Moving exhibit pays tribute to lost space shuttles’ crews

With the blessings of all 14 families of lost astronauts, a new memorial to the Challenger and Columbia space shuttle disasters opened in June at the Kennedy Space Center in Florida. The permanent exhibit includes the first pieces of shuttle wreckage ever on public display, but fittingly focuses more on the lives lost.

“Forever Remembered” is housed inside the space center’s new $100 million exhibit about the space shuttle Atlantis. Below the nose of the intact shuttle, visitors enter a hall lit by tributes to each astronaut from the lost missions, those from Challenger on the left and Columbia on the right. Each display includes glimpses of the astronaut’s life. Items include plans for remodeling the home of Challenger pilot Michael Smith and a recovered page in Hebrew from the Columbia flight journal of Ilan Ramon, a payload specialist and the first Israeli astronaut.
Past the hall, visitors enter a small gallery with a single piece of each shuttle: a body panel from Challenger (shown at left) and cockpit window frames from Columbia
. There are no extended written descriptions or flashy videos. In short, it’s a place for pondering rather than learning. As a ninth-grader in school 50 miles away when Challenger exploded in 1986 and as an adult who waited for a telltale sonic boom that never came when Columbia was lost during re-entry in 2003, I found the effect powerful.
The exhibit’s exit hallway reveals the tragedies from multiple perspectives on video displays. One video details the massive efforts to recover the wreckage and remains from the disasters, from the ocean for Challenger and from land for Columbia. Others focus on the emotional tolls and the critical shuttle launches that followed each completed investigation.

Michael Curie, Kennedy Space Center’s news chief, says family members have been both supportive and grateful for the exhibit. “They feel that it humanizes their family members in a way that never has been done before,” he says. Indeed, “Forever Remembered” is an effective reminder of the very real risks each astronaut willingly and bravely faced.

Why male giraffes drink potential mates’ pee

A female giraffe has a great Valentine’s Day gift for potential mates: urine.

Distinctive anatomy helps male giraffes get a taste for whether a female is ready to mate, animal behaviorists Lynette and Benjamin Hart report January 19 in Animals. A pheromone-detecting organ in giraffes has a stronger connection to the mouth than the nose, the researchers found. That’s why males scope out which females to mate with by sticking their tongues in a urine stream.
Animals such as male gazelles will lick fresh urine on the ground to track if females are ready to mate. But giraffes’ long necks and heavy heads make bending over to investigate urine on the ground an unstable and vulnerable position, says Lynette Hart, of the University of California, Davis.

The researchers observed giraffes (Giraffa giraffa angolensis) in Etosha National Park in Namibia in 1994, 2002 and 2004. Bull giraffes nudged or kicked the female to ask her to pee. If she was a willing participant, she urinated for a few seconds, while the male took a sip. Then the male curled his lip and inhaled with his mouth, a behavior called a flehmen response, to pull the female’s scent into two openings on the roof of the mouth. From the mouth, the scent travels to the vomeronasal organ, or VNO, which detects pheromones.

The Harts say they never saw a giraffe investigate urine on the ground.

Unlike many other mammals, giraffes have a stronger oral connection — via a duct — to the VNO, than a nasal one, examinations of preserved giraffe specimens showed. One possible explanation for the difference could be that a VNO-nose link helps animals that breed at specific times of the year detect seasonal plants, says Benjamin Hart, a veterinarian also at the University of California, Davis. But giraffes can mate any time of year, so the nasal connection may not matter as much.

These adorable Australian spike-balls beat the heat with snot bubbles

Animals cover themselves in all kinds of unsavory fluids to keep cool. Humans sweat, kangaroos spit and some birds will urinate on themselves to survive hot days. It turns out that echidnas do something much cuter — though perhaps just as sticky (and slightly icky) — to beat the heat.

The spiny insectivores stay cool by blowing snot bubbles, researchers report January 18 in Biology Letters. The bubbles pop, keeping the critters’ noses moist. As it evaporates, this moisture draws heat away from a blood-filled sinus in the echidna’s beak, helping to cool the animal’s blood.
Short-beaked echidnas (Tachyglossus aculeatus) look a bit like hedgehogs but are really monotremes — egg-laying mammals unique to Australia and New Guinea (SN: 11/18/16). Previous lab studies showed that temperatures above 35° Celsius (95° Fahrenheit) should kill echidnas. But echidnas don’t seem to have gotten the memo. They live everywhere from tropical rainforests to deserts to snow-capped peaks, leaving scientists with a physiological puzzle.

