WEBVTT 1 00:00:03.399 --> 00:00:07.719 Welcome to Bedtime Astronomy. Explore the wonders of the cosmos 2 00:00:07.759 --> 00:00:12.279 with our soothing Bedtime Astronomie podcast. Each episode offers a 3 00:00:12.359 --> 00:00:16.320 gentle journey through the stars, planets, and beyond, perfect for 4 00:00:16.399 --> 00:00:20.239 unwinding after a long day. Let's travel through the mysteries 5 00:00:20.239 --> 00:00:22.440 of the universe as you drift off into a peaceful 6 00:00:22.480 --> 00:00:23.800 slumber under the night sky. 7 00:00:27.000 --> 00:00:30.839 Imagine, imagine for just a second that you've just landed 8 00:00:30.879 --> 00:00:34.799 the ultimate remote construction job. Oh boy, right, you have 9 00:00:34.880 --> 00:00:37.560 been hired to build a house, and not just a shack. 10 00:00:37.759 --> 00:00:42.399 We're talking a highly advanced, incredibly stardy, literally life saving shelter. 11 00:00:43.200 --> 00:00:47.600 But there is a massive, seemingly impossible catch to this gig. 12 00:00:48.200 --> 00:00:51.960 The nearest hardware store, the absolute closest place you can 13 00:00:52.000 --> 00:00:54.719 go to grab a two by four or a bag 14 00:00:54.759 --> 00:00:57.359 of cement, or even just a handful of nails, is 15 00:00:57.439 --> 00:00:59.920 exactly two hundred and thirty eight thousand miles. 16 00:00:59.719 --> 00:01:03.039 Away, which is a rather long commute. 17 00:01:02.600 --> 00:01:06.680 A terrible commute. You're standing there in this completely barren, airless, 18 00:01:06.719 --> 00:01:10.000 absolutely silent landscape. You are surrounded by nothing but gray 19 00:01:10.079 --> 00:01:12.840 dust and jagged rocks, and your boss basically taps you 20 00:01:12.879 --> 00:01:15.519 on the shoulder and says, all right, start building. Oh 21 00:01:15.560 --> 00:01:18.159 and by the way, if these walls aren't perfectly sealed 22 00:01:18.159 --> 00:01:20.079 and structurally sound by the time the sun goes down, 23 00:01:20.120 --> 00:01:21.079 you won't survive the night. 24 00:01:21.280 --> 00:01:24.200 It sounds like a stress stream, honestly, but that is 25 00:01:24.239 --> 00:01:27.959 the exact kind of mind bending reality that aerospace engineers 26 00:01:28.000 --> 00:01:29.079 are grappling with right now. 27 00:01:29.359 --> 00:01:33.280 Exactly we are looking at the literal foundation of humanity's 28 00:01:33.319 --> 00:01:36.519 future in space. Today, we're taking a deep dive into 29 00:01:36.519 --> 00:01:41.239 some truly groundbreaking research coming out of the Ohio State University. 30 00:01:40.799 --> 00:01:43.280 Yeah, led by researchers Sigis and Sarah. 31 00:01:43.079 --> 00:01:47.239 Wolf Right and featured on physicist dot org. Originating from 32 00:01:47.359 --> 00:01:50.959 Acta Astronautica. The mission for our deep dive today is 33 00:01:51.000 --> 00:01:53.640 to explore exactly how scientists are figuring out how to 34 00:01:53.680 --> 00:01:57.000 take that barren, gray moon dirt and turn it into 35 00:01:57.079 --> 00:02:01.480 highly durable structures using incredibly advance as laser three D printing, 36 00:02:01.959 --> 00:02:02.439 and not. 37 00:02:02.319 --> 00:02:04.840 Just the printing itself, which is complex enough, but the 38 00:02:05.560 --> 00:02:07.280 hidden variables no one thinks about. 39 00:02:07.480 --> 00:02:10.560 Right, We're going to break down how this technology actually works. 40 00:02:10.680 --> 00:02:12.919 We'll look at why the specific ground you choose to 41 00:02:12.919 --> 00:02:15.560 print on turns out to be the ultimate secret to success, 42 00:02:15.719 --> 00:02:18.240 and we'll explore how mastering the art of construction in 43 00:02:18.280 --> 00:02:21.120 the harsh, unforgiving vacuum of space might just be the 44 00:02:21.159 --> 00:02:23.919 exact key we need to save our own precious resources 45 00:02:24.039 --> 00:02:24.879 right here on Earth. 46 00:02:25.280 --> 00:02:27.680 Okay, let's unpack this, because the sheer scale of the 47 00:02:27.680 --> 00:02:30.639 problem these researchers trying to solve is just it's staggering. 48 00:02:30.879 --> 00:02:34.759 It requires a complete fundamental shift in how we even 49 00:02:34.840 --> 00:02:39.360 conceptualize the act of building. Think about it. When you 50 00:02:39.400 --> 00:02:43.240 construct something on Earth, you take your entire environment for granted. 