Science Friday - Moon Rock Research | Science of Unraveling Sweaters

Episode Date: November 22, 2023

Moon Rocks Collected In 1972 Reveal New SecretsIt’s hard to imagine, but the moon we all know and love hasn’t always been in the sky. Like all of us, the moon has an age. Until recently, our lunar neighbor has been estimated to be about 4 billion years old.But new research on lunar crystals from the Apollo 17 mission has helped researchers pinpoint a more specific age for the moon—and it’s about 40 million years older than previously thought.That difference may sound like a drop in the bucket given the time scales, but lead study author Dr. Jennika Greer says this is a big deal, because it tells us more about what the solar system was like in its earlier years. Greer, a postdoctoral researcher at the University of Glasgow in Scotland, joins guest host Flora Lichtman to talk about her methods and why the early universe was so fascinating.The Science Behind Your Unraveling SweatersIt’s sweater season once again, but you may have noticed that some of your newer sweaters aren’t standing the test of time. Perhaps they are pilling, unraveling, or losing their shape. But if you look at sweaters from the ‘80s or ‘90s, they may still look brand new. Last month, an article by Amanda Mull in the Atlantic about declining sweater quality made the rounds online, and we wanted to know more.What, scientifically, went wrong in sweaters? And why are sweaters so bad now?Guest host Flora Lichtman unravels the science of sweaters with Dr. Imran Islam, knit expert and assistant professor at the Fashion Institute of Technology in New York City. They chat about the fibers that make up sweaters, what physics has to do with how long they last, and what to look for when purchasing knitwear.To stay updated on all things science, sign up for Science Friday's newsletters. Transcripts for each segment will be available the week after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Do you also feel like your newer sweaters just keep falling apart? You know, nowadays if you go to the market, if you see something very cheap, you see the peeling. Like right after, like after a few days, like you're going to see that. You witness them. It's Wednesday, November 22nd, but every day is Science Friday. I'm sci-fri producer and sweater enthusiast Rasha Eredi. For years, years, I've been searching for the perfect white, chunky knit sweater. very when Harry met Sally inspired.

But all I have to show for it is a pile of raggedy, fraying sweaters. If you, like me, are also desperate for an answer, we are going to unravel the science behind sweaters. But first, guest host Flora Lichten talks with a cosmochemist about getting closer to discovering the moon's real age. It's hard to imagine, but the moon that we know and love hasn't always been in the sky. Like all of us, it has an age. and that age has, for a while, been estimated to be about 4 billion years old. But recent research on lunar crystals from the Apollo 17 mission has helped us pinpoint a more specific age for the moon. And it turns out it's about 40 million years older than we thought.

Okay, I know that might sound like a drop in the bucket when you're 4 billion years old. But my next guest says it's actually a really big deal because it tells us about what the solar system was like when it was just a baby. joining me now to talk about this is the study's lead author, Dr. Jenica Greer, postdoctoral researcher at the University of Glasgow in Scotland. Welcome to Science Friday. Hi, thanks for having me. Okay, let's start with this. Why is it exciting that the moon is 40 million years older than we thought? Or is it exciting?

Yeah, I think it's at least important because 40 million years may be, like you said, a drop in the bucket compared to our solely. system's entire history. But you can put some pretty important bookmarks on either side that really put that 40 million years into context. So the earliest solar system solids formed around 4.56 billion years ago. And the oldest terrestrial solids that we know of formed around 4.4 billion years ago. Okay, so we have space rocks forming like 4.56 billion years ago. And then when you say terrestrial, do you mean Earth rock? Yes. So we have Earth Zircons. And that's forming later. Yes, at 4.4 billion years ago. So the time between those two when you have the very first solids in the solar system, the stuff that's forming right after the sun formed to when you have a planet with crustal properties. processes with surface processes is about 160 million years. So 40 million years is pretty significant when you compare it to that. People have been using computational models to try to figure out how moon formation looked.

And some of those models put the time to form the moon after the giant impact at around 100 years. Whoa, like very, very specific. Yeah, 40 million years is nothing to sniff at when it comes to early solar system processes. It sounds like this is a very high drama part of the solar system's history, too. Absolutely. A lot of really important stuff happened really quickly. And then you have this kind of quiescence almost where you have the planets doing their own thing. But you can also look at an object like the moon. where you have a lot of important stuff happening, and right now we look at it.

And pretty much the only geologic process that's active on the moon right now is impact events. Remind me how the moon was born. So the leading theory for how the moon was formed, and this is a theory that basically has to explain a bunch of different characteristics of the Earth-Moon system, is that there was a large Mars-sized impactor that hit the proto-earth and mixed a bunch of material and some of the material that kind of flew off later coalesced to form the moon. What did the moon look like in the early days? Would it be recognizable to us now? So when people look at the moon, the things.

that we readily identify are the dark patches. And those are lava flows that only developed later in the moon's history. If you use a pair of binoculars to look at the moon, you might see craters. And those were definitely not there 4.4 billion years ago. Let's talk about how you figured this out. Where did the moon samples come from? So these were samples that were picked up by Apollo 17 astronauts. The Apollo 17 mission was unique among the Apollo program in that one of the astronauts that landed on the moon was actually a trained geologist. These rocks were brought back by the astronauts, characterized by scientists, and eventually, as these materials were requested by the broader scientific community, they get analyzed for all sorts of different things by so many different people.