Mammals evaporate water to keep cool when temperatures climb above their body temperatures, says environmental physiologist Christine Cooper of Curtin University in Perth, Australia. “Lots of mammals do that by either licking, sweating or panting,” she says. “Echidnas weren’t believed to be able to do that.” But it’s known that the critters blow snot bubbles when it gets hot.

So, armed with a heat-vision camera and a telephoto lens, Cooper and environmental physiologist Philip Withers of the University of Western Australia in Perth drove through nature reserves in Western Australia once a month for a year to film echidnas.

In infrared, the warmest parts of the echidnas’ spiny bodies glowed in oranges, yellows and whites. But the video revealed that the tips of their noses were dark purple blobs, kept cool as moisture from their snot bubbles evaporated. Echidnas might also lose heat through their bellies and legs, the researchers report, while their spikes could act as an insulator.
“Finding a way of doing this work in the field is pretty exciting,” says physiological ecologist Stewart Nicol of the University of Tasmania in Hobart, Australia, who was not involved in the study. “You can understand animals and see how they’re responding to their normal environment.” The next step, he says, is to quantify how much heat echidnas really lose through their noses and other body parts.

Monotremes parted evolutionary ways with other mammals between 250 million and 160 million years ago as the supercontinent Pangaea broke apart (SN: 3/8/15). So “they have a whole lot of traits that are considered to be primitive,” Cooper says. “Understanding how they might thermoregulate can give us some ideas about how thermal regulation … might have evolved in mammals.”

Yes, we can meet the climate change challenge

More than a century ago, scientists proved that carbon dioxide in Earth’s atmosphere could act like a thermostat — adding more CO2 would turn up the heat, removing it would chill the planet. But back then, most scientists thought that Earth’s climate system was far too large and stable to change quickly, that any fluctuations would happen over such a long timescale that it wouldn’t matter much to everyday life (SN: 3/12/22, p. 16).

Now all it takes is a look at the Weather Channel to know how wrong scientists were. Things are changing fast. Last year alone, Europe, South Asia, China, Japan and the American West endured deadly, record-breaking heat waves (SN: 12/17/22 & 12/31/22, p. 38). As I write this, torrential rains are bringing death and destruction to California. And with levels of climate-warming gases continuing to increase in the atmosphere, extreme weather events will become even more frequent.
Given the vastness of this threat, it’s tempting to think that any efforts that we make against it will be futile. But that’s not true. Around the world, scientists and engineers; entrepreneurs and large corporations; state, national and local governments; and international coalitions are acting to put the brakes on climate change. Last year, the United States signed into law a $369 billion investment in renewable energy technologies and other responses (SN: 12/17/22 & 12/31/22, p. 28). And the World Bank invested $31.7 billion to assist other countries.

In this issue, contributing correspondent Alexandra Witze details the paths forward: which responses will help the most, and which remain challenging. Shifting to renewable energy sources like wind and solar should be the easiest. We already have the technology, and costs have plunged over the last decade. Other approaches that are feasible but not as far along include making industrial processes more energy efficient, trapping greenhouse gases and developing clean fuels. Ultimately, the goal is to reinvent the global energy infrastructure. Societies have been retooling energy infrastructures for centuries, from water and steam power to petroleum and natural gas to nuclear power and now renewables. This next transformation will be the biggest yet. But we have the scientific understanding and technological savvy to make it happen.

This cover story kicks off a new series for Science News, The Climate Fix. In future issues, we will focus on covering solutions to the climate crisis, including the science behind innovations, the people making them happen, and the social and environmental impacts. You’ll also see expanded climate coverage for our younger readers, ages 9 and up, at Science News Explores online and in print.

With this issue, we also welcome our new publisher, Michael Gordon Voss. He comes to us with deep knowledge of the media industry, experience in both for-profit and nonprofit publishing and a love of science. Before joining Science News Media Group, Voss was publisher of Stanford Social Innovation Review, and vice president and associate publisher at Scientific American. With his arrival, publisher Maya Ajmera takes on her new role as executive publisher. Under her leadership, we have seen unprecedented growth. We’re fortunate to have these two visionaries directing our business strategy amid a rapidly changing media environment.

It’s possible to reach net-zero carbon emissions. Here’s how

Patricia Hidalgo-Gonzalez saw the future of energy on a broiling-hot day last September.

An email alert hit her inbox from the San Diego Gas & Electric Company. “Extreme heat straining the grid,” read the message, which was also pinged as a text to 27 million people. “Save energy to help avoid power interruptions.”

