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More than 68 million infected with the novel coronavirus and more than 1.5 million dead. 2020 has been a year defined by global sickness and loss.

In the face of this extraordinary threat, it’s easy to forget how much we have accomplished. Doctors, nurses and staff in hospitals around the world have learned how to better care for those sick with COVID-19. Researchers have uncovered secrets of a virus that, not so long ago, was wholly unknown.

Accelerated efforts to create vaccines succeeded beyond even the most optimistic predictions, with the United Kingdom granting emergency use of a vaccine on December 2 and the United States poised to follow suit before the end of the year.

Meanwhile, public health officials have fought to inform the public about how to reduce the risk of infection amid an onslaught of false reports about cures and treatments, and denials about the pandemic’s severity. Millions of people have donned masks and dramatically reshaped their daily lives to help fight the virus.

In early January, we had no tests for detecting the virus, no treatments, no vaccines. And though we’re not where we want to be, we’ve made progress on all those fronts. But we still have so much to learn. Here are pressing questions that scientists seek to answer. — Emily DeMarco

Why do some people get sick while others don’t?

A person’s age and preexisting medical conditions are risk factors for more severe disease, and men appear to be at higher risk than women (SN: 4/23/20). But scientists don’t have many answers to explain the wide variety of experiences people have with SARS-CoV-2, the coronavirus that causes COVID-19. Many people have no symptoms. Some struggle to breathe, suffer strokes, or progress to organ failure and death.

People who develop severe disease do have something in common: “a very severe inflammatory response,” says cancer immunologist Miriam Merad of the Ichan School of Medicine at Mount Sinai in New York City. The body’s own immune response can get out of whack and inflict inflammatory damage in a misguided attempt to make things right (SN: 8/29/20, p. 8).

Scientists have begun to pick out immune system players that seem to gum up the works during a severe bout of COVID-19. For example, a problem can arise with type 1 interferons, proteins that kick off the initial immune response to an intruder and activate production of pathogen-destroying antibodies. Patients with severe COVID-19 can have a weak interferon response; in some patients, genetic errors can interfere with the production of interferons, in others, the immune system incapacitates the proteins (SN: 9/25/20).

Meanwhile, some severely sick people produce an excess of other components of the body’s early immune response. In nearly 1,500 people hospitalized with COVID-19, Merad and colleagues measured four immune proteins that contribute to inflammation. High levels of two of the proteins, interleukin-6 and TNF alpha, predicted that a patient would go on to have severe illness and possibly die, even after accounting for age, sex and underlying medical conditions, the researchers reported in August in Nature Medicine.

It may be that people with no or mild symptoms have some degree of preexisting immunity. Some people who haven’t been exposed to SARS-CoV-2 have white blood cells called T cells that nonetheless recognize the virus. This appears to be due to past colds from common coronaviruses, researchers reported in October in Science. They speculated that this preexisting T cell immunity may contribute to differences in COVID-19 disease severity. — Aimee Cunningham

What are the long-term health consequences of an infection?

This question could take years to resolve.

For now, we know that for some people, the symptoms and suffering from COVID-19 can go on for months after the initial infection (SN: 7/2/20). There isn’t an agreed-upon definition for what some call “post-COVID syndrome” or “long COVID,” but symptoms tend to include fatigue, shortness of breath, brain fog and heart abnormalities. And these problems aren’t necessarily tied to a more severe initial illness.

It’s not yet clear how widespread the syndrome is or what to do about it. But studies are beginning to offer clues as to how common persistent illness is. Of 143 patients in Italy who had been hospitalized with COVID-19, 32 percent had one or two symptoms and 55 percent had three or more symptoms an average of two months after first feeling sick, researchers reported in August in JAMA. And in a survey of 274 symptomatic adults who had a positive test for SARS-CoV-2 but weren’t hospitalized, 35 percent were not back to their normal state of health two to three weeks after testing, according to a July study in Morbidity and Mortality Weekly Report.

One of the largest surveys so far comes from the COVID Symptom Study, in which people logged their symptoms into an app. Of 4,182 users with COVID-19, 13.3 percent had symptoms lasting more than four weeks, 4.5 percent had symptoms for more than eight weeks and 2.3 percent topped 12 weeks. The risk of persistent symptoms rose with age, researchers reported in October in a preliminary study posted at medRxiv.org.

To learn about the long-term physical and mental health effects of COVID-19, the U.S. National Institutes of Health plans to follow for months to years people who have been infected. And a trial by Steven Deeks, an internal medicine physician at the University of California, San Francisco School of Medicine, and colleagues will assess the role of inflammation in persistent health effects.

Long-term studies of entire communities will be especially important to learn how common persistent symptoms are, how long they last and why they’re happening, Deeks says. “Right now, we have just a whole long list of questions,” he says. “It’s going to take a lot to figure this out.” — Aimee Cunningham

How long might immunity last?

There are signs that the immune system can learn how to deal with the virus, bestowing at least temporary immunity. Most people appear to make immune proteins that stop SARS-CoV-2 in its tracks, called neutralizing antibodies, and also T cells that help coordinate the immune response or kill infected cells, says epidemiologist Aubree Gordon of the University of Michigan in Ann Arbor. Those antibodies and T cells can stick around in the body for at least six months, if not longer, studies suggest. “So that’s promising,” Gordon says.

But scientists don’t know how long a person will be protected from a future bout with the virus. “There’s just been a limited time for people to study this,” she says.

Still, SARS-CoV-2 is not the only coronavirus that infects people. For instance, four others that cause the common cold circulate around the globe. “We can get some evidence from what goes on with some of the human endemic coronaviruses,” says immunologist Brianne Barker of Drew University in Madison, N.J. For those viruses, protection lasts about a year. People can get infected with the same virus over and over again once their immunity wears off, though the severity of a second infection varies. The duration of immunity after an infection with the coronaviruses that cause SARS and MERS is unknown.

To date, there have been a few documented reinfections with SARS-CoV-2, suggesting that, for some, immunity doesn’t last very long. Efforts — including a study Gordon is working on — are under way to figure out how common reinfection really is and whether subsequent infections are any different from the initial one. — Erin Garcia de Jesus

What can we expect from the treatments and vaccines being developed?

