NOVA Science Trust Logo

Slime molds are enormously diverse, coming in all sorts of colors, shapes, and textures. Image Credit: Melissa McMasters, Flickr

Eight smart things slime molds can do without a brain

<p>Once you’ve seen a slime mold—its gooey, delicately branching structure oozing in a vaguely unsettling way along a log or leaf—you’re unlikely to forget it. They’re unmistakable because there’s nothing else quite like them. </p><p>Slime molds branched off from the evolutionary tree before animals split from plants and fungi. And they don’t quite fit into any other group: Some live as individual cells but come together and work as a group when conditions are right. Others are huge single-celled organisms that can grow to be several feet across and contain thousands (sometimes millions!) of nuclei with no membrane between them.</p><p><i>Physarum polycephalum</i> is perhaps the best-known slime mold, thanks to its distinctive bright yellow color and the fact that it’s easy to grow in a lab—and much of what we know about slime molds comes from research with <i>Physarum</i>. “I think they’re quite beautiful, really,” says ecologist and entomologist <a href="https://www.sydney.edu.au/science/about/our-people/academic-staff/tanya-latty.html">Tanya Latty</a>, who has worked with slime molds extensively in her Sydney, Australia, laboratory, of <i>Physarum</i> and its compatriots. “They have these lovely patterns of veins, a fractal look to them.” She even likes the way they smell—vaguely fruity. </p>
<div class="related"></div>
<p>Latty refers to them affectionately as “little slimy aliens.” And those aliens are everywhere. There are at least 900 species of slime mold in the world, some with colorful nicknames, like ‘dog vomit’ and ‘witch’s butter.' They love wet, temperate forests but live just about anywhere, including in huge numbers in soil. </p><p>Much of slime mold research has its roots in Japan, in part because <a href="https://www.popsci.com/emperors-love-slime-mold/">Emperor Hirohito</a> himself was a biologist who loved slime molds and even discovered a new species. While we still know little about how slime molds behave in the wild, lab research has turned up some surprising things about their capacity to do, well, anything at all. <i>Physarum</i> and other so-called “acellular slime molds” (named for their many free-floating nuclei) are super gross, super cool organisms with no brain or nervous system—yet seem somehow capable of learning and making choices. Read on for a list of eight of their slime mold superpowers.</p>
<h3><b>1. They can smell food</b></h3><p>We humans have receptors in our noses that detect chemicals wafting off of food into the air. Slime molds have almost the same thing: receptors all over their cell body that detect chemical cues that tell them food is nearby.</p><p>And it doesn’t stop there. A slime mold actually has many different types of receptors, each attuned to a different cue in its environment, such as moisture or pH. They can even detect light using photoreceptors similar to those in our eyes. That means that even though it is a single cell, a slime mold has something akin to eyes and a nose. </p><h3><b>2. They can pulsate their way to that food</b></h3><p>Here’s where things get gross—and cool—thanks to a transportation system not really found anywhere else in nature.</p><p>Within the blob of a slime mold sits a network of veins. Long proteins encircle those veins, and crowds of nuclei stream through them in a thick goo called “protoplasm.” The proteins squeeze and relax, pushing the protoplasm through the veins to the “growth front” of the slime mold, or the part that’s moving forward.</p><p>The sensory receptors on a slime mold’s surface are constantly pulsing in response to the signals they’re receiving, and this rhythm creates that flowing ooze. Once a receptor detects food, it starts pulsing faster. And since the inside of a slime mold is essentially one big fluid dynamics experiment, when the pulses quicken, the protoplasm starts to flow in the direction of the food—and the slime mold follows. That means a slime mold is totally decentralized: no brain, no problem.</p>
<figure class="richtext-image full-width">
<img alt="Edge of a yellow slime mold" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Physarum_growth_front.width-990_ju4eSk5.jpg"/>
<figcaption><p>Close-up view of a growth front of a<i> Physarum polycephalum</i> slime mold. Image Credit: Norbert Hülsmann, Flickr<br/></p>
</figcaption>
</figure>
<p></p>
<h3><b>3. And they can devise the best route to their meals </b></h3><p>“That you can do experiments on something that looks like a brainless ball of mucus is incredible to me,” Latty says of slime mold science. “I find it fascinating that it can do anything at all.”</p><p>But, as it turns out, it can! If you put a slime mold in a maze and put oat flakes—one of its favorite foods—at the entrance and exit, it will slowly search the labyrinth until it finds the shortest path from one end to the other, allowing it to munch on both snacks at once. It can perform much more complicated versions of this task, as well, in one case connecting 37 different points. (Note that the number of possible ways to connect 37 points is somewhere in the neighborhood of an eight, followed by 54 zeros. That is quite the oozy calculator.)</p><p>In a famous experiment, researcher <a href="http://www.cris.hokudai.ac.jp/cris/en/research/ob/ob_innovative/nakagaki.html">Toshiyuki Nakagaki</a> and his team gave their slime mold a real-world problem: Find the most efficient transportation network in the greater Tokyo area. Arranging oat flakes to represent key towns and cities, they put their slime mold in the center where Tokyo would be. The result <a href="https://www.wired.com/2010/01/slime-mold-grows-network-just-like-tokyo-rail-system/">looked an awful lot like the actual Tokyo rail</a> system.</p><h3><b>4. They can re-form if they get torn apart</b></h3><p>One of the genius elements of a slime mold is its protoplasm. Each tiny bit is interchangeable, meaning that every individual protoplasm unit can become a vein or a pseudopod—the temporary, limb-like projections that extend out in the direction the slime mold is moving—or any other part of a slime mold. That is, except for its organelles, which seem to be fixed as one thing, even as they slosh around inside the slime mold.</p><p>That’s why it was possible for a team of <a href="https://www.researchgate.net/profile/Hans-Guenther_Doebereiner">researchers in Germany</a> to shred slime molds into thousands of tiny fragments—only to watch those bits slowly join back together. Compared to other single-celled organisms, slime molds barely have membranes at all, Latty says. “It’s just this flowing gooey stuff that happens to stick together. So if you cut one into two bits and put them near each other, they just flow together again.”</p><p>So can you kill a slime mold? It’s hard to say. There’s a beetle that eats slime molds, and a handful of other slime mold predators, but “we don’t know if they eat enough of the body to make a difference,” she says. “You could lose half of the biomass, and it wouldn’t matter. It would just reorganize itself and be like, ‘I’m fine!’”</p>
<div class="ad"></div>
<h3><b>5. They can choose a healthy diet</b></h3><p>In her research, Latty found that slime molds will move toward a substance like sugar and will also move away from substances like salt. But was this just a response to stimuli, or something else?</p><p>Answering this question proved complicated. “When I design an experiment for a bee, I know that it can smell, what range of colors it can see, and to work with a particular behavior,” she says. But slime molds’ worlds are profoundly different than ours. “Something that’s amoeboid, can be cut up into little bits, and you have no idea what its perceptual reality is—that’s difficult to design for.”</p><p>To learn more about slime mold nutrition, Latty helped her colleague <a href="http://dussutou.free.fr/">Audrey Dussutour</a> presented <i>Physarum</i> with 35 recipes made of different ratios of the elements it needs to survive, protein and sugar, creating a kind of slime mold creme brulee. They found that slime molds will avoid food sources that will harm them and prioritize food that will help them.</p><p>And not only that, but slime molds can also stretch out tendrils to feed on more than one food source at a time—and do so in the right ratio, so that they receive optimum nutrition. “It’s not just getting protein or carbohydrates, they try to get a particular balance,” Latty says. While animals might balance their nutrition by switching up what they’re eating, slime molds divide their biomass over the food so they’re taking what they need from each.</p>
<figure class="richtext-image full-width">
<img alt="Reddish slime mold beads on log" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Carnival_candy_slime_mold.width-990_BpErbVw.jpg"/>
<figcaption><p>Carnival candy slime mold (<i>Arcyria denudata</i>). Image Credit: Mary Keim, Flickr<br/></p>
</figcaption>
</figure>
<p>In another of Latty’s favorite studies, she looked at how slime molds make tradeoffs between quality and risk when it comes to their meals. In that experiment, the slime mold had to choose between high-quality food in bright light (which slime molds don’t like) and lower-quality food in darkness. Then she and her colleagues changed up the choices—in some cases having the slime mold choose between very similar foods in light and dark, and in others creating more contrast. </p><p>“If you’re a basic system, you’d expect you always choose one,” she says. “You have a simple rule that always works. If you’re sophisticated, you get some information about quality of food and intensity of light and do some calculations to figure out if it’s worth it.” Latty’s slime molds fell definitively in the latter category: They were much more likely to venture into the light if the food quality was five times better than the one in the dark. “That implies slime molds are able to process information between two different attributes of a food source, which seems like a pretty sophisticated thing for, well, mucus,” she says.</p><h3><b>6. They can “remember” where they’ve been, by leaving themselves gross, slimy breadcrumbs</b></h3><p>Another study that Latty helped her colleague <a href="https://chrisrreid.wordpress.com/">Chris Reid</a> complete found that, in searching for food, slime molds rarely retrace their steps. Could they remember where they’d been? The answer was written in slime—like the stuff that slugs leave behind. Just as ants leave trails of pheromones to show where they’ve found food, this slime is a form of “external memory” that tells the slime mold: search elsewhere. </p><p>Realizing that slime molds could functionally “remember” things without a brain changed Latty’s perspective on many life-forms’ capacities to interact with their environment. “It opened my eyes to the fact that <a href="https://www.quantamagazine.org/the-thoughts-of-a-spiderweb-20170523/">brains are not the be-all-end-all</a> of behavior,” she says.</p><p>And that has big implications for lots of small organisms. “Slime molds are good representatives because they’re big enough and easy enough to work with. We don’t know if they’re the oddballs. I suspect not.”</p><h3><b>7. They can “get used to” situations and remember things even</b> <b><i>without</i></b><b> leaving a trail</b></h3><p>Many more advanced organisms are capable of habituation—that is, they can get used to difficult things in their environment, especially if they’re rewarded for it. But what about slime molds? Latty helped Dussutour set up an experiment in slime mold habituation for a slime that they christened “Blob.” They would put Blob on one side of a little bridge, food on the other, and coat the bridge with salt, which is unpleasant for Blob and its slimy compatriots, but not harmful.</p><p>Under normal circumstances, it would take an hour for a “control” slime mold to cross an unsalted bridge and claim its prize. The first day of Dussutour’s experiment, it took 10 hours for Blob to cross the salty version. The next day it took 8 hours. And the day after that it completed the journey in even less time—until eventually Blob could cross the salted bridge as fast as the control bridge. Blob had “gotten used to” salt! Dussutour repeated the experiment thousands of times and got the same results.</p><h3><b>8. They can teach their friends what they’ve learned</b></h3><p>After that, Dussutour started wondering whether a Blob that had learned to deal with salt could teach other Blobs the same. One key, gross fact here is that Blobs stick together—literally. If you take two slime molds and put them next to each other, they’ll combine. Their membranes fuse, they open up their insides, and their veins intertwine to create a new single organism.</p><p>Over time, the team found that if they let slime molds that had learned to tolerate salt socialize with slime molds that hadn’t for three hours, they would wind up with all slime molds that like salt. “It makes you think: What even is learning? Does this count?” Latty says. “It sits right there in that grey zone. It’s thought provoking.”</p>
<div class="cove-video">
<iframe allowfullscreen="" class="inline-cove-player" frameborder="0" height="100%" id="partnerPlayer" marginheight="0" marginwidth="0" scrolling="no" src="//player.pbs.org/partnerplayer/3CHUp_qyT_WUv1r5ddqmaw==/?topbar=false&amp;end=0&amp;endscreen=true&amp;start=0&amp;autoplay=false" width="100%">
</iframe>
</div>
<div class="newsletter"></div>