It worked. People cut their energy use. Demand plunged, blackouts were avoided and California successfully weathered a crisis exacerbated by climate change. “It was very exciting to see,” says Hidalgo-Gonzalez, an electrical engineer at the University of California, San Diego who studies renewable energy and the power grid.
This kind of collective societal response, in which we reshape how we interact with the systems that provide us energy, will be crucial as we figure out how to live on a changing planet.

Earth has warmed at least 1.1 degrees Celsius since the 19th century, when the burning of coal, oil and other fossil fuels began belching heat-trapping gases such as carbon dioxide into the atmosphere. Scientists agree that only drastic action to cut emissions can keep the planet from blasting past 1.5 degrees of warming — a threshold beyond which the consequences become even more catastrophic than the rising sea levels, extreme weather and other impacts the world is already experiencing.

The goal is to achieve what’s known as net-zero emissions, where any greenhouse gases still entering the atmosphere are balanced by those being removed — and to do it as soon as we can.

Scientists say it is possible to swiftly transform the ways we produce and consume energy. To show the way forward, researchers have set out paths toward a world where human activities generate little to no carbon dioxide and other greenhouse gases — a decarbonized economy.

The key to a decarbonized future lies in producing vast amounts of new electricity from sources that emit little to none of the gases, such as wind, solar and hydropower, and then transforming as much of our lives and our industries as possible to run off those sources. Clean electricity needs to power not only the planet’s current energy use but also the increased demands of a growing global population.

Once humankind has switched nearly entirely to clean electricity, we will also have to counter­balance the carbon dioxide we still emit — yes, we will still emit some — by pulling an equivalent amount of carbon dioxide out of the atmosphere and storing it somewhere permanently.

Achieving net-zero emissions won’t be easy. Getting to effective and meaningful action on climate change requires overcoming decades of inertia and denial about the scope and magnitude of the problem. Nations are falling well short of existing pledges to reduce emissions, and global warming remains on track to charge past 1.5 degrees perhaps even by the end of this decade.

Yet there is hope. The rate of growth in CO2 emissions is slowing globally — down from 3 percent annual growth in the 2000s to half a percent annual growth in the last decade, according to the Global Carbon Project, which quantifies greenhouse gas emissions.

There are signs annual emissions could start shrinking. And over the last two years, the United States, by far the biggest cumulative contributor to global warming, has passed several pieces of federal legislation that include financial incentives to accelerate the transition to clean energy. “We’ve never seen anything at this scale,” says Erin Mayfield, an energy researcher at Dartmouth College.

Though the energy transition will require many new technologies, such as innovative ways to permanently remove carbon from the atmosphere, many of the solutions, such as wind and solar power, are in hand — “stuff we already have,” Mayfield says.
The current state of carbon dioxide emissions
Of all the emissions that need to be slashed, the most important is carbon dioxide, which comes from many sources such as cars and trucks and coal-burning power plants. The gas accounted for 79 percent of U.S. greenhouse gas emissions in 2020. The next most significant greenhouse gas, at 11 percent of emissions in the United States, is methane, which comes from oil and gas operations as well as livestock, landfills and other land uses.

The amount of methane may seem small, but it is mighty — over the short term, methane is more than 80 times as efficient at trapping heat as carbon dioxide is, and methane’s atmospheric levels have nearly tripled in the last two centuries. Other greenhouse gases include nitrous oxides, which come from sources such as applying fertilizer to crops or burning fuels and account for 7 percent of U.S. emissions, and human-made fluorinated gases such as hydrofluorocarbons that account for 3 percent.

Globally, emissions are dominated by large nations that produce lots of energy. The United States alone emits around 5 billion metric tons of carbon dioxide each year. It is responsible for most of the greenhouse gas emissions throughout history and ceded the spot for top annual emitter to China only in the mid-2000s. India ranks third.

Because of the United States’ role in producing most of the carbon pollution to date, many researchers and advocates argue that it has the moral responsibility to take the global lead on cutting emissions. And the United States has the most ambitious goals of the major emitters, at least on paper. President Joe Biden has said the country is aiming to reach net-zero emissions by 2050. Leaders in China and India have set net-zero goals of 2060 and 2070, respectively.

Under the auspices of a 2015 international climate change treaty known as the Paris agreement, 193 nations plus the European Union have pledged to reduce their emissions. The agreement aims to keep global warming well below 2 degrees, and ideally to 1.5 degrees, above preindustrial levels. But it is insufficient. Even if all countries cut their emissions as much as they have promised under the Paris agreement, the world would likely blow past 2 degrees of warming before the end of this century.

