Science Friday - Moon Maps, Brain Replay, Contact Tracing. May 8, 2020, Part 2

Episode Date: May 8, 2020

Have you ever had to learn something new and repeat it over and over—until it feels like you’re doing it in your sleep? Maybe you are. In research published this week in the journal Cell Reports, scientists monitored the brain activity of two people implanted with fine grids of neural electrodes as part of a brain-computer interface study for tetraplegia: paralysis of all four limbs. With the implants and a computer model to process the signals, the study participants were able to use their thoughts to control the movement of a cursor on a computer screen. In the study, the participants were asked to play a memory-pattern game similar to the old “Simon” handheld electronic game, pressing a sequence of four buttons in a given order. Then, they were asked to rest and relax—even to nap if they wanted—while the researchers continued to observe their brain activity. They found that the participants’ brains replayed sequences of the game’s patterns during shallow, stage one non-REM sleep. The researchers think that this replaying may be connected to mechanisms the brain uses for memory consolidation and learning. Beata Jarosiewicz, one of the authors of the study, joins guest host John Dankosky to discuss their findings. While research continues on vaccines, antivirals, and other medical solutions to the coronavirus outbreak, there are already non-pharmaceutical interventions that public health experts know work. One of them is contact tracing, the process of identifying the people who have been exposed to a known person with COVID-19, and then helping those people avoid infecting others. But while using public health workers for contact tracing has helped contain diseases like Ebola and HIV, contact tracing effort for the much more contagious novel coronavirus could rely in part on digital tools. Around the globe, countries from Iceland, to Singapore have developed smartphone apps. Now, in the U.S., states are also looking to invest in contact tracing—both by hiring thousands of workers to help, but also developing their own apps. And last month, Apple and Google announced they were teaming up to develop a platform for all smartphones to opt in to a system that would tell them if they’d been exposed. But can an app do everything a person can? And will people trust an app with their health information? Producer Christie Taylor talks to two public health experts, Johns Hopkins University’s Crystal Watson, and Massachusetts General Hospital’s Louise Ivers, about the intensive and nuanced work of contact tracing and how digital solutions can fit in the picture. For centuries, we’ve been trying to get a better understanding of the surface of the moon. Different cultures have imagined faces, rabbits, and even toads hiding in the rocky features. Astronauts have walked on the lunar terrain—bringing back photographs and rock samples. And so far, there have been 21 moon landings. The most recent happened last January, when China successfully put a lander on the far side of the moon. Recently, USGS scientists used their expertise in map-making to pull together some of these scientific observations to catalogue the geology of the moon. They stitched together six Apollo-era moon maps, combined with modern satellite data, to create a 360-degree map of the geological structures on the moon. This “Unified Geologic Map of the Moon” was published last month. USGS research geologist James Skinner, one of the creators of the map, takes us through the terrain of the lunar surface, and talks about what it can tell us about the evolution of the moon. Plus. Michelle Nichols of the Adler Planetarium gives moon gazing tips to help you spot the different geological features of the moon.   Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm John Dankoski, and I'm sitting in for Ira Flato. Ira's fine. He's just having a long-planned staycation week. Later this hour, we're going to talk about a public health tool called contact tracing and take a geologic tour of the moon. But first, imagine some sort of repetitive action that you've had to learn to do over and over again, maybe fishing for horse mackerel and animal crossing. You do this to the point where you say, I feel like I'm doing this in my sleep. Well, maybe you are.

Writing this week in the journal Cell Reports, a team of researchers studying two people with neural implants say that it appears that during sleep, people's brains replay parts of what they've been learning that day. Joining me now to talk about the study is one of the authors of that report, Biotrashievich. She was a research assistant professor at Brown University, working on the BrainGate Project when this research happened.

now she's a senior research scientist at Neuropace, a company in California. Dr. Welcome to Science Friday. Thanks for being here. Thank you so much for having me. First, tell us about these study participants. Why did they have this neural implant installed in the first place? They were two different gentlemen, one that had ALS and one that had a brainstem stroke, I believe. And they were enrolled in the Braingate pilot clinical trial, which the main purpose of the Braingate clinical trial is to try to develop brain computer interfaces that will help people with paralysis. But our participants are also happy to participate in

other basic neuroscience type research studies. And this was an example of that. So before we get to the study, I do want to ask a little bit more about this brain control interface. So this is essentially allowing them to do everything from typing an email to maybe composing music on a keyboard. Can you tell us a bit more about how exactly it works? Sure. So the area that we're recording from is the motor cortex, and specifically the hand and arm area of motor cortex. In this brain area, individual neurons have what are so-called firing rates. For example, if the person is imagining moving their hand upward, there might be a subset of neurons that increase their spiking rate above baseline,