Because of crucial advances in 2020, “we know more about the virus and some of the complications it causes and how to prevent and predict and treat those complications,” says Amesh Adalja, an infectious disease physician at Johns Hopkins Center for Health Security.

Doctors have learned tricks that help people breathe easier, such as putting hospitalized COVID-19 patients on their stomachs. And two drugs — the antiviral remdesivir and the steroid dexamethasone — have shown promise against the virus (SN: 6/16/20). The U.S. Food and Drug Administration approved remdesivir for use in hospitalized COVID-19 patients ages 12 and older in October because some studies showed that it can shorten hospital stays. But the drug, which is the only FDA-approved drug for COVID-19, didn’t reduce the chance of dying or going on a ventilator in a large study by the World Health Organization (SN: 10/16/20).

In November, the FDA gave a cancer drug called baricitinib emergency use authorization. In combination with remdesivir, the drug shaved an extra day off hospital stays compared with remdesivir alone in a large clinical trial. But many doctors aren’t convinced of baricitinib’s effectiveness.

Ideally, doctors could treat people before they are sick enough to need the hospital. Some drugs are in early stage clinical trials to determine if they can help people early in an infection (SN: 9/26/20, p. 8). Some antibodies taken from COVID-19 survivors and lab-made antibodies are also being put to the test (SN: 9/22/20). Lab-made antibodies from Eli Lilly and Company and Regeneron were given emergency use authorization in November for treating people newly diagnosed with COVID-19, making the therapies the first available to people who aren’t ill enough to go to the hospital. (Regeneron Pharmaceuticals is a major donor to the Society for Science & the Public, which publishes Science News.)

Vaccines are being developed on a fast track. Russia was the first country to announce it had a vaccine for the public, though scientists question its efficacy (SN: 8/11/20). China has also given the nod for emergency use of some vaccines for the military (SN: 8/1/20, p. 6) and general public, although those vaccines are still in testing too. The United Arab Emirates authorized two vaccines made in China for use by its citizens.

Both Pfizer and Moderna announced in November that their mRNA-based vaccines were about 95 percent effective at preventing illness (SN: 11/16/20; SN: 11/18/20). On December 2, the United Kingdom OK’d Pfizer’s vaccine for emergency use, making the vaccine the first to get the nod after thorough testing. AstraZeneca and the University of Oxford reported that their vaccine prevents illness too, and may cut down on transmission of the virus (SN: 11/23/20).

Over 200 other vaccines are in development worldwide, says Esther Krofah, executive director of FasterCures, part of the Milken Institute think tank. But getting doses of a vaccine, at least initially, “will not be as straightforward as calling up your local CVS,” she says.

In the United States, 21 million health care workers and about 3 million people living in long-term care facilities are expected to be first in line for the vaccines (SN: 12/1/20). Children may be among the last to be immunized. That’s because vaccines haven’t been tested in kids under 12, and children are less likely to die or develop severe disease than adults.

Bottom line: A COVID-19 vaccine may not be widely available in the United States until late spring or summer 2021.

Even when a vaccine is approved for broad use and there’s a large enough supply, “the bigger challenge will come in distributing vaccines widely,” says Julie Swann, a health systems engineer at North Carolina State University in Raleigh. Pfizer’s vaccine, for instance, has to be kept frozen at supercold temperatures. So distributors must either be able to give out all of their doses within a couple of days after receiving a shipment, or have access to special freezers or dry ice to keep the vaccines cold enough. Big cities may have more access to those measures than rural areas.

Many of the vaccines in testing require two doses. Keeping track of who has gotten which vaccine and when it’s time for a booster, and whether booster shots are available, could also be challenging, Swann says. — Tina Hesman Saey

Will the pandemic end in 2021?

“I don’t think anyone can say with clarity what the end of the pandemic might look like,” says Michael Osterholm, an epidemiologist at the University of Minnesota in Minneapolis. If a vaccine can confer long-lasting immunity, on the order of years to decades, widespread community transmission around the globe could cease, he says.

But “a vaccine is nothing until it becomes a vaccination in somebody’s arm,” Osterholm says. And those arms must be willing. Vaccine development has progressed at a record pace, but some experts worry that speed, and the politicization of certain drugs, have seeded distrust (SN: 8/1/20, p. 6). “Acceptance is going to be a huge issue,” he says.

Of course, many countries managed to slow the virus’ spread without a vaccine. In the United States, “we don’t have to wait to get this under control,” says public health researcher Megan Ranney of Brown University in Providence, R.I. “We already know that basic, multimodal public health interventions work.”

Such interventions include widespread and easily accessible testing that spurs contact tracing and case isolation, as well as consistent public health messaging around the importance of wearing masks, social distancing and avoiding crowded indoor spaces.

Thus far in the United States, these basic public health interventions have been patchy and inadequate on a national scale (SN: 7/1/20). That’s allowed the “first wave” of infections to slosh around the country, growing in size to about 200,000 new cases each day in early December. Whether this dire trend worsens in the early months of 2021 depends in large part on federal action, both Osterholm and Ranney say.

“We need a national plan, and we don’t have a national plan,” Osterholm says. That may change with the election of Joe Biden, who campaigned on creating a coronavirus national plan. Osterholm is part of the president-elect’s Transition COVID-19 Advisory Board, which has begun planning a new federal response.

Broadly, that plan includes clear and consistent public health messaging, a well-funded national testing strategy, support for states to boost contact tracing, supplying personal protective equipment to essential workers and mask mandates. “If we have all those things in place, the coming year could be somewhat similar to where we’ll be with widespread vaccination,” Ranney says. People could go about most normal activities with a little extra caution, wearing masks and avoiding crowds indoors.

Still, measures like universal mask wearing, social distancing and contact tracing only work if people abide by them. As the pandemic wears on, experts worry that complacency and fatigue could further fracture an already uneven response to the disease.