<p>From remembering where they’ve been to recreating the Tokyo rail network, these “slimy aliens” are capable of way more than we give them credit for.</p>

Ecologist Dominique Gonçalves observes a female lead elephant in Mozambique's Gorongosa National Park. Image courtesy of Dominique Gonçalves

The secret to peace between elephants and farmers in Mozambique? Bees

<p>The elephants of Gorongosa National Park are notorious troublemakers: grain tramplers, crop stealers, silo destroyers. Given the chance, they will cross the river that acts as a southern boundary between Gorongosa and the rest of rural Mozambique, and raid nearby villages in search of a snack. The materials the community usually uses to build storehouses are “nothing for an elephant,” says <a href="https://gorongosa.org/dominique-goncalvez/">Dominique Gonçalves</a>, an elephant ecologist at the park.</p>
<div class="related"></div>
<p>In a way, this problem is a sign of success. During the Mozambican Civil War, which stretched from the 1970s into the 1990s, Gorongosa lost more than 90% of its 2,500 elephants. But as of 2019, the population had recovered significantly, reaching 600—and some of its younger males had begun to wander out of the park looking for food.</p><p>As one of Gorongosa’s keystone species, the park’s elephants interact with their environment in a way that is essential to its health. The trees they knock down on their daily walks provide shelter for antelopes and exposed roots for porcupines; the seeds from the huge amounts of greenery they eat are dispersed in their dung, which in turn provides food for dung beetles. Still, “people need their space to have their schools, their markets, their farms,” says Gonçalves, who grew up a few hours away from Gorongosa in Beira. And when people’s ability to meet those basic needs is disrupted, serious conflict can break out. They’re less likely to cooperate with conservation efforts in that case—and in other parts of Africa, communities frustrated by elephants’ raids have killed them in retaliation.</p><p>The solution Gonçalves and her colleagues found is simple and elegant. Using a technique developed in Kenya, they built a series of fences made from beehives strung with twine across the most heavily trafficked river crossings. “Most things in the natural world are ruled by fear and risk aversion,” Gonçalves says. Elephants are afraid of bees, whose stings can be especially painful on their sensitive ears. A pilot study published this year showed that the presence of a <a href="https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/conl.12679">beehive fence</a> reduced the odds of an elephant crossing the river by 95%. This idea—that an animal’s perception of danger influences where it spends time, leading to a cascade of effects on its larger ecosystem—is known as the “landscape of fear.”</p>
<figure class="richtext-image full-width">
<img alt="Beehives strung between fence posts" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Beehive_fence_1.width-990_9jqRgwH.jpg"/>
<figcaption><p>Beehives strung between fenceposts deter elephants from crossing onto farmers' field near Gorongosa National Park in Mozambique. Image courtesy of Dominique Gonçalves</p>
</figcaption>
</figure>
<p>Most wild landscapes have certain elements in common: food, shelter, water sources. “Those things are easy in principle to map,” says <a href="https://eeb.princeton.edu/people/robert-pringle">Rob Pringle</a>, an ecologist at Princeton University. “But the other element is, where does the animal feel safe? That is a trickier thing to make tangible.” To put it in human terms, he says, you might avoid a dark alley at 3 a.m. because you perceive it as high risk but find a busy public park at noon to be comparatively safe.</p>
<p>As it happens, Gorongosa is also the site of a much bigger project exploring this concept. Elephants were not the only animals in Gorongosa that suffered during the Civil War. Almost all of the area’s large carnivores—hyenas, wild dogs, leopards—had their local populations wiped out. But the landscape itself remained undamaged. That meant the remaining herbivores, including baboons and a variety of antelope species, bounced back fairly quickly once the war ended.</p><p>The result was an exceptionally low-risk setting for these herbivores, and over the next two decades they began to behave accordingly. Baboons, which normally sleep in trees, began sleeping on the ground. Warthogs stopped digging holes, holes that are normally important habitat for other species. And a type of antelope called a “bushbuck” began leaving the cover of the bush to browse more nutritious plants on wide-open plains that were normally too dangerous. This access to better quality food caused the bushbuck population to skyrocket.</p>
<div class="ad"></div>
<p>Before Steven Lima and Lawrence Dill <a href="http://gambusia.zo.ncsu.edu/readings/Lima%20and%20Dill%201990.pdf">proposed</a> the landscape of fear theory in the 1990s, prevailing ideas about ecosystem dynamics were much more simplistic: more predators means more prey killed, and fewer predators means more prey survive. “The default idea was that carnivores kept plants healthy by keeping herbivores at low abundance,” Pringle says—and, of course, that’s true to an extent. But that idea, he argues, misses part of the predator-prey dynamic by ignoring how prey animals change their behavior in response to their predators while they’re still alive. The outcomes are similar, but the mechanism is totally different.</p><p>Looking to substantiate the theory, Oz Schmitz of Yale University famously <a href="https://science.sciencemag.org/content/319/5865/952/tab-figures-data">showed</a> that the presence of spiders in a cage with grasshoppers was enough to modify plant growth as the grasshoppers changed their diets—even when Schmitz altered the spiders’ mouthparts so they couldn’t hunt the grasshoppers. In a similar experiment with <a href="https://esajournals.onlinelibrary.wiley.com/doi/10.1890/11-0424.1">crabs and snails</a>, just the scent of a crab was enough to cause snails to change their feeding behavior. Many scientists also see this dynamic at play in willow and <a href="https://www.yellowstonepark.com/things-to-do/wolves-bring-yellowstone-back">aspen resurgence</a> in Yellowstone National Park after the reintroduction of wolves there in 1994 changed the behavior of the elk that eat those trees. And in Gorongosa, a study by Pringle and several colleagues <a href="https://science.sciencemag.org/content/364/6436/173">showed</a> the bushbuck could be encouraged to avoid areas of the floodplain with a combination of recorded leopard calls and synthetic big cat urine, a dynamic that intensified when they began reintroducing groups of African wild dogs to the park in 2018.</p><p>That change, in turn, affected plant life in Gorongosa. Herbivores like bushbuck and elephants shape their environments by transplanting nutrients in their urine and feces, by eating young plants and cropping leaves, by trampling their way through underbrush. And where an antelope feels safe “is where it’s going to spend a lot of time feeding,” Pringle says. “So the impact of that animal on plants is going to be stronger in areas where it feels safe.”</p>
<figure class="richtext-image full-width">
<img alt="Girls with tranquilized elephant" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Girls_with_elephant_Ls8bwR2.width-990_thwRsXu.jpg"/>
<figcaption><p>Dominique Gonçalves and girls from a local community gather with a male elephant that has been tranquilized so it can be fitted with a GPS collar. Image courtesty of Dominique Gonçalves</p>
</figcaption>
</figure>
<p>Watching the Gorongosa elephants carefully since the start of the park’s beehive fence project, Gonçalves has noticed some unusual behavior. “Sometimes I’ll see them walking along the fence, touching it carefully, and going away,” she says. “Sometimes they just stand and stare at the fence, and I wonder if they’re analyzing what it’s going to do.”</p>
<p>Not all methods of elephant defense remain effective over time, as the elephants often habituate or learn ways around them. But the fences continue to be effective for now, and Gonçalves and her colleagues hope they will remain so, since pain and fear are such innate and powerful motivators. They’re now working to expand their project, which they hope will grow to involve 600 beehives this winter. (The lengths of the fences themselves vary. Some are just a couple of beehives strung together, but one particularly wide spot involves a dozen.)</p><p>Fear works better than a plain physical barrier, Gonçalves says, because “it works with the mind, with the behavior of the elephant.” In that way, the project sets an important precedent for future conservation in Mozambique—a non-lethal method of control that doesn’t create unnecessary divisions between the community and the park. “That kind of old, fenced conservation may not be really what we want,” she says, because it sends the wrong message to the people who live next door: “That’s the national park, and that’s us. There’s no connection at all.”</p><p>The beehive fences also bring alternative income for these communities (which sell the resulting honey), helping to rebuild relationships between them and their elephant neighbors. “As they come with us, they start to realize that these aren’t just ‘park problems,’” she says of the community members who have joined her team. “They start to realize everyone has a role.” She’s especially proud to have recently hired 15 women, when previously there was only one. “We’re very strongly encouraging women to join,” she adds, “to change perceptions about what women can and cannot do; to remind them what it means for all of us to have our natural heritage and this wildlife around us.”</p>
<div class="cove-video">
</div>
<div class="newsletter"></div>