meaning above their sort of steady state firing rate level. And then when the person moves their hand rightward, there might be another set of neurons that increase their firing rate. And it turns out even in people with paralysis, neurons still have these sorts of patterns. So if we know, for example, all of the preferred directions of all the neurons that we're recording from, and we know at each moment in time what their firing rates are relative to baseline, whether they're increasing or decreasing their rates, we can look at that pattern across all of the recorded neurons and figure out based on that,

the direction in which the person wants to move their hand. For example, to control a mouse on a mouse pad or their finger on a track pad, and then we can use that information to move a computer cursor in that same direction. So talk about the physical implant itself. How tiny are these electrodes? Each of the microelectrod arrays is a 4 by 4 millimeter square array, and it's got 100 electrodes on it, arranged 10 by 10. Each one of them is about a millimeter and a half long, and we have usually two of these arrays implanted in each participant. Tell me more about how you are interpreting what these.

electrodes sense. I mean, how exactly do you know that the activity in a certain patch of neurons means like go up into the left as opposed to go up into the right? Can you just explain that a little bit further? Sure. So we present a task on the computer screen where we give the participant a cursor that they control and a target somewhere on the screen. And we ask them to imagine that they're moving their hand to control a mouse, for example, to move the cursor towards that target. And then we do this a few times and after a few iterations, we have enough data to start creating a model that maps each neuron's activity to particular intended movement directions. Once we have that model, we can allow the person to start controlling that cursor with their brain activity, and then we can

further refine our estimate of that mapping by continuing to collect data as they're doing this task with the presented targets. And then we can turn off that presented target task and then allow them to do something practical or fun with their brain computer interface. Like, for example, play the Simon game or, as you mentioned earlier, type emails or chat messages to their friends and so forth. So let's get to the Simon game. So in this study that we're talking about, the participants had to do this game, which some people might remember as a memory computer game called Simon. Maybe you can describe the game and exactly what it was they had to do as part of the study. Sure. So the game has four colored wedges, sort of arranged in a circle around a center,

a cursor that appears initially in the center. And four of the targets light up in a particular sequence, and there's an associated sound with each target. And the person tries to remember that sequence and then replicate it by moving the cursor to those same targets in that same order. And most of the time, we played the same sequence of four targets in a given. session where each session consisted of rest and then playing the game and then another rest period. And then we interleaved some other random sequences that were more rare that occurred only twice each that were different from this repeated sequence. And it was this repeated sequence we were looking for replay of in post-task rest. So tell us what you found. What did you observe here?

We found that these, the repeated sequences that were replayed frequently, that first of all, the person was able to remember them more easily because they were faster at repeating those sequences during the game than the control sequences. And secondly, we found that those repeated sequences were replayed during rest after the task more than those control sequences were when you compare them relative to the pre-task rest.

And by replayed, I mean, if you look at the patterns of neural activity over time and just try to, correlate that with the repeated sequences that we saw during the game, we saw higher correlations in general with the repeated sequences than with the control sequences. So what this means is that the brain seemed to be replaying these learned sequences and rest more often than we expected by chance. And it was replaying the sequence as though they were playing the game. I mean, if you'd actually turned on the game, would their brain have been hitting the patterns? Would they have

been activating the various colored blocks in the correct order? That's an interesting question. So the correlations were not quite high enough that I think we would see too many of those repetitions too robustly. Probably most of the time you'd see the cursor kind of wandering around aimlessly and then occasionally hitting that same sequence of four targets. Another difference is that the timescale, we saw the repetitions during post-task rest of these repeated sequences, either happening quite a bit faster, like on the order of 10 times faster

than during waking, or a little bit slower, like one and a half to two times slower. It's possible that some of the replay events happen during specific physiological events in the brain that map onto more consolidation in one of these timescales than the other, but we're not quite sure, and that could be a good subject for follow-up studies. So the shorthand that I was thinking about whenever we were reading about this study was something that I'm sure we've all experienced, which is you do something over and over again, and then you feel like you dream about it at night. Were these participants dreaming, or was this a different level of sleep? Well, they definitely didn't enter REM sleep, rapid eye movement sleep, where the vivid story-like dreams occur when you're sleeping,

because a 30-minute nap period isn't really enough time for them to enter that dream state. but it's possible to have sort of, you know, hallucinatory type dreams when you're first drifting off into sleep. We think it's possible that the patients were experiencing these replays as memories or as these sort of hallucinatory dreams. We didn't actually study that specifically in this study, but when, you know, just anecdotally, when we did happen to ask the participant, did you feel like you were thinking about the game or something else maybe? The participant would answer us, it's none of your business what I was thinking about. So I'm guessing it wasn't the game. So, yeah, in the sleep state that they entered that we did see a little bit of in every session is called non-REM stage one, which is the first stage of sleep that you enter as you're drifting off into sleep.