51 00:02:43.680 --> 00:02:45.719 What do you mean like taking gravity for granted? 52 00:02:45.800 --> 00:02:49.319 Gravity absolutely, but also the atmosphere. You assume there is 53 00:02:49.400 --> 00:02:52.960 air to help regulate the temperature of your tools, your materials. 54 00:02:53.199 --> 00:02:56.000 You assume your building materials like steel or lumber, are 55 00:02:56.080 --> 00:02:57.759 relatively uniform and predictable. 56 00:02:57.919 --> 00:02:58.159 Right. 57 00:02:58.439 --> 00:03:01.879 The Ohio State team is tackling scenario where absolutely none 58 00:03:01.919 --> 00:03:05.199 of those earthly assumptions apply, none of them. They are 59 00:03:05.240 --> 00:03:08.719 trying to develop a fabrication process they can take the natural, 60 00:03:09.039 --> 00:03:11.719 incredibly harsh environment of the Moon and use it to 61 00:03:11.800 --> 00:03:14.000 manufacture small heat resistant. 62 00:03:13.599 --> 00:03:17.280 Objects, which is the crucial first step toward building sturdy, 63 00:03:17.560 --> 00:03:20.840 non toxic habitats and tools for future astronauts exactly. But 64 00:03:20.879 --> 00:03:23.199 to even begin that kind of research, I mean, you 65 00:03:23.319 --> 00:03:26.039 need the raw material. You need dirt, and you can't 66 00:03:26.080 --> 00:03:29.159 just requisition a dump truck full of actual Apollo moon 67 00:03:29.240 --> 00:03:32.639 dirt to run hundreds of experimental three D printing trials 68 00:03:32.639 --> 00:03:33.680 in an Ohio lab. 69 00:03:34.280 --> 00:03:37.759 Definitely not. No. Real lunar regolith is one of the rarest, 70 00:03:38.039 --> 00:03:41.840 most highly protected and precious materials on our planet. Yeah, 71 00:03:41.960 --> 00:03:44.800 the Apollo emissions only brought back a tiny fraction and 72 00:03:44.840 --> 00:03:48.759 it's locked away in volts for highly specialized analysis. Yeah, 73 00:03:48.840 --> 00:03:50.759 it's not for industrial stress testing. 74 00:03:50.599 --> 00:03:51.719 So they use a stand in. 75 00:03:51.879 --> 00:03:52.120 Right. 76 00:03:52.199 --> 00:03:56.080 The researchers utilize something called lunar regolith simulant, which is 77 00:03:56.240 --> 00:04:00.240 essentially fake lunar soil. It's a synthetic version one of 78 00:04:00.240 --> 00:04:03.680 the fine dusty material that covers the Moon. And what 79 00:04:03.719 --> 00:04:06.800 really blew my mind was learning how incredibly specific this 80 00:04:06.840 --> 00:04:10.400 fake dirt is. They use a simulant called LHS one. 81 00:04:10.560 --> 00:04:13.599 Yes, LHS one, The LAHS stands for Lunar Highland Simulant. 82 00:04:13.759 --> 00:04:16.399 Right, this isn't just you know, generic gray sand they 83 00:04:16.399 --> 00:04:18.920 picked up at a landscaping supply store far from it 84 00:04:19.160 --> 00:04:22.600 LHS one is meticulously designed to replicate the specific soil 85 00:04:22.639 --> 00:04:25.319 found in the Lunar Highlands, and the Highlands are described 86 00:04:25.319 --> 00:04:28.920 as this heavily cratered area rife with dark colored basaltic rock. 87 00:04:29.600 --> 00:04:31.560 But I think we really need to visualize this before 88 00:04:31.560 --> 00:04:34.120 we get into the lasers and the printing. What are 89 00:04:34.160 --> 00:04:36.800 we actually talking about when we say heavily cratered area 90 00:04:36.920 --> 00:04:39.160 rife with dark colored basaltic rock. 91 00:04:39.439 --> 00:04:43.120 Well, what's fascinating here is how specific and challenging that 92 00:04:43.160 --> 00:04:47.120 particular geological profile is for a manufacturing process. When you 93 00:04:47.160 --> 00:04:48.800 look up at the moon for your backyard, you see 94 00:04:48.839 --> 00:04:52.480 lighter areas in darker areas. The Lunar Highlands are those lighter, 95 00:04:52.519 --> 00:04:55.680 heavily elevated, incredibly ancient regions, And the fact that they're 96 00:04:55.720 --> 00:04:59.519 heavily cratered is not just a passing geographic detail. It 97 00:04:59.560 --> 00:05:02.319 is the entire higher context for why this dirt behaves 98 00:05:02.319 --> 00:05:02.879 the way it does. 99 00:05:02.959 --> 00:05:05.000 Because craters mean impacts. 100 00:05:04.839 --> 00:05:10.680 Exactly relentless catastrophic bombardment by meteorites and micrometeorites for billions 101 00:05:10.680 --> 00:05:15.959 of years. Every single impact crushes, shatters and pulverizes the bedrock, 102 00:05:16.160 --> 00:05:18.920 and that bedrock contains a massive amount of dark colored 103 00:05:18.920 --> 00:05:19.720 basaltic rock. 104 00:05:19.800 --> 00:05:21.959 The salt that's volcanic rock, right like you'd see in 105 00:05:21.959 --> 00:05:23.000 Hawaii or Iceland. 