<p>Scientists use animals’ “landscapes of fear” to set limits and reestablish balance in Gorongosa National Park, where top predators were wiped out.</p>

Less-invasive ventilators use a mask rather than a tube inserted into the patient's throat. Image Credit: Juanmonino, iStock

Covid-19 patients sharing ventilators is possible—but not ideal

<p>On March 20, as severe cases of COVID-19 spiked in northern Italy, emergency medicine doctor Marco Garrone paused during a chaotic shift <a href="https://twitter.com/drmarcogarrone/status/1241135134188937218?s=20">to tweet</a> a photo: two patients, next to each other in hospital beds, with arcs of tubing connecting them to the same ventilator. “This is what we are down to,” he wrote. “Splitting ventilators, and facing serious dilemmas like choosing who will be actually ventilated when everybody should. <a href="https://twitter.com/hashtag/TakeThisSeriously?src=hash">#TakeThisSeriously</a>”</p><p>A month later, as caseloads skyrocketed across the pond in New York City, Columbia Presbyterian Hospital hurried to draft protocols for ventilator sharing. And around the same time, an emergency medicine doctor in Michigan named Charlene Babcock posted a <a href="https://www.youtube.com/watch?v=uClq978oohY">YouTube tutorial</a> featuring step-by-step directions on how to modify a ventilator so it can accommodate multiple patients. That video racked up nearly a million views in the ensuing weeks.</p>
<div class="related"></div>
<p>“Here’s my disclaimer,” Babcock says to the camera. “This is off-label use of the ventilator.” But, she adds, extreme circumstances may call for measures that otherwise would be deemed too risky. “If it was me, and I had four patients—and they all needed intubation, and I only had one ventilator—I would simply have a shared discussion with all four families and say: ‘I can pick one to live, or we can try to have all four live.’”</p><p>The appearance of ventilator sharing (or “coventilating”) this spring in places where the novel coronavirus has hit the most severely prompts a number of questions: How does a ventilator work? Why is it possible for more than one patient to use a ventilator at once? And if it’s possible, why aren’t more doctors in hard-hit areas doing it? Good news: This is the first in a NOVA series answering burning coronavirus questions just like these.</p>
<div class="pullquote">
<p>Have a COVID-related question for us? Follow the #CovidQs hashtag on Facebook and Twitter to submit your inquiry or ask us on Reddit @novapbs.</p>
</div>
<h3><b>How do ventilators work? </b></h3><p>Treating a patient in extreme respiratory distress is “like staring out the window and seeing people free fall,” says Albert Kwon, an anesthesiologist at New York Medical College. Doctors don’t know how long their patients have been “falling” or how long they’ll continue to fall without intervention; they must make an on-the-spot assessment about whether a parachute is necessary.</p><p>In that case, they can choose from several options, ranging from less to more invasive. All ventilators provide oxygen and promote its absorption in the bloodstream while also helping rid the body of the resulting carbon dioxide. The ones you’ve probably heard the most about during the COVID-19 pandemic provide a stream of air into the lungs via a tube inserted into a patient’s throat.</p><p>This stream of air exerts positive pressure, which is the opposite of how breathing usually works. When we breathe in on our own, our diaphragm muscles move down in our chests, increasing available space and creating an area of <i>negative</i> pressure that causes air to rush in. (There is one ventilator that works on negative pressure, which you’ve probably heard of: <a href="https://amhistory.si.edu/polio/howpolio/ironlung.htm">the iron lung</a>.) </p>
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/mouselungs.width-990_k2SexPP.jpg"/>
<figcaption><p>High-magnification images show the surface of alveoli in healthy mouse lungs (left) and lungs with ventilator-induced damage (right). Image Credit: Kate Hamlington Smith, University of Colorado School of Medicine</p>
</figcaption>
</figure>
<p>One reason COVID-19 patients need to use ventilators is because their lungs become so stiff that the diaphragm isn’t strong enough to complete its normal movement, causing breathing to slow or stop. Ventilation also keeps the lungs inflated while they heal. That’s important because inflamed capillaries in sick lungs can leak a protein-rich fluid, increasing surface tension in the liquid that normally coats the lungs and making them vulnerable to collapse. </p><p>But even healthy lungs are at risk during this process, because their tissues are not usually subject to positive pressure. That means that getting pressure levels wrong during ventilation can be dangerous. Too low, and a patient doesn’t get enough oxygen. Too high, and the lungs can become overinflated, causing their tissue to tear.</p><p>At first glance, the ventilator used in the most severe COVID-19 cases looks fairly simple: a tube that goes down the patient’s throat, two hoses that connect the tube to the machine itself (one for pushing air into the lungs and one for bringing carbon dioxide back out of the body); seals, valves, and filters to keep gases moving in the right direction; and a central case. But inside that case lives a much more complicated device, replete with pressure, flow, and oxygen sensors, and sets of circuitry and alarms associated with each element. A standard hospital ventilator has 1,500 parts, features several layers of fail-safes, and can cost around $30,000. </p><p>“The number of safeties that have to be on a medical device like this is amazing,” says Nevan Hanumara, a research scientist in MIT’s Precision Engineering Research Group. “This is second only to aerospace.”</p>
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/iStock-1216256777.width-990_lXzLNKf.jpg"/>
<figcaption><p>A medical ventilator. Image Credit: Nenov, iStock</p>
</figcaption>
</figure>
<h3><b>Why isn’t ventilator sharing more common? </b></h3><p>Ventilators have such complicated inner workings in part because ventilation is much more involved than just turning on a hose. The process requires doctors to consider myriad disease factors and patient measurements, making it almost an art rather than a science. "Tidal volume," for example, refers to the amount of air in each breath, "resistance" to the ease with which air moves through the lungs, and "compliance" to how stiff or flexible the lung tissue itself is. Clinicians can also adjust how fast patients breathe and regulate air pressure at each stage of those breaths.</p><p>All this means that while setting up coventilation is relatively simple—in her YouTube video, Babcock simply uses a cheap plastic adaptor to make space for more hoses—that doesn’t necessarily mean it’s safe. The first problem, Hanumara points out, is that coventilating requires using the same pressure with two very different sets of lungs. The healthier lungs receive more air because they inflate more easily, while the sicker, less flexible lungs won’t get as much.</p>
<div class="ad"></div>
<p>Secondly, he adds, sensors calibrated for one person’s measurements may not work for two, meaning the appropriate alarms might not be triggered if there is an emergency. Some COVID-19 patients, for example, experience sudden, catastrophic changes in their lung health; without alarms, it’s much more difficult to catch these changes in time. And finally there’s the matter of cross-contamination. Although two coronavirus patients sharing a ventilator can’t give each other their infections, they might still swap pneumonia microbes, or even tuberculosis.</p><p>Given these risks, research on coventilation has divided the respiratory care community. Among the more recent studies, Assistant Director of Research at SUNY Downstate Department of Emergency Medicine Lorenzo Paladino successfully coventilated four sheep for 12 hours in 2008. (Garrone, the Italian doctor, looked to that study when setting up his coventilated patients in March.) Paladino and his coauthors chose sheep for their study because adults have similar respiratory physiology and weight as humans, and aimed for 12 hours because emergency protocols allow for delivery of equipment from the Strategic National Stockpile anywhere in the continental US within that time.</p><p>The study was prompted by the 2001 anthrax attacks and 2003 SARS outbreak, Paladino says, and was meant to provide a stopgap “bridge” measure for emergency physicians with inadequate supplies waiting for backup in a disaster situation—not to replace single ventilation in the long term. Before COVID-19, the technique was most famously used after the 2017 Las Vegas concert shooting, when a single ER saw a huge surge of gunshot patients and coventilated them to keep them alive while they waited for surgery.</p><p>Paladino compares the technique to a life vest. “We don’t condone crossing the Atlantic in a life vest,” he says. “But if I’m in the middle of the Atlantic, I would rather have a life vest than not. And I would hope that a boat is coming to pick me up soon.”</p>