Every nation continues to find its own path forward. “At the end of the day, all the solutions are going to be country-specific,” says Sha Yu, an earth scientist at the Pacific Northwest National Laboratory and University of Maryland’s Joint Global Change Research Institute in College Park, Md. “There’s not a universal fix.”

But there are some common themes for how to accomplish this energy transition — ways to focus our efforts on the things that will matter most. These are efforts that go beyond individual consumer choices such as whether to fly less or eat less meat. They instead penetrate every aspect of how society produces and consumes energy.

Such massive changes will need to overcome a lot of resistance, including from companies that make money off old forms of energy as well as politicians and lobbyists. But if society can make these changes, it will rank as one of humanity’s greatest accomplishments. We will have tackled a problem of our own making and conquered it.

Here’s a look at what we’ll need to do.

Make as much clean electricity as possible
To meet the need for energy without putting carbon dioxide into the atmosphere, countries would need to dramatically scale up the amount of clean energy they produce. Fortunately, most of that energy would be generated by technologies we already have — renewable sources of energy including wind and solar power.

“Renewables, far and wide, are the key pillar in any net-zero scenario,” says Mayfield, who worked on an influential 2021 report from Princeton University’s Net-Zero America project, which focused on the U.S. economy.

The Princeton report envisions wind and solar power production roughly quadrupling by 2030 to get the United States to net-zero emissions by 2050. That would mean building many new solar and wind farms, so many that in the most ambitious scenario, wind turbines would cover an area the size of Arkansas, Iowa, Kansas, Missouri, Nebraska and Oklahoma combined.
Such a scale-up is only possible because prices to produce renewable energy have plunged. The cost of wind power has dropped nearly 70 percent, and solar power nearly 90 percent, over the last decade in the United States. “That was a game changer that I don’t know if some people were expecting,” Hidalgo-Gonzalez says.

Globally the price drop in renewables has allowed growth to surge; China, for instance, installed a record 55 gigawatts of solar power capacity in 2021, for a total of 306 gigawatts or nearly 13 percent of the nation’s installed capacity to generate electricity. China is almost certain to have had another record year for solar power installations in 2022.

Challenges include figuring out ways to store and transmit all that extra electricity, and finding locations to build wind and solar power installations that are acceptable to local communities. Other types of low-carbon power, such as hydropower and nuclear power, which comes with its own public resistance, will also likely play a role going forward.
Get efficient and go electric
The drive toward net-zero emissions also requires boosting energy efficiency across industries and electrifying as many aspects of modern life as possible, such as transportation and home heating.

Some industries are already shifting to more efficient methods of production, such as steelmaking in China that incorporates hydrogen-based furnaces that are much cleaner than coal-fired ones, Yu says. In India, simply closing down the most inefficient coal-burning power plants provides the most bang for the buck, says Shayak Sengupta, an energy and policy expert at the Observer Research Foundation America think tank in Washington, D.C. “The list has been made up,” he says, of the plants that should close first, “and that’s been happening.”

To achieve net-zero, the United States would need to increase its share of electric heat pumps, which heat houses much more cleanly than gas- or oil-fired appliances, from around 10 percent in 2020 to as much as 80 percent by 2050, according to the Princeton report. Federal subsidies for these sorts of appliances are rolling out in 2023 as part of the new Inflation Reduction Act, legislation that contains a number of climate-related provisions.

Shifting cars and other vehicles away from burning gasoline to running off of electricity would also lead to significant emissions cuts. In a major 2021 report, the National Academies of Sciences, Engineering and Medicine said that one of the most important moves in decarbonizing the U.S. economy would be having electric vehicles account for half of all new vehicle sales by 2030. That’s not impossible; electric car sales accounted for nearly 6 percent of new sales in the United States in 2022, which is still a low number but nearly double the previous year.

Make clean fuels
Some industries such as manufacturing and transportation can’t be fully electrified using current technologies — battery powered airplanes, for instance, will probably never be feasible for long-duration flights. Technologies that still require liquid fuels will need to switch from gas, oil and other fossil fuels to low-carbon or zero-carbon fuels.

One major player will be fuels extracted from plants and other biomass, which take up carbon dioxide as they grow and emit it when they die, making them essentially carbon neutral over their lifetime. To create biofuels, farmers grow crops, and others process the harvest in conversion facilities into fuels such as hydrogen. Hydrogen, in turn, can be substituted for more carbon-intensive substances in various industrial processes such as making plastics and fertilizers — and maybe even as fuel for airplanes someday.