106 00:05:23.040 --> 00:05:26.319 Precisely. It's an igneous rock formed from the rapid cooling 107 00:05:26.399 --> 00:05:29.160 of lava. So you have this volcanic, mineral rich rock 108 00:05:29.600 --> 00:05:32.639 that has been smashed into a fine powder over eons. 109 00:05:32.920 --> 00:05:35.480 But here is the critical difference between dirt on Earth 110 00:05:35.480 --> 00:05:37.920 and dirt on the Moon. On Earth, when rocks get 111 00:05:38.000 --> 00:05:39.959 crushed into sand, what happens. 112 00:05:39.680 --> 00:05:42.360 Wind and water roll the grains around. They get smooth 113 00:05:42.759 --> 00:05:45.720 like sea glass or the soft sand on a beach exactly. 114 00:05:46.120 --> 00:05:48.959 But on the Moon there is no wind, there is 115 00:05:49.000 --> 00:05:52.800 no water, there is no atmospheric friction, none. So this dirt, 116 00:05:53.040 --> 00:05:57.920 this regolith is composed of incredibly sharp, jagged, microscopic shards 117 00:05:57.920 --> 00:06:01.600 of glass and volcanic rock. It is incredibly abrasive, it 118 00:06:01.639 --> 00:06:06.160 holds a powerful static charge, and it is highly chemically reactive. 119 00:06:06.360 --> 00:06:10.199 That paints such a wild picture. It's like microscopic, statically 120 00:06:10.319 --> 00:06:11.480 charged razor blades. 121 00:06:11.600 --> 00:06:13.399 That's a very accurate way to put it. And the 122 00:06:13.519 --> 00:06:17.279 LHS one simulant is engineered to mimic that exact brutal composition. 123 00:06:17.399 --> 00:06:19.120 The researchers are trying to figure out how to feed 124 00:06:19.120 --> 00:06:22.560 the equivalent of statically charged volcanic glass shards into a 125 00:06:22.600 --> 00:06:24.240 delicate manufacturing machine. 126 00:06:24.279 --> 00:06:27.720 It is the furthest thing from the smooth, uniform spools 127 00:06:27.759 --> 00:06:31.160 of plastic filament that you feed into a normal desktop 128 00:06:31.160 --> 00:06:34.480 three D printer. Oh, completely, it really makes you appreciate 129 00:06:34.519 --> 00:06:37.920 the challenge of relying on a simulant. I mean, LHS 130 00:06:37.920 --> 00:06:41.360 one is obviously a brilliant scientific achievement in its own right, 131 00:06:41.439 --> 00:06:43.720 just to be able to recreate that highland composition in 132 00:06:43.759 --> 00:06:47.160 a lab, but it also opens up this whole avenue 133 00:06:47.199 --> 00:06:50.199 of speculation about the leap from the lab to the 134 00:06:50.240 --> 00:06:51.439 actual lunar surface. 135 00:06:51.680 --> 00:06:52.120 Adaman. 136 00:06:52.560 --> 00:06:55.680 Well, the researchers are using this fake soil to practice, 137 00:06:55.879 --> 00:06:59.279 but how perfectly can we really emulate billions of years 138 00:06:59.319 --> 00:07:02.319 of cosmicis The actual dirt on the Moon hasn't just 139 00:07:02.360 --> 00:07:05.360 been crushed, it has been baked by unshielded solar radiation. 140 00:07:05.759 --> 00:07:08.879 It's been bombarded by solar wind and subjected to massive 141 00:07:08.879 --> 00:07:12.360 temperature swings every single lunar day and night for millennia. 142 00:07:12.519 --> 00:07:15.000 That is a very valid concern. It's a huge. 143 00:07:14.839 --> 00:07:17.560 Variable, right, Well, LIHS one is the best stand and 144 00:07:17.639 --> 00:07:20.759 we have. It makes you wonder what microscopic chemical quirks 145 00:07:20.879 --> 00:07:24.560 the actual historical moondust might possess that a lab made 146 00:07:24.639 --> 00:07:27.720 simulant might miss. It's like practicing a recipe with store 147 00:07:27.759 --> 00:07:29.800 bought tomatoes when you know the final meal has to 148 00:07:29.839 --> 00:07:32.800 be cooked with tomatoes grown in a highly specific, mineral 149 00:07:32.879 --> 00:07:36.279 rich volcanic caled era. Yeah, it's close, but the environment 150 00:07:36.360 --> 00:07:37.160 leaves a fingerprint. 