Animal and human forms of communication may be much closer than we previously thought.

The Law all Languages Obey

United States

Northern Mariana Islands

Puerto Rico

American Samoa

Guam

U.S. Virgin Islands

U.S. Minor Outlying Islands

US & Territories

The search for extraterrestrial life is an age-old quest. But recent breakthroughs make today an era like no other in the history of astronomy. From the exhilarating probing of our own solar system and the Kepler mission’s astounding discovery of thousands of extrasolar planets, to the next-generation telescopes under development, the prospects for finding life beyond Earth have never been stronger. Still, daunting hurdles remain. How can we study anything light years away, let alone a little planet? In the vast universe, where should we even start to look? Is our failure to hear any other voices in the galaxy a sign that we are special? NOVA Wonders joins leading explorers now searching the galaxy for life and intelligence on other planets—and asks, if we do find other life in the universe…what would that mean?

Hunt for clues in the universe to answer one of humanity's biggest questions: Are we alone?

Are We Alone?

<div class="rich-text">Toxoplasma gondii is a parasite that invades the brains of mice and organs of cats, resulting in a disease called toxoplasmosis. This parasite can also infect humans by way of cat feces. Although Toxoplasma research is still in its early stages, scientists estimate that one-third of the human population has been infected.
</div>

<div class="rich-text">Toxoplasma gondii is a parasite that invades the brains of mice and organs of cats.</div>

Can Cat Poop Make You Crazy?

The National Science Foundation

The Gordon and Betty Moore Foundation

the Alfred P. Sloan Foundation

The John Templeton Foundation

NOVA Science Trust Logo

NOVA Wonders takes viewers on a journey to the frontiers of science, where researchers are tackling some of the biggest questions about life and the cosmos. From the mysteries of astrophysics to the secrets of the body to the challenges of inventing technologies that could rival—and even surpass—the abilities of the human mind, these six hours reveal how far we’ve come in our search for answers, how we managed to get here, and how scientists hope to push our understanding of the universe even further. Along the way, we meet the remarkable people who are transforming our world and our future.

A 6-part series exploring the biggest questions on the frontiers of science.

NOVA Wonders

A 6-part series exploring the biggest questions on the frontiers of science.

Meet Rana el Kaliouby

What if our high-tech devices understood—and could respond to—our emotions? Computer scientist <a href="https://twitter.com/kaliouby">Rana el Kaliouby</a> is on a mission to humanize technology with artificial emotional intelligence, or what she calls “Emotion AI.”
“I spent a lot of time wondering about the future. I am curious when we have A.I. and it becomes more mainstream, how is that going to affect the way we communicate with each other?” she asks, adding she’s most interested in using AI to improve mobility, mental health and education.The co-founder and CEO of Boston-based software company <a href="https://www.affectiva.com/">Affectiva</a>, Rana is developing an “Emotion A.I.” platform that combines facial expression with tone of voice to infer how a person is feeling. It does this with a programming approach known as “deep learning,” which hunts for patterns in enormous data sets – such as the more than five million faces from 75 countries found in the world’s largest emotion data repository.When it comes to reading someone’s emotions, Rana says, about 60% comes from facial expressions and gestures. For her, teaching machines to measure and interpret human emotions has the <a href="https://www.youtube.com/watch?v=iQxS9Eq-hms">potential to dramatically improve lives</a>—by allowing doctors and nurses to deliver better care, enhancing consumer experiences, engaging students and personalizing their learning, increasing road safety by tracking driver alertness, and enabling people with autism to better communicate with their families and peers.Born in Cairo and raised in the Middle East, Rana earned her Bachelor’s and Master’s degrees in computer science from the American University in Cairo and a Ph.D. from the computer laboratory at the University of Cambridge.While studying in the U.K., far away from her family, she became acutely aware how difficult it could be to express feelings via technology. “There was one day when I was at the computer lab and I was actually, literally, in tears because I was that homesick,” she tells NOVA Wonders. “And I was chatting with my husband at the time and the only way I could tell him that I was really upset was to basically type, ‘I&#x27;m crying.’ And that was when I realized that all of these emotions that we have as humans, they&#x27;re basically lost in cyberspace, and I felt we could do better.”Today, as <a href="https://www.ted.com/talks/rana_el_kaliouby_this_app_knows_how_you_feel_from_the_look_on_your_face">her popular TED talk</a> demonstrates, Rana excels at making complex computer science accessible to all audiences. Recently inducted into the Women in Engineering Hall of Fame, Rana was selected as a World Economic Forum (WEF) Young Global Leader and serves on WEF’s Global Future Council on AI and Robotics. WIRED named her one of 25 Geniuses Who Are Creating the Future of Business, Entrepreneur honored her as one of The 7 Most Powerful Women to Watch, and MIT Technology Review featured her among the Top 35 Innovators Under 35.One of Rana’s goals is to inspire a new, more diverse generation of scientists and engineers. “When NOVA Wonders approached me, I just felt that that’s very in line with my passion of getting more young people in science, especially underrepresented minorities like young girls or people around the world, like the Middle East, where I grew up,” she says. “The way to solve problems in the world is to become scientists and technologists and build things that haven’t been built before and discover things that people really don&#x27;t know about.”

What if our high-tech devices understood—and could respond to—our emotions? Computer scientist <a href="https://twitter.com/kaliouby">Rana el Kaliouby</a> is on a mission to humanize technology with artificial emotional intelligence, or what she calls “Emotion AI.”