In one of the Princeton team’s scenarios, the U.S. Midwest and Southeast would become peppered with biomass conversion plants by 2050, so that fuels can be processed close to where crops are grown. Many of the biomass feedstocks could potentially grow alongside food crops or replace other, nonfood crops.
Cut methane and other non-CO2 emissions
Greenhouse gas emissions other than carbon dioxide will also need to be slashed. In the United States, the majority of methane emissions come from livestock, landfills and other agricultural sources, as well as scattered sources such as forest fires and wetlands. But about one-third of U.S. methane emissions come from oil, gas and coal operations. These may be some of the first places that regulators can target for cleanup, especially “super emitters” that can be pinpointed using satellites and other types of remote sensing.

In 2021, the United States and the European Union unveiled what became a global methane pledge endorsed by 150 countries to reduce emissions. There is, however, no enforcement of it yet. And China, the world’s largest methane emitter, has not signed on.

Nitrous oxides could be reduced by improving soil management techniques, and fluorinated gases by finding alternatives and improving production and recycling efforts.

Sop up as much CO2 as possible
Once emissions have been cut as much as possible, reaching net-zero will mean removing and storing an equivalent amount of carbon to what society still emits.

One solution already in use is to capture carbon dioxide produced at power plants and other industrial facilities and store it permanently somewhere, such as deep underground. Globally there are around 35 such operations, which collectively draw down around 45 million tons of carbon dioxide annually. About 200 new plants are on the drawing board to be operating by the end of this decade, according to the International Energy Agency.

The Princeton report envisions carbon capture being added to almost every kind of U.S. industrial plant, from cement production to biomass conversion. Much of the carbon dioxide would be liquefied and piped along more than 100,000 kilometers of new pipelines to deep geologic storage, primarily along the Texas Gulf Coast, where underground reservoirs can be used to trap it permanently. This would be a massive infrastructure effort. Building this pipeline network could cost up to $230 billion, including $13 billion for early buy-in from local communities and permitting alone.

Another way to sop up carbon is to get forests and soils to take up more. That could be accomplished by converting crops that are relatively carbon-intensive, such as corn to be used in ethanol, to energy-rich grasses that can be used for more efficient biofuels, or by turning some cropland or pastures back into forest. It’s even possible to sprinkle crushed rock onto croplands, which accelerates natural weathering processes that suck carbon dioxide out of the atmosphere.

Another way to increase the amount of carbon stored in the land is to reduce the amount of the Amazon rainforest that is cut down each year. “For a few countries like Brazil, preventing deforestation will be the first thing you can do,” Yu says.

When it comes to climate change, there’s no time to waste
The Princeton team estimates that the United States would need to invest at least an additional $2.5 trillion over the next 10 years for the country to have a shot at achieving net-zero emissions by 2050. Congress has begun ramping up funding with two large pieces of federal legislation it passed in 2021 and 2022. Those steer more than $1 trillion toward modernizing major parts of the nation’s economy over a decade — including investing in the energy transition to help fight climate change.

Between now and 2030, solar and wind power, plus increasing energy efficiency, can deliver about half of the emissions reductions needed for this decade, the International Energy Agency estimates. After that, the primary drivers would need to be increasing electrification, carbon capture and storage, and clean fuels such as hydrogen.
The trick is to do all of this without making people’s lives worse. Developing nations need to be able to supply energy for their economies to develop. Communities whose jobs relied on fossil fuels need to have new economic opportunities.

Julia Haggerty, a geographer at Montana State University in Bozeman who studies communities that are dependent on natural resources, says that those who have money and other resources to support the transition will weather the change better than those who are under-resourced now. “At the landscape of states and regions, it just remains incredibly uneven,” she says.

The ongoing energy transition also faces unanticipated shocks such as Russia’s invasion of Ukraine, which sent energy prices soaring in Europe, and the COVID-19 pandemic, which initially slashed global emissions but later saw them rebound.

But the technologies exist for us to wean our lives off fossil fuels. And we have the inventiveness to develop more as needed. Transforming how we produce and use energy, as rapidly as possible, is a tremendous challenge — but one that we can meet head-on. For Mayfield, getting to net-zero by 2050 is a realistic goal for the United States. “I think it’s possible,” she says. “But it doesn’t mean there’s not a lot more work to be done.”

How ghostly neutrinos could explain the universe’s matter mystery

The answer to one of the greatest mysteries of the universe may come down to one of the smallest, and spookiest, particles.

Matter is common in the cosmos. Everything around us — from planets to stars to puppies — is made up of matter. But matter has a flip side: antimatter. Protons, electrons and other particles all have antimatter counterparts: antiprotons, positrons, etc. Yet for some reason antimatter is much rarer than matter — and no one knows why.
Physicists believe the universe was born with equal amounts of matter and antimatter. Since matter and antimatter counterparts annihilate on contact, that suggests the universe should have ended up with nothing but energy. Something must have tipped the balance.

