gravity is really good!

More thermally habitable that even Earth? We destroyed it that badly that living in the Moon is better already?

No no no, these caves are so special that they happen to be at temperatures that are just as comfortable, if not more comfortable than the Earth's! The temperature of this cave is actually related to why the Earth's temperatures are generally friendly to us, its because we're 1 AU from the sun!

so now i see the future of exploration… and it is made of humans living in caves and possibly digging even further? creating safe space for humans to gather materials in close by meteorites and bringing them back in those caves

I think thats the key! A lot easier to manage than dealing with the hazards of the surface if you ask me!

100% but moonbase will be of interest to people that want to invest only if they can find a way to make even more money i guess? and correct me if i am wrong but the only valid reason to have bases on the moon would probably be because it s much easier to leave from the moon than from earth to capture those asteroids full of precious stones? diamonds? etc?

Using the Moon as a hub for further space travel is a very real possibility, and using these caves as the location for that would be great. This kind of space exploration is not at the point of investing in it for profit, but funding it for science.

Are there aliens? Wink if yes.

blinks rapidly

Did you find the cheese?

The pit I studied is actually the surface of a planetary swiss. Keep an eye out for my next research project titled "Uncovering the possibilites of Lunar Charcuterie"

Will we send a rover to explore them?

I hope so! Check out the mission proposal "Moon Diver" that I worked on with some NASA JPL scientists and Engineers from a few years ago! We want to send a rover to rappel down into the caves!

Are there any steps that may be taken to possibly take advantage of these caves for human life (or life from Earth in general) to then migrate or create colonies on the Moon?

SO fascinating to see these things happening in real time. Huge fan of Ender's Game and always found the themes of space and how to navigate it interesting. I believe in 'Speaker for the Dead', Ender was living on this planet that had cave systems and were used for that planet's population as it was the best way to inhabit it. Long tangent, this stuff's just really neat to learn of.

I think just getting there is the main thing, and possibly understanding how to take advantage of lunar materials for in situ production of select things. We have the ability to do it as a species, just need to go for it (and throw enough money at it)!

I’m sure you’re aware we didn’t go to the moon. Do you think it is possible to visit there one day? How does the van Allen belt impact that potential?

Haha i hope your joking, if not I'd be glad to debate with you about it! But yes I do think we will visit it again one day, and potentially go to these lava tubes!

And the van allen belts are not an issue, the Apollo astronauts just went arround the high radiation inner ones and barely intersected the weak outer one, I'm sure Artemis astronauts would do the same! :)

Soo did you put down a home and some root over there ? Can we come ?

House party July 20th next year!

What do you think of the show For All Mankind? Inspiring or nah?

Inspiring but also kind of sad. I appreciate that it showcases what humans are capable scientifically and engineering wise, but it is sad how militarized everything has become in that universe. That being said, its an amazing show so far (only halfway through season 2) and I do think its a relatively realistic look at how that wcenario would have played out

Fun fact, when they decide to build a lunar base at Shackleton crater because of lunar ice, they showed a map of ice at the south pole. Many of the people I've worked with were the onrs who produced that map originally over the span of the last 13 years using data from the same spacecraft I work on!

How excited were you when you made the discovery? Were you...over the Moon about it?

You cant see me but I facepalmed pretty hard. Ahaha

I've actually been pretty ambivalent about this project for a while actually haha, it was drawn our for a lot longer than it needed to be and that was increadibly frustrating and sad 🙃 haha

Is your father Steve Horvath?

I have an uncle named Steve, but there are many Steve's in the world. What does the Steve you know do for a living?

Do lunar worms live there?

Like the Star Wars one? Yeah. Thats actually how they got the footage for the movie.

So you watched the film 12 to the Moon and decided to do an IAMA?

I mean basically, the decade or so I've spent in pursuing this career since high school has also had a part too though!