So what would the purpose of this replay be? Is it the brain going through a checklist of things that it did? Is there a purpose in terms of learning? What do you think it is? We didn't directly address that in this study once again, but we think that what's happening is, you know, based on decades. of research and, you know, throughout different labs in the country and modeling work and so forth, we think what's happening is a process called memory consolidation. This is a process by which memories acquire more permanence in their neural representation. And what seems to be happening is

that this brain structure called the hippocampus, which is very plastic, meaning it can learn things quickly, but its memories also can degrade quickly as a result. The hippocampus can rapidly store new memories that are, for example, emotionally salient or important for some other reason to the person, and sort of take a snapshot of the neocortical brain activity that's happening during the original processing of that to be remembered event. The neocortex is that wrinkly outer layer of your brain, and that's the brain area that seems to be responsible for taking in sensory information, processing it, integrating it across different modalities, helping you make decisions, creating voluntary movements.

All of these different things happen in different brain areas. And the hippocampus kind of takes a snapshot of all of the neurons that were simultaneously active during this event, the pattern of activity over time. And then it gradually feeds that information into the neocortex to help it incorporate meaningful information into its existing knowledge base in a slow enough way that it doesn't disrupt previous memories

that have been stored there, previous mechanisms of processing that everyday sensory information. So if these electrodes had been placed in a different part of the brain, like a language center or some other part of the brain that is in charge of doing something other than moving your hand about, do you think that you'd see the same sort of replay effects? Yeah, I think so. We have seen studies come out from other laboratories showing replay of other kinds of cognitive of tasks, for example, visual memory tasks and even just from blips that were observed during

the day. But the replay in these previous studies was on a larger scale. It was the averaged activity of thousands of neurons. So does this research tell you anything that can help to improve your brain computer interface? Anything that will help you make this work more efficiently or effectively for the people you're trying to help? That's an excellent question. As far as this particular study, I think all it really speaks to is the issue of how memories might be consolidated in the human cortex. It might have applications down the road to memory prosthetics or ways that we could potentially help people with memory disorders like Alzheimer's or hippocampal dysfunction. But as for motor brain computer interfaces, not that I can think of right now. Biatta Yaroshevich is a senior research scientist at Neuropace in California.

She previously was a research assistant professor at Brown University working on the Brain Gate Project. Dr. Thank you so much for sharing this really interesting research with us. I really appreciate it. Thank you so much for having me. When we come back, we'll talk about contact tracing, a tool that many public health experts are saying is a key to controlling the COVID epidemic both now and in the long run. Please stay with us. This is Science Friday. I'm John Dankowski. As some states send workers back into the world, many are asking, What's next in the spread of coronavirus in the U.S.?

There's still no vaccine or proven treatments, and reliable testing remains out of reach for many. But in the meantime, there's one intervention that has almost universal buy-in, contact tracing. That's the process of identifying everyone, a person with COVID has potentially infected, calling them all up and then telling them to stay put so they don't infect anyone. That's for every single identified person with COVID. Now, to this end, states are looking to hire huge. human contact tracers, while companies like Apple and Google and others in tech are working on smartphone apps that could automatically notify people if they're at risk. But what factors will

determine the success of contact tracing? SciFRI producer Christy Taylor talked to two public health experts about what makes this process so complicated. Before you get too excited about an app for tracking COVID, public health researchers want to caution that there's no true replacement for the human labor of contact tracing. It's a difficult, labor-intensive process and different estimates point to a need for as many as 100 to 300,000 contact traces in the country. Joining me today is Dr. Crystal Watson, a senior scholar at Johns Hopkins University's Center for Health Security and lead author of an April report from the center outlining a contact tracing plan for the country, and Dr. Louise Ivers, Executive Director of Massachusetts General Hospital's

Center for Global Health and Associate Professor of Medicine at Harvard Medical School. Welcome to Science Friday, both of you. Thank you. Thanks very much. This phrase contact tracing has been in the news a lot. It's been part of a lot of public health discussions. At its simplest, what is it, Dr. Watson, and how does it help slow the spread of a disease? So contact tracing is really intended to break chains of transmission among people. So the idea is that when someone becomes sick, they are quickly isolated, either in their home or in a health care facility, if that's needed, if they need medical care.

