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Bennu asteroid reveals its contents to scientists − and clues to how the building blocks of life on Earth may have been seeded

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theconversation.com – Timothy J McCoy, Supervisory Research Geologist, Smithsonian Institution – 2025-01-29 10:06:00

Bennu asteroid reveals its contents to scientists − and clues to how the building blocks of life on Earth may have been seeded

This photo of asteroid Bennu is composed of 12 Polycam images collected on Dec. 2, 2024, by the OSIRIS-REx spacecraft.
NASA

Timothy J McCoy, Smithsonian Institution and Sara Russell, Natural History Museum

A bright fireball streaked across the sky above mountains, glaciers and spruce forest near the town of Revelstoke in British Columbia, Canada, on the evening of March 31, 1965. Fragments of this meteorite, discovered by beaver trappers, fell over a lake. A layer of ice saved them from the depths and allowed scientists a peek into the birth of the solar system.

Nearly 60 years later, NASA’s OSIRIS-REx mission returned from space with a sample of an asteroid named Bennu, similar to the one that rained rocks over Revelstoke. Our research team has published a chemical analysis of those samples, providing insight into how some of the ingredients for life may have first arrived on Earth.

Born in the years bracketing the Revelstoke meteorite’s fall, the two of us have spent our careers in the meteorite collections of the Smithsonian Institution in Washington, D.C., and the Natural History Museum in London. We’ve dreamed of studying samples from a Revelstoke-like asteroid collected by a spacecraft.

Then, nearly two decades ago, we began turning those dreams into reality. We joined NASA’s OSIRIS-REx mission team, which aimed to send a spacecraft to collect and return an asteroid sample to Earth. After those samples arrived on Sept. 24, 2023, we got to dive into a tale of rock, ice and water that hints at how life could have formed on Earth.

An illustration of a small spacecraft with solar panels and an extending arm hovers above an asteroid's rocky surface in space.
In this illustration, NASA’s OSIRIS-REx spacecraft collects a sample from the asteroid Bennu.
NASA/Goddard/University of Arizona

The CI chondrites and asteroid Bennu

To learn about an asteroid – a rocky or metallic object in orbit around the Sun – we started with a study of meteorites.

Asteroids like Bennu are rocky or metallic objects in orbit around the Sun. Meteorites are the pieces of asteroids and other natural extraterrestrial objects that survive the fiery plunge to the Earth’s surface.

We really wanted to study an asteroid similar to a set of meteorites called chondrites, whose components formed in a cloud of gas and dust at the dawn of the solar system billions of years ago.

The Revelstoke meteorite is in a group called CI chondrites. Laboratory-measured compositions of CI chondrites are essentially identical, minus hydrogen and helium, to the composition of elements carried by convection from the interior of the Sun and measured in the outermost layer of the Sun. Since their components formed billions of years ago, they’re like chemically unchanged time capsules for the early solar system.

So, geologists use the chemical compositions of CI chondrites as the ultimate reference standard for geochemistry. They can compare the compositions of everything from other chondrites to Earth rocks. Any differences from the CI chondrite composition would have happened through the same processes that formed asteroids and planets.

CI chondrites are rich in clay and formed when ice melted in an ancient asteroid, altering the rock. They are also rich in prebiotic organic molecules. Some of these types of molecules are the building blocks for life.

This combination of rock, water and organics is one reason OSIRIS-REx chose to sample the organic-rich asteroid Bennu, where water and organic compounds essential to the origin of life could be found.

Evaporites − the legacy of an ancient brine

Ever since the Bennu samples returned to Earth on Sept. 24, 2023, we and our colleagues on four continents have spent hundreds of hours studying them.

The instruments on the OSIRIS-REx spacecraft made observations of reflected light that revealed the most abundant minerals and organics when it was near asteroid Bennu. Our analyses in the laboratory found that the compositions of these samples lined up with those observations.

The samples are mostly water-rich clay, with sulfide, carbonate and iron oxide minerals. These are the same minerals found in CI chondrites like Revelstoke. The discovery of rare minerals within the Bennu samples, however, surprised both of us. Despite our decades of experience studying meteorites, we have never seen many of these minerals.

We found minerals dominated by sodium, including carbonates, sulfates, chlorides and fluorides, as well as potassium chloride and magnesium phosphate. These minerals don’t form just when water and rock react. They form when water evaporates.

We’ve never seen most of these sodium-rich minerals in meteorites, but they’re sometimes found in dried-up lake beds on Earth, like Searles Lake in California.