Profile: Rana el Kaliouby

Rana el Kaliouby is on a mission to humanize technology with artificial emotional intelligence.
Computer scientist Rana el Kaliouby is on a mission to humanize technology with artificial emotional intelligence, or what she calls “Emotion AI.” Born in Cairo and raised in the Middle East, Rana is the co-founder and CEO of the Boston-based software company Affectiva. There, she’s developing a “deep learning” platform that combines facial expression with tone of voice to infer how a person is feeling.
Profile: Rana el KalioubyPublished: September 26, 2018Rana el Kaliouby: Our devices know who we are, where we are, what we’re doing. They have a sense of our calendar. But they have no idea what we’re feeling.It’s completely oblivious to whether you’re having a good day, a bad day. Are you stressed? Are you upset? Are you lonely?Talithia Williams: In other words, our machines have no emotional intelligence. And that’s important. Our host, Rana el Kaliouby would know. She’s devoted her career to solve just that.It all started back when she was a grad student from Egypt at the University of Cambridge.el Kaliouby: There was one day where I was at the computer lab, and I was actually, literally in tears because I was that homesick. And I was chatting with my husband at the time and the only way I could tell him that I was really upset was to basically type, “I’m crying.” And that was when I realized, all of these emotions that we have as humans, they’re basically lost in cyberspace and I thought we could do better.Williams: But to do better, how? Rana’s next stop was MIT where she continued work on a new algorithm. One the could pick up on the important features of human behavior. Could tell whether you’re feeling happy, sad, angry, scared. You name it.el Kaliouby: It’s in your facial expressions. It’s in your tone of voice. It’s in your very nuanced kind of gestural cues.Williams: Because she thinks this could transform the way we interact with technology. Our cars would alert us if we get sleepy. Our phones could tell us whether that text really was a joke. Our computers could tell if those web ads are wasting their time.But where to start? She decided to go with the most emotive part of the human body.el Kaliouby: The way our face works is basically we have about 45 facial muscles. So, for example, the zygomatics muscle is the one we use to smile. Take all these muscle combinations and you map them to an expression of emotion like anger or disgust or excitement. The way you then train an algorithm to do that is you feed it tens of thousands of examples of people doing these expressions.Williams: First, her algorithm could only recognize three expressions. But it was enough to push her to take a leap.el Kaliouby: and I remember very clearly, my dad was like, “What? You’re leaving MIT to run a company? Why would you ever do that?” In fact, the first couple of years, I kept the start up a secret from my family.Williams: Eventually, Rana would convince her parents. But convincing investors was a whole other story.el Kaliouby: It is very unusual, especially for women coming from the Middle East to be in technology and to be leaders. I remember this one when I was supposed to be presenting to an audience. And I walked into the room and people assumed I was the coffee lady.Williams: And investors were not the hardest to convince.el Kaliouby: All these doubts in my mind, like, are probably shaped by my upbringing, right? Where, women don’t lead companies and maybe I should be back home with my husband. I think I’ve learned over the years to have a voice and to use my voice and to believe in myself.Williams: And once she did that…el Kaliouby: We have this golden opportunity to reimagine how we connect with machines and therefore as humans how we connect with one another.Williams: Today, Rana’s company, called Affectiva, has raised millions and has a learning algorithm that can recognize 20 different facial expressions. Many of her clients are marketing companies who want to know whether their ads are working. And she’s also developing software for automotive safety. But an application she’s especially proud of is this.Ned Sahin: Most autistic children struggle with the basic communication skills that you and I take for granted.Williams: A collaboration with neuroscientist Ned Sajin and his company brain power that allows autistic children to read the emotions in people’s faces.el Kaliouby: Imagine that we have technology that can sense and understand emotion and that becomes like an emotion hearing aid that can help these individuals understand in real-time how people are feeling. It think that is a great example of how A.I.—emotion A.I. in particular—can really transform these people’s lives in a way that wasn’t possible before this kind of technology.

Rana el Kaliouby is on a mission to humanize technology with artificial emotional intelligence.

Chicago's mesmerizing skyline is a sight to behold—but for migrating birds who fly at night, the dazzling lights can be an inescapable death trap. Image Credit: Mlenny, iStock