151 00:07:37.319 --> 00:07:40.040 That is a brilliant way to frame the limitation, and 152 00:07:40.079 --> 00:07:42.720 it is a limitation the researchers are entirely aware of. 153 00:07:43.720 --> 00:07:46.920 You can synthesize the mineral composition of basaltic rock, you 154 00:07:46.959 --> 00:07:50.319 can crush it to the correct jagged geometry, but you 155 00:07:50.360 --> 00:07:55.000 cannot easily synthesize four billion years of continuous radiation exposure 156 00:07:55.240 --> 00:07:56.240 in an airless void. 157 00:07:56.360 --> 00:07:59.480 So what happens if the real dust reacts differently. 158 00:07:59.240 --> 00:08:03.959 Well, the real regolith might have microscopic iron nanoparticles embedded 159 00:08:03.959 --> 00:08:08.879 within the glass yards, literally vaporized iron from micrometeorite impacts 160 00:08:09.040 --> 00:08:12.720 that cooled instantly. Wow, those nanoparticles could completely alter how 161 00:08:12.720 --> 00:08:15.639 the dust interacts with electromagnet fields or the extreme heat 162 00:08:15.639 --> 00:08:17.959 of a laser. But You have to remember the LHS 163 00:08:18.040 --> 00:08:21.000 one simulant is the absolute baseline. 164 00:08:20.519 --> 00:08:22.360 The baseline, meaning if we can't do it with the 165 00:08:22.399 --> 00:08:24.439 fake stuff, we're doomed with the real stuff. 166 00:08:24.680 --> 00:08:28.600 Precisely, if you cannot make the manufacturing process work with 167 00:08:28.680 --> 00:08:33.799 the perfect, uncontaminated, chemically identical lab equivalent, you have zero 168 00:08:33.960 --> 00:08:37.759 hope of making it work with the unpredictable, radiation soaked 169 00:08:37.759 --> 00:08:43.320 reality of the lunar Highlands. Shwe Wolf and the Ohio 170 00:08:43.360 --> 00:08:47.080 State team had to prove the fundamental physics of the concept. First. 171 00:08:47.519 --> 00:08:49.720 They had to prove that this chaotic powder could be 172 00:08:49.759 --> 00:08:51.919 transformed into a highly durable structure. 173 00:08:51.960 --> 00:08:53.559 And they can't just mix it with water to make 174 00:08:53.639 --> 00:08:54.639 lunar concrete. 175 00:08:54.919 --> 00:08:58.480 No, because liquid water is arguably the most precious resource 176 00:08:58.519 --> 00:09:01.080 in space, you aren't going to waitted on mixing cemit. 177 00:09:01.360 --> 00:09:03.200 You need a completely different method. 178 00:09:02.960 --> 00:09:05.480 Which brings us to the technology they actually used. And 179 00:09:05.519 --> 00:09:07.200 this sounds like it was pulled straight from a sci 180 00:09:07.200 --> 00:09:11.799 fi novel. It's called laser directed energy deposition additive manufacturing. 181 00:09:11.919 --> 00:09:13.639 It is quite a mouthful of a technical term. 182 00:09:13.799 --> 00:09:15.320 It really is. I'm going to stumble over. 183 00:09:15.200 --> 00:09:17.720 It, laser directed energy deposition, right. 184 00:09:18.000 --> 00:09:21.159 But the underlying concept is just incredible. The researchers are 185 00:09:21.240 --> 00:09:26.519 using a special, highly concentrated laser to literally melt this fine, 186 00:09:26.679 --> 00:09:30.159 dusty synthetic material into layers, and then they fuse it 187 00:09:30.200 --> 00:09:33.159 with a base surface. And they aren't just melting the 188 00:09:33.200 --> 00:09:36.679 dirt on its own. The process involves precisely combining different 189 00:09:36.759 --> 00:09:41.039 feedstocks like metal and ceramics during the printing process. 190 00:09:40.720 --> 00:09:42.960 To manufacture small heat resistant objects. 191 00:09:43.039 --> 00:09:45.240 Yes, okay, I want to try to visualize this for you. 192 00:09:45.639 --> 00:09:47.679 Think about a hot glue gun that you might use 193 00:09:47.720 --> 00:09:50.519 for a crafting project. You feed a solid stick of 194 00:09:50.519 --> 00:09:53.279 glue into the back, a heating element melts it, and 195 00:09:53.320 --> 00:09:56.559 you squeeze out a precise line of liquid glue that 196 00:09:56.679 --> 00:09:59.759 instantly cools and hardens into whatever shape your draw. 197 00:10:00.000 --> 00:10:01.279 It's a good foundational analogy. 198 00:10:01.360 --> 00:10:04.000 Now scale that up to an unimaginable extreme. Instead of 199 00:10:04.000 --> 00:10:06.559 a plastic glue stick, the material being fed in is 200 00:10:06.679 --> 00:10:11.039 crushed alien rock mixed with metals and ceramics. Instead of 201 00:10:11.080 --> 00:10:15.120 a tiny electrical heating element, the heat source is a concentrated, 202 00:10:15.279 --> 00:10:19.080 high powered laser beam. And instead of crafting a diorama 203 00:10:19.159 --> 00:10:23.559 for a school project, the ultimate goal is building massive, sturdy, 204 00:10:23.840 --> 00:10:27.360 non toxic habitats that will keep human beings alive in 205 00:10:27.399 --> 00:10:28.559 a lethal environment. 