Bennu’s rocks formed 4.5 billion years ago on a larger parent asteroid. That asteroid was wet and muddy. Under the surface, pockets of water perhaps only a few feet across were evaporating, leaving the evaporite minerals we found in the sample. That same evaporation process also formed the ancient lake beds we’ve seen these minerals in on Earth.

Bennu’s parent asteroid likely broke apart 1 to 2 billion years ago, and some of the fragments came together to form the rubble pile we know as Bennu.

These minerals are also found on icy bodies in the outer solar system. Bright deposits on the dwarf planet Ceres, the largest body in the asteroid belt, contain sodium carbonate. The Cassini mission measured the same mineral in plumes on Saturn’s moon Enceladus.

We also learned that these minerals, formed when water evaporates, disappear when exposed to water once again – even with the tiny amount of water found in air. After studying some of the Bennu samples and their minerals, researchers stored the samples in air. That’s what we do with meteorites.

Unfortunately, we lost these minerals as moisture in the air on Earth caused them to dissolve. But that explains why we can’t find these minerals in meteorites that have been on Earth for decades to centuries.

Fortunately, most of the samples have been stored and transported in nitrogen, protected from traces of water in the air.

Until scientists were able to conduct a controlled sample return with a spacecraft and carefully curate and store the samples in nitrogen, we had never seen this set of minerals in a meteorite.

An unexpected discovery

Before returning the samples, the OSIRIS-REx spacecraft spent over two years making observations around Bennu. From that two years of work, researchers learned that the surface of the asteroid is covered in rocky boulders.

We could see that the asteroid is rich in carbon and water-bearing clays, and we saw veins of white carbonate a few feet long deposited by ancient liquid water. But what we couldn’t see from these observations were the rarer minerals.

We used an array of techniques to go through the returned sample one tiny grain at a time. These included CT scanning, electron microscopy and X-ray diffraction, each of which allowed us to look at the rock at a scale not possible on the asteroid.

Cooking up the ingredients for life

From the salts we identified, we could infer the composition of the briny water from which they formed and see how it changed over time, becoming more sodium-rich.

This briny water would have been an ideal place for new chemical reactions to take place and for organic molecules to form.

While our team characterized salts, our organic chemist colleagues were busy identifying the carbon-based molecules present in Bennu. They found unexpectedly high levels of ammonia, an essential building block of the amino acids that form proteins in living matter. They also found all five of the nucleobases that make up part of DNA and RNA.

Based on these results, we’d venture to guess that these briny pods of fluid would have been the perfect environments for increasingly complicated organic molecules to form, such as the kinds that make up life on Earth.

When asteroids like Bennu hit the young Earth, they could have provided a complete package of complex molecules and the ingredients essential to life, such as water, phosphate and ammonia. Together, these components could have seeded Earth’s initially barren landscape to produce a habitable world.

Without this early bombardment, perhaps when the pieces of the Revelstoke meteorite landed several billion years later, these fragments from outer space would not have arrived into a landscape punctuated with glaciers and trees.The Conversation

Timothy J McCoy, Supervisory Research Geologist, Smithsonian Institution and Sara Russell, Professor of Planetary Sciences, Natural History Museum

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The Conversation

Social media before bedtime wreaks havoc on our sleep − a sleep researcher explains why screens alone aren’t the main culprit

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theconversation.com – Brian N. Chin, Assistant Professor of Psychology, Trinity College – 2025-04-08 07:49:00

Social media use before bedtime can be stimulating in ways that screen time alone is not.
Adam Hester/Tetra Images via Getty Images

Brian N. Chin, Trinity College

“Avoid screens before bed” is one of the most common pieces of sleep advice. But what if the real problem isn’t screen time − it’s the way we use social media at night?

Sleep deprivation is one of the most widespread yet overlooked public health issues, especially among young adults and adolescents.

Despite needing eight to 10 hours of sleep, most adolescents fall short, while nearly two-thirds of young adults regularly get less than the recommended seven to nine hours.

Poor sleep isn’t just about feeling tired − it’s linked to worsened mental health, emotion regulation, memory, academic performance and even increased risk for chronic illness and early mortality.

At the same time, social media is nearly universal among young adults, with 84% using at least one platform daily. While research has long focused on screen time as the culprit for poor sleep, growing evidence suggests that how often people check social media − and how emotionally engaged they are − matters even more than how long they spend online.

As a social psychologist and sleep researcher, I study how social behaviors, including social media habits, affect sleep and well-being. Sleep isn’t just an individual behavior; it’s shaped by our social environments and relationships.