Chatty birds may put their friends at risk of colliding with buildings

Had there not been bodies, <a href="https://www.fieldmuseum.org/about/staff/profile/236">David Willard</a> might never have returned.But on an early morning in September of 1978, Willard, an ornithologist at Chicago’s Field Museum, was dismayed to find his suspicions confirmed: Speckling the pavement outside the McCormick Place convention center were the corpses of several small birds. En route to their southern homes, they’d met their ends the night before, colliding with the glass windows of the lakeside low-rise after flitting toward its unnatural glow.The trip to McCormick Place was an unusual detour for Willard, who had stopped by on his way to work after hearing that the brightly lit building was taking out feathered flyers in droves. But in the months and years that followed, Willard found himself retracing his steps around the convention center over and over again, gathering the injured and dead.
<div class="ad"></div>
Some days, there were none. On others, after nights of buffeting winds, the bodies numbered close to 200. All, it seemed, had gravitated toward the convention center’s artificial lights. But over time, it became clear that not all birds were represented equally. Several species of sparrows, warblers, and thrushes—grimly known in birding circles as “super colliders”—were particularly abundant among the fallen.With only corpses to query, Willard began to bring the bodies to the Field Museum. These ill-fated migrants became the first to join a vast repository that, today, numbers more than 70,000. Now, this still-growing collection is helping Willard and his colleagues uncover exactly what draws doomed birds to their deaths.Their <a href="http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2019.0364">work</a>, published today in Proceedings of the Royal Society B, suggests that when it comes to bird-building collisions, light is not the only fatal attraction. Being chatty could be a migrating bird’s Achilles heel: As they careen toward buildings, social species that use chirps to navigate may continue to call to their comrades—inadvertently luring them to an untimely end.“This work is really compelling,” says <a href="http://nrem.okstate.edu/graduate-students/sirena-lao/">Sirena Lao</a>, an ecologist studying bird-building collisions at Oklahoma State University who was not involved in the study. “We know from previous studies that some birds seem to be more vulnerable to these types of collisions, but it was never really clear why...and this provides insight on an aspect of bird behavior that influences [these events].”It’s been more than 40 years since Willard took that fateful first walk at McCormick Place (though, on many a spring or fall morning, the now-retired ornithologist can still be spotted scouring the sidewalks near the convention center). In the decades since, Chicago’s bird body salvage program operates nearly citywide with the help of local volunteers. Together, the team has amassed tens and thousands of birds from around Chicago, representing more than 100 species.
<div class="related"></div>
Over the years, other ornithologists like <a href="https://lsa.umich.edu/eeb/people/faculty/wingerb.html">Benjamin Winger</a>, a biologist at the University of Michigan, began to take interest in the project. As Winger combed through the data, he was surprised to find that, despite decades of collection, warbling vireos (Vireo gilvus)—some of the most common birds on the Chicago skyline—were conspicuously absent among the fallen. Others, however, like white-throated sparrows (Zonotrichia albicollis), were oddly abundant.Upon closer inspection, a pattern began to emerge: Among night-flying, migratory perching birds (passerines), those overrepresented in the casualty cohort—the super colliders—had something in common: They all used short vocal cues called flight calls to navigate at night. The same held true when the researchers include another set of data from Cleveland.Flight calls are thought to help groups of birds maintain communication and travel as a cohesive unit. Like most migratory behaviors, these teeny tweets aren’t well understood, but other studies have shown call rates skyrocket when species pass over illuminated cities.Artificial light has long been known to bewilder airborne birds, which rely on cues like starlight and a <a href="https://www.pbs.org/wgbh/nova/article/birds-quantum-entanglement/">light-sensitive internal compass</a> to maneuver through dimly lit skies. It’s thought that birds may be drawn to the glow, then <a href="https://www.nytimes.com/2017/10/02/science/september-11-tribute-lights-birds.html">get disoriented</a> in its presence, says <a href="https://sites.udel.edu/aeroecologyprogram/people/">Sergio Cabrera-Cruz</a>, a wildlife ecologist studying the <a href="https://www.nature.com/articles/s41598-018-21577-6">effects of artificial light on bird migration</a> at the University of Delaware who was not involved in the study.Now, the new research suggests there’s more to the story than lit buildings sending birds abuzz. For some reason, birds that flight call are at a higher risk of crashing.The researchers didn’t measure flight calls directly, so why this is remains unclear. Though these vulnerable birds have flight calling in common, the actual vocalizations might not cause collisions directly, Winger says. The culprit may be another aspect of their behavior altogether. But the possibility remains: Because vocalizations attract other birds, flight callers could be felling friends en masse, like accidental sirens beckoning sailors to their deaths.
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/BenWinger1928.width-990_jkTTQZ1.jpg"/>
<figcaption>Sparrows that died after colliding with buildings in Chicago, and were collected by researchers at the Field Museum. Image Credit: Roger Hart/University of Michigan Photography
<div class="credit"></div>
</figcaption>
</figure>
These sobering findings underscore the need to rethink how wildlife is being affected by urban landscapes, says <a href="http://calisilab.ucdavis.edu/">Rebecca Calisi Rodríguez</a>, a biologist specializing in bird behavior at the University of California, Davis who was not involved in the study. In light-polluted cities, the same assets that help these birds make decisions as groups have now become double-edged swords, she explains.“This really speaks to the fact that all these wonderful technologies that humans are coming up with are not always great for wildlife,” Calisi Rodríguez says.And with humankind’s built environment ever expanding, these issues are more urgent than ever. In the United States alone, <a href="https://bioone.org/journals/The-Condor/volume-116/issue-1/CONDOR-13-090.1/Birdbuilding-collisions-in-the-United-States--Estimates-of-annual/10.1650/CONDOR-13-090.1.full">between 400 million and 1 billion birds</a> die each year when they crash into human-made structures. (For reference, about 7.5 billion migratory birds enter the country each year.)But as awareness grows, teams around the world are working to minimize the effects of light pollution on these avian aeronauts. In 1999, Chicago became the first city to establish a <a href="https://www.chicagotribune.com/news/local/breaking/ct-met-earth-hour-chicago-20190329-story.html">Lights Out program</a>, encouraging building managers to <a href="https://www.chicagotribune.com/news/local/breaking/ct-met-earth-hour-chicago-20190329-story.html">turn off excess lighting</a> during migratory seasons. As a result, deaths have dropped dramatically. Even at McCormick Place, the light regime has changed, and fatalities have decreased 75 percent since 1978. Willard’s morning strolls are now far more pleasant.Still, the fight is far from over. Many of the most dangerous buildings for birds are those humans find most attractive or useful—towering structures that feature big windows and greenery. Reflective glass can be especially problematic for birds active during daylight hours, but they pose a hazard for nocturnal migrants as well: Birds drawn to well-lit buildings may roost near them at night, only to collide with their glossy windows the next morning.Luckily, effective renovations are often pretty straightforward, Lao says, like the installation of bird-safe glass, which is more obviously patterned and visible, or deterrents like netting.But there’s no substitute for simply shutting off unneeded lights—a practice that could serve up benefits to birds and humans alike, Calisi Rodríguez says. “Lights at night hurt these nocturnal species, but <a href="https://www.pbs.org/wgbh/nova/article/track-social-jet-lag-twitter/">it’s not great for us either</a>,” she says. “We’re animals too. Minimizing light at night…isn’t just for these birds. It would be good for all of us.”
<div class="newsletter"></div>

Forty years and 70,000 bodies tell the grim tale of why some night-flying birds might crash into buildings more often than others.