<h3><b>The future of coventilation</b></h3><p>Not every patient is a good candidate for coventilating, Paladino stresses. Patients with active asthma should be excluded, as should those who tend to “fight” the ventilator, trying to draw a breath when the machine is expelling air, or vice versa. But even with these caveats in place, in the wake of the COVID-19 pandemic, six major organizations—including heavyweights like the Society of Critical Care Medicine and the American Society of Anesthesiologists—have made statements against coventilating, judging it too risky and ethically questionable to be worth considering. “There’s a very legitimate concern that instead of saving two people, you just highly increased the risk of mortality for two people,” says Bradford Smith, a biomedical engineer at the University of Colorado Anschutz Medical Campus. </p><p>These serious risks point to the urgency of the recent situations in Italy and New York that have led doctors to try coventilation. Smith, who recently published a “preprint” (a not-yet-peer-reviewed preliminary study) suggesting an algorithm to match patients for safer coventilation, runs down the list of options he would try before resorting to the technique: fixing old, broken ventilators; using available machines normally used for surgical anesthesia; attaching endotracheal tubes to similar but less-invasive machines used for sleep apnea. “This is so rife with problems that the first time I heard about it, I thought, 'This is the stupidest thing I’ve ever heard,’” Smith says. “But people are taking steps to mitigate all those issues.”</p><p>Coventilating practitioners can use filters between patients to help prevent cross-contamination, for example. And protocols drawn up by Columbia Presbyterian and the Department of Health and Human Services (HHS) this spring suggest workarounds to allow for some adjustment of ventilator settings, better monitoring of both patients, and use of some built-in alarms.</p><p>As in Paladino’s case, most research on coventilation stems from a drive to prepare for the worst. Smith says he was initially inspired to work on his algorithms because he was afraid he would have to use them. (“With the news coming out of Italy, I was on these chain emails of critical care physicians, and things sounded pretty dire,” he says.) And the fact that HHS thought it necessary to convene a taskforce in Washington D.C.—which included Paladino and Babcock—to produce coventilation guidelines for future use speaks to the severity of both the pandemic and predictions for global health over the next two years.</p><p>Smith hasn’t had to use his algorithms, but he fears fall flu season may provide another opportunity. He also wonders if they may be of use in other places around the world where ventilator supplies are meager, to give physicians and respiratory therapists valuable context about how different types of patients may react to coventilation.</p><p>“This is not how nations, or even states, deal with a ventilator problem,” Paladino says. Instead, he sees coventilation playing an important role for communities that are rural or isolated, or lack access to medical care. Imagine a small hospital that owns just three ventilators and then receives six desperately sick COVID-19 patients in one night. Then what? “One night you see a spike, and you ask for help from the neighbors,” he says. In the meantime, coventilating just might keep those patients alive.</p><p></p><p><i>Stream</i> <b><i>Decoding COVID-19</i></b><i> starting on Wednesday, May 13 at 7/6c on the PBS Video app or online to learn more:</i></p>
<div>
<iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" frameborder="0" height="270" src="https://www.youtube.com/embed/nqB2htCtcBg?feature=oembed" width="480"></iframe>
</div>
<p></p>
<div class="newsletter"></div>

<p>The science of coventilation for coronavirus cases illustrates a complicated dilemma.</p>

An artist's rendering of the Mars 2020 rover Perseverance. Image Credit: NASA

NASA’s Perseverance Mars rover and first-ever space helicopter launch Thursday

<div class="related"></div>
<p>NASA scientists are about to get one step closer to knowing what, if anything, has lived on Mars, with <a href="https://www.nasa.gov/nasalive">the launch</a> of the Mars 2020 spacecraft at Cape Canaveral, Florida, on Thursday, July 30. <a href="https://mars.nasa.gov/mars2020/">The mission</a> will take a rover called Perseverance and the first-ever space helicopter to the red planet, hopefully arriving in February 2021. The objectives of the mission center on detecting Mars’ habitability, and even signs of past life, as well as experiments that investigate the possibility of human exploration. </p><p>One of Perseverance’s main goals will be to collect samples that could prove Mars was once home to microscopic life. Understanding Mars’ past climate and learning more about its geology will also help researchers fill in longstanding gaps in our understanding about how the planet was formed and how it has changed over time. That could help us more fully grasp why Earth and its neighbor—which were originally made from the same deep space materials—<a href="https://www.pbs.org/wgbh/nova/video/the-planets-mars/">turned out to be</a> such contrasting compatriots. And that’s just the first step in an ambitious mission to bring humans back to the Moon, and then eventually to Mars.</p><p>The mission’s <a href="https://www.pbs.org/wgbh/nova/article/2020-latest-mars-rover-will-land-jezero-crater/">carefully chosen</a> landing site is the Jezero Crater, where an ancient river delta full of mineral-rich sediments joined a huge lake—the kind of place scientists think might have supported life. Mars orbiters have already spent years collecting information and images from 200 miles above Jezero. But pinpointing signs of ancient life will require a closer look, and that’s where Perseverance comes in. </p>
<div class="ad"></div>
<p>The robotic scientist, which weighs about 2,300 pounds and is the size of a small car, will spend at least one Mars year (about 687 Earth days) using a specially designed drill to collect intact rock cores—rather than pulverizing the rock the way its predecessor <a href="https://mars.nasa.gov/msl/home/">Curiosity</a> did—and store these samples on the surface until future missions can return them to Earth. All this study requires a new <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/">set of instruments</a>, which, like any prepared student, Perseverance is toting on its back. One instrument can detect organic matter; another measures the composition of rocks and soil. Together, they’ll help us learn with greater precision than ever before what Mars is made of.</p><p>Perseverance (<a href="https://www.space.com/nasa-mars-2020-rover-name-perseverance.html">nicknamed ‘Percy</a>’) also carries one particularly ambitious tool, a proof-of-concept experiment called <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/moxie/">MOXIE</a> (Mars Oxygen In-Situ Resource Utilization Experiment). Nestled inside the rover itself, MOXIE will test whether it might be possible for future astronauts to turn the planet’s carbon dioxide atmosphere into oxygen for both breathing and rocket propellant. </p>
<figure class="richtext-image full-width">
<img alt="Ingenuity space helicopter" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/PIA23720_hires.width-990_ES7NY0q.jpg"/>
<figcaption><p>An artist's redering of the space helicopter Ingenuity, which will be the first aircraft to attempt controlled flight on another planet. Image Credit: NASA</p>
</figcaption>
</figure>
<p>This veritable Swiss Army knife of instruments will be accompanied by the first-ever space helicopter, dubbed Ingenuity. The diminutive aircraft weighs only four pounds, but it will attempt to do something big: fly in another world. Ingenuity will use four carbon-fiber blades spinning at 40 rotations per second to navigate gravity that is a fraction of Earth’s and an atmosphere that is just 1% as dense as our own. </p><p>Showing that Martian flight and local oxygen creation are both possible on this small scale will open important doors. In the short term, flying vehicles on Mars could offer perspectives of the landscape that can’t be accessed by rovers on the surface or spacecraft in near orbit. It could also provide key transport services between distant missions and access to areas that would be difficult for rovers to get to. In the long term, though, such technologies lay an essential foundation for NASA’s <a href="https://www.nasa.gov/artemisprogram">Artemis Program</a>, helping us take our first steps back to the Moon—and, perhaps some day, beyond.</p>
<div class="newsletter"></div>

