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Inspired by how ants move through narrow spaces by shortening their legs, scientists have built a robot that draws in its limbs to navigate constricted passages.

The robot was able to hunch down and walk quickly through passages that were narrower and shorter than itself, researchers report January 20 in Advanced Intelligent Systems. It could also climb over steps and move on grass, loose rock, mulch and crushed granite.

Such generality and adaptability are the main challenges of legged robot locomotion, says robotics engineer Feifei Qian, who was not involved in the study. Some robots have specialized limbs to move over a particular terrain, but they cannot squeeze into small spaces (SN: 1/16/19).
“A design that can adapt to a variety of environments with varying scales or stiffness is a lot more challenging, as trade-offs between the different environments need to be considered,” says Qian, of the University of Southern California in Los Angeles.

For inspiration, researchers in the new study turned to ants. “Insects are really a neat inspiration for designing robot systems that have minimal actuation but can perform a multitude of locomotion behaviors,” says Nick Gravish, a roboticist at the University of California, San Diego (SN: 8/16/18). Ants adapt their posture to crawl through tiny spaces. And they aren’t perturbed by uneven terrain or small obstacles. For example, their legs collapse a bit when they hit an object, Gravish says, and the ants continue to move forward quickly.

Gravish and colleagues built a short, stocky robot — about 30 centimeters wide and 20 centimeters long — with four wavy, telescoping limbs. Each limb consists of six nested concentric tubes that can draw into each other. What’s more, the limbs do not need to be actively powered or adjusted to change their overall length. Instead, springs that connect the leg segments automatically allow the legs to contract when the robot navigates a narrow space and stretch back out in an open space. The goal was to build mechanically intelligent structures rather than algorithmically intelligent robots.

“It’s likely faster than active control, [which] requires the robot to first sense the contact with the environment, compute the suitable action and then send the command to its motors,” Qian says, about these legs. Removing the sensing and computing components can also make the robots small, cheap and less power hungry.

The robot could modify its body width and height to achieve a larger range of body sizes than other similar robots. The leg segments contracted into themselves to let the robot wiggle through small tunnels and sprawled out when under low ceilings. This adaptability let the robot squeeze into spaces as small as 72 percent its full width and 68 percent its full height.
Next, the researchers plan to actively control the stiffness of the springs that connect the leg segments to tune the motion to terrain type without consuming too much power. “That way, you can keep your leg long when you are moving on open ground or over tall objects, but then collapse down to the smallest possible shape in confined spaces,” Gravish says.
Such small-scale, minimal robots are easy to produce and can be quickly tweaked to explore complex environments. However, despite being able to walk across different terrains, these robots are, for now, too fragile for search-and-rescue, exploration or biological monitoring, Gravish says.

The new robot takes a step closer to those goals, but getting there will take more than just robotics, Qian says. “To actually achieve these applications would require an integration of design, control, sensing, planning and hardware advancement.”

But that’s not Gravish’s interest. Instead, he wants to connect these experiments back to what was observed in the ants originally and use the robots to ask more questions about the rules of locomotion in nature (SN: 1/16/20).

“I really would like to understand how small insects are able to move so rapidly across certain unpredictable terrain,” he says. “What is special about their limbs that enables them to move so quickly?”

The dwarf planet Quaoar has a ring that is too big for its metaphorical fingers. While all other rings in the solar system lie within or near a mathematically determined distance of their parent bodies, Quaoar’s ring is much farther out.

“For Quaoar, for the ring to be outside this limit is very, very strange,” says astronomer Bruno Morgado of the Federal University of Rio de Janeiro. The finding may force a rethink of the rules governing planetary rings, Morgado and colleagues say in a study published February 8 in Nature.
Quaoar is an icy body about half the size of Pluto that’s located in the Kuiper Belt at the solar system’s edge (SN: 8/23/22). At such a great distance from Earth, it’s hard to get a clear picture of the world.

So Morgado and colleagues watched Quaoar block the light from a distant star, a phenomenon called a stellar occultation. The timing of the star winking in and out of view can reveal details about Quaoar, like its size and whether it has an atmosphere.

The researchers took data from occultations from 2018 to 2020, observed from all over the world, including Namibia, Australia and Grenada, as well as space. There was no sign that Quaoar had an atmosphere. But surprisingly, there was a ring. The finding makes Quaoar just the third dwarf planet or asteroid in the solar system known to have a ring, after the asteroid Chariklo and the dwarf planet Haumea (SN: 3/26/14; SN: 10/11/17).

Even more surprisingly, “the ring is not where we expect,” Morgado says.
Known rings around other objects lie within or near what’s called the Roche limit, an invisible line where the gravitational force of the main body peters out. Inside the limit, that force can rip a moon to shreds, turning it into a ring. Outside, the gravity between smaller particles is stronger than that from the main body, and rings will coalesce into one or several moons.

“We always think of [the Roche limit] as straightforward,” Morgado says. “One side is a moon forming, the other side is a ring stable. And now this limit is not a limit.”

For Quaoar’s far-out ring, there are a few possible explanations, Morgado says. Maybe the observers caught the ring at just the right moment, right before it turns into a moon. But that lucky timing seems unlikely, he notes.

Maybe Quaoar’s known moon, Weywot, or some other unseen moon contributes gravity that holds the ring stable somehow. Or maybe the ring’s particles are colliding in such a way that they avoid sticking together and clumping into moons.

The particles would have to be particularly bouncy for that to work, “like a ring of those bouncy balls from toy stores,” says planetary scientist David Jewitt of UCLA, who was not involved in the new work.