If the United States “continues on the path we’re on now, we’re going to continue to see increasing numbers of people hospitalized and dead, continue to go through this seesaw of full lockdown then full reopening, confusing messages, unmitigated anxiety and fear and a worsening economy,” Ranney says. — Jonathan Lambert

Once the pandemic ends, will the virus still circulate?

When the pandemic eventually fizzles out, the coronavirus itself will probably stick around for a while, experts say. How long, however, depends on how well our immune system and available vaccines protect us from reinfection.

So far, it’s impossible to say how frequently reinfections with SARS-CoV-2 happen based on the small number of these cases identified. But if reinfections become common in the face of waning immunity, then the virus is likely here to stay.

For example, if immunity lasts around 40 weeks, as it does for some cold-causing coronaviruses, then there may be yearly outbreaks of COVID-19, researchers reported in May in Science. If the immune system’s memory of the virus lasts slightly longer, say two years, then there may be biannual outbreaks. Permanent immunity could mean the virus may disappear entirely, though that possibility is unlikely since respiratory viruses like influenza and viruses that cause colds rarely lead to this sort of long-lasting immunity.

Adding an effective vaccine to the mix would help build — and maintain — immunity among people to control potential future outbreaks. And if a vaccine is highly effective and enough people take it plus any boosters or follow-up vaccinations as needed, that could help prevent the virus from spreading at all. But those are big ifs.

Because SARS-CoV-2 can be spread by people without symptoms, some experts do not anticipate the virus will go away any time soon, unlike the coronavirus that caused SARS. That virus stopped circulating among people a little more than a year after it appeared, in part because it wasn’t spread by people with no symptoms. That allowed public health experts to more easily isolate sick patients and quarantine their contacts to prevent the virus’ spread. It’s estimated that around 30 percent of people infected with SARS-CoV-2 don’t show symptoms, making such total containment much harder.

“From everything we’re seeing so far,” says Barker, the Drew University immunologist, “this virus may become endemic and may be with us for a long time.” — Erin Garcia de Jesus

My companions scanned the treetops with binoculars and a thermal-imaging monocular. I stared at the branches and leaves, pretending I knew what to look for. It was a cool June evening just before sunset on a village road on Langkawi Island, Malaysia.

“There’s one! Up there,” one of the biologists called out. I squinted at the spot, about five meters up the tree trunk, and saw only a brown knob speckled with gray. Where? Then the knob stirred. Its top edge rose and turned, and I was staring into a pair of bulging eyes set on a small head with a short snout.

My first colugo. The size of a house cat, colugos are nocturnal mammals that live in trees. Colugos are also called “flying lemurs,” which is a misnomer because they cannot fly and they are not lemurs. A colugo has a cape of skin that stretches from its neck to the tips of its four limbs and tail. That skin, furry on top, helps colugos glide far and hide well in the canopy.

“Wait … Oh, it has a baby!” called zoologist Priscillia Miard of Universiti Sains Malaysia in Penang and leader of that evening’s search. She passed me her binoculars as the team discussed the identity of this colugo.

A tiny head popped out from beneath the mother’s fur, like a child peering out from under a blanket. Baby colugos cling to their mother’s furless undersides until about age 6 months, nursing on nipples near mom’s armpits.

I had seen two colugos just 15 minutes into our search!

The mother colugo lifted her tail. “It’s pooping,” said Miard, without the slightest note of concern that we were standing right below. Miard later told me that colugo feces are like dried lentils — nothing messy.

For an animal that is the closest living relative to all primates, having branched off about 80 million years ago, colugos remain a big mystery (SN: 9/3/16, p. 17). Today, the two living species of colugos are found only in Southeast Asia, though recent studies suggest that two is an imperfect count. Miard and other scientists have begun to upend what little knowledge exists about these mammals, revealing how colugos communicate and how they glide more than the length of a football field.

Into the night

Colugos popped unexpectedly into Miard’s life three years ago. The then 28-year-old French researcher had spent five years in Borneo studying nocturnal primates, including tarsiers and slow lorises. In 2017, Miard visited Langkawi, famous for its beaches and paddy fields, where she saw colugos “everywhere” — in orchards, on golf courses, at resorts and along well-traveled village roads. Because colugos were abundant and easy to find and observe in Langkawi, Miard pivoted to study them. In August, she successfully defended her Ph.D. thesis at Universiti Sains Malaysia for her research on colugo ecology.

But as I stood by her side looking up, Miard did not mention her Ph.D. She focused on the mother colugo — now a few dried lentils lighter — which seemed ready to start her night. The colugo climbed to the far end of a branch and turned her head toward the road. Then she leaped.

The colugo spun around, stretched her legs and tail, and glided like a magic carpet across the road to another tree trunk. Then she hopped, hopped, hopped up the tree into the leaves and out of sight.

She glided to four other trees over the next 15 minutes. By then, Miard and her teammates — biologists Muhammad Fizri bin Ahmad Zubir and Célia Lacomme — had recognized the mother colugo’s fur coloration. They had been following her for some time, naming her “Batwoman” because, months ago, locals thought the researchers were looking into the trees for bats.

Streetlights and passing cars and motorcycles lit the road, but a few meters away, the trees were dark. Miard and Lacomme switched on their red-light head lamps to illuminate the treetops. Something moved on a nearby tree trunk. Another colugo! Miard pointed her camera, saw testicles and announced that the colugo was male.

Master gliders

All colugos are master gliders, considered among the best of the 60-odd species of mammals that can glide. One Sunda colugo (Galeopterus variegatus) was recorded gliding 145 meters, almost the length of three Olympic swimming pools.

That sustained glide was reported in 2011 in the Journal of Experimental Biology by Gregory Byrnes, a biologist at Siena College in Loudonville, N.Y., and colleagues. At the time, most researchers assumed gliding was an energy-efficient way for colugos to travel. Byrnes’ team tested that idea by gluing data loggers onto wild Sunda colugos in Singapore and recording almost 260 glides among four individuals.

Sunda colugos often climb before gliding. In the study, a Sunda colugo could climb a total of 320 meters and glide 1,342 meters in one night. “No one ever took into consideration that in order to glide, you’ve got to climb,” Byrnes says. His team fed colugo data into metabolic models of other tree-dwelling mammals to estimate how much energy colugos expend to both glide and climb. When climbing is included as part of gliding behavior, and in forests where treetops overlap, a colugo could save energy crawling through the canopy rather than gliding, he says.