<p>The Mars 2020 mission will begin with July 30th’s launch from Cape Canaveral, Florida, at 7:50 a.m. EDT.</p>

Notre Dame Cathedral on fire in April 2019. Image credit: Wandrille de Préville, Wikimedia Commons

3D models help preserve landmarks like Notre Dame

<p>At the Neolithic village of <a href="https://blog.historicenvironment.scot/2016/05/3d-4d-digital-monitoring-sea-defences-skara-brae/">Skara Brae</a> off the northern coast of Scotland, serpentine green slopes overlay the remains of a community so complete that many of the houses feature stone beds, dressers, and cupboards—even though the village is older than both Stonehenge and the pyramids of Giza. The site, which was once home to some 50 people, overlooks the blustery Bay of Skaill. Over the millennia, wind and water have slowly eaten into the hills around the ruins, putting them at risk of eventual destruction.</p>
<div class="related"></div>
<p>For the last decade, the preservation organization Historic Environment Scotland (HES) has been visiting Skara Brae deveoping strategies to protect what’s sometimes known as the “Scottish Pompeii” from encroaching erosion. One of their most successful efforts has nothing to do with wood or stone and everything to do with light. Every two years, HES conservators bring laser scanners to the remote northern island to gather a 3D image of Skara Brae, including both its structures and the surrounding dunes and cliffs. Comparing the resulting data set to its predecessors has helped them identify to the millimeter how the landscape has changed.</p><p>“To be able to monitor what’s going on is essential,” says Sophia Mirashrafi, who helps coordinate <a href="https://www.engineshed.scot/about-us/teams/digital-documentation-and-digital-innovation/the-rae-project/">HES’s digital projects</a> and get them ready for presentation to the public. “Scanning doesn’t stop the water from eroding the site, but it can be used to help inform decisions about how it can be protected.” She and her team also used the scans—known as point-cloud models—to create interactive virtual experiences that give the public up-close access to parts of the village.</p><p>When we think about preserving cultural heritage, Mirashrafi says, we usually think about the physical: propping up carved stone, reconstructing rotted wood, uncovering precious metal. But, just as it’s being used at Skara Brae, laser scanning (also known as LIDAR) has become an essential tool at cultural sites around the world, from Notre Dame to Rapa Nui, in augmenting physical preservation, helping conservators make better decisions, and enriching experiences of the sites for both scientists and the public.</p>
<figure class="richtext-image full-width">
<img alt="Aerial digital map of Skara Brae" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/SkaraBraePlan_Pointcloud.width-990_cCzKQYZ.jpg"/>
<figcaption><p>Historic Environment Scotland has used drones equipped with LIDAR scanners and photogrammetry to create aerial 3D models of the Skara Brae Neolithic site, which is older than Stonehenge. Image courtesy of Historic Environment Scotland </p>
</figcaption>
</figure>
<p></p>
<p>At the most basic level, a point-cloud model is a collection of 3D coordinates that conservators, art historians, and researchers can use to “sample reality,” says architect and computer scientist Livio De Luca, who heads the vast team of <a href="https://www.sciencemag.org/news/2020/03/scientists-are-leading-notre-dame-s-restoration-and-probing-mysteries-laid-bare-its">scientists racing to preserve</a> Notre Dame Cathedral in Paris after the catastrophic fire that destroyed its roof in April 2019. Laser sensors mounted on rotating heads collect data on more than 100 three-dimensional points per second over a 180-degrees axis by measuring the amount of time it takes for light to leave the sensor, bounce off a given spot on a structure or object, and return.</p><p>Users move scanners of different resolutions (some for capturing fine details, other for larger landscapes) gradually around the site to produce a digital cloud of points. Each data set overlaps with the last, allowing them to combine those data sets in an algorithmic process called registration, and create a 360-degree “picture” of that site—kind of like doing a 3D jigsaw puzzle. Even though the lasers collect so much data so quickly, the process is still slow and painstaking. It took a team more than two weeks to scan Notre Dame, De Luca says, using some 400 scanning stations to capture as many data points as possible.</p><p>After the initial puzzle is done, the next step is to turn the cloud of points into a “watertight mesh” using a computer program—converting them from a dense constellation to an interconnected surface. Conservators often combine this mesh with data from another digital data-gathering technique called photogrammetry, which can harvest information about a structure’s texture, color, and general shape from overlapping photos of that structure. </p><p>LIDAR (which stands for Light Detection and Ranging) “gives you quantifiable accuracy,” says architect and computer engineer John Ristevski, CEO of the digital heritage nonprofit CyArk, whose mission revolves around scanning sites of historical and cultural interest around the world. “In contrast, photogrammetry provides great textures and beautiful geometry, but it’s not completely reliable. We want both.”</p>
<div class="ad"></div>
<p>As the technology has improved, point-cloud models have come to play an essential role when heritage sites are damaged. Ristevski’s colleagues at CyArk finished scanning one of <a href="https://artsexperiments.withgoogle.com/bagan/">Bagan, Myanmar’s huge stone temples</a> just three months before a 7.1 magnitude earthquake hit the city in 2016. Using <a href="https://www.youtube.com/watch?v=N5Y33-VvsbA">their scans</a>, CyArk was able to create detailed assessments of the damage and help with plans for restoration. Similarly, a Vassar professor, a 3D tourism company, and the company that makes the video game Assassin’s Creed had all <a href="https://www.youtube.com/watch?v=QBzKsTZ81Sw">scanned Notre Dame Cathedral</a> before its fire. “The point cloud represents the main source to rebuild something, using geometrical information in a precise and accurate way,” De Luca says. “If by other kinds of restoration we were able to approximate shapes in the past, now we’re able to reproduce shapes millimeter by millimeter.”</p><p>Point-cloud modeling can also help conservators do experiments that would be impossible in real life. At Notre Dame, a new phase of reconstruction began this month to rebuild the stone ribs that once held up arches in the ceiling. Before this effort begins in earnest, members of the cathedral team will scan each individual stone, a process that will allow them to rebuild the ribs virtually—ensuring they do not compromise the rest of the structure before they are rebuilt in real life. “We’re able to more safely and, from a scientific point of view, more accurately test how they will behave in rebuilding,” De Luca says.</p><p>For HES, point-cloud modeling has not just been essential in erosion monitoring; it has also become an important teaching tool. Using LIDAR scanners and drones capable of photogrammetry, the organization has been able to scan the tops of walls (known as “wall heads”), allowing conservators a much more complete view of the structure than ever possible before. “Scaffolding is very expensive, and it’s difficult to get people up there,” says Mirashrafi. Having access to point-cloud models of the upper parts of the buildings has allowed conservators and stone masons working on the many sites HES cares for to get up close to ceilings they couldn’t access otherwise and to better monitor the health of those wall heads—even using their virtual counterparts as teaching tools for masons-in-training.</p>
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Ahu_Nau_Nau2.width-990_O9x2EeF.jpg"/>
<figcaption><p>Staffers from the digital heritage nonprofit CyArk traveled to Rapa Nui (Easter Island) in early 2020. There, they taught workshops in point-cloud modeling, which will allow local resource managers and Indigenous groups to monitor the erosion of the island’s 500 moai, or enormous, ancient stone statues. Image Credit: CyArk</p>
</figcaption>
</figure>
<p></p>
<p>CyArk was founded by Iraqi-American Ben Kacyra as a way to fight the kind of cultural destruction that was typical of the Taliban and ISIS in Iraq and Afghanistan over the last decades. But as modeling technology has become cheaper and more portable, the company’s mission has changed as well, Ristevski says, with less emphasis on secure data storage and individual projects and more on <a href="https://openheritage3d.org/">open access</a> and education.</p><p>Since its founding, for example, CyArk has stored copies of each site it scans in a secure facility 200 feet underground—the same facility that, according to urban legend, stores Elvis Presley’s master tapes. “We still do that, but it’s a less interesting piece of our work,” Ristevski says. Two years ago, CyArk also began putting its data sets online under a Creative Commons license. “Things that are burrowed away somewhere is one avenue, but now it’s more about sharing and opening up data,” he says.</p><p>Similarly, where CyArk once sought to digitize 500 cultural heritage sites under their own steam, Ristevski says what now excites him is the educational workshops the organization runs around the world. “We’ve seen a lot more adoption of this, especially in the last three or four years,” he says. In early 2020, for example, Ristevski and other CyArk staffers traveled to the South Pacific to <a href="https://www.youtube.com/watch?v=79DfInkneRA&amp;feature=emb_title">give a workshop</a> for monument staff and local Indigenous communities at Rapa Nui, also known as Easter Island. That site, much like Skara Brae, faces continual damage from wind and waves, so CyArk did a set of initial point-cloud models to act as a baseline, allowing for annual monitoring of how each of the island’s enormous stone statues is weathering. Helping local authorities monitor their own site makes it possible to scan all 500 sites on the island, he says, whereas CyArk might only have had time or resources for one or two.</p><p>A technique like point-cloud modeling can also create an opportunity for sorting through and storing many types of information. Notre Dame is a perfect example. “Even if today we are building a lot of data around this physical aspect, we are also building a ‘knowledge cathedral’ at the same time,” De Luca says. For his team, that means building a “digital twin” of the cathedral, a real-time virtual clone of the physical object that records more than just the geometric dimensions of the cathedral before and after the fire. This digital twin also manages the myriad chemistry, physics, art history, archaeology, and engineering data generated by its many restoration projects—from managing the <a href="https://www.pbs.org/wgbh/nova/video/stabilizing-notre-dames-buttresses/">flying buttresses</a> to cataloguing each of the thousands of pieces of tangled, burnt wood that once made up the “forest” in the cathedral’s attic—and makes it available within a few minutes of its collection.</p>
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Rob1.width-990_AItVyE6.png"/>
<figcaption><p>Point-cloud images of huge stone statues at Rapa Nui, also known as Easter Island. Image Credit: CyArk</p>
</figcaption>
</figure>
<p></p>
<p>Past Skara Brae, even farther north into the cold reaches of the Atlantic ocean, sits Mousa Broch, a 40-foot-tall Iron Age stone tower built around 300 BCE on a bluff overlooking the sea. Even for the few visitors that make it to the Shetland Islands, Mousa Broch is difficult to access, requiring a strenuous hike. But point-cloud modeling has allowed Mirashrafi’s team not just to gather essential records of the building for posterity but also to open the site (or a version of it) to the public.</p><p>As part of their scanning efforts, they’ve translated the point-cloud version of Mousa Broch into a version most computers can handle, through a site called <a href="https://sketchfab.com/HistoricEnvironmentScotland">SketchFab</a> (which Mirashrafi calls the “YouTube of 3D models.”) “Sharing for education and interpretation is something we’re equally interested in,” she says. Flocks of storm petrels roost at Mousa Broch at night, so as an extra immersive touch, the team layered recordings of the seabirds over the model animation. The result: a <a href="https://sketchfab.com/3d-models/mousa-broch-shetland-88a87c90cde8477a87523caa511c1796">rich virtual experience</a> that was previously largely inaccessible.</p><p>In this vein, Mirashrafi says she’s been especially impressed with point-cloud modeling’s potential for storytelling. Being able to digitally recreate a structure or item with such accuracy helps her team fight archaeology’s tendency to strip items of their cultural context. Though the digital can never replace the physical—“When you go out and scan a site, it doesn’t negate the necessity for historians and conservators”—a digital replica is a powerful tool, she says, whether it’s used to help recreate a site before a rock fall or to help the public experience a little bit of new history.</p><p>Through point-cloud models, a lost or destroyed site can be reconstructed; an artifact can be put back virtually where it was originally found. “So often in museum contexts, it’s hand’s off, don’t touch, don’t talk, don’t question,” she says. “These kinds of virtual environments encourage manipulation and questioning,” in a richer way than you might see behind glass.</p>
<div class="cove-video">
<iframe allowfullscreen="" class="inline-cove-player" frameborder="0" height="100%" id="partnerPlayer" marginheight="0" marginwidth="0" scrolling="no" src="//player.pbs.org/partnerplayer/ZACs206MAMDaup76pLSohw==/?topbar=false&amp;end=0&amp;endscreen=true&amp;start=0&amp;autoplay=false" width="100%">
</iframe>
</div>
<div class="newsletter"></div>