And then a public health worker will ask them about who they've had contact with during the time they may have been infectious with the SARS-CoV-2 virus. Once they have identified the contacts, which could be from one to three days before they develop symptoms, to up to seven days after symptoms have resolved, then those contacts are contacted themselves. Public health workers get in touch with them and ask them to stay at home in quarantine. for 14 days. If they can't stay at home in quarantine for 14 days, then they offer them another facility to quarantine from safely. But the idea is that they are then staying out of circulation in the community. And if they are indeed infected, then hopefully they won't be passing along that infection to other people. Dr. Ivers, we just talked about that definition of contact tracing. And to my years, it sounds almost deceptively simple. You know, you find people, you talk to them,

then you talk to more people. You've personally done this. with a lot of other outbreaks, what makes it actually complicated in real time? Yeah, I think it's complicated only by the fact that humans are complicated, you know, people. Contact tracing is really, when it's successful, is very people-centered. It requires establishing trust. It has to be an activity that people understand is confidential. You have to make it very accessible. when you talk to a person who has an infection,

they are obviously going through their own health issues and they have needs that we need to be able to address and manage and assess. And the same is true when speaking to contacts. Contacts who've been exposed to an illness might be fearful, they might be concerned. As Dr. Watson said, they may need support to be able to isolate themselves, put themselves in quarantine. They may have other worries. it may be a crisis for them. So there are many pieces, there are many human factors to it.

That's one side. On the other side, when we look at an epidemic that's very fast growing and that has a very high reproductive number, we have to be able to identify and very quickly isolate contacts in order to be effective. And so one of the challenges of the human endeavor around contact tracing is that it's resource intense. You need a lot of people. It can be slow, which is sometimes okay if the disease is slow moving, but it can also be incomplete. So everyone does not necessarily remember who the people were that they were in contact with or may have exposed.

At the moment, that is probably not a huge problem because so many of us are socially distancing. But as we re-enter more normal society, when we take the bus or an airplane or we go to public spaces, the human memory of who you've been around may be more incomplete. So those are some of the challenges to contact tracing in the context of this particular infectious disease outbreak. Contact tracing has been used to combat outbreaks of HIV, Ebola, a lot of other infections around the world. Have we learned anything about the right and the wrong ways to go about contact tracing from these decades of experience? I think what's important to highlight is perhaps you said earlier, you know, ordinary people are learning a lot about contact tracing now. it's a new concept for many people, but it's certainly not new to public health. And public health

experts, community health workers, disease investigation specialists, people have been doing this for a very long time and they understand its complexity. And so certainly, I think a way to not do things right would be to kind of erase that lived experience and scientific experience and knowledge and try to jump over it somehow thinking that technology could just no longer need the human factor. So I think knowing how to do contact tracing right just highlights some of the things we spoke about already, about remembering that people are involved, remembering that outbreaks are not just scientific events. There are human events where infections are in social context. There's a social science to this as well.

And so it's important to meet people where they're at, to adapt your efforts to the local community and to get at some of that kind of cultural humility. So Google and Apple have actually teamed up to offer this Bluetooth-based solution for people's smartphones. We'll tell each other when they've been in contact with someone who has a confirmed or suspected case. Other people are working on smartphone apps. Crystal, your report has called for technology to be part of the conversation. where does it actually fit into the Johns Hopkins vision at this point? Yeah, I think it has the potential to be helpful.

It has the potential to be a workforce multiplier for those large numbers of contact tracers that we need across the country. I do think that it can help particularly in a couple of aspects. The first is identifying additional contacts that someone who's sick with the disease may not remember they were in contact with. or may not know those people if they were out in a public setting. I think it can be helpful with that. It can also be helpful with identifying and contacting those contacts more quickly.

This virus moves very fast. The illness progresses quickly and the virus spreads quickly. So the faster we can notify contacts and ask them to quarantine safely at home, the less spread we're going to have. So by addressing those two issues, I do think technologies can be helpful. And Louise, you're working with the team at MIT that's building rules or protocols around how to do this smartphone tracing without violating privacy. Why is that part so important?

Well, I think there's two things maybe to highlight around this work at MIT that I've been involved with. One is actually that the Apple and Google approach right now would use Bluetooth energy to try to identify when phones have been in proximity to each other. And so I think the first step is trying to really identify the efficacy of that approach. It's not 100% certain yet that the information that would be made available, but that kind of technology is in the range of being medically relevant or public health relevant.

So it's important to try to understand the confidence with which we might be able to alert people so that we don't have too little of an alert so that we're detecting the right amount and that we wouldn't have a false alarm. The other piece of it, though, is really, as you said, centered around privacy. I mean, it's interesting because from a public health perspective, public health has authorities

to know confidential information in important outbreaks like this. And yet, it does that by establishing confidence, by being a trusted body. If we were to enable a technology that is pervasive, and held in the private sector to collect large volumes of information about who we associate with,

who we're in contact with, or where we go or other things, it certainly could be very concerning to collect all of that information in a database. So the group at MIT is led by Professor Ron Ravast, who's a cryptographer, and who really centers his ideas around the protocol

of using Bluetooth, for example, around the idea that it could be done in a way that was private and protected the privacy of individuals owning phones. I mean, is it possible to go too far in the wrong direction in preserving privacy? Does the Apple-Google partnership really give public health workers enough to work with? Crystal, what is your privacy slash information balance ideal? Yeah, so privacy is obviously very important to all of us.