Some physicists think lightweight subatomic particles called neutrinos could point to an answer. These particles are exceedingly tiny, with less than a millionth the mass of an electron (SN: 4/21/21). They’re produced in radioactive decays and in the sun and other cosmic environments. Known for their ethereal tendency to evade detection, neutrinos have earned the nickname “ghost particles.” These spooky particles, originally thought to have no mass at all, have a healthy track record of producing scientific surprises (SN: 10/6/15).

Now researchers are building enormous detectors to find out if neutrinos could help solve the mystery of the universe’s matter. The Hyper-Kamiokande experiment in Hida City, Japan, and the Deep Underground Neutrino Experiment in Lead, S.D., will study neutrinos and their antimatter counterparts, antineutrinos. A difference in neutrinos’ and antineutrinos’ behavior might hint at the origins of the matter-antimatter imbalance, scientists suspect.

Watch the video below to find out how neutrinos might reveal why the universe contains, well, anything at all.

Sea urchin skeletons’ splendid patterns may strengthen their structure

Sea urchin skeletons may owe some of their strength to a common geometric design.

Components of the skeletons of common sea urchins (Paracentrotus lividus) follow a similar pattern to that found in honeycombs and dragonfly wings, researchers report in the August Journal of the Royal Society Interface. Studying this recurring natural order could inspire the creation of strong yet lightweight new materials.

Urchin skeletons display “an incredible diversity of structures at the microscale, varying from fully ordered to entirely chaotic,” says marine biologist and biomimetic consultant Valentina Perricone. These structures may help the animals maintain their shape when faced with predator attacks and environmental stresses.

While using a scanning electron microscope to study urchin skeleton tubercules — sites where the spines attach that withstand strong mechanical forces — Perricone spotted “a curious regularity.” Tubercules seem to follow a type of common natural order called a Voronoi pattern, she and her colleagues found.
Using math, a Voronoi pattern is created by a process that divides a region into polygon-shaped cells that are built around points within them called seeds (SN: 9/23/18). The cells follow the nearest neighbor rule: Every spot inside a cell is nearer to that cell’s seed than to any other seed. Also, the boundary that separates two cells is equidistant from both their seeds.

A computer-generated Voronoi pattern had an 82 percent match with the pattern found in sea urchin skeletons. This arrangement, the team suspects, yields a strong yet lightweight skeletal structure. The pattern “can be interpreted as an evolutionary solution” that “optimizes the skeleton,” says Perricone, of the University of Campania “Luigi Vanvitelli” in Aversa, Italy.

Urchins, dragonflies and bees aren’t the only beneficiaries of Voronoi architecture. “We are developing a library of bioinspired, Voronoi-based structures” that could “serve as lightweight and resistant solutions” for materials design, Perricone says. These, she hopes, could inspire new developments in materials science, aerospace, architecture and construction.

Herminia Pasantes discovered how taurine helps brain cells regulate their size

When Herminia Pasantes Ordóñez was about 14 years old, in 1950, she heard her mother tell her father that she would never find a husband. Pasantes had to wear thick glasses for her poor eyesight. In her mother’s eyes, those glasses meant her future as a “good woman” was doomed. “This made my life easier,” says Pasantes, “because it was already said that I was going to study.”

At a time when it was uncommon for women to become scientists, Pasantes studied biology at the National Autonomous University of Mexico in Mexico City, or UNAM. She was the first member of her family to go to college.
She became a neurobiologist and one of the most important Mexican scientists of her time. Her studies on the role of the chemical taurine in the brain offer deep insights into how cells maintain their size — essential to proper functioning. In 2001, she became the first woman to earn Mexico’s National Prize for Sciences and Arts in the area of physical, mathematical and natural sciences.

“We basically learned about cell volume regulation through the eyes and work of Herminia,” says Alexander Mongin, a Belarusian neuroscientist at Albany Medical College in New York.

Pasantes did get married, in 1965 while doing her master’s in biochemistry at UNAM. She had a daughter in 1966 and a son in 1967 before starting a Ph.D. in natural sciences in 1970 at the Center for Neurochemistry at the University of Strasbourg in France. There, she worked in the laboratory of Paul Mandel, a Polish pioneer in neurochemistry.