<p>Laser-scanning technology can create exceptionally detailed 3D models of cultural sites, bringing them to life online—and helping experts restore them if disaster strikes.</p>

Russian spacewalkers explore the spherical Prichal docking module, which is attached to the Nauka multipurpose laboratory module of the International Space Station. Image credit: NASA Johnson, Flickr

Daily life on the International Space Station: A Q&A with a space archaeologist

<p>Soon after photos started arriving from the International Space Station (ISS), Justin Walsh spotted something unexpected: frosting. Tucked into a plastic bag hanging off the station wall, near a can opener and bottle of ketchup, were telltale red, yellow, and green tubes. Walsh was mystified. “What does frosting imply? Baking,” he said recently over Zoom. But baking in space is pretty much impossible. </p>
<div class="related"></div>
<p>He got his resolution when astronaut Kayla Barron <a href="https://www.instagram.com/reel/CZmgSeupMuq/?utm_source=ig_web_copy_link">posted on Instagram</a> that she’d made a birthday cake for a colleague. “They did it by cutting the tops off of muffins and gluing them together with honey, then covering the whole thing with icing and frosting,” Walsh says. To Walsh, an art historian and archaeologist at Chapman University, the frosting was physical proof of something less concrete: astronauts’ bond with one another. Cooking and eating “is not only about sustenance; it's about social relations,” he says—even 250 miles above Earth. </p><p>He, fellow space archaeologist Alice Gorman, and their colleagues received the frosting photo as part of the Sampling Quadrangle Assemblages Research Experiment, known as SQuARE. The ISS, which is administered by multiple space agencies, is essentially a <a href="https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-the-iss-58.html">network of modules</a> for cooking, sleeping, science research, and other uses that’s slightly larger than a six-bedroom house. Between January and March, astronauts on board took daily photos of six carefully chosen sites around their temporary home first at the same time each day, then at random times. The project was an interstellar version of the archaeological technique known as quick testing, in which archaeologists divide a new site into a grid of one-meter squares and dig “test pits” that provide a basic sense of what they might find. </p><p>In SQuARE, those “pits” are one-square-meter areas marked off with tape, scattered across the American, European, and Japanese modules of the ISS in areas used for work, science experiments, cooking, and hygiene. The team will analyze the resulting photos in hopes of understanding how each area is used over time and, from there, identify opportunities to improve space habitat design. </p><p>NOVA talked with Walsh about the challenges of space archaeology and why astronauts eat so many tortillas. </p>
<p><b>Alissa Greenberg: Usually, archaeologists excavate sites because it’s the only way to learn about life in those places—all the people are long dead. But we can talk to these astronauts. Why not do that?</b></p><p><b>Justin Walsh:</b> It's true that, for the most part, archaeologists do study the distant past. Contemporary archaeology developed starting in the 1970s. The first example of it was a project called the Tucson Garbage Project by a guy named William Rathje at the University of Arizona. He got the City of Tucson sanitation department to drop off samples of neighborhood garbage on a regular basis, and he and his graduate students went through it to understand the patterns of usage of different items.</p><p>What's really fascinating about it is that they then went and interviewed people from the neighborhood about their consumption habits. So first of all, he found that people were throwing out lots of meat that they weren't using. So he was able to show that people were being wasteful with this particular commodity. But then he went to talk to people about these things, and he found out some interesting facts. Such as when you ask people questions, the way sociologists and anthropologists often do, they are not necessarily really good at articulating the realities of their lives—or they don't want to. Which is also perfectly fair and understandable! I would not blame them for that. But what it shows is that what archaeology can do is provide additional insights into human practices and that those insights don't have to be about the distant past.</p><p>So, you can say, “Well why don't you just talk to the crew and ask?” or “Doesn't NASA document all that stuff?” Okay, we can absolutely do that, but that doesn't always work well—especially for astronauts, who are 100% good at staying on message and will not say anything to jeopardize their next flight to space. And as for the space agency, they don't do any forensic work on what's happened on the space station before. They're in the present and the future—and the past is <i>gone</i>. They're not thinking about what they can learn.</p>
<figure class="richtext-image full-width">
<img alt="Mesh bags full of condiments and food items hang from a space station wall" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/iss066e130191_1.width-990_qW6eQSP.jpg"/>
<figcaption><p>One of the SQuARE sample locations, in a U.S. module galley area, marked by yellow tape at each corner. On the wall, mesh bags hold ketchup, Sriracha sauce, chocolate, and other food items. In the upper right corner are plastic bags holding tubes of frosting, which indicated that a kind of “space cooking” activity was happening in this location. Image courtesy of Justin Walsh</p>
</figcaption>
</figure>
<p><b>AG: Why do you find space culture so compelling?</b></p><p><b>JW:</b> Because humans are doing things there in an environment that we are 100% not adapted for. We literally cannot survive. So, we have to come up with all these technologies that allow us to survive in that environment, living in microgravity. And on top of that, there's the other issues of confinement and isolation: the bad food, the distance from family and friends. How do they work together and live together? </p><p>One of the phrases that I like is that a crewed spacecraft is “<a href="https://nap.nationalacademies.org/read/12387/chapter/1">a microsociety in a miniworld</a>.” You have the transmission of culture and traditions—"this is how we do things, this is how this is laid out”— being handed down almost from generation to generation. For example, on the ISS they have dinner together every Friday. Most of the time it's in the Russian service module; sometimes it's in the American service module. Or on ISS their food is carefully designed, and there are different kinds of traditions associated. Things like there's no bread, because crumbs are bad in space. If you inhale a crumb, that could really be a problem, so instead they use tortillas for everything. Tortillas don't make crumbs.</p><p><b>AG: Can you talk about this most recent study? What’s the goal here?</b></p><p><b>JW:</b> We've been doing this study of historic photos that document life on the space station over 21 years. We've got this body of photographs, both published photographs from Flickr and also unpublished photographs that NASA has now given us—thousands and thousands of photographs. We've been working for the last three years to develop machine learning techniques that would allow the automated tagging of people, places, and objects in the photos. But they were taken essentially randomly. They weren't taken at precise intervals. How do we even characterize what the potential problems might be with that? One way is by doing an actually systematic survey of the material culture of the space station over the short term. That's what SQuARE is.</p>
<figure class="richtext-image full-width">