And eventually the sample gets allocated to my co-author, Bedong Zhang, and he uses a technique called nanosemes to get a uranium-led age out of this crystal. Nanosimms. That sounds technical. Yeah. It stands for nanoscale, secondary ionization mass spectrometry. The uranium lead system in zircon is kind of the gold standard for geochronology because you have uranium that's readily incorporated into these zircon crystals. It decays through radioactive decay to lead. And because the zircon hopefully didn't incorporate any lead when it crystallize, all of the lead that's present should be the result of the uranium that was there. So you can use the uranium lead ratio to figure out how old it is, because we know the half-life of uranium.

Because of the importance of this age and because it's so ancient, we have to look at the structure at the nanoscale of this crystal to make sure that it hasn't been altered since its formation. And that's what we were able to do in this study. So we needed to double check that the age that my co-author measured was the correct age, because a lot of stuff has happened to the moon's surface since these rocks first formed. Okay, got it. So your co-author calculated an age, and you guys were like, these grains are super old, we got to double check. Right. And you used this other technique. Yeah, and it's an example of how as we've progressed in technology, we can start using these techniques to, you know, look at the nanoscale and try to better understand these samples. It's, I mean, I would say that now if you're going to present the scientific community with an age, this ancient, you will then be expected to provide evidence. at the nanoscale of what's been going on.

That's really cool. And kind of mind-blowing, actually. I mean, this is a realm that we haven't had access to. This is not something that would have been possible when these rocks were first returned to Earth. Right. Like just in the last 50 years, this technology evolved, right? Right.

So the atom probe is maybe a really. around 50 years old rocks like this couldn't have been analyzed until the laser was first introduced to the atom probe, and that was about 20 years ago. But there was a study done in 2014 that basically did this for a terrestrial zircon, the oldest terrestrial zircon. And since then, it's been kind of not expected, but it's considered due diligence at this point. Do you have a dream material that you want to analyze? Well, actually, that's kind of interesting. This technique, atom probe, is now being applied to biologic samples.

So people are doing human tissue. People are now doing fluids by freezing them out. There's a huge space in atom probe for trying to analyze these really, unusual samples because people are interested in the distribution of atoms at the atomic scale. Does it tell you something other than how old a material is, the distribution of atoms? Well, sure. Another project that I've been working on is looking at space weathering products from the moon. So the moon is an airless body. It doesn't have a protective atmosphere. And it's being constantly bombarded by the solar wind and micrometeorites. So the sun is, you know,

throwing off waves of particles all the time. And it's impacting the surfaces of these grains. And it's altering them. And something really interesting I've been working on is you have these rocks, this lunar soil, rich in oxygen, because oxygen is a mineral building element. And you've got hydrogen, the most abundant element in the sun, constantly being blown off. So when you've got hydrogen and you've got oxygen, you can form water. And even though that hydrogen only really impacts the top about 100 nanometers of the soil, it could be that these space weathered grains could be a potential resource for water for future astronauts. Let me ask you this. What is it like to actually hold these sort of ancient, I know it's just like dust, but like what's it like to hold these sort of ancient grains in your hand?

What's it like to hold the moon in your hands? I'm not the best person to ask this because during my PhD, I was a resident graduate student at the Field Museum. And the Field Museum has the world's largest private meteorite collection. So I was like always handling space rocks. So it's almost routine. I would say that the more daunting aspect of that is knowing that you're holding something that decades of scientific research has gone into. And so many people have analyzed this and gotten the body of knowledge that you have access to. And now you're given the sample, you do not want to mess that up.

You do not want to drop it. Any close calls? No. And, you know, that is for the benefit of NASA. Please keep allocating me samples. Yeah. That's about all the time we have for now. I'd like to thank my guest, Dr. Jenica Greer, postdoctoral researcher at the University of Glasgow in Scotland.

Thanks for having me. It is officially sweater weather. Time to pull out those chunky weaves. Now, I look forward to this annual ritual, but I have never. noticed that my new sweaters often look like they're hanging on by a thread, while my old sweaters still look brand new. Is this real? And why? Why do sweaters suddenly seem to stink? Today we are unraveling sweater science with Dr. Imran Islam, knit expert and assistant professor at the Fashion Institute of Technology in New York City. Welcome to Science Friday.

Thank you. Okay, well, what is your approach to sweaters? Do you just, like invest in one great sweater and that's it for you? Yes, I would say yes. I'm relieved, okay? Please keep going. In what way? Well, if you look at the statistics currently, approximately 62% of the textile fibers are synthetic fiber, like polyester, nylon, acrylic, that sort of thing.