The lab was trying to find out everything there was to know about the retina, the layer of tissue at the back of the eye that is sensitive to light. Pasantes decided to test whether free amino acids, a group that aren’t incorporated into proteins, were present in the retinas and brain of mice. Her first chromatography — a lab technique that lets scientists separate and identify the components of a sample — showed an immense amount of taurine in both tissues. Taurine would drive the rest of her scientific career, including work in her own lab, which she started around 1975 at the Institute of Cellular Physiology at UNAM.

Taurine turns out to be widely distributed in animal tissues and has diverse biological functions, some of which were discovered by Pasantes. Her research found that taurine helps maintain cell volume in nerve cells, and that it protects brain, muscle, heart and retinal cells by preventing the death of stem cells, which give rise to all specialized cells in the body.
Contrary to what most scientists had believed at the time, taurine didn’t work as a neurotransmitter sending messages between nerve cells. Pasantes demonstrated for the first time that it worked as an osmolyte in the brain. Osmolytes help maintain the size and integrity of cells by opening up channels in their membranes to get water in or out.

Pasantes says she spent many years looking for an answer for why there is so much taurine in the brain. “When you ask nature a question, 80 to 90 percent of the time, it responds no,” she says. “But when it answers yes, it’s wonderful.”

Pasantes’ lab was one of the big four labs that did groundbreaking work on cell volume regulation in the brain, says Mongin.

Her work and that of others proved taurine has a protective effect; it’s the reason the chemical is today sprinkled in the containers that carry organs for transplants. Pasantes’ work was the foundation for our understanding of how to prevent and treat brain edema, a condition where the brain swells due to excessive accumulation of fluid, from head trauma or reduced blood supply, for example. She and other experts also reviewed the role of taurine for Red Bull, which added the chemical to its formula because of potentially protective effects in the heart.

Pasantes stopped doing research in 2019 and spends her time talking and writing about science. She hopes her story speaks to women around the world who wish to be scientists: “It is important to send the message that it is possible,” she says.

Years before she was accepted into Mandel’s lab, her application to a Ph.D. in biochemistry at the UNAM was rejected. Pasantes says the reason was that she had just had her daughter. Looking back, this moment was “one of the most wonderful things that could’ve happened to me,” Pasantes says, because she ended up in Strasbourg, where her potential as a researcher bloomed.

Rosa María González Victoria, a social scientist at the Autonomous University of the State of Hidalgo in Pachuca, Mexico, who specializes in gender studies, recently interviewed Pasantes for a book about Mexican women in science. González Victoria thinks Pasantes’ response to that early rejection speaks to the kind of person she is: “A woman that takes those no’s and turns them into yes’s.”

The heaviest neutron star on record is 2.35 times the mass of the sun

A fast-spinning neutron star south of the constellation Leo is the most massive of its kind seen so far, according to new observations.

The record-setting collapsed star, named PSR J0952-0607, weighs about 2.35 times as much as the sun, researchers report July 11 on “That’s the heaviest well-measured neutron star that has been found to date,” says study coauthor Roger Romani, an astrophysicist at Stanford University.

The previous record holder was a neutron star in the northern constellation Camelopardalis named PSR J0740+6620, which tipped the scales at about 2.08 times as massive as the sun. If a neutron star grows too massive, it collapses under its own weight and becomes a black hole. These measurements of hefty neutron stars are of interest because no one knows the exact mass boundary between neutron stars and black holes.
That dividing line drives the quest to find the most massive neutron stars and determine just how massive they can be, Romani says. “It’s defining the boundary between the visible things in the universe and the stuff that is forever hidden from us inside of a black hole,” he says. “A neutron star that’s on the hairy edge of becoming a black hole — just about heavy enough to collapse — has at its center the very densest material that we can access in the entire visible universe.”

PSR J0952-0607 is in the constellation Sextans, just south of Leo. It resides 20,000 light-years from Earth, far above the galaxy’s plane in the Milky Way’s halo. The neutron star emits a pulse of radio waves toward us each time it spins, so astronomers also classify the object as a pulsar. First reported in 2017, this pulsar spins every 1.41 milliseconds, faster than all but one other pulsar.

That’s why Romani and his colleagues chose to study it — the fast spin led them to suspect that the pulsar might be unusually heavy. That’s because another star orbits the pulsar, and just as water spilling over a water wheel spins it up, gas falling from that companion onto the pulsar could have sped up its rotation while also boosting its mass.

Observing the companion, Romani and his colleagues found that it whips around the pulsar quickly — at about 380 kilometers per second. Using the companion’s speed and its orbital period of about six and a half hours, the team calculated the pulsar’s mass to be more than twice the mass of the sun. That’s a lot heavier than the typical neutron star, which is only about 1.4 times as massive as the sun.