The “big advantage” of gliding is that it saves colugos time, Byrnes says. Gliding lets an animal cross open space in a few seconds so that it can spend more time feeding or traveling even farther, he says.

Colugos pull off those long-distance glides with their gliding skin, known as a patagium. While other gliders like flying squirrels have a patagium that stretches to the hind feet, a colugo’s patagium continues all the way to the tip of the tail. A more expansive patagium gives a colugo extra “wing area,” which lifts and slows the animal, allowing a gentler descent than other gliders, Byrnes says. The extra skin also helps the animal glide far.

And there is more to the patagium than skin and fur. Byrnes and his collaborators have found that the thin patagium is rich in muscles, and some parts are stiffer than others. A colugo may be able to flex those muscles to change the shape and stiffness of its patagium and thereby adjust its aerodynamics midair. Understanding the gliding biomechanics of colugos might help in the design of robotics and wing technology, Byrnes says.

That evening in Langkawi, Batwoman glided down the road, across the road and up the road. Never a sound. Once, she was gliding straight toward a tree, and just before impact, she turned, cut a sharp arc and landed on the next trunk. Wow.

High talk

When Batwoman reached her fifth tree of the night, another colugo swooped in from the dark and hopped up the trunk toward her.

Colugos were once thought to be solitary animals, Miard says. Social interactions were brief and rarely seen. But newer observations by Miard and others suggest that colugos form loose social groups of females or a mother and her offspring — even those that are weaned. Miard has seen up to six colugos in a tree. Males, though, seem to travel alone, joining groups of females only temporarily.

Miard trained her camera on the newcomer, which passed by Batwoman and continued into the canopy. Not a glance. Miard looked disappointed. “Oh no, he didn’t even say hi.”

To my ear, Batwoman hasn’t made a sound. But she may have been calling in ultrasound, inaudible to humans. Miard and colleagues discovered ultrasound calls from colugos, reporting the finding in 2019 in Bioacoustics. A microphone picked up the ultrasound signals during a bat survey, and Miard tracked the source to colugos. Many nocturnal animals, including bats, tarsiers and slow lorises, communicate in ultrasound, probably to avoid detection by predators. Colugos likely do the same. In November, Miard and colleagues will play the ultrasound calls in the field and listen for colugo responses.

It’s 8:15 p.m., dinnertime. Batwoman crawled into the thick foliage and gingerly pulled some leaves for a sniff. Miard explained that colugos eat mostly leaves. Batwoman shoved some leaves into her mouth and began to chew. Fizri and Lacomme recorded the observations on a behavior checklist on their smartphones.

“Wait, the baby is trying to eat leaves,” said Miard, looking through the binoculars. Lacomme shined her red-light head lamp at Batwoman. The baby colugo reached out from under its mother, tugged a few small leaves and tried to nibble them. Maybe the baby is learning what to eat from its mother, Miard said. It was too dim for me to tell if the baby actually ate the leaves. Lacomme’s red-light head lamp wasn’t bright enough. White light might have offered a better view.

But Miard won’t shine white light on nocturnal mammals. “When we use white light on colugos, they freeze, but not when we use red light,” she told me later. The freezing, she says, is a sign that white light disturbs the nocturnal mammals.

Miard’s concern makes sense. White light, which is commonly used in nocturnal animal studies, can quickly saturate the sensitive optic cells in nocturnal animals’ eyes and cause temporary blindness, says primatologist Amanda Melin of the University of Calgary in Canada. “These moments of blindness are likely disorienting and potentially harmful,” Melin says. “Red light is likely far less disruptive as it will be much lower intensity” than white light.

Eager pursuit

Around 9 p.m., another colugo glided in and joined Batwoman on a tree. This one seemed more interested than the last; he poked Batwoman and bit her sides. The newcomer, a male, wanted to mate, Miard said. But every time he got close, Batwoman pulled away.

Miard clutched her camera tight. Colugo romance makes prized footage. Gazing into the canopy, Miard backed away from the tree and onto the road — into the path of an oncoming car that just managed to stop before hitting her.

“F—, we are going to miss the most important part. We know they are going to make babies, but I can’t see them,” Miard said. She turned to Fizri: “Where’s the thermal camera?”

Minutes later, Miard spotted the colugos near the top of the tree. “You are really lucky,” she told me. “Many exciting things tonight.”

Batwoman continued to test the male, which I decided to name “Eager.” She glided to another tree, then another and yet another with Eager close behind. The colugos lingered on one tree. Miard sat by the road, camera in hand, eyes on Batwoman.

“Come on guys…. Please let him do it, please … Batwoman,” Miard muttered.

Our small group piqued the curiosity of locals. A couple, standing at the porch of a nearby house, watched us for about 10 minutes, then came over. “It’s a kubong,” Fizri told them, giving the local Malay name for colugo.

The couple knew the name but not the animal. They thought colugos lived only in forests. “Does it eat fruit? Is it like a bat?” they asked in hushed tones. Fizri lowered his smartphone and began to explain colugo ecology. The opportunity to talk colugo with local residents and correct misconceptions is one of the reasons Miard likes to study colugos in villages.

Colugo conservation

Perhaps because they are nocturnal and well camouflaged, colugos live hidden in plain sight. Zoologist Dzulhelmi Nasir, now with the Malaysian Palm Oil Board, has studied colugos in Borneo. Most locals have never heard of colugos, he says. People often confuse the animals with flying squirrels or a giant fruit bat called kluang in Malay.

Confusion or misconceptions about the colugos can be deadly for the animals. In parts of Malaysia, orchard and plantation owners see colugos as fruit pests and kill them, Miard told me. But colugos rarely eat fruits and flowers, according to a study published in 2006 in Biodiversity & Conservation, as well as Miard’s own unpublished research. Fortunately, here in Langkawi, there are few commercial orchards, and locals leave colugos alone.