Using Artificial Intelligence to Diagnose Melanoma

A deep learning system has learned to accurately identify skin cancers in photographs.
Dr. Roberto Novoa of Stanford Medical School used a database of nearly 130,000 images from the internet to train a deep learning algorithm to identify skin cancers as accurately as his fellow dermatologists.
Using Deep Learning to Identify MelanomaPublished: April 1, 2019Geoff Hinton: For the foreseeable future, which I think is about five years, what we&#x27;ll see is this deep learning invading lots and lots of different areas. And it&#x27;s going to make life a lot better.Talithia Williams: At least that&#x27;s the hope. Just consider medicine.Yann Lecun: Deep learning systems are very good at identifying tumors in images, skin conditions, you know, things like that.Williams: One of the first attempts with real patients was conducted by Dr. Rob Novoa, a dermatologist at Stanford&#x27;s Medical School. He knew nothing about deep learning until…Roberto Novoa: I came across the fact that algorithms could now classify hundreds of dog breeds as well as humans. When I saw this, I thought, &quot;My god, if it can do this for dog breeds, it can probably do this for skin cancer as well.&quot;So, we gathered a database of nearly 130,000 images from the internet, and these images had labels of melanoma, skin cancer, benign mole. And using those, we began training our algorithms.Williams: The next step was to see how it stacked up against human doctors.Novoa: The algorithms did as well as, or better than our sample of dermatologists, who were from academic practices in California and all over the country.Williams: And all this can be put on a phone.Novoa: Give it a moment, and it accurately classified it as a benign…Technology has always changed the way we practice medicine, and will continue to do so, but I&#x27;m skeptical as to its ability to completely eliminate entire fields. It will change them, but it won&#x27;t eliminate them.Williams: Rather than replace doctors, Rob thinks this will expand access to care.ROB NOVOA: In the future, a primary care doctor or nurse practitioner in a rural setting, would be able to take a picture of this and be able to more accurately diagnose what&#x27;s going on with it.

A deep learning system has learned to accurately identify skin cancers in photographs.

Saturn's striking rings are probably its most recognizable feature—and they're not just for show. These rings seem to have shaped, and been shaped by, some of the planet's tiniest moons. Image Credit: NASA/JPL-Caltech/Space Science Institute