My bias is slightly on the side of public health, where public, public. health officials and contact tracers really do need some more granular data to be able to identify cases and contacts, but most importantly, to support them. We've talked about enabling isolation and quarantine that's providing supplies, support for family members, whatever it takes to have those people be able to stay at home or stay isolated or quarantined safely. And so if public health doesn't have information that can identify people, then they cannot provide that service, which is, I think, core to this epidemic response. So I do think they need some information. I think it can be opt-in. This is very core to public health. They collect sensitive data routinely, and they know how to

handle it. And as long as they have the trust of the community, I think this is the balance that needs to be struck, that public health needs enough information to take action and support people throughout this pandemic. Trust keeps coming up in this conversation about public health and the ways in which public health efforts rely on trust. I know there was a study out of Oxford that suggested that we need something like 60% of a population to use something like a contact tracing app if it's going to be successful in giving meaningful information. Louise, I mean, as someone who, again, has done this contact tracing in person, And how do you see trust working into a more electronic version of that?

The trust will have to come when, you know, the public health authorities and officials find a technology that meets their needs, which I think relies on the efficacy of the technology to detect contacts and a low rate of false alarms, establishes a privacy balance that's appropriate and that's integrated into their workflows. and then public health can be, you know, connected into specific applications and then asking the citizens using the trust they have. And again, public health authorities do this. This is what they're trained for. This is what they have experienced doing. So the integration with that is the most important piece. Just a quick reminder. I'm Christy Taylor and this is Science Friday from WNYC Studios. Talking to Dr. Crystal Watson and Dr. Louise Ivers about public health, contact tracing, and the various solutions for doing so in coronavirus times. What about testing? Does contact tracing also need us to be testing people at a certain threshold? In my opinion, I think we need to be

testing anyone with COVID-19 like symptoms. Anything on top of that would obviously be an improvement, but I think that is the bare minimum. We need to be able to identify cases, symptomatic cases, and quarantine their contacts. Then if those contacts develop the disease, whether they're symptomatic or asymptomatic, they'll be quarantined at home. They won't be out in circulation. So that helps address the asymptomatic and pre-symptomatic transmission issue that we have here, which is very complicating for containing this disease.

So I do think that's the bare minimum. One of the problems we're having with testing right now, in addition to access, is that the testing is not very timely. So by the time a positive test comes back, it may have been three, four, five days since that person was tested. And if we wait to identify contacts and ask them to quarantine until that positive test, many of them may have already become infectious and gone out to infect others. So the timeliness of the test is very important too. So we're talking then about this human army of contact tracers, you know, 100,000 to 300,000. Is it as simple as hiring them and training them? Or, you know, is there more to this picture of building a contact tracing network beyond that?

I think it's going to be a complex and resource-intensive undertaking. We do need to hire people. We need to hire people quickly, but obviously they need to be trained very well. We need to hire the right people who have the skills to be very compassionate and to preserve privacy. They're good people, people. But they also have great fidelity with tracking and recording data and making sure that that data is maintained privately. So there are key skills that we need to look for. And then we also need to manage these workforce as well.

This is a lot of people that we're going to be hiring to do this work. And so there is going to need to be good management, good strategy, good technical support. And that's what hopefully we can look to the federal level to the CDC to provide some of that support. Louise. You know, one of the complexities is the, you know, in Massachusetts, for example, there are 351 boards of health. who do contact tracing. So we didn't really touch on how that adds to the nuance of this, right, that you had 351 different groups of people doing this

in Massachusetts alone. Because in some ways, I think when you think this seems simple, why don't we just do it? You know, there are a number of challenges to the implementation of it, but that does not mean that we could not do it. Just to respond to that, our call for contact tracing at a national level

really is for support and kind of a vision for contact tracing. We really wrote our report hoping to get the support at the federal level, both in terms of funding and guidance and training and technical support. But it's definitely not realistic to have one contact tracing army that's led at the federal level. That's just not how our public health system works. Anything else that you hope people keep in mind as we're embarking on this effort, Louise? There's no one single silver bullet to respond to this pandemic. We need comprehensive, integrated approaches to outbreak management and control. And so it's really important for any technology that comes about to realize that it's going to have to be integrated into that comprehensive approach.