<img alt="Photo of 3 astronauts with numbers labeling objects and people in the scene" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/iss018e043629_9452806214_o_v3.width-990_xdqMU3n.jpg"/>
<figcaption><p>A NASA astronaut, a JAXA astronaut, and a Hungarian-American space tourist pose in the Russian service module Zvezda in 2008. The wall behind them is decorated with items including flags, mission patches, portraits of Soviet space heroes, and Russian Orthodox religious objects such as painted icons. Image courtesy of Justin Walsh</p>
</figcaption>
</figure>
<p>In archaeology, we take soil that’s all the same type, same color, same consistency, and different from what's above it and what's below it or what's adjacent to it, as a group that reflects a particular period of time. We take all of those items as relating to one another, and therefore they are separate from and need to be interpreted differently from what’s above or below. So we're treating each photo that way, because it is a slice of time, separate from the next day or the previous day.</p><p>The fact that we're doing this one picture a day for each of six squares for 60 days, 360 images that were taken systematically at precisely defined locations, will allow us to better understand what the historic photos are all about. And likewise, what's happening in the historic photos—because there's so many of them and such a variety of things going on in them—will help us to interpret what we're seeing in the systematically recorded images.</p>
<div class="ad"></div>
<p><b>AG: What have you found so far?</b></p><p><b>JW:</b> We thought that the two experimental areas that we selected probably were not going to show very much change over time because they're basically just racks with scientific equipment. In fact, we were asked, “Are you sure you want to use those areas? Don’t you want to see where more activity is happening?” We had to say no because archaeology is not a treasure hunt. We want to actually see the full range. How would we be able to tell the difference between low activity and high activity if we’re only looking at high-activity areas?</p><p>It turns out that one of those areas <i>is</i> seeing hardly any change. But in one of the other areas, we actually have seen a lot of things moving around. Things are being stored there, like laptops and a video camera. It seems to be kind of a staging area for what's happening next door, a veggie experiment. So that's really interesting, because that shows that when things aren't happening in the location, it can be repurposed.</p><p>Another thing we’ve been seeing in the eating area is books. In one case there's been an actual physical book on the wall, just kind of stuck there for the time being—somebody put it down. But we've also seen an iPad with an e-book that was on. So, in a leisure moment, when you're eating by yourself, maybe you read a book or a magazine.</p><p>The way it works right now is that there's this kind of plate hooked to an adjustable arm. And the plate has some Velcro on the front of it, so that the back of the iPad that has Velcro on it can be stuck to it. And that's fine, maybe that's a good enough solution. But now we have evidence of a different way in which the space is being used. And in future space habitat designs you might want to accommodate it in order to make a better experience. If nobody had evidence that this is how this is being done, we wouldn't even be able to think of solutions.</p>
<figure class="richtext-image full-width">
<img alt="Two astronauts take a photo of themselves in a small mirror hanging on a cluttered wall of the space station" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/iss066e146542.width-990_gLFl5hC.jpg"/>
<figcaption><p>In an image of a SQuARE sample in a U.S. hygiene area, NASA astronauts Mark Vande Hei and Kayla Barron take a self-portrait in the mirror. Image courtesy of Justin Walsh</p>
</figcaption>
</figure>
<p>Another aspect of the photo study—we placed a <a href="https://osf.io/preprints/socarxiv/ra4c3/">preprint of this on SocArXiv</a>—is we had all these images from Flickr, 8,000 of them, and helpfully NASA has captioned all of them. We were able to scrape them and peel out particular words: the names of the crew members and the locations. Just with those two pieces of data from each item, for the first time it's possible to map out where men and women are across the International Space Station by module. </p><p>And if we look at nationality by module, it does seem like there are some real results. In the Russian segment, unsurprisingly, Russians make up the majority of people. And unsurprisingly, in the U.S. segment Americans make up the majority of people who are in those modules. So this indicates that in what claims to be an international space station, there are national zones. That's not something anybody has ever been able to show data for. Again, anecdotally you might have expected that to be the case. But we're able to show the reality. And this is because of the way the ISS is managed. Those are official designations. Each agency decides what happens in its own module and what their own crew do. So as a result, you end up with inefficiencies.</p><p><b>AG: You’ve mentioned the future design of space habitats. Do you know if people doing that are watching your project? What kind of questions are they hoping you’ll answer?</b></p><p><b>JW:</b> The ISS is maybe the most expensive building project humans have ever undertaken. A staggering amount of money for one piece of architecture, and $3 billion or $4 billion on NASA alone to maintain it each year. I think that we're looking to be able to give more accurate and more precise descriptions of the functions of different areas and how that relates to what the originally designed and planned functions of those spaces are. It's really important to be able to understand whether people are using spaces the way they're intended. If they're not, how are they being used?</p><p>We have at the moment four different commercial organizations that are planning, designing, building their own space stations, partly funded by NASA. And NASA and the other space agencies in ISS—except for the Russians—are currently already building a new space station that's going to go into orbit around the moon: Lunar Gateway. There are key problems that they're already focused on sorting out. But also, how do astronauts and designers create the conditions that mimic, or are as my colleague Alice says, are surrogates for, gravity? That is to say, handrails, bungee cords, Velcro, resealable bags. Where do we see Velcro building up over time? Those are areas where it might not have been foreseen, where it ended up that the crew realized that they were going to need more “gravity.” First of all, we have to identify those areas. And, second of all, then we have to understand <i>why</i> those areas are requiring “gravity,” because of the kinds of activities that are going on there. And then third, how do we anticipate that for future designs? </p><p>Those kinds of questions, the space station companies really want to know that. Even when they have astronauts on their staff or in their executive boardroom, they still realize that there's a difference between anecdotes and data. So the really amazing thing about this is that, as (terrible pun) out of this world as this project is, it's the rare archaeological project that can actually have concrete and practical implications for the future.</p><p><i>This interview has been edited for length and clarity.</i></p><p><i>Correction: Due to a punctuation error, a previous version of this article indicated that the Russian space agency was building Lunar Gateway. It is actually a project of the four non-Russian ISS space agencies.</i></p>
<div class="newsletter"></div>

<p data-block-key="ahv45">Archaeologists are working to understand how astronauts really use their space on the ISS—and help improve space habitats of the future.<br/></p>