So typically when we say sweater, historically sweater based on wool fiber. and some sort of like, you know, a cashmere, you know, that kind of exudic fibers too. There was a little bit of cotton too at some point. But nowadays it's mostly acrylic, polyester, you know, that kind of material. More and more you will find in the sweater process. But why is that worse? Like why does that translate to my sweater falling apart? Well, definitely all this natural fiber I just mentioned, wool or cashmere or cotton.

they do have inherent property that goes with the thermal insulation. Let's say wool has some sort of crimp or wavy shape, you know when those are collected from the sheep. And when you make the fabric out of it, so because of the wavy shape of the fiber, there is a air pocket. Within the air pocket, there is a trapped air that use as a natural insulator. So wool has an inherent thermal property.

Now, for man-made fiber, you have to recreate that. That's number one. So something inherent versus something recreated, like regenerators. So these are one difference. Right. The imitators are always not as good as the original. Exactly. Yeah.

And another thing is the, I would say, the moisture property. So wool is known as hygroscopic. So hygroscopic means it absorbs water, but keep it inside the cell. But the outside seems dry. but still it absorbs water and cotton absorbs thoroughly. But, you know, if you think about the polyester or acryly, they don't absorb their hydrophobic fiber. And what happened is that when there is a friction, because most of the time we wear sweater on top of something. It is our topmost dress or article when you wear.

There must be something inside. So there is a constant friction when you wear one dress on top of another. And because of the friction, there is a static electricity. And then also some of the fibers are broken on the surface. So broken fibers and also static electricity, these two combine together so that all the broken fibers come close to each other. They form a fiber ball, which you know as a peeling. I know peeling, believe me.

So specifically anywhere, let's say acrylic, especially, you know, nowadays if you go to the market, if you see something very cheap, you see the peel. you see the peeling, like right after, like after a few days, like you're going to see that, you witness that. But in the previous, when you use the wool and cashmere or that sort of thing, it tends to generate less static electricity and tend to form less peeling. Basically, because of the structure of the fiber and because it can absorb water rather than repel it, like it seems like these are the key reasons why these natural fibers do better. Exactly. Yep, exactly. I want to look at my sweater right now to see what it says about its makeup. And, okay, it says it's 85% polyester, 15% nylon.

So I believe for your sweater, the 15% nylon is to give it a little bit of strength because nylon is known for a stronger fiber. If you remember some of the nylon cord, we used to tie something. Yes. So the purpose, basically the sweater should be 100% polyester for that one. the producer, they add a little bit of nylon just so that it. So I could get it over my head. So, yes, probably it will give you a little bit of strength.

We'll little bit of reduce the peeling property. But again, the warmth you are looking at, like when they produce, the fibers are straight. Like, you know, it comes through a device called spinneret. It is look like your shower head. Do you remember the shower head? When you drop the water, water is coming from straight from there. So the man-made fiber, they produce like that. So those are straight.

But in order to get the thermal insulation property, there is a particular technological textureization. So basically, all the straight fibers becomes zigzag shape, you know, so that it will hold. Yeah, they perm the fibers. Right. They perm the fiber. Exactly. That would be the best way to describe.

So. And then within the cone shape, they try to imitate that air pocket that you are getting inherently from wool or other natural fiber. So that air pocket is tend to help them to be natural insulate or something. So I'm assuming that what we're talking about, the move away from natural fibers isn't just happening with sweaters. Like this sort of degradation and quality must be part of this bigger, best fashion story problem. Is that true? Yes, that's true. Basically, the more you are going away. Again, if you remember

like 10, 15 years or 20 years ago, like we used to have like one or two sweaters per winter or something, something like this. So nowadays if you look for the people, they have a number of sweaters in their closet even for the same winter. So that is one of the reasons.

People have a high level of demand of different types of article within the sweater category. And you know, to cope up, with the supply and demand. So producer has to go through a route. Like, for instance, in order to, if you want to think about a wool, you know, you have to

think about the all natural variables. Or if you think about the cotton, you have to think about all the natural thing that you cannot control much. It goes with the weather and some sort of thing, like natural ingredients. But for synthetic material like polyester or acrylic, you can make it in a lab and in a bulk quantity with a less with a lesser price. you have to deal with less number of variables. Most of the things are under your control.

So, you know, to adapt the fast fashion and supply and demand, the manufacturer rely upon more of a synthetic fiber. And also, since you are buying more articles for the same season, that means you are not willing to pay more for one article. My next sweater is going to be thrifted. That is what I'm taking from this. I'm going to go back to the 80s, I don't know, maybe 90s. That seems like the era I need to be looking in.

Yeah, I mean, trip store would be another good way. Definitely. The wool sweater and everything, they have longer lifetime. And tripting would be, like, tripster would be a good way to get them easily. Thank you for joining me today. You welcome. Dr. Imran Islam is a knit expert and assistant professor at the Fashion Institute of Technology in New York City.

And that's it for today. Lots of folks help put this show together, including Jordan Smudjik. Charles Burgquist. George Harper. John Dancosky. Join us tomorrow for Wild Mustangs and a pig opera. See you then. I'm Rasha Reedy.