And we talked about testing and contact tracing, identifying clusters, social, supports for people who are able to stay at home. So I think the biggest message is that we have to be ambitious about different approaches. We certainly can do it, but there's no single one thing, I think, that's going to get us there. We have to make sure that we're trying to do things in a comprehensive way. Well, thank you both so much for joining me. Dr. Crystal Watson is a senior scholar at Johns Hopkins University's Center for Health Security and Dr. Louise Ivers, executive director of Massachusetts General Hospital Center for Global Health. Thank you very much. Thank you.

After the break, the last full supermoon of the year happened last night. We'll give you some lunar gazing tips, and we'll talk about a new moon map. We'll be right back after this short break. This is Science Friday. I'm John Dan Koski. For centuries, we've been trying to get a better understanding of the surface of the moon. Different cultures have imagined faces, rabbits, and even toads hiding in the rocky features. Astronauts have, of course, walked on the lunar terrain, bringing back. photographs and rock samples, and there have been 21 total moon landings, the most recent last

January when China successfully put a lander on the far side of the moon. There are countless scientific observations of the moon, but how are researchers using all of this data to fill in the picture of the lunar surface? Science Friday producer Alexa Lim tells us more. When you think of space exploration, the U.S. Geological Survey is probably not the first agency that comes to mind. The U.S.GS scientists use their efforts. expertise in mapmaking to catalog the geology of the moon. They stitched together six Apollo era moon maps combined with modern satellite data to create a 360 degree view of the geological structures on the moon. Last month, the agency published what they called the Unified Geologic

Map of the Moon. James Skinner is one of the creators of that map. He's a research geologist with the U.S. Geological Survey's Astrogeology Science Center. Welcome. Thank you. I didn't realize that The USGS had an astrogeology wing. Why is the USGS particularly equipped to map places outside of the Earth? I think we're particularly equipped to do it just because we are a geological survey, and what geological surveys do is explore and put things onto a map. So this is a compilation of six different maps that were created at one to five million scale. So that means one millimeter on the map is five million millimeters on the ground, and that's equal to one kilometer.

often if you have boundaries where different people are mapping different areas. When you cross those boundaries of the maps, you'll have kind of discrepancies. This is very common for geologic mapping that happens on Earth and happens at different scales on multiple bodies. And so this new map that was put out is an attempt to reconcile all of those six different maps and coordinate them and refine them and put them into one unified global geologic map of the moon. So is it fair to call you a celestial? cartographer? Celestial cartographer, to me, would kind of imply the star. So I would prefer astrogeologist.

Astrogeologist. Okay, that works. So the first thing that caught my eye were all the colors on the map. It looks like one of those giant jawbreaker candies. So what do all the colors represent? I love the intersection of science and technology with art and rendering something that is technically complicated into a way that we can all use it and perceive it. And that's what geologic mapping to me is.

It's a piece of art, and it's the intersection of art and science. So the colors on this map, which are many, they kind of break down on time scheme. So the colors that are being represented are basically age groups. And the youngest ages that you see on this map are yellows. And those are derived from Copernican age craters, which are about a billion years old or younger. So a billion years and younger, and we're talking about that being the youngest age. So there's kind of a difference on what we think of as being young, what we're talking about. things that are off of this world.

So the next kind of, you go back in time and you're kind of stepping back into time is these Palestinian craters which are green. And then you go back in time, you have these embryon age craters and those are usually depicted in blue. And then you have these browns and kind of these tan colors. And those are the nectarian and pre-necterian units. And those are the ones that are, you know, 3.9 to 4.5 billion years old. So really primordial, really ancient, kind of crustal rocks.

And so that's kind of the background of all the different crater terrains. And then superpos on top of that, you have these really pink and bright and warm colors. And those are the younger age basalts or lavas that have erupted onto the surface and filled in the lower parts. These kinds of units, these warmer units occur in the centers of impact craters. And I guess it makes sense, but I didn't realize there were geologic eras on the moon. they're on Earth, how many geological errors are there on the moon? There are four. And then there's kind of an extra one to squeeze in there called the pre-necterian.

So if we go from right when the body was formed, so four and a half billion years ago, that's in time called the pre-nectarian. And then there's the nectarian, and then there's the embryon, and then there's a Erastinian, and then there's the Copernican. And all of these are named for impact craters and basins on the moon. So the Copernican is obviously named for the Copernicus crater. The Erastinian is named for Peritostanis crater. And the embryan is named for Mari Embrym, which is the Sea of Rain or the Sea of Showers.

Interestingly, all three of those impact craters are on the lunar near side. They've been studied in detail and they all overlap one another. And that's really interesting because they sent the boundaries for these divisions, these kind of chronologic divisions on the moon. So we can see those. And you see bright things on the moon. They're either the highland materials, and typically the highlands are composed of a lot of impact craters.