And one of the most common yet underestimated factors shaping modern sleep? How we engage with social media before bed.

Emotional investment in social media

Beyond simply measuring time spent on social media, researchers have started looking at how emotionally connected people feel to their social media use.

Some studies suggest that the way people emotionally engage with social media may have a greater impact on sleep quality than the total time they spend online.

In a 2024 study of 830 young adults, my colleagues and I examined how different types of social media engagement predicted sleep problems. We found that frequent social media visits and emotional investment were stronger predictors of poor sleep than total screen time. Additionally, presleep cognitive arousal and social comparison played a key role in linking social media engagement to sleep disruption, suggesting that social media’s effects on sleep extend beyond simple screen exposure.

I believe these findings suggest that cutting screen time alone may not be enough − reducing how often people check social media and how emotionally connected they feel to it may be more effective in promoting healthier sleep habits.

How social media disrupts sleep

If you’ve ever struggled to fall asleep after scrolling through social media, it’s not just the screen keeping you awake. While blue light can delay melatonin production, my team’s research and that of others suggests that the way people interact with social media may play an even bigger role in sleep disruption.

Here are some of the biggest ways social media interferes with your sleep:

  • Presleep arousal: Doomscrolling and emotionally charged content on social media keeps your brain in a state of heightened alertness, making it harder to relax and fall asleep. Whether it’s political debates, distressing news or even exciting personal updates, emotionally stimulating content can trigger increased cognitive and physiological arousal that delays sleep onset.

  • Social comparison: Viewing idealized social media posts before bed can lead to upward social comparison, increasing stress and making it harder to sleep. People tend to compare themselves to highly curated versions of others’ lives − vacations, fitness progress, career milestones − which can lead to feelings of inadequacy and anxiety that disrupt sleep.

  • Habitual checking: Social media use after lights out is a strong predictor of poor sleep, as checking notifications and scrolling before bed can quickly become an automatic habit. Studies have shown that nighttime-specific social media use, especially after lights are out, is linked to shorter sleep duration, later bedtimes and lower sleep quality. This pattern reflects bedtime procrastination, where people delay sleep despite knowing it would be better for their health and well-being.

  • Fear of missing out, or FOMO: The urge to stay connected also keeps many people scrolling long past their intended bedtime, making sleep feel secondary to staying updated. Research shows that higher FOMO levels are linked to more frequent nighttime social media use and poorer sleep quality. The anticipation of new messages, posts or updates can create a sense of social pressure to stay online and reinforce the habit of delaying sleep.

Taken together, these factors make social media more than just a passive distraction − it becomes an active barrier to restful sleep. In other words, that late-night scroll isn’t harmless − it’s quietly rewiring your sleep and well-being.

How to use social media without sleep disruption

You don’t need to quit social media, but restructuring how you engage with it at night could help. Research suggests that small behavioral changes to your bedtime routine can make a significant difference in sleep quality. I suggest trying these practical, evidence-backed strategies for improving your sleep:

  • Give your brain time to wind down: Avoid emotionally charged content 30 to 60 minutes before bed to help your mind relax and prepare for sleep.

  • Create separation between social media and sleep: Set your phone to “Do Not Disturb” or leave it outside the bedroom to avoid the temptation of late-night checking.

  • Reduce mindless scrolling: If you catch yourself endlessly refreshing, take a small, mindful pause and ask yourself: “Do I actually want to be on this app right now?”

A brief moment of awareness can help break the habit loop.The Conversation

Brian N. Chin, Assistant Professor of Psychology, Trinity College

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Providing farmworkers with health insurance is worth it for their employers − new research

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theconversation.com – John Lowrey, Assistant Professor of Supply Chain and Health Sciences, Northeastern University – 2025-04-08 07:48:00

Farmworkers at Del Bosque Farms pick and pack melons on a mobile platform in Firebaugh, Calif., in July 2021.
AP Photo/Terry Chea

John Lowrey, Northeastern University; Timothy Richards, Arizona State University, and Zachariah Rutledge, Michigan State University

Agricultural employers who provide farmworkers with health insurance earn higher profits, even after accounting for the cost of that coverage. In addition, farmworkers who get health insurance through their employers are more productive and earn more money than those who do not.

These are the key findings from our study published in the March 2025 issue of the American Journal of Agricultural Economics.

To conduct this research, we crunched over three decades of data from the Labor Department’s National Agricultural Workers Survey. We focused on California, the nation’s largest producer of fruits, nuts and other labor-intensive agricultural products in the U.S., from 1989 to 2022.