But across Southeast Asia, colugos are losing their forest homes to agriculture and development. The region lost 293,000 square kilometers of forest from 2000 to 2014, an area about the size of Arizona, according to a 2018 report in Nature Geoscience.

On the International Union for Conservation of Nature’s Red List of Threatened Species, the Sunda colugo and the Philippine colugo (Cynocephalus volans) are categorized as “least concern” for risk of extinction. The Sunda colugo, in particular, with its wide distribution from Vietnam to Indonesia, is unlikely to be threatened.

But that assessment might be too rosy. Those two species may actually be eight, or as many as 14, based on genetic evidence reported in 2016 in Science Advances. If so, instead of the Sunda colugo being one widely distributed species, there are several colugo species confined to smaller areas that may be more susceptible to local extinction.

Zoologists had always noted that colugos look different across Southeast Asia. By the 1950s, about 20 species and subspecies were recognized based on physical differences. But zoologists decided to simplify things and lump all subspecies into two species, says geneticist Victor Mason, an author of the 2016 report, who studied colugo phylogeny at Texas A&M University in College Station.

Mason and colleagues looked for signs of species diversity hidden in the genetic makeup of colugos, a task that required samples of colugo DNA from across Southeast Asia. The researchers turned to museum specimens in Singapore and the United States. “There’s hundreds of colugo skulls just sitting in drawers in tiny boxes collecting dust” amassed more than a century ago by European explorers, says Mason, now at the University of Bern’s Institute of Cell Biology in Switzerland.

Using DNA from the museum specimens, Mason and colleagues found up to 14 colugo groups with significant genetic differences. More work is needed to weigh these differences and review the diversity of colugo species. And more surveys of colugo populations and their whereabouts are needed, Miard says, to reliably tell if and where colugos are threatened.

The good news is that colugos appear to adapt well to forested human environments, including the villages in Langkawi. The animals feed on the leaves of five to seven different trees nightly, Dzulhelmi says based on his studies in Langkawi and Borneo. He says that if a township could plant enough trees in gardens, parks and zoos to support free-living colugos, locals could see and learn about the animals and appreciate them.

After 50 minutes of courtship, Eager the male colugo has given up. Batwoman glided back up the road — with four humans on her tail — and began feeding again. We spotted a few more colugos that night, but we stayed close to Batwoman.

Around 11 p.m., Batwoman was still plucking leaves. Suddenly, I felt the air brush my hair — a colugo glided past me to land on a tree about three meters away. I moved in for a closer look at the only colugo I spotted before my guides. But it began to rain, and we ran for shelter.

The next morning, we moved our survey to a leafy resort on the island. In two hours, we found 17 colugos, all hugging trees, motionless in the daylight. I spotted two before Miard did and tried to hide my glee. But the thrill was not mine alone. Soon after we found the 11th colugo, Miard couldn’t hold it in any longer: “I love colugos!”

In the film The Martian, astronaut Mark Watney (played by Matt Damon) survives being stranded on the Red Planet by farming potatoes in Martian dirt fertilized with feces.

Future Mars astronauts could grow crops in dirt to avoid solely relying on resupply missions, and to grow a greater amount and variety of food than with hydroponics alone (SN: 11/4/11). But new lab experiments suggest that growing food on the Red Planet will be a lot more complicated than simply planting crops with poop (SN: 9/22/15).

Researchers planted lettuce and the weed Arabidopsis thaliana in three kinds of fake Mars dirt. Two were made from materials mined in Hawaii or the Mojave Desert that look like dirt on Mars. To mimic the makeup of the Martian surface even more closely, the third was made from scratch using volcanic rock, clays, salts and other chemical ingredients that NASA’s Curiosity rover has seen on the Red Planet (SN: 1/31/19). While both lettuce and A. thaliana survived in the Marslike natural soils, neither could grow in the synthetic dirt, researchers report in the upcoming Jan. 15 Icarus.

“It’s not surprising at all that as you get [dirt] that’s more and more accurate, closer to Mars, that it gets harder and harder for plants to grow in it,” says planetary scientist Kevin Cannon of the Colorado School of Mines in Golden, Colo., who helped make the synthetic Mars dirt but wasn’t involved in the new study.

Soil on Earth is full of microbes and other organic matter that helps plants grow, but Mars dirt is basically crushed rock. The new result “tells you that if you want to grow plants on Mars using soil, you’re going to have to put in a lot of work to transform that material into something that plants can grow in,” Cannon says.

Biochemist Andrew Palmer and colleagues at the Florida Institute of Technology in Melbourne planted lettuce and A. thaliana seeds in imitation Mars dirt under controlled lighting and temperature indoors, just as astronauts would on Mars. The plants were cultivated at 22° Celsius and about 70 percent humidity.

Seeds of both species germinated and grew in dirt mined from Hawaii or the Mojave Desert, as long as the plants were fertilized with a cocktail of nitrogen, potassium, calcium and other nutrients. No seeds of either species could germinate in the synthetic dirt, so “we would grow up plants under hydroponic-like conditions, and then we would transfer them” to the artificial dirt, Palmer says. But even when given fertilizer, those seedlings died within a week of transplanting.

Palmer’s team suspected that the problem with the synthetic Mars dirt was its high pH, which was about 9.5. The two natural soils had pH levels around 7. When the researchers treated the synthetic dirt with sulfuric acid to lower the pH to 7.2, transplanted seedlings survived an extra week but ultimately died.

The team also ran up against another problem: The original synthetic dirt recipe did not include calcium perchlorate, a toxic salt that recent observations suggest make up to about 2 percent of the Martian surface. When Palmer’s team added it at concentrations similar to those seen on Mars, neither lettuce nor A. thaliana grew at all in the dirt.

“The perchlorate is a major problem” for Martian farming, says Edward Guinan, an astrobiologist at Villanova University in Pennsylvania who was not involved in the work. But calcium perchlorate may not have to be a showstopper. “There are bacteria on Earth that enjoy perchlorates as a food,” Guinan says. As the microbes eat the salt, they give off oxygen. If these bacteria were taken from Earth to Mars to munch on perchlorates in Martian dirt, Guinan imagines that the organisms could not only get rid of a toxic component of the dirt, but perhaps also help produce breathable oxygen for astronauts.