Impact craters on the moon, if they're younger, they have rays. It's a really bright rays that are coming from them. But over time, those rays darkened because they've just been pummeled by cosmic radiation and solar radiation. So things that have rays are going to be young. That's geologically speaking young, but they're going to be typically Copernic and an age. So Copernic is the largest, brightest crater that still has some rays to it.

And I was looking at this morning, and there's over 10,000 discrete bodies of rocket are identified on this map. So 10,000 little circles and polygons. So that's what this map does a really good job. It unifies everything, but it also starts subdividing those different units and placing them in the correct time scheme. Like you said, you know, you found 10,000. different, I guess, units on the map.

Can you kind of take us through some of the specific ones, like navigate us through some of these interesting patterns or correlations that you saw on the map? Yeah, sure. So I think one of the most interesting groups of units that are on this map are what's called the Oriental group. And it is named for Mari Oriental, which is, if you're looking at the map, I've got a flat map here that's on the wall that I'm looking at. And it's kind of these blue impact crater units that are kind of in the central

kind of western side of the map. And so this is a really good expression of what this map is trying to do. And so it shows those units, they're called the Oriental Group, and it's a pristine example of overprinting, that is cross-cutting relationships that result from a very large impact crater. And so this crater is so large that it's not even a crater anymore, it's actually a basin. And if they get to be this big, there's multiple rings. So it doesn't have just one rim. It's so big that it has multiple rings around it, it formed the rim. So this is a really good example of when you have a large impact crater, it basically resets everything around it.

There's so much rock and material that's being ejected from this one place on the moon. Way back when this impact crater formed that it is spreading out all this ejected material all over this region of the moon. It's basically resetting everything. You kind of look at it like an etch-a-sketched. So this region of the moon was etch-sketched away, and then it kind of reset the timing. So all the things that are sitting on top of that are the younger pieces. So that's a really interesting, kind of one of the key places that we look at and understand the temporal sequencing and how it can kind of fits together in both time and space.

Your next map, you're going to zoom in and make more detailed map of the south pole of the moon. Why are you focusing there? The south pole is interesting because it has regions that are permanently shadowed. And in those permanently shadowed regions, we understand there to be ice to place. So isoposets are going to be critical for exploration, and so it's important for us to start understanding what the distribution of geologic terrains are in those areas. So those four of us mapping it, we each have a little pie piece that we're mapping, and what we're trying to do is take this map that was produced and try to adapt those units that are identified there at 500,000 scales. So this is a perfect example of utility of this kind of product, is extrapolating out into local scales. We want to understand, so we're seeing these kinds of different kinds of terrains,

and we want to be able to see how they all fit together. So we might be able to get a little more information about where we might send, you know, the next generation of explorers. When we send robots and our next explorers there, whether they're robots or humans, we will use this map to start to winnow down the regions that we'll go to. We're not going to be able to select sites specifically from this map, just because the scale is so different. It's the global map.

But what it does allow us to do is to start focusing in on those regions. And it also lets us start to understand, you know, what and where particular resources might be. And resources mean different things. It can be solar illumination that we need to have for powering things. And if something is stable enough, if the rock terrain is stable enough to be able to take some kind of solar cells, it allows us to identify where aggregates might be that we need to push together, lunar bulldozer to be able to protect a habitation unit. So it allows us to start seeing those kinds of things and what materials and what

resources might be there, where they would be, and distribution of them, and how much there might be. Okay, so you have this map of the moon. You've also worked on a map of Mars. If you could choose anywhere else, inside the solar system, outside the solar system, wherever, where would you personally want to map next? So you're saying besides the moon or Mars? Yeah.

that's hard. So I think that Venus is really interesting because I like these terrestrial bodies. So those are the bodies that kind of sit inside the Ashford belt and the inner solar system. Because they seem like they fit on a continuum of kind of Earth-like planets. So even the moon that looks kind of alien when we look at it from a geologic mapping perspective. It's kind of like a frozen little mini-Earth. Venus is kind of on the other side of Earth where it has a runaway greenhouse effect. is a little bit larger than the earth. It has massive volcanism. The cross is apparently smashing

into each other and forming really large mountain chains and big fractures. And so Venus is a nice place to do this kind of work as well. Because there's some really interesting features to identify. All right. Well, we'll have to keep an eye out for it. Please do. All right. Well, thanks so much for joining us. Thank you so much. It was a pleasure. James Skinner is a research geologist with the U.S. Geological Survey's Astrogeology Science Center, and we have that map up on our website at Science Friday.com. Now, if you want to be able to spot those mountains and highlands for yourself,

my next guest is here to give us some moon viewing tips. Michelle Nichols is Director of Public Observing at the Adler Planetarium in Chicago. Welcome. Thank you. So for someone just starting out, the beginner moon gazer, what feature should you look for to help navigate and orient yourself on the moon? Well, the first thing to do is to figure out when the moon is actually going to be visible. So if people are not familiar with moon phases or when you should go out, best advice I can give is to look up the date of new moon.