206 00:10:29.039 --> 00:10:31.399 But the hot glue gun analogy only takes this so 207 00:10:31.480 --> 00:10:35.519 far because melting rock is fundamentally physically different than melting plastic. 208 00:10:35.840 --> 00:10:39.240 Right, I assume basaltic rock doesn't just cheerfully melt and flow. 209 00:10:39.039 --> 00:10:41.879 Like wax, not at all. The physics of laser directed 210 00:10:42.000 --> 00:10:45.559 energy deposition, especially when applied to a geological material like 211 00:10:45.759 --> 00:10:49.440 LHS one, are incredibly volatile. When you use a hot 212 00:10:49.480 --> 00:10:52.279 glue gun, you are dealing with a polymer specifically designed 213 00:10:52.279 --> 00:10:55.639 by chemical engineers to melt at a low uniform temperature 214 00:10:55.720 --> 00:10:59.240 and cool smoothly. Basaltic rock and ceramic feat stocks are 215 00:10:59.240 --> 00:11:01.120 not designed by no to be cooperative. 216 00:11:01.279 --> 00:11:03.639 So what does the laser actually have to do to. 217 00:11:03.639 --> 00:11:07.039 Melt these materials. The special laser has to generate immense 218 00:11:07.559 --> 00:11:12.080 concentrated thermal energy. We're talking about thousands of degrees focused 219 00:11:12.120 --> 00:11:13.919 onto an area that might be just fractions of a 220 00:11:13.960 --> 00:11:18.759 millimeter wide. You are instantaneously transforming a solid crystalline rock 221 00:11:18.879 --> 00:11:22.320 dust into a superheated glowing pool of molten magma. 222 00:11:22.440 --> 00:11:27.159 Wow, tiny localized magma pool exactly, and as the laser 223 00:11:27.200 --> 00:11:29.600 moves along its program path to draw the shape. 224 00:11:29.759 --> 00:11:32.799 That microscopic pool of magma is left behind, and it 225 00:11:32.840 --> 00:11:36.240 immediately begins to cool and solidify back into a solid 226 00:11:36.320 --> 00:11:39.080 rock glass matrix. And this is where we run into 227 00:11:39.120 --> 00:11:41.559 a massive engineering hurdle. It's a concept known as thermal 228 00:11:41.559 --> 00:11:42.360 shock resistance. 229 00:11:42.399 --> 00:11:44.879 Okay, hold on, thermal shock resistance. Break that down for me. 230 00:11:44.919 --> 00:11:46.080 Explain it to me, like I'm five. 231 00:11:46.200 --> 00:11:48.799 Imagine taking a thick glass baking dish straight out of 232 00:11:48.799 --> 00:11:51.679 a four hundred degree oven and immediately dropping it into 233 00:11:51.679 --> 00:11:53.919 a sink full of ice water. What happens? 234 00:11:54.080 --> 00:11:56.399 It shatters violently. I've actually done that and it's. 235 00:11:56.360 --> 00:12:00.480 Terrifying, right, And it shatters because of thermal shock. When 236 00:12:00.519 --> 00:12:03.159 a material is heated to a highly energetic state like 237 00:12:03.200 --> 00:12:06.279 a liquid, and then rapidly cools down to a solid state, 238 00:12:06.759 --> 00:12:09.519 the outer layer is exposed to the cooler environment, cool 239 00:12:09.600 --> 00:12:13.240 down and shrink much faster than the inner layers, which 240 00:12:13.240 --> 00:12:14.799 are still hot and expanded. 241 00:12:15.000 --> 00:12:17.320 So the outside is trying and contract, but the inside 242 00:12:17.360 --> 00:12:18.200 is still pushing out. 243 00:12:18.360 --> 00:12:23.080 Yes, this creates massive internal stress. The material is literally 244 00:12:23.120 --> 00:12:26.639 pulling itself apart from the inside. If the material does 245 00:12:26.679 --> 00:12:30.360 not have high thermal shock resistance, that internal stress will 246 00:12:30.360 --> 00:12:34.039 cause the newly printed layer to instantly crack, shatter, or warp. 247 00:12:33.919 --> 00:12:36.720 Which is a huge problem. You can't build a sturdy 248 00:12:36.799 --> 00:12:39.679 lunar habitat if your foundational bricks are shattering from the 249 00:12:39.679 --> 00:12:41.679 inside out just seconds after you print them. 250 00:12:41.799 --> 00:12:45.559 Exactly. If the structural integrity is compromised at the microscotic 251 00:12:45.679 --> 00:12:49.120 level during the cooling phase, the entire macro structure is useless. 