Saturn’s Innermost Moons Are Red Ravioli, Thanks to Its Rings

In the fall of 2016, <a href="https://www.pbs.org/wgbh/nova/article/what-saturn-can-tell-us-about-earth-and-beyond/">Cassini</a> was dipping into the dregs of its fuel stores.By this point, the NASA spacecraft had already spent the better part of 12 years meandering through Saturn’s neck of the woods, <a href="https://www.pbs.org/wgbh/nova/video/amazing-discoveries-from-cassini/">stockpiling data</a> on the ringed planet and its enigmatic moons. Less than a year later, in September of 2017, engineers would <a href="https://www.pbs.org/wgbh/nova/video/why-did-nasa-kill-cassini/">deliberately</a> send the probe <a href="https://www.pbs.org/wgbh/nova/video/saying-goodbye-to-cassini/">plunging</a> down toward Saturn’s surface, <a href="https://www.pbs.org/wgbh/nova/article/farewell-cassini/">ending its life</a> in a fiery blaze.But even in its terminal months, Cassini was gathering steam for a last hurrah.
<div class="ad"></div>
During the final stages of its mission, Cassini executed a series of orbits that sent it weaving between Saturn and its main rings, drawing the spacecraft close enough to conduct flybys of five small ring moons—Pan, Daphnis, Atlas, Pandora, and Epimetheus—interlaced into the planet’s assemblage of icy girdles.Now, the observations collected on these snaking sojourns, <a href="http://science.sciencemag.org/lookup/doi/10.1126/science.aat2349">published today</a> in the journal Science, paint a compelling portrait of how Saturn’s innermost moons might have come to be. A probable culprit? The planet’s own trademark rings, which likely had a role in shaping these moons from the start. For millions of years, Saturn’s moons and rings have been locked in an intimate, cataclysmic tête-à-tête of continual coevolution—one that’s still very much at work.“This is a robust, evolving system,” says <a href="https://www.seti.org/our-scientists/matthew-tiscareno">Matthew Tiscareno</a>, a planetary scientist and Saturn ring expert at the SETI Institute who participated in the Cassini mission, but was not involved in the study. “These moons...might have grown up together with the rings.”
<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/Y5HBHnRyZhT109rCdyRU5Q==/?topbar=false&amp;end=0&amp;endscreen=true&amp;start=0&amp;autoplay=false" width="100%">
</iframe>
</div>
It wasn’t so long ago that these ideas were far from top of mind, however. The so-called “Five Fabulous Flybys” weren’t even in the mission’s original objectives. “We weren’t really supposed to be studying these moons,” says study author <a href="https://science.jpl.nasa.gov/people/Buratti/">Bonnie Buratti</a>, a planetary scientist at NASA’s Jet Propulsion Laboratory. “It was serendipitous—a golden apple that fell into our laps.”But when the time came to direct the spacecraft inward, NASA scientists seized on the opportunity to get up close and personal with some of the planet’s innermost moons. “We realized it could be a brand-new mission,” says <a href="https://science.jpl.nasa.gov/people/Spilker/">Linda Spilker</a>, Cassini’s Project Scientist. “A chance to go where a spacecraft had never gone before. It was a no-brainer.”
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/PIA21449_fig2_copy.width-990_rUgQk0N.jpg"/>
<figcaption>Three of Saturn's small ring moons: Atlas, Daphnis, and Pan. Pan's equatorial band is much thinner and more sharply defined. The "core" of Atlas, beneath its fringe, is small relative to Pan's. Pan is about 18 miles in diameter and orbits 83,000 miles away from Saturn. Daphnis is only about 5 miles across and orbits 85,000 miles from Saturn. Atlas' diameter is about 19 miles and it orbits 86,000 miles from Saturn. Image Credit: NASA/JPL-Caltech/Space Science Institute
<div class="credit"></div>
</figcaption>
</figure>
After all, Saturn’s moons, which number at least 62, are an irrefutably odd cast of characters. And many of the ones nearest to the planet’s surface are some of the strangest of all.Two of the most inner moons, Pan and Daphnis, orbit in gaps within Saturn’s main set of rings, circling the planet like cosmic gutterballs. A set of others, including Atlas and Pandora, behave like nippy, militant sheepdogs, corralling the outer edges of Saturn’s A- and F-rings, respectively. Further out, Epimetheus engages another moon (Janus) in a bizarrely regular rendezvous, in which they exchange orbital positions every four years. Prior to Cassini’s approach, Pan, Daphnis, Atlas, Pandora, and Epimetheus had never been studied up close. But thanks to measurements taken by six of Cassini’s 12 instruments, these five mysterious moons have finally begun to come into focus.
<div class="related"></div>
This isn’t the first time these eccentric little satellites have taken center stage. The first images Cassini beamed back of Pan and Atlas, two of Saturn’s innermost moons, showed that both boast prominent equatorial ridges, or rocky bulges at their midsections that give the moons perplexingly pot-bellied shapes.At first, many were flummoxed. “None of us expected to find these tiny ravioli moons at Saturn,” says <a href="https://www.wellesley.edu/astronomy/facultystaff/french">Richard French</a>, a planetary scientist at Wellesley College who was involved in the Cassini mission, but did not contribute to the study.In the years since, Pan and Atlas have also been compared to UFOs, dumplings, and empanadas. But Buratti is partial to the image of ballerinas in tutus. And the new findings suggest that these moons are probably just as dynamic as their dancing namesakes.Based