And so that means the moon is in the same direction of the sky as the sun, so you're not going to see it. Then maybe a couple of days later, if it happens to be clear, go out right around sunset, look to the west, and you'll see a very tiny sliver. And so after that date, then the moon is going to continue to move in its orbit around the earth, and you'll see more and more of the moon lit up by the sun. And so then that way you can then get a sense of what you're going to be seeing from one night to the next. And then when you get to full moon, which is about two weeks after new moon, that's when you can see the full entire moon, the entire side that faces us, You can see those light areas and those dark areas.

That's a great time to really start to get to know the moon. Right. And should you grab a moon map? Is that helpful to help you look at things? Yeah, it's sometimes it's helpful. So just a simple moon map. If you don't have a telescope or a pair of binoculars, then just getting to know those light areas, those dark areas,

those dark areas are hardened lava regions and the lighter areas are mountains. So that's a great time to get to know those regions. and then when you do have a small telescope or a pair of binoculars, then you could start to see some craters and some other features. There's a way to kind of see sunrise on the moon? Yeah. So when you're looking at the moon and you see there's a dividing line between light and dark. And we call that the Terminator. And if you were standing on that line between light and dark,

you would be seeing either sunrise or sunset on the moon, depending on where the moon is in its orbit around the Earth. And so where you would be there, the shadows would be really long, just like they are here on Earth when it's close to sunset. And the closer we get to sunset, the shadows get longer and longer. So that would be what you would be seeing if you were standing on the moon. And then if you're looking at it through telescope or binoculars, you can see these long shadows.

You can see little bits right on that Terminator. that have been lit up by the sun, but other bits haven't experienced sunrise yet. And when you look the next day, you can see other little bits that have been lit up by the sun. So it's really neat to explore because the moon looks rather 3D at that point. And so it really becomes a place to look at at that time. I'm Alexa Lim, and this is Science Friday from WNYC Studios. And sometimes when you walk outside, it looks like the moon has overtaken the entire sky. This is due to something called the moon illusion. What is that? People probably notice this quite a bit. If you see the full moon and it's really, really close to the horizon, it may look enormous. And then when you look at it a few hours later and it's higher up above the horizon, not quite so big, but it is an illusion. It's your brain trying to reconcile stuff that's close by you, some trees, houses, buildings. And then the moon, which your brain knows is far away. So what you

you can do to kind of test this out right when you see the moon as close to the horizon as you possibly can. And we're talking full moon is when this shows up best. Look at it. Stick your thumb out at arms length. Hold your arms straight out. Stick your thumb out. Close one eye. Compare the size of the full moon to the size of your thumb. And then do that again a few hours later. And I'm going to have to give the punchline to it, but it'll be the same size. And it's really kind of freaky when you see that for the first time and you really compare it to something standard like the size of your thumb. So try it out. It's kind of fun and kind of weird. Next week, you're joining Science Friday for a live stream to talk about our other favorite

celestial neighbor, the sun. What will you be doing during that event? Well, we are going to be talking about viewing the sun safely through a telescope, some features that are visible on the sun. We're going to be inviting folks to make artwork that is inspired by the sun and share those images with us as they're making them. It's going to be a lot of fun. We're going to connect to objects in the Adler Planetarium's historic collection. So there's going to be a lot of accessibility points for many people to enjoy our other really important celestial neighbor, the sun. Great.

Well, thanks so much for joining us. Thank you so much for having me. Michelle Nichols is the director of public observing at the Adler Planetarium in Chicago. And you can join Michelle at our online event next week. It's in all ages astro artist club next Tuesday, May 12th at 7.30 p.m. Eastern. You can sketch and learn more about the sun. You can find more information on our website at science friday.com slash astro club. This is Science Friday. I'm Alexa Lynn. If you missed any parts of this program or would like to hear it again, subscribe to our podcasts, or you can ask your smart speaker to play Science Friday. Every day is Science Friday these days. And on the Science Friday Vox Pop app, we want to hear about your home food fermentation projects. Are you making kimchi in the closet, beer in the basement, or yogurt in the pressure cooker? Let us know on the Science Friday Voxpop app, wherever you get your apps.

Say hi to us on social media, Facebook, Twitter, Instagram, or you can email us. The address is SciFri at ScienceFri.com. Send feedback and tell us what you'd like us to cover, too. Ira's back next week. I'm John Dankoski.