252 00:12:49.440 --> 00:12:53.720 Here's where it gets really interesting because that exact problem, 253 00:12:54.120 --> 00:12:58.360 the internal stress, the cracking, the failure to create a 254 00:12:58.480 --> 00:13:01.679 durable structure, leads to directly to the primary and frankly 255 00:13:01.720 --> 00:13:06.200 surprising finding of this entire research project. Sisushu, the lead 256 00:13:06.240 --> 00:13:09.039 author from Ohio State, discovered that the final material is 257 00:13:09.080 --> 00:13:12.759 incredibly sensitive to its environment. But the breakthrough wasn't about 258 00:13:12.759 --> 00:13:16.080 tweaking the laser power or changing the dust mixture. Yeah, 259 00:13:16.120 --> 00:13:18.600 the real plot twist was about the ground they. 260 00:13:18.480 --> 00:13:20.080 Were building on this substrate dilemma. 261 00:13:20.200 --> 00:13:23.080 Yes, the study revealed that the overall quality of the 262 00:13:23.080 --> 00:13:25.960 material depends greatly on the surface onto which the soil 263 00:13:26.039 --> 00:13:28.679 is printed. It's not just the ink, it's the paper 264 00:13:28.720 --> 00:13:32.039 you're printing on. The researchers tried to print this molten 265 00:13:32.279 --> 00:13:34.960 lhs IE mixture onto stainless steel. 266 00:13:34.679 --> 00:13:36.039 Surfaces, and how did that go? 267 00:13:36.279 --> 00:13:39.360 It was a disaster, highly challenging. The researchers called it. 268 00:13:39.360 --> 00:13:42.679 It likely warped, failed to stick, or just fractured entirely. 269 00:13:42.759 --> 00:13:45.039 So then they tried to print it onto glass surfaces, 270 00:13:45.120 --> 00:13:48.960 again highly challenging, a failure. But then they tried a 271 00:13:48.960 --> 00:13:52.960 completely different base. They printed the superheated molten lunar simulant 272 00:13:53.000 --> 00:13:57.639 onto a circle made of a luminous silicate ceramic ah. 273 00:13:57.080 --> 00:14:00.840 And suddenly it adhered beautifully. It worked. The dirt and 274 00:14:00.879 --> 00:14:04.240 the ceramic played nicely together. The entire success of turning 275 00:14:04.279 --> 00:14:07.559 moon dirt into a durable structure relied entirely on the 276 00:14:07.600 --> 00:14:11.240 specific material of the foundation they were printing on. But wait, 277 00:14:11.320 --> 00:14:15.120 hold on, why does ceramic work when heavy duty stainless 278 00:14:15.120 --> 00:14:18.799 steel fails. Steel feels like it should be the strongest, 279 00:14:18.879 --> 00:14:20.519 most stable thing you could build on. 280 00:14:21.039 --> 00:14:24.000 This is perhaps the most crucial scientific insight of the 281 00:14:24.120 --> 00:14:27.320 entire deep dive, because it moves us from abstract three 282 00:14:27.399 --> 00:14:31.759 D printing concepts into hard atomic chemistry. Why did the 283 00:14:31.759 --> 00:14:35.279 stainless steel fail? It comes back to that intense heat 284 00:14:35.320 --> 00:14:38.120 and the rapid cooling we were just discussing. It involves 285 00:14:38.159 --> 00:14:40.480 something called thermal expansion coefficients. 286 00:14:40.519 --> 00:14:42.080 Okay, you're going to have to translate that one forward 287 00:14:42.120 --> 00:14:44.000 to two thermal expansion coefficient. 288 00:14:44.120 --> 00:14:46.840 It is simply a measurement of how much a specific 289 00:14:46.879 --> 00:14:49.320 material expands when it gets hot and how much it 290 00:14:49.360 --> 00:14:52.799 shrinks when it gets cold. Every material has a different coefficient. 291 00:14:53.039 --> 00:14:55.720 Steel expands and contracts at a very very different rate 292 00:14:55.759 --> 00:14:57.159 than basaltic rock. Ah. 293 00:14:57.240 --> 00:14:59.559 Okay, I see where this is going. So imagine you 294 00:14:59.559 --> 00:15:03.360 deposit a pool of superheated molten rock onto a room 295 00:15:03.399 --> 00:15:08.600 temperature stainless steel plate. The heat transfers into the steel. Now, 296 00:15:08.600 --> 00:15:11.039 as the molten dirt starts to cool down and tries 297 00:15:11.080 --> 00:15:14.120 to shrink, the steel beneath it is also reacting to 298 00:15:14.159 --> 00:15:18.720 the heat, expanding or contracting at its own, unique, completely 299 00:15:18.720 --> 00:15:19.440 different speed. 300 00:15:19.639 --> 00:15:22.279 It's like two people tied together trying to run in 301 00:15:22.360 --> 00:15:23.440 opposite directions. 