What’s more, the exact treatment required to make Martian dirt farmable may vary, depending on where astronauts make their homestead. “It probably depends where you land, what the geology and chemistry of the soil is going to be,” Guinan says.

To explore how that variety might affect future agricultural practices, geochemist Laura Fackrell of the University of Georgia in Athens and colleagues mixed up five new types of faux Mars dirt. The recipes for these fake Martian materials, also reported in the Jan. 15 Icarus, are based on observations of Mars’ surface from the Curiosity, Spirit and Opportunity rovers, as well as NASA’s Mars Global Surveyor spacecraft and Mars Reconnaissance Orbiter.

Each new artificial Mars dirt represents a mix of materials that could be found or made on the Red Planet. One is designed to represent the average composition across Mars, similar to the synthetic material created by Cannon’s team. The other four varieties have slightly different makeups, such as dirt that is particularly rich in carbonates or sulfates. This collection “expands the palette of what we have available” as test-beds for agricultural experiments, Fackrell says.

She’s now using her stock to run preliminary plant growth experiments. So far, a legume called moth bean, which has similar nutritional content to a soybean but is more drought resistant, has grown the best. “But they’re not necessarily super healthy,” Fackrell says. Future experiments could explore what nutrient cocktails help plants survive in the various fake Martian terrains. But this much is clear, Fackrell says: “It’s not quite as easy as it looks in The Martian.”

When one of Hye-Sook Park’s experiments goes well, everyone nearby knows. “We can hear Hye-Sook screaming,” she’s heard colleagues say.

It’s no surprise that she can’t contain her excitement. She’s getting a closeup look at the physics of exploding stars, or supernovas, a phenomenon so immense that its power is difficult to put into words.

Rather than studying these explosions from a distance through telescopes, Park, a physicist at Lawrence Livermore National Laboratory in California, creates something akin to these paroxysmal blasts using the world’s highest-energy lasers.

About 10 years ago, Park and colleagues embarked on a quest to understand a fascinating and poorly understood feature of supernovas: Shock waves that form in the wake of the explosions can boost particles, such as protons and electrons, to extreme energies.

“Supernova shocks are considered to be some of the most powerful particle accelerators in the universe,” says plasma physicist Frederico Fiuza of SLAC National Accelerator Laboratory in Menlo Park, Calif., one of Park’s collaborators.

Some of those particles eventually slam into Earth, after a fast-paced marathon across cosmic distances. Scientists have long puzzled over how such waves give energetic particles their massive speed boosts. Now, Park and colleagues have finally created a supernova-style shock wave in the lab and watched it send particles hurtling, revealing possible new hints about how that happens in the cosmos.

Bringing supernova physics down to Earth could help resolve other mysteries of the universe, such as the origins of cosmic magnetic fields. And there’s a more existential reason physicists are fascinated by supernovas. These blasts provide some of the basic building blocks necessary for our existence. “The iron in our blood comes from supernovae,” says plasma physicist Carolyn Kuranz of the University of Michigan in Ann Arbor, who also studies supernovas in the laboratory. “We’re literally created from stars.”

Lucky star

As a graduate student in the 1980s, Park worked on an experiment 600 meters underground in a working salt mine beneath Lake Erie in Ohio. Called IMB for Irvine-Michigan-Brookhaven, the experiment wasn’t designed to study supernovas. But the researchers had a stroke of luck. A star exploded in a satellite galaxy of the Milky Way, and IMB captured particles catapulted from that eruption. Those messengers from the cosmic explosion, lightweight subatomic particles called neutrinos, revealed a wealth of new information about supernovas.

But supernovas in our cosmic vicinity are rare. So decades later, Park isn’t waiting around for a second lucky event.

Instead, her team and others are using extremely powerful lasers to re-create the physics seen in the aftermath of supernova blasts. The lasers vaporize a small target, which can be made of various materials, such as plastic. The blow produces an explosion of fast-moving plasma, a mixture of charged particles, that mimics the behavior of plasma erupting from supernovas.

The stellar explosions are triggered when a massive star exhausts its fuel and its core collapses and rebounds. Outer layers of the star blast outward in an explosion that can unleash more energy than will be released by the sun over its entire 10-billion-year lifetime. The outflow has an unfathomable 100 quintillion yottajoules of kinetic energy (SN: 2/8/17, p. 24).

Supernovas can also occur when a dead star called a white dwarf is reignited, for example after slurping up gas from a companion star, causing a burst of nuclear reactions that spiral out of control (SN: 4/30/16, p. 20).

In both cases, things really get cooking when the explosion sends a blast of plasma careening out of the star and into its environs, the interstellar medium — essentially, another ocean of plasma particles. Over time, a turbulent, expanding structure called a supernova remnant forms, begetting a beautiful light show, tens of light-years across, that can persist in the sky for many thousands of years after the initial explosion. It’s that roiling remnant that Park and colleagues are exploring.

Studying supernova physics in the lab isn’t quite the same thing as the real deal, for obvious reasons. “We cannot really create a supernova in the laboratory, otherwise we would be all exploded,” Park says.

In lieu of self-annihilation, Park and others focus on versions of supernovas that are scaled down, both in size and in time. And rather than reproducing the entirety of a supernova all at once, physicists try in each experiment to isolate interesting components of the physics taking place. Out of the immense complexity of a supernova, “we are studying just a tiny bit of that, really,” Park says.

For explosions in space, scientists are at the mercy of nature. But in the laboratory, “you can change parameters and see how shocks react,” says astrophysicist Anatoly Spitkovsky of Princeton University, who collaborates with Park.

The laboratory explosions happen in an instant and are tiny, just centimeters across. For example, in Kuranz’s experiments, the equivalent of 15 minutes in the life of a real supernova can take just 10 billionths of a second. And a section of a stellar explosion larger than the diameter of Earth can be shrunk down to 100 micrometers. “The processes that occur in both of those are very similar,” Kuranz says. “It blows my mind.”