An elderly woman in a red sweatshirt runs down a path in a park

Image Credit: David Tett via Centre for Ageing Better

How exercise may help prevent Alzheimer's

<p>Your brain loves it when you exercise. Of course, you yourself may not love every sweaty minute of your kickboxing class or Saturday afternoon run—but your brain revels in it. That’s because exercise doesn’t just increase muscle tone. It doesn’t just goose energy levels and enhance mood, fighting <a href="https://www.pbs.org/wgbh/nova/video/depression-memory-alzheimers/">depression</a> and anxiety. It also heightens problem-solving skills and memory. And, research has increasingly shown, it protects against <a href="https://www.pbs.org/wgbh/nova/video/determined-fighting-alzheimers/">Alzheimer’s disease</a>—both delaying onset of the disease and slowing decline in patients who have already been diagnosed.</p>
<div class="related"></div>
<p>As baby boomers age and more Americans live longer, Alzheimer’s is on the rise. In 2020, some 5.8 million people in the U.S. were living with this most common form of dementia, in which inflammation and tangles of misformed proteins in the brain accompany progressive <a href="https://www.pbs.org/wgbh/nova/video/alzheimers-screening-test/">memory loss</a> and inability to perform day-to-day tasks.</p><p>Despite decades of research, effective treatments for Alzheimer’s have eluded researchers; even a full explanation of what happens inside an Alzheimer’s patient’s brain has remained out of reach. This is in part because the disease is incredibly knotty and multifaceted, says Fang Yu, a researcher at Arizona State University who specializes in applying new dementia science to human trials. Alzheimer’s affects myriad processes in the brain, our most complicated organ, but most treatments developed thus far have only been able to tackle one aspect of the disease at a time, she says. “Even if there is a medication that can help target certain pathways, there are many pathways needed.” </p><p>That’s why Yu’s Alzheimer’s studies have often focused on the power of moving our bodies. Exercise is unique in that it also affects the body and brain in many ways, she says, making it an important intervention for addressing the complexity of Alzheimer’s. </p><p>It’s “something quite special,” agrees Christiane Wrann, a neuroscientist at Harvard University and Massachusetts General Hospital. While you’re dancing, bicycling, or running, it may seem like “you’re doing something that doesn’t have anything to do with the brain,” she says. “But you’re actually getting improvement in cognitive function.”</p>
<h3><b>How does it work?</b></h3><p>Perhaps the most straightforward way in which exercise safeguards against Alzheimer’s is by improving cardiovascular health. The effects of a good sweat session don’t stop at our hearts—they help improve the condition of our other organs and blood vessels as well. Those healthier vessels deliver an upgrade in the connections among brain cells called neurons, Wrann says. With reinforced wiring, it’s easier for nourishing oxygen to get in, for waste products to get out, and for the neurons to talk to one another. And improved fitness of the heart and lungs also seems to help the brain take up glucose more efficiently, which helps keep neurons healthy.</p><p>Plus, <a href="https://www.pbs.org/wgbh/nova/video/cannabis-reverses-brain-aging/">research on mice</a>—a common, if imperfect, source of new Alzheimer’s science, since it’s not possible to ethically conduct some kinds of research on living humans—has shown that exercise is a rare cause of “adult neurogenesis,” or the growth of new neurons in adulthood. Although it’s difficult to prove fully that the same happens in humans, it seems like <a href="https://www.researchgate.net/publication/323624428_The_Role_of_FNDC5Irisin_in_the_Nervous_System_and_as_a_Mediator_for_Beneficial_Effects_of_Exercise_on_the_Brain">one key player is irisin</a>, a hormone manufactured in the muscles in response to exercise, Wrann explains. Irisin is special because it carries a pass to get through the blood-brain barrier, the barricade of tissue and blood vessels that keeps harmful substances from reaching the brain. </p><p>Once inside, <a href="https://www.researchgate.net/publication/354038429_Exercise_hormone_irisin_is_a_critical_regulator_of_cognitive_function">irisin helps the brain</a> create a neurotransmitter called BDNF, which is important to hippocampus health. The hippocampus is a center of learning and memory in the brain, and Alzheimer’s patients’ hippocampi tend to shrink as their health declines, Yu says. The ability to sprout new cells in the hippocampus, and to prune away connections that aren’t needed anymore—two processes that BDNF supports—is key to stabilizing and protecting it.</p>
<div class="ad"></div>
<p>A series of studies at Wrann’s lab in Boston has also shown that, at least in mice, irisin produced during exercise has powerful anti-inflammatory effects in the brain. That could be an important insight because some new research points to <a href="https://www.pbs.org/wgbh/nova/article/brain-inflammation/">inflammation</a>, rather than previously implicated amyloid plaques, as a possible cause of neuron death in Alzheimer’s. Inflammation is caused by the immune response to negative stimuli—not just viruses or bacteria but also, for example, misfolded proteins in the brain. In an Alzheimer’s patient, the immune system may respond to the presence of these plaques by attacking them, Wrann explains, and in its enthusiasm, it may also attack the synapses that connect neurons. “If it gets completely out of control, you have this ‘friendly fire’ that causes damage to the neurons,” she says. But her research indicates irisin may bind to receptors on specialized cells deep within the brain, calming that inflammatory response.</p><p>And one last piece of the puzzle is <a href="https://www.pbs.org/wgbh/nova/article/healing-sleep/">sleep</a>—not a type of exercise in itself, but caught up in something of a love triangle with exercise and Alzheimer’s disease. When it comes to dementia prevention, sleep and exercise may work together, says neuroscientist Miranda Chappel-Farley, a Ph.D. candidate at University of California, Irvine. Studies have shown that more exercise leads to better quality sleep, which is an important protective factor itself against Alzheimer’s. And people getting better sleep are more likely to feel up to exercising. Together, they create a powerful bulwark against dementia and represent a lifestyle factor ignored at your peril, says Chappel-Farley, who cautions against “targeting exercise but not paying attention to sleep.” </p>
<h3><b>What kind of exercise is best?</b></h3><p>Aerobic exercise seems to be the champion when it comes to protection against Alzheimer’s and maintaining executive function. Of course, most of the mice participating in Alzheimer’s trials run on their wheels, but that doesn’t mean you have to. Biking, dancing, swimming, or any activity that gets your heart rate up is a good candidate, Yu says. That’s because it has the potential to increase BDNF levels; spur blood flow and shore up blood vessels; and decrease “white matter hyperintensities,” abnormal changes that affect how the brain transmits electrical signals.</p><p>Newer research also indicates that resistance-based muscle-building exercise may support a broad spectrum of cognitive functions. That effect seems especially promising in patients who have already been diagnosed with Alzheimer’s, where it may help slow their decline, adds Yu, who often works with dementia patients. There, the goal is not improvement but slowing deterioration. “And that’s basically what my research has shown: that exercise can level and stabilize,” she says.</p><p>Tai chi and other types of movement that incorporate mindfulness also decrease stress and inflammation and improve sleep, she adds. And some research suggests that a mix of many types of exercises may provide stronger improvement than a single activity. In a review of <a href="https://europepmc.org/article/med/34004389">71 studies of exercise and dementia</a>, Yu and her colleagues found the most consistently effective exercise was “mixed component,” a blend of muscle-building and aerobic workouts.</p><p>Still, “it’s important to highlight that there’s a lot we don’t know yet,” says Chappel-Farley, since exercise comes in so many forms and can be adjusted by duration, intensity, frequency, and timing. “It’s not totally clear which might be best.” Does it take a certain amount of exercise for our brains to reap the benefits? Are there any findings in the extensive mouse research on this topic that can’t be transferred to humans? </p><p>Wrann says that data is encouraging so far, indicating that the more you exercise the more benefit you’ll experience. And really, what’s the risk? “My big message is that exercise is good for you,” Yu agrees. “Even if in the future we find that it doesn’t prevent Alzheimer’s for everyone, it’s still good for your health and quality of life.”</p><p>But Wrann also remains mindful of people who can’t exercise because of a disability or physical limitations, or who may develop Alzheimer’s despite getting plenty of exercise; there’s still no silver dementia bullet. While it’s unlikely that researchers could develop a drug that can affect the body in as many ways as exercise can, she’s hopeful about irisin’s potential as a source of new drug therapies. Because it’s a powerful anti-inflammatory that can already wriggle through the blood-brain barrier, she wonders if it might be possible to use irisin to create a drug that goes even beyond the positive effects of exercise. Inflammation in the brain seems to be central to many neurological conditions. That way, she says, “we could reach people with Alzheimer’s disease—or beyond.”</p>
<div class="newsletter"></div>

<p data-block-key="eldwf">Exercise could be a powerful defense against Alzheimer’s disease. Three dementia researchers explain how it works.</p>

Alissa Greenberg

Articles