302 00:15:23.480 --> 00:15:27.240 Precisely, this creates an immense sheer force right at the 303 00:15:27.279 --> 00:15:30.519 boundary layer where the two materials touch. The printed layer 304 00:15:30.519 --> 00:15:33.679 of rock essentially rips itself off the steel surface, or 305 00:15:33.720 --> 00:15:36.440 the stress causes the rock to turn brittle and shatter 306 00:15:37.039 --> 00:15:39.600 the glass surface. Failed for similar reasons. It couldn't handle 307 00:15:39.639 --> 00:15:40.559 the thermal disparity. 308 00:15:40.799 --> 00:15:44.159 All right, So why is the illuminousilicate ceramic the hero 309 00:15:44.320 --> 00:15:46.039 of the story. What is it doing differently? 310 00:15:46.440 --> 00:15:50.639 It's entirely different chemistry. Luminosilicate is a compound made of aluminium, silicon, 311 00:15:50.679 --> 00:15:54.200 and oxygen. Now look at our lunar Highland simulant. The 312 00:15:54.320 --> 00:15:57.759 dark colored basaltic rock is also heavily composed of silicates. 313 00:15:58.320 --> 00:16:00.759 They share a fundamental chemical family. 314 00:16:00.360 --> 00:16:03.159 So they recognize each other chemically speaking. 315 00:16:02.960 --> 00:16:06.399 In a way. Yes, When the laser melts the simulant 316 00:16:06.440 --> 00:16:09.679 onto the ceramic base, they aren't just two distinct layers 317 00:16:09.679 --> 00:16:12.000 sitting loosely on top of one another like a sticker 318 00:16:12.039 --> 00:16:15.320 on a metal bumper. The heat causes the two compounds 319 00:16:15.360 --> 00:16:18.000 to interact and they actually form crystals together. 320 00:16:18.120 --> 00:16:19.799 Wait, they grow crystals. 321 00:16:19.960 --> 00:16:23.519 Yes, they undergo a chemical reaction at the boundary layer. 322 00:16:24.320 --> 00:16:27.279 The molten rock and the solid ceramic interlock at the 323 00:16:27.279 --> 00:16:31.240 atomic level, growing shared crystal structures across the divide. 324 00:16:31.279 --> 00:16:32.279 That is incredible. 325 00:16:32.399 --> 00:16:36.120 It is this deep chemical handshake is what enhances the 326 00:16:36.120 --> 00:16:39.080 thermal stability and the chanical strength that the study highlights. 327 00:16:39.720 --> 00:16:42.440 The base surface isn't just a passive table you're building on. 328 00:16:42.799 --> 00:16:46.240 It becomes an active, integrated partner in the structural integrity 329 00:16:46.240 --> 00:16:47.039 of the final object. 330 00:16:47.120 --> 00:16:50.480 That is absolutely wild. So it is essentially welding with rock, 331 00:16:50.799 --> 00:16:53.159 but instead of melting two pieces of metal together so 332 00:16:53.200 --> 00:16:56.320 they pool, you are coaxing the molten dirt and the 333 00:16:56.360 --> 00:17:00.879 ceramic foundation to grow a shared microscoptic roots set of crystals. 334 00:17:00.960 --> 00:17:02.840 That is a very elegant way to describe it, a 335 00:17:02.879 --> 00:17:04.240 microscopic root system. 336 00:17:04.440 --> 00:17:07.240 It makes perfect sense why that would drastically increase the 337 00:17:07.279 --> 00:17:10.880 mechanical strength and the thermal stability. If they are chemically 338 00:17:10.920 --> 00:17:14.079 locked together with these crystalline roots, they can handle the 339 00:17:14.079 --> 00:17:17.640 immense stress of cooling down without ripping apart. But if 340 00:17:17.640 --> 00:17:21.119 we extrapolate that finding out of the laboratory and try 341 00:17:21.160 --> 00:17:24.480 to apply it to an actual mission, the implications for 342 00:17:24.599 --> 00:17:27.079 lunar based design are just massive. 343 00:17:27.119 --> 00:17:29.359 They alter the entire architectural paradigm. 344 00:17:29.480 --> 00:17:33.359 Right because if this study proves that you absolutely cannot 345 00:17:33.400 --> 00:17:37.240 reliably three D print sturdy structures directly onto steel plates, 346 00:17:37.559 --> 00:17:39.960 and you certainly can't put them onto glass, and you 347 00:17:40.000 --> 00:17:43.599 presumably can't print them directly onto the loose, chaotic, unmelted 348 00:17:43.680 --> 00:17:46.759 dust of the Moon's surface without a proper base. How 349 00:17:46.799 --> 00:17:50.559 does that fundamentally change the architectural plans for a lunar settlement. 350 00:17:50.960 --> 00:17:53.079 It suggests that the very first step of building a 351 00:17:53.079 --> 00:17:55.759 moon base isn't turning on the three D printers to 352 00:17:55.759 --> 00:17:57.319 make walls exactly. 