We determined that if 20% more farmworkers got health insurance coverage, they would have earned $23,063 a year in 2022, up from $22,482 if they did not. Their employers, meanwhile, would earn $7,303 in net profits per worker annually in this same scenario, versus $6,598.

Why it matters

Roughly half of California’s agricultural employers are facing labor shortages at a time when the average age of U.S. farmworkers is also rising.

Some of them, including grape producers, are responding by investing more heavily in labor-saving equipment, which helps reduce the need for seasonal manual labor. However, automated harvesting isn’t yet a viable or affordable option for labor-intensive specialty crops such as melons and strawberries.

Despite labor shortages, agricultural employers may be reluctant to increase total compensation for farmworkers. They may also be wary of providing additional benefits such as health insurance for two main reasons.

First, seasonal workers are, by definition, transient, meaning that the employer who provides coverage may not necessarily be the same one who benefits from a healthier worker. Second, it costs an employer money but doesn’t necessarily benefit them in the future if the worker moves on.

Most U.S. farmworkers are immigrants from Mexico or Central America. Roughly 42% are immigrants who are in the U.S. without legal authorization, down from 55% in the early 2000s.

As the share of farmworkers who are unauthorized immigrants has declined, the share who are U.S. citizens – including those born here – has grown and now stands at about 39%.

The low wages farmworkers earn offer little incentive for more U.S. citizens and permanent residents to take these jobs. These jobs might become more attractive if employers offered health care coverage to protect the health of the worker and their household.

Farmworkers who lack legal authorization to be in the U.S. are not eligible for private health insurance policies, and many can’t enroll in Medicaid, a government-run health insurance program that’s primarily for low-income Americans and people with disabilities. Regardless, some employers do take steps to help them gain access to health care services. As of 2025, a large share of farmworkers remain uninsured, including many citizens and immigrants with legal status.

Limited access to health care is an unfortunate reality for farmworkers, whose jobs are physically demanding and dangerous. In addition, farmworkers are paid at or near the minimum wage and are constantly searching for their next employment opportunity. This uncertainty causes high levels of stress, which can contribute to chronic health issues such as hypertension.

What still isn’t known

It is hard to estimate the effect of employer-provided health insurance on workers and employers, since labor market outcomes are a result of highly complex interactions.

For example, wages, productivity and how long someone keeps their job are highly interdependent variables determined by the interaction between what workers seek and what employers offer. And wages do not always reflect a worker’s skills and abilities, as some people are more willing to accept a job with low pay if their compensation includes good benefits such as health insurance.

The Research Brief is a short take about interesting academic work.The Conversation

John Lowrey, Assistant Professor of Supply Chain and Health Sciences, Northeastern University; Timothy Richards, Professor of Agribusiness, Arizona State University, and Zachariah Rutledge, Assistant Professor of Agricultural, Food and Resource Economics, Michigan State University

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Being alone has its benefits − a psychologist flips the script on the ‘loneliness epidemic’

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theconversation.com – Virginia Thomas, Assistant Professor of Psychology, Middlebury – 2025-04-04 07:18:00

Studies show that choosing ‘me time’ is not a recipe for loneliness but can boost your creativity and emotional well-being.
FotoDuets/iStock via Getty Images Plus

Virginia Thomas, Middlebury

Over the past few years, experts have been sounding the alarm over how much time Americans spend alone.

Statistics show that we’re choosing to be solitary for more of our waking hours than ever before, tucked away at home rather than mingling in public. Increasing numbers of us are dining alone and traveling solo, and rates of living alone have nearly doubled in the past 50 years.

These trends coincided with the surgeon general’s 2023 declaration of a loneliness epidemic, leading to recent claims that the U.S. is living in an “anti-social century.”

Loneliness and isolation are indeed social problems that warrant serious attention, especially since chronic states of loneliness are linked with poor outcomes such as depression and a shortened lifespan.

But there is another side to this story, one that deserves a closer look. For some people, the shift toward aloneness represents a desire for what researchers call “positive solitude,” a state that is associated with well-being, not loneliness.

As a psychologist, I’ve spent the past decade researching why people like to be alone – and spending a fair amount of time there myself – so I’m deeply familiar with the joys of solitude. My findings join a host of others that have documented a long list of benefits gained when we choose to spend time by ourselves, ranging from opportunities to recharge our batteries and experience personal growth to making time to connect with our emotions and our creativity.