Laser focus

To replicate the physics of a supernova, laboratory explosions must create an extreme environment. For that, you need a really big laser, which can be found in only a few places in the world, such as NIF, the National Ignition Facility at Lawrence Livermore, and the OMEGA Laser Facility at the University of Rochester in New York.

At both places, one laser is split into many beams. The biggest laser in the world, at NIF, has 192 beams. Each of those beams is amplified to increase its energy exponentially. Then, some or all of those beams are trained on a small, carefully designed target. NIF’s laser can deliver more than 500 trillion watts of power for a brief instant, momentarily outstripping the total power usage in the United States by a factor of a thousand.

A single experiment at NIF or OMEGA, called a shot, is one blast from the laser. And each shot is a big production. Opportunities to use such advanced facilities are scarce, and researchers want to have all the details ironed out to be confident the experiment will be a success.

When a shot is about to happen, there’s a space-launch vibe. Operators monitor the facility from a control room filled with screens. When the time of the laser blast nears, a voice begins counting down: “Ten, nine, eight …”

“When they count down for your shot, your heart is pounding,” says plasma physicist Jena Meinecke of the University of Oxford, who has worked on experiments at NIF and other laser facilities.

At the moment of the shot, “you kind of want the Earth to shake,” Kuranz says. But instead, you might just hear a snap — the sound of the discharge from capacitors that store up huge amounts of energy for each shot.

Then comes a mad dash to review the results and determine if the experiment has been successful. “It’s a lot of adrenaline,” Kuranz says.

Lasers aren’t the only way to investigate supernova physics in the lab. Some researchers use intense bursts of electricity, called pulsed power. Others use small amounts of explosives to set off blasts. The various techniques can be used to understand different stages in supernovas’ lives.

A real shocker

Park brims with cosmic levels of enthusiasm, ready to erupt in response to a new nugget of data or a new success in her experiments. Re-creating some of the physics of a supernova in the lab really is as remarkable as it sounds, she says. “Other­wise I wouldn’t be working on it.” Along with Spitkovsky and Fiuza, Park is among more than a dozen scientists involved in the Astrophysical Collisionless Shock Experiments with Lasers collaboration, or ACSEL, the quest Park embarked upon a decade ago. Their focus is shock waves.

The result of a violent input of energy, shock waves are marked by an abrupt increase in temperature, density and pressure. On Earth, shock waves cause the sonic boom of a supersonic jet, the clap of thunder in a storm and the damaging pressure wave that can shatter windows in the aftermath of a massive explosion. These shock waves form as air molecules slam into each other, piling up molecules into a high-density, high-pressure and high-temperature wave.

In cosmic environments, shock waves occur not in air, but in plasma, a mixture of protons, electrons and ions, electrically charged atoms. There, particles may be diffuse enough that they don’t directly collide as they do in air. In such a plasma, the pileup of particles happens indirectly, the result of electromagnetic forces pushing and pulling the particles. “If a particle changes trajectory, it’s because it feels a magnetic field or an electric field,” says Gianluca Gregori, a physicist at the University of Oxford who is part of ACSEL.

But exactly how those fields form and grow, and how such a shock wave results, has been hard to decipher. Researchers have no way to see the process in real supernovas; the details are too small to observe with telescopes.

These shock waves, which are known as collisionless shock waves, fascinate physicists. “Particles in these shocks can reach amazing energies,” Spitkovsky says. In supernova remnants, particles can gain up to 1,000 trillion electron volts, vastly outstripping the several trillion electron volts reached in the biggest human-made particle accelerator, the Large Hadron Collider near Geneva. But how particles might surf supernova shock waves to attain their astounding energies has remained mysterious.

Magnetic field origins

To understand how supernova shock waves boost particles, you have to understand how shock waves form in supernova remnants. To get there, you have to understand how strong magnetic fields arise. Without them, the shock wave can’t form.

Electric and magnetic fields are closely intertwined. When electrically charged particles move, they form tiny electric currents, which generate small magnetic fields. And magnetic fields themselves send charged particles corkscrewing, curving their trajectories. Moving magnetic fields also create electric fields.

The result is a complex feedback process of jostling particles and fields, eventually producing a shock wave. “This is why it’s so fascinating. It’s a self-modulating, self-controlling, self-reproducing structure,” Spitkovsky says. “It’s like it’s almost alive.”

All this complexity can develop only after a magnetic field forms. But the haphazard motions of individual particles generate only small, transient magnetic fields. To create a significant field, some process within a supernova remnant must reinforce and amplify the magnetic fields. A theoretical process called the Weibel instability, first thought up in 1959, has long been expected to do just that.

In a supernova, the plasma streaming outward in the explosion meets the plasma of the interstellar medium. According to the theory behind the Weibel instability, the two sets of plasma break into filaments as they stream by one another, like two hands with fingers interlaced. Those filaments act like current-­carrying wires. And where there’s current, there’s a magnetic field. The filaments’ magnetic fields strengthen the currents, further enhancing the magnetic fields. Scientists suspected that the electromagnetic fields could then become strong enough to reroute and slow down particles, causing them to pile up into a shock wave.

In 2015 in Nature Physics, the ACSEL team reported a glimpse of the Weibel instability in an experiment at OMEGA. The researchers spotted magnetic fields, but didn’t directly detect the filaments of current. Finally, this year, in the May 29 Physical Review Letters, the team reported that a new experiment had produced the first direct measurements of the currents that form as a result of the Weibel instability, confirming scientists’ ideas about how strong magnetic fields could form in supernova remnants.

For that new experiment, also at OMEGA, ACSEL researchers blasted seven lasers each at two targets facing each other. That resulted in two streams of plasma flowing toward each other at up to 1,500 kilometers per second — a speed fast enough to circle the Earth twice in less than a minute. When the two streams met, they separated into filaments of current, just as expected, producing magnetic fields of 30 tesla, about 20 times the strength of the magnetic fields in many MRI machines.

“What we found was basically this textbook picture that has been out there for 60 years, and now we finally were able to see it experimentally,” Fiuza says.