on Cassini’s measurements, Buratti and her colleagues discovered that the flared skirts of Atlas and Pan (and perhaps Daphnis, which wears a very subtle belt) were smoother and more pristine than the cores they adorned. They also appeared to be made up of a loose, low-density material. This indicates that the moons weren’t born with these fringes, and could have formed in multiple stages, Buratti says.That doubled the number of genesis events the researchers had to explain: one for the body, and one for the bulge. They still aren’t sure exactly how the ring moons got their start. One possibility is that they were born out of a larger planetary body that broke apart, seeding shrapnel in Saturn’s rings; another is that they formed from an agglomeration of particles entirely within the ring system itself.Whatever the case, it’s likely that Pan, Daphnis, and Atlas were once simple, naked spheres. But as these moons pirouetted through their parent planet’s rings, whirling and twirling through a haze of ice and rock, they slurped up the slurry of particles jostled out of place. Due to the thinness of the rings, dust glommed primarily onto the moons’ equators, giving them their pot-bellied physique.Even today, moons like these might still be expanding their waistlines. Beyond a certain point, however, passing particles might have a hard time sticking due to the pull from Saturn’s gravity, Spilker says. “The skirts can only get so big,” she says.
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Pandora.width-990_xr3CTNQ.jpg"/>
<figcaption>Saturn's moon, Pandora, which is roughly 52 miles in diameter. It orbits 88,000 miles away from Saturn. Image Credit: NASA/JPL-Caltech/Space Science Institute
<div class="credit"></div>
</figcaption>
</figure>
Costume changes aside, the proximity between ring and moon might explain another striking find from Cassini’s cameras: Moons orbiting deep within the ring system are more likely to have a rouge-red hue—one that bears an uncanny resemblance to the crimson particles that speckle Saturn’s rings. Such is the case with Pan, the innermost and ruddiest moon, followed closely by the slightly less rosy Daphnis and Atlas.It’s not yet clear what exactly gives the ring material its blush (theories include iron or a combination of organic molecules). Whatever they are, these inscrutable scarlet sparkles don’t seem to travel well. The further out from Saturn a moon orbits, the less likely it is to be red. Instead, more distant moons like Epimetheus are blue—likely due to a frigid spray of azure particles and vapors erupting off the <a href="http://science.sciencemag.org/content/315/5813/815">geologically active moon</a> <a href="https://www.pbs.org/wgbh/nova/video/is-there-life-on-enceladus/">Enceladus</a>.These icy plumes jet far inward—but tight-orbiting moons like Pan appear to be protected from Enceladus’ paintbrush by the same rings that stain them red. And with pigments encroaching in from both directions, Saturn’s inner moons manifest in a dazzling gradient of cosmic color.
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Epimetheus.width-990_JsfrCWD.png"/>
<figcaption>Saturn's moon Epimetheus, which is about 72 miles in diameter, and orbits about 94,000 miles away from the planet. Image Credit: NASA / JPL / Cassini-ISS / Justin Cowart
<div class="credit"></div>
</figcaption>
</figure>
It’s clear that Saturn’s inner moons are shaped by their surroundings. But these small satellites aren’t just passive passengers. As they orbit, moons can push and pull rings, sculpting and massaging them into new configurations. Some like Pan even blaze their own trails as they orbit, maintaining the gaps in which they reside like intrepid little vacuums. Moons can also be influential from afar, as when the icy plumes jetting off Enceladus feed into one of Saturn’s outermost rings. In Saturn’s neighborhood, rings and moons engage in a perpetual tango—and the choreography is always changing.“This definitely points to the fact that rings and moons in this system are absolutely not independent,” says <a href="https://web.physics.udel.edu/about/directory/faculty/sarah-dodson-robinson">Sarah Dodson-Robinson</a>, a planetary scientist at the University of Delaware who was not involved in the study. “They exert a lot of control over each other.”These processes are only a fraction of the forces still at work today, Buratti says. Recent work hints that the planet’s rings (and perhaps, by extension, its ring moons) might actually be <a href="http://science.sciencemag.org/content/early/2019/01/16/science.aat2965">quite young</a>—relatively speaking, that is, at 100 or 200 million years old. But on the timescale of a 4.5-billion-year-old planet, that makes Saturn’s most recognizable accessories fairly late additions to its wardrobe. And the rings’ tenure might be brief: In another hundred million years, they could be gone entirely.“This really shows that there is no substitute for going and looking,” French says. “We speculated about what we thought Saturn’s rings would be like, but every mission has revealed them to be more interesting and complex than we thought before.”With so much going on, the Saturn of today might be unrecognizable a few million years into the future. After all, in active planetary systems, the only constant is change.“In our old view of the Solar System, we thought, ‘Everything has been like this forever,’” Buratti says. “But it’s actually an ongoing process of violence. There are impacts, things rearranging themselves. It’s one giant, dynamic system.”
<div class="newsletter"></div>