YouTube video
Being alone can help remind people who they are.

So it makes sense to me why people live alone as soon as their financial circumstances allow, and when asked why they prefer to dine solo, people say simply, “I want more me time.”

It’s also why I’m not surprised that a 2024 national survey found that 56% of Americans considered alone time essential for their mental health. Or that Costco is now selling “solitude sheds” where for around US$2,000 you can buy yourself some peace and quiet.

It’s clear there is a desire, and a market, for solitude right now in American culture. But why does this side of the story often get lost amid the warnings about social isolation?

I suspect it has to do with a collective anxiety about being alone.

The stigma of solitude

This anxiety stems in large part from our culture’s deficit view of solitude. In this type of thinking, the desire to be alone is seen as unnatural and unhealthy, something to be pitied or feared rather than valued or encouraged.

This isn’t just my own observation. A study published in February 2025 found that U.S. news headlines are 10 times more likely to frame being alone negatively than positively. This type of bias shapes people’s beliefs, with studies showing that adults and children alike have clear judgments about when it is – and importantly when it is not – acceptable for their peers to be alone.

This makes sense given that American culture holds up extraversion as the ideal – indeed as the basis for what’s normal. The hallmarks of extraversion include being sociable and assertive, as well as expressing more positive emotions and seeking more stimulation than the opposite personality – the more reserved and risk-averse introverts. Even though not all Americans are extraverts, most of us have been conditioned to cultivate that trait, and those who do reap social and professional rewards. In this cultural milieu, preferring to be alone carries stigma.

But the desire for solitude is not pathological, and it’s not just for introverts. Nor does it automatically spell social isolation and a lonely life. In fact, the data doesn’t fully support current fears of a loneliness epidemic, something scholars and journalists have recently acknowledged.

In other words, although Americans are indeed spending more time alone than previous generations did, it’s not clear that we are actually getting lonelier. And despite our fears for the eldest members of our society, research shows that older adults are happier in solitude than the loneliness narrative would lead us to believe.

YouTube video
It’s all a balancing act – along with solitude, you need to socialize.

Social media disrupts our solitude

However, solitude’s benefits don’t automatically appear whenever we take a break from the social world. They arrive when we are truly alone – when we intentionally carve out the time and space to connect with ourselves – not when we are alone on our devices.

My research has found that solitude’s positive effects on well-being are far less likely to materialize if the majority of our alone time is spent staring at our screens, especially when we’re passively scrolling social media.

This is where I believe the collective anxiety is well placed, especially the focus on young adults who are increasingly forgoing face-to-face social interaction in favor of a virtual life – and who may face significant distress as a result.

Social media is by definition social. It’s in the name. We cannot be truly alone when we’re on it. What’s more, it’s not the type of nourishing “me time” I suspect many people are longing for.

True solitude turns attention inward. It’s a time to slow down and reflect. A time to do as we please, not to please anyone else. A time to be emotionally available to ourselves, rather than to others. When we spend our solitude in these ways, the benefits accrue: We feel rested and rejuvenated, we gain clarity and emotional balance, we feel freer and more connected to ourselves.

But if we’re addicted to being busy, it can be hard to slow down. If we’re used to looking at a screen, it can be scary to look inside. And if we don’t have the skills to validate being alone as a normal and healthy human need, then we waste our alone time feeling guilty, weird or selfish.

The importance of reframing solitude

Americans choosing to spend more time alone is indeed a challenge to the cultural script, and the stigmatization of solitude can be difficult to change. Nevertheless, a small but growing body of research indicates that it is possible, and effective, to reframe the way we think about solitude.

For example, viewing solitude as a beneficial experience rather than a lonely one has been shown to help alleviate negative feelings about being alone, even for the participants who were severely lonely. People who perceive their time alone as “full” rather than “empty” are more likely to experience their alone time as meaningful, using it for growth-oriented purposes such as self-reflection or spiritual connection.

Even something as simple as a linguistic shift – replacing “isolation” with “me time” – causes people to view their alone time more positively and likely affects how their friends and family view it as well.

It is true that if we don’t have a community of close relationships to return to after being alone, solitude can lead to social isolation. But it’s also true that too much social interaction is taxing, and such overload negatively affects the quality of our relationships. The country’s recent gravitational pull toward more alone time may partially reflect a desire for more balance in a life that is too busy, too scheduled and, yes, too social.

Just as connection with others is essential for our well-being, so is connection with ourselves.The Conversation

Virginia Thomas, Assistant Professor of Psychology, Middlebury

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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