“It’s a terrific study,” says Emmanuel Fonseca, a radio astronomer at West Virginia University in Morgantown who measured the mass of the previous record holder but was not involved in the new work. “It helps nuclear physicists actually constrain the nature of matter within these extreme environments.”

Mammal ancestors’ shrinking inner ears may reveal when warm-bloodedness arose

Hot or not? Peeking inside an animal’s ear — even a fossilized one — may tell you whether it was warm- or cold-blooded. Using a novel method that analyzes the size and shape of the inner ear canals, researchers suggest that mammal ancestors abruptly became warm-blooded about 233 million years ago, the team reports in Nature July 20.

Warm-bloodedness, or endothermy, isn’t unique to mammals — birds, the only living dinosaurs, are warm-blooded, too. But endothermy is one of mammals’ key features, allowing the animals to regulate their internal body temperatures by controlling their metabolic rates. This feature allowed mammals to occupy environmental niches from pole to equator, and to weather the instability of ancient climates (SN: 6/7/22).
When endothermy evolved, however, has been a mystery. Based on fossil analyses of growth rates and oxygen isotopes in bones, researchers have proposed dates for its emergence as far back as 300 million years ago.

The inner ear structures of mammals and their ancestors hold the key to solving that mystery, says Ricardo Araújo, a vertebrate paleontologist at the University of Lisbon. In all vertebrates, the labyrinth of semicircular canals in the inner ear contains a fluid that responds to head movements, brushing against tiny hair cells in the ear and helping to maintain a sense of balance. That fluid can become thicker or thinner depending on body temperature.

“Mammals have very unique inner ears,” Araújo says. Compared with cold-blooded vertebrates of similar size, the dimensions of mammals’ semicircular canals — such as thickness, length and radius of curvature — is particularly small, he says. “The ducts are very thin and tend to be very circular compared with other animals.” By contrast, fish have the largest for their body size.

What if, Araújo and his colleagues hypothesized, the size and shape of the ear canals are related to the animal’s body temperature? In warm-blooded animals, the fluid becomes less viscous, and the canals may have shrunk to compensate. If so, it might be possible to trace how the shape of fossilized inner ear canals changed over time to discover when warm-bloodedness emerged in the mammal lineage.

To test that hypothesis, the researchers created a tool they call the “thermo-motility index” to link warm-bloodedness to those inner ear dimensions in 341 different vertebrates. Accounting for size differences, the value of this index turned out to closely track an animal’s body temperature, from fish to reptiles to mammals. Reptiles had low index values; mammals were high.

The team then applied this index to the fossilized ear canals of 56 extinct mammal ancestor species. To their surprise, the data showed a sharp change in inner ear morphology around 233 million years ago. That would correspond to an increase in body temperature of between 5 and 9 degrees Celsius — suggesting that endothermy evolved abruptly around that time, the team concludes.
“The fact that it is a sharp break in the data [suggests] the transition happened rapidly, within about a million years,” says coauthor Kenneth Angielczyk, a paleontologist at the Field Museum in Chicago.

It’s a clever study, says Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in the work. “I’ve been using [computed tomography] data to study the shapes of inner ears for years, to try to infer how extinct species moved and how they could hear, and it never occurred to me that inner ear shape is related to metabolism and could be used to predict body temperatures of fossil species.”

However, Brusatte notes that there is a limit to what scientists can glean from fossilized ear canals alone, as they don’t reveal what soft tissues may have been present, such as the hair cells, or the actual viscosity of the ear fluid. “Shape alone may not always be sufficient to predict something as complex as body temperature or metabolic style.”

The timing of the purported shift, about 233 million years ago, corresponds to a geologically brief interlude of highly unstable climate known as the Carnian Pluvial Episode (SN: 9/30/21). “It was a time when global temperatures were changing a lot, and it was also a very wet, humid time,” Angielczyk says. “One of the benefits of endothermy is that it stabilizes the internal body environment, lets you operate independent of environmental conditions.”

The finding highlights how “the whole Triassic was a bit insane,” Araújo says. The start of the Triassic was epically hot, coming on the heels of the “Great Dying” mass extinction at the end of the Permian Period (SN: 12/6/18). Vertebrate species had just begun to recover from that event when they were hit with the Carnian Pluvial Episode. Yet the Triassic also saw the dawn of both mammals and dinosaurs — both of which managed to survive.

It was “a crucial time period in the history of life,” Araújo says. All of that instability may have armed both groups with the evolutionary tools they needed to weather yet another mass extinction at the end of the Triassic 201 million years ago (SN: 7/1/22).