Surfing a shock wave

Once the researchers had seen magnetic fields, the next step was to create a shock wave and to observe it accelerating particles. But, Park says, “no matter how much we tried on OMEGA, we couldn’t create the shock.”

They needed the National Ignition Facility and its bigger laser.

There, the researchers hit two disk-shaped targets with 84 laser beams each, or nearly half a million joules of energy, about the same as the kinetic energy of a car careening down a highway at 60 miles per hour.

Two streams of plasma surged toward each other. The density and temperature of the plasma rose where the two collided, the researchers reported in the September Nature Physics. “No doubt about it,” Park says. The group had seen a shock wave, specifically the collisionless type found in supernovas. In fact there were two shock waves, each moving away from the other.

Learning the results sparked a moment of joyous celebration, Park says: high fives to everyone.

“This is some of the first experimental evidence of the formation of these collisionless shocks,” says plasma physicist Francisco Suzuki-Vidal of Imperial College London, who was not involved in the study. “This is something that has been really hard to reproduce in the laboratory.”

The team also discovered that electrons had been accelerated by the shock waves, reaching energies more than 100 times as high as those of particles in the ambient plasma. For the first time, scientists had watched particles surfing shock waves like the ones found in supernova remnants.

But the group still didn’t understand how that was happening.

In a supernova remnant and in the experiment, a small number of particles are accelerated when they cross over the shock wave, going back and forth repeatedly to build up energy. But to cross the shock wave, the electrons need some energy to start with. It’s like a big-wave surfer attempting to catch a massive swell, Fiuza says. There’s no way to catch such a big wave by simply paddling. But with the energy provided by a Jet Ski towing surfers into place, they can take advantage of the wave’s energy and ride the swell.

“What we are trying to understand is: What is our Jet Ski? What happens in this environment that allows these tiny electrons to become energetic enough that they can then ride this wave and be accelerated in the process?” Fiuza says.

The researchers performed computer simulations that suggested the shock wave has a transition region in which magnetic fields become turbulent and messy. That hints that the turbulent field is the Jet Ski: Some of the particles scatter in it, giving them enough energy to cross the shock wave.

Wake-up call

Enormous laser facilities such as NIF and OMEGA are typically built to study nuclear fusion — the same source of energy that powers the sun. Using lasers to compress and heat a target can cause nuclei to fuse with one another, releasing energy in the process. The hope is that such research could lead to fusion power plants, which could provide energy without emitting greenhouse gases or dangerous nuclear waste (SN: 4/20/13, p. 26). But so far, scientists have yet to get more energy out of the fusion than they put in — a necessity for practical power generation.

So these laser facilities dedicate many of their experiments to chasing fusion power. But sometimes, researchers like Park get the chance to study questions based not on solving the world’s energy crisis, but on curiosity — wondering what happens when a star explodes, for example. Still, in a roundabout way, understanding supernovas could help make fusion power a reality as well, as that celestial plasma exhibits some of the same behaviors as the plasma in fusion reactors.

At NIF, Park has also worked on fusion experiments. She has studied a wide variety of topics since her grad school days, from working on the U.S. “Star Wars” missile defense program, to designing a camera for a satellite sent to the moon, to looking for the sources of high-energy cosmic light flares called gamma-ray bursts. Although she is passionate about each topic, “out of all those projects,” she says, “this particular collisionless shock project happens to be my love.”

Early in her career, back on that experiment in the salt mine, Park got a first taste of the thrill of discovery. Even before IMB captured neutrinos from a supernova, a different unexpected neutrino popped up in the detector. The particle had passed through the entire Earth to reach the experiment from the bottom. Park found the neutrino while analyzing data at 4 a.m., and woke up all her collaborators to tell them about it. It was the first time anyone working on the experiment had seen a particle coming up from below. “I still clearly remember the time when I was seeing something nobody’s seen,” Park recalls.

Now, she says, she still gets the same feeling. Screams of joy erupt when she sees something new that describes the physics of unimaginably vast explosions.

Just how hot is your chili pepper? A new chili-shaped device could quickly signal whether adding the pepper to a meal might set your mouth ablaze.

Called the Chilica-pod, the device detects capsaicin, a chemical compound that helps give peppers their sometimes painful kick. In general, the more capsaicin a pepper has, the hotter it tastes. The Chilica-pod is sensitive, capable of detecting extremely low levels of the fiery molecule, researchers report in the Oct. 23 ACS Applied Nano Materials.

The device could someday be used to test cooked meals or fresh peppers, says analytical chemist Warakorn Limbut of Prince of Songkla University in Hat Yai, Thailand. People with a capsaicin allergy could use the gadget to avoid the compound, or farmers could test harvested peppers to better indicate their spiciness, he says.      

A pepper’s relative spiciness typically is conveyed in Scoville heat units — an imperfect measurement determined by a panel of human taste testers. Other more precise methods for determining spiciness are time-intensive and involve expensive equipment, making the methods unsuitable for a quick answer.

Enter the portable, smartphone-compatible Chilica-pod. Built by Limbut and colleagues, the instrument’s sensor is composed of stacks of graphene sheets. When a drop of a chili pepper and ethanol solution is added to the sensor, the capsaicin from the pepper triggers the movement of electrons among the graphene atoms. The more capsaicin the solution has, the stronger the electrical current through the sheets.

The Chilica-pod registers that electrical activity and, once its “stem” is plugged into a smartphone, sends the information to an app for analysis. The device can detect capsaicin levels as low as 0.37 micromoles per liter of solution, equivalent to the amount in a pepper with no heat, one test showed.

Limbut’s team used the Chilica-pod to individually measure six dried chili peppers from a local market. The peppers’ capsaicin concentrations ranged from 7.5 to 90 micromoles per liter of solution, the team found. When translated to Scoville heat units, that range corresponds to the spice of peppers like serrano or cayenne — mild varieties compared to the blazing hot Carolina reaper, one of the world’s hottest peppers (SN: 4/9/18).   

Paul Bosland, a plant geneticist and chili breeder at New Mexico State University in Las Cruces who wasn’t involved in the study, notes that capsaicin is just one of at least 24 related compounds that give peppers heat. “I would hope that [the device] could read them all,” he says.