The planet’s trademark rings appear to have played a crucial role in crafting the color and shape of some of its smallest moons.

The International Space Station, which maintains a low orbit a few hundred miles above Earth's surface, is home to thousands of microbial species. Image Credit: NASA Johnson, flickr

Bacteria Get Funky in Space. Scientists Are Fighting With Metal.

Journeying into the vast outer reaches of space might seem an exercise in isolation. But even when pushing the boundaries of the final frontier, humans are never truly alone: Everywhere we go, <a href="https://www.pbs.org/wgbh/nova/video/nova-wonders-whats-living-in-you/">a few trillion microbial hitchhikers</a> come along.In most cases, that’s a plus: Host-microbe partnerships are a <a href="https://www.pbs.org/wgbh/nova/video/nova-wonders-whats-living-in-you/">necessary</a> part of human existence. But occasionally, these relationships sour. And outside the constraints of Earth’s gravity, the rules of infection can shift.“Wherever we go, bacteria come with,” says <a href="https://www.colorado.edu/faculty/zea-luis/">Luis Zea</a>, a microbiologist and bioastronautics expert at the University of Colorado, Boulder. “It’s extremely important to study bacterial behavior in space, including their resistance to drugs and their ability to cause disease, to ensure long-term safe exploration of space.”
<div class="ad"></div>
There’s now a decent body of evidence that bacteria get a little funky in outer space. Unshackled by gravity, some thrive, growing faster than normal or mounting heftier defenses against the antimicrobial effects of normally powerful drugs. Additionally, several species, including the Salmonella bacteria of food-poisoning fame, seem to develop enhanced abilities to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4159036/">cause disease</a> in microgravity. Other microbes, however, do just the opposite, becoming sluggish and tame once freed of Earth’s gravitational pull.
<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/1QpQ96_iPAGqlyj7Q9jMSw==/?topbar=false&amp;end=0&amp;endscreen=true&amp;start=0&amp;autoplay=false" width="100%">
</iframe>
</div>
Zea is one of several researchers investigating what factors determine the trajectory a microbe might take. One of his projects involves studying how <a href="https://www.colorado.edu/faculty/zea-luis/projects">biofilms</a>—aggregates of bacterial cells that take on special properties, often helping them glom onto surfaces and withstand the effects of antibiotics—form and fare in the microgravity of space.
<div class="related"></div>
But bacterial caprice is only half of the equation. Complicating matters is the fact that microgravity seems to <a href="https://www.pbs.org/wgbh/nova/article/space-flight-mouse-immunity/">discombobulate</a> the mammalian immune system, potentially making astronauts more vulnerable to pathogens lurking in their vicinity. For instance, recent research suggests immune cells that normally keep troublesome microbes in check falter during space travel, allowing dormant infections—like those caused by <a href="https://www.sciencealert.com/herpes-loves-something-about-space-that-s-triggering-flare-ups-in-astronauts">herpes viruses</a>—to flare up. Disease is no picnic in any context, but the stakes are far higher in space: Medical assistance is hard to come by hundreds of miles above Earth’s surface.This ups the ante on keeping potentially harmful pathogens out of spacecraft environments, where several strains of multidrug-resistant bacteria <a href="http://dx.doi.org/10.3389/fmicb.2019.00543">have already been isolated</a>. But aboard the International Space Station (ISS), “there is only a stringent list of disinfectants we can use,” says NASA microbiologist <a href="https://www.nasa.gov/feature/microbiology/">Sarah Wallace</a>. Many of the chemicals we use to scrub down kitchens and bathrooms on our home planet are too noxious for this habitable satellite, first launched into low Earth orbit in 1998. After all, when fumes build up on the ISS, “you can’t just roll down the window,” Wallace says.To circumvent this, researchers like <a href="https://prof.beuth-hochschule.de/grohmann/">Elisabeth Grohmann</a>, a microbiologist at the Beuth University of Applied Sciences in Germany, are developing a new set of metal-based materials to combat the spread of disease. Their work shows that treating surfaces near high-traffic areas, like the doors of ISS bathrooms, with a metal-based antimicrobial coating effectively kills off a panoply of pathogens, including bacteria, fungi, and viruses. The team’s compound, called AGXX, contains silver and ruthenium, which engage each other in a chemical cycle, yielding a self-regenerating, multi-purpose veneer with a long lifespan.“This coating can be used on any kind of material—there’s not really a limitation on where it can go,” Grohmann says. But, she adds, that doesn’t mean there will be any kind of push to coat the entire ISS with AGXX. Not only would that be expensive and logistically impractical, but it could also do more harm than good. Our bodies, which house just as many bacterial cells as human cells, aren’t meant to live in sterile spaces. And just as they do on Earth, many of the benign and beneficial microbes that have colonized the ISS might play important roles in keeping more infectious strains at bay.
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/sarah_wallace_sarah_stahl.width-990_xHqWUsl.jpg"/>
<figcaption>NASA microbiologists Sarah Wallace (left) and Sarah Stahl (right) in their Johnson Space Center lab, where they are working to streamline microbial identification techniques for use aboard the International Space Station. Image Credit: Rachel Barry
<div class="credit"></div>
</figcaption>
</figure>
As it stands (or orbits), the ISS is by no means a virulent cesspool of disease. Though human pathogens have been isolated on the satellite, most of them are the same regulars that frequent our homes and workplaces here on Earth, and only cause problems if they happen to find their way into inappropriate places, like the inside of an open wound.“The ISS is probably as clean as your home, and cleaner than a college dorm room,” Wallace says (though the latter might not set a particularly high bar). “Our astronauts aren’t being exposed to really awful things all the time—it’s almost the opposite.”Still, when it comes to the spacebound bacteria that can cause us issues, understanding their quirks remains an important pursuit. By figuring out how these hardy little cells adapt to extreme conditions, researchers might learn important lessons about how to stop them in their tracks—which could inform efforts here on Earth, where the threat of antibiotic resistance grows with each passing year. “The ISS is almost a simple, model system, where you can control and observe colonization of surfaces without too many other factors,” says <a href="https://www.kent.edu/biology/profile/laura-g-leff">Laura Leff</a>, a bacterial ecologist at Kent State University. “If we can’t control it there, we can’t control it elsewhere. So the applicability could be really broad.”With ideas like these in mind, Wallace and her colleagues at NASA are developing new <a href="https://www.nasa.gov/feature/genes-in-space-3-successfully-identifies-unknown-microbes-in-space/">techniques</a> to identify and <a href="https://www.nature.com/articles/s41598-017-18364-0">study microbes</a> and their <a href="https://msystems.asm.org/content/4/1/e00281-18">adaptations</a> on the ISS without having to ship samples to laboratories on Earth. The hope is that these tools and others might lead to enhanced diagnostics, and a clearer understanding of how different bacterial strains could be impairing—or bolstering—the health of the humans they encounter.Whether friend or foe, when it comes to microbes, the only constant is the tenacity of the bacteria themselves, Leff says. “They’ll find a way to succeed, regardless of environmental conditions.”
<div class="newsletter"></div>

Bacteria, both good and bad, go wherever humans do. Understanding their quirks in outer space is key to preserving astronauts’ health.

A gene called TIA1 might play a big role in determining how female mice remember stressful and scary experiences. Image Credit: zsv3207, iStock

Do Genes Dictate How Mice Cope With Trauma?