353 00:17:57.680 --> 00:18:00.440 The first step has to be establishing an app absolutely 354 00:18:00.640 --> 00:18:05.119 massive foundation pad of aluminous silicate ceramic. You would have 355 00:18:05.160 --> 00:18:09.319 to essentially pave the lunar surface with these specific chemically 356 00:18:09.319 --> 00:18:13.960 compatible ceramic tiles before the massive laser deposition machines could 357 00:18:14.000 --> 00:18:16.960 even begin their work of building the habitats. 358 00:18:16.480 --> 00:18:19.720 Which adds an entirely new layer of logistical complexity to 359 00:18:19.759 --> 00:18:23.279 the engineering blueprints. You weren't just bringing high tech printers 360 00:18:23.319 --> 00:18:26.079 on a rocket. You are bringing or you have to 361 00:18:26.079 --> 00:18:30.359 figure out how to manufacture incredibly specific ceramic subflooring. 362 00:18:30.559 --> 00:18:32.920 It's like realizing you can't build your dream house until 363 00:18:32.960 --> 00:18:36.400 you've invented and poured a completely new type of concrete slab. 364 00:18:36.720 --> 00:18:40.240 You've identified the exact cascading logistical challenge that makes offer 365 00:18:40.279 --> 00:18:44.720 of construction so incredibly daunting. Every solution immediately requires a 366 00:18:44.759 --> 00:18:47.680 prerequisite solution. You want to build a wall out of 367 00:18:47.720 --> 00:18:51.000 dirt to save weight on the rocket. Great idea, but 368 00:18:51.079 --> 00:18:54.079 now you need a heavy ceramic foundation so the wall 369 00:18:54.079 --> 00:18:56.799 doesn't shatter due to thermal shocks. It never ends, it 370 00:18:56.839 --> 00:19:00.640 doesn't and this substrate dilemma. The realization that the printing 371 00:19:00.680 --> 00:19:05.000 surface is critically important is really just one single variable 372 00:19:05.279 --> 00:19:09.279 in a massive chaotic equation. As senior author Sarah Wolf 373 00:19:09.319 --> 00:19:12.319 points out, there are a multitude of other environmental factors 374 00:19:12.400 --> 00:19:15.039 that heavily impact the stability of the final structure. 375 00:19:15.440 --> 00:19:17.640 Yeah, the study found that it wasn't just the ground. 376 00:19:17.680 --> 00:19:20.200 The amount of oxygen in the atmosphere, the strength of 377 00:19:20.240 --> 00:19:23.400 the laser, and the speed of the printing process all 378 00:19:23.480 --> 00:19:25.160 drastically alter the outcome. 379 00:19:25.599 --> 00:19:27.920 And this brings us to a harsh reality check about 380 00:19:27.960 --> 00:19:32.279 laboratory research versus field application. Wolf notes that conditions in 381 00:19:32.319 --> 00:19:35.720 space are really hard to emulate in a simulant. She 382 00:19:35.799 --> 00:19:39.119 acknowledges that while a highly specific combination of laser strength, 383 00:19:39.240 --> 00:19:42.279 print speed, and a nice ceramic substrate might work perfectly 384 00:19:42.319 --> 00:19:45.799 in a controlled Ohio state lab, a resource scarce environment 385 00:19:45.920 --> 00:19:47.240 is a completely different beast. 386 00:19:47.359 --> 00:19:49.599 It's one thing to make a soufle in a commercial kitchen, 387 00:19:49.839 --> 00:19:51.440 it's another to make it in a hurricane. 388 00:19:51.440 --> 00:19:54.960 Precisely, the technologies created for this kind of work must 389 00:19:55.000 --> 00:20:00.519 be engineered to survive what the researchers classify as extreme vacuum, dust, 390 00:20:00.680 --> 00:20:02.359 and thermal environmental conditions. 391 00:20:02.599 --> 00:20:06.319 Wolf mention extreme vacuum and thermal conditions, and I really 392 00:20:06.319 --> 00:20:08.480 want to paint a picture of what those extreme conditions 393 00:20:08.480 --> 00:20:11.279 actually mean, because it is so easy to read the 394 00:20:11.319 --> 00:20:14.400 words extreme vacuum on a page and not fully grasp 395 00:20:14.920 --> 00:20:18.759 the sheer active hostility of that environment. Let's contrast the 396 00:20:18.799 --> 00:20:22.000 two realities. In the Ohio State laboratory, the researchers have 397 00:20:22.160 --> 00:20:25.759 total godlike control. The room is climate controlled to a 398 00:20:25.799 --> 00:20:29.359 comfortable seventy degrees. The air pressure is a standard comfortable 399 00:20:29.400 --> 00:20:33.720 one atmosphere. The electrical grid provides a perfectly stable, uninterrupted 400 00:20:33.759 --> 00:20:36.359 flow of power to the laser and the LHS one 401 00:20:36.400 --> 00:20:40.640