For better or worse, memory operates most potently at emotional extremes. Happy memories often tend to stick; so, too, do some of the ones we’d most like to forget.Much of how the brain selectively consolidates such events remains mysterious. But today, in a <a href="https://www.cell.com/cell-reports/fulltext/S2211-1247(19)30227-X">study</a> published in the journal Cell Reports, a team of researchers takes the first steps towards pulling back the veil on how a gene called TIA1 might control fear-based memories in mice. If confirmed in humans, the findings could someday have implications for understanding stress-related psychiatric conditions such as post-traumatic stress disorder (PTSD).
<div class="ad"></div>
Animals’ ability to remember impactful experiences is arguably one of our greatest assets in the quest for survival. In humans, a good memory is what keeps us afloat, from maintaining to-do lists to giving us pause before ingesting spoiled foods. But memory can also become a double-edged sword—especially when recollections of a traumatic experience become intrusive or debilitating, and start to interfere with daily life. Occasionally, this can manifest in psychiatric illness like PTSD.Not all trauma sticks with us, however, and the same traumas don’t affect individuals in the same way. For years, researchers have been working to uncover what aspects of our biology underlie these differences, and how vulnerable individuals can be identified and supported. “Environment plays a big role in psychiatric disorders like PTSD,” says <a href="https://icahn.mssm.edu/profiles/rachel-yehuda">Rachel Yehuda</a>, a neurobiologist and PTSD expert at the Icahn School of Medicine at Mount Sinai who was not involved in the study. “But there’s always been this nagging question about why people respond differently to adversity.”To untangle these dynamics in mice, a team led <a href="https://www.biochem.cumc.columbia.edu/research-labs/kandel-lab">Joseph Rayman</a> and <a href="https://neuroscience.columbia.edu/profile/erickandel">Eric Kandel</a>, neuroscientists at Columbia University’s Zuckerman Institute, focused their efforts on TIA1, a protein that’s abundant in the hippocampus, the memory consolidation center of the brain. Previous work from Kandel’s group had shown that TIA1 helps cells manage stress in their environment, but whether this translated up to the level of behavior remained unclear. So the researchers bred male and female mice that lacked the gene that encodes TIA1 and put their stress management skills to the test. 
<div class="related"></div>
A typical mouse doesn’t think much of the scent of ethanol. But if that smell is wafted in a rodent’s direction while tiny electric shocks are being administered to its feet, it will learn to avoid areas that reek of the otherwise innocuous odor—a clear indicator that it has crystallized a fear-based memory. When male mice were taught this association, all of them shied away from chambers that bore the scent of alcohol, regardless of their TIA1 status. But to Rayman’s surprise, female mice producing normal amounts of TIA1 didn’t take the same pains to avoid the odor. It seemed that while the females remembered the scent of alcohol, and the distressing foot shocks that often came with it, the association simply wasn’t as bothersome. In females in which the TIA1 had been snipped out, however, the pendulum swung in the opposite direction: These mice were far more likely to recoil from the odious scent.Given the myriad differences between the hormones and physiology in biological males and females, there’s probably not one single explanation for this discrepancy, Rayman says. But one discrepancy stood out to the researchers: Female mice naturally produce more TIA1 than males. This could help explain why the females seemed a bit more resilient to stress in the first place—and why switching the gene off entirely constituted a much more striking change.If that was the case, the researchers reasoned, then upping, rather than damping down, the production of TIA1 in male mice might extinguish some of the effects of fearful memories. And that’s exactly what they found: Male mice bred to churn out gobs of TIA1 were far less likely to shy away from the scent of ethanol.These results illustrate two things, Rayman explains. First, TIA1’s role in forming stressful memories seems to operate on a sliding scale—meaning the amount of TIA1 an individual produces could have bearing on how they internalize difficult experiences. Second, the differences between the sexes could “shed some insight into what makes male and female brains different when processing fear memories,” he says. This latter point is especially intriguing, he says, given that both PTSD and anxiety disorders “afflict women at a far greater incidence and with greater potency.”Of course, mice learning to be wary of a specific smell isn’t the same as human trauma. But Rayman argues that “among all psychiatric illnesses, PTSD is profitably studied in mice. It’s a disorder of fear and memory, and those are highly evolutionarily conserved.” The researchers are now conducting preliminary studies in humans, and so far, the results hint that TIA1 functions similarly across species, Rayman says.Still, “this doesn’t guarantee that [TIA1] will be associated with human PTSD—that’s a big leap,” Yehuda, the Mount Sinai neurobiologist, says. “But it’s an impossible leap without having some animal basis.”
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/TIA1_stress_granules.width-990_KmmImIt.png"/>
<figcaption>A cell showing TIA1 in yellow and green. TIA1 helps cells deal with stress by sequestering non-essential molecules so resources can be diverted to deal with the situation at hand. Image Credit: Joseph Rayman, Kandel Lab, Columbia University’s Zuckerman Institute
<div class="credit"></div>
</figcaption>
</figure>
Additionally, more work is needed to fully understand exactly what TIA1 is doing at the cellular level, and how those activities might ultimate influence memory. It’s also too early to say if there’s an “ideal” amount of TIA1 for a well-functioning brain. And that answer, if it exists, might vary by biological sex or an individual’s genetic background. Still, this work points to the fact that this protein—formerly understood as an cellular asset for enduring molecular stress—can also govern biology at the level of behavior, Rayman says.“These authors got it right,” Yehuda says. “When it comes to translating research [from mouse to human], translation isn’t transliteration. But this is an elegant piece of science that may help explain some aspect of individual difference when it comes to avoiding fear cues.”This discovery “hits at a time when we are beginning to fully appreciate the complexity” of the relationship between brain and behavior, says <a href="https://www.bumc.bu.edu/busm/profile/ann-rasmusson/">Ann Rasmusson</a>, a psychiatrist at Boston University who was not involved in the study. Many genes factor into psychiatric illness—a fact that’s precluded a one-size-fits-all solution when it comes to diagnosis or treatment. TIA1 is likely to be only one thread in the very complex tapestry that weaves together emotion and memory. But every new factor identified could constitute critical intel, especially for the patients for whom all standard therapies seem to fail. At the same time, that also means that a single “risky” gene is by no means a guarantee of illness or adversity. “Genes are an important piece of the puzzle, but there are so many other systems involved, and you may well have something to compensate,” Rasmusson says. “That’s something that should also give us hope.”
<div class="newsletter"></div>

Scientists have uncovered a gene that affects how mice encode fear-based memories—which could inform the study of psychiatric disorders like PTSD in humans.

Brand: NOVA Wonders

Hero Feature