The observation is solid, says Jewitt, who helped discover the first objects in the Kuiper Belt in the 1990s. But there’s no way to know yet which of the explanations is correct, if any, in part because there are no theoretical predictions for such far-out rings to compare with Quaoar’s situation.

That’s par for the course when it comes to the Kuiper Belt. “Everything in the Kuiper Belt, basically, has been discovered, not predicted,” Jewitt says. “It’s the opposite of the classical model of science where people predict things and then confirm or reject them. People discover stuff by surprise, and everyone scrambles to explain it.”

More observations of Quaoar, or more discoveries of seemingly misplaced rings elsewhere in the solar system, could help reveal what’s going on.

“I have no doubt that in the near future a lot of people will start working with Quaoar to try to get this answer,” Morgado says.

For nearly 650 years, the fortress walls in the Chinese city of Xi’an have served as a formidable barrier around the central city. At 12 meters high and up to 18 meters thick, they are impervious to almost everything — except subatomic particles called muons.

Now, thanks to their penetrating abilities, muons may be key to ensuring that the walls that once protected the treasures of the first Ming Dynasty — and are now a national architectural treasure in their own right — stand for centuries more.

A refined detection method has provided the highest-resolution muon scans yet produced of any archaeological structure, researchers report in the Jan. 7 Journal of Applied Physics. The scans revealed interior density fluctuations as small as a meter across inside one section of the Xi’an ramparts. The fluctuations could be signs of dangerous flaws or “hidden structures archaeologically interesting for discovery and investigation,” says nuclear physicist Zhiyi Liu of Lanzhou University in China.
Muons are like electrons, only heavier. They rain down all over the planet, produced when charged particles called cosmic rays hit the atmosphere. Although muons can travel deep into earth and stone, they are scattered or absorbed depending on the material they encounter. Counting the ones that pass through makes them useful for studying volcano interiors, scanning pyramids for hidden chambers and even searching for contraband stashed in containers impervious to X-rays (SN: 4/22/22).

Though muons stream down continuously, their numbers are small enough that the researchers had to deploy six detectors for a week at a time to collect enough data for 3-D scans of the rampart.

It’s now up to conservationists to determine how to address any density fluctuations that might indicate dangerous flaws, or historical surprises, inside the Xi’an walls.

Today’s red jungle fowl — the wild forebears of the domesticated chicken — are becoming more chickenlike. New research suggests that a large proportion of the wild fowl’s DNA has been inherited from chickens, and relatively recently.

Ongoing interbreeding between the two birds may threaten wild jungle fowl populations’ future, and even hobble humans’ ability to breed better chickens, researchers report January 19 in PLOS Genetics.

Red jungle fowl (Gallus gallus) are forest birds native to Southeast Asia and parts of South Asia. Thousands of years ago, humans domesticated the fowl, possibly in the region’s rice fields (SN: 6/6/22).
“Chickens are arguably the most important domestic animal on Earth,” says Frank Rheindt, an evolutionary biologist at the National University of Singapore. He points to their global ubiquity and abundance. Chicken is also one of the cheapest sources of animal protein that humans have.

Domesticated chickens (G. gallus domesticus) were known to be interbreeding with jungle fowl near human settlements in Southeast Asia. Given the unknown impacts on jungle fowl and the importance of chickens to humankind, Rheindt and his team wanted to gather more details. Wild jungle fowl contain a store of genetic diversity that could serve as a crucial resource for breeding chickens resistant to diseases or other threats.

The researchers analyzed and compared the genomes — the full complement of an organism’s DNA — of 63 jungle fowl and 51 chickens from across Southeast Asia. Some of the jungle fowl samples came from museum specimens collected from 1874 through 1939, letting the team see how the genetic makeup of jungle fowl has changed over time.

Over the last century or so, wild jungle fowl’s genomes have become increasingly similar to chickens’. Between about 20 and 50 percent of the genomes of modern jungle fowl originated in chickens, the team found. In contrast, many of the roughly 100-year-old jungle fowl had a chicken-ancestry share in the range of a few percent.

The rapid change probably comes from human communities expanding into the region’s wilderness, Rheindt says. Most modern jungle fowl live in close vicinity to humans’ free-ranging chickens, with which they frequently interbreed.

Such interbreeding has become “almost the norm now” for any globally domesticated species, Rheindt says, such as dogs hybridizing with wolves and house cats crossing with wildcats. Pigs, meanwhile, are mixing with wild boars and ferrets with polecats.
Wild populations that interbreed with their domesticated counterparts could pick up physical or behavioral traits that change how the hybrids function in their ecosystem, says Claudio Quilodrán, a conservation geneticist at the University of Geneva not involved with this research.

The effect is likely to be negative, Quilodrán says, since some of the traits coming into the wild population have been honed for human uses, not for survival in the local environment.

Wild jungle fowl have lost their genetic diversity as they’ve interbred too. The birds’ heterozygosity — a measure of a population’s genetic diversity — is now just a tenth of what it was a century ago.

“This result is initially counterintuitive,” Rheindt says. “If you mix one population with another, you would generally expect a higher genetic diversity.”

But domesticated chickens have such low genetic diversity that certain versions of jungle fowl genes are being swept out of the population by a tsunami of genetic homogeneity. The whittling down of these animals’ genetic toolkit may leave them vulnerable to conservation threats.

“Having lots of genetic diversity within a species increases the chance that certain individuals contain the genetic background to adapt to a varied range of different environmental changes and diseases,” says Graham Etherington, a computational biologist at the Earlham Institute in Norwich, England, who was not involved with this research.

A shallower jungle fowl gene pool could also mean diminished resources for breeding better chickens. The genetics of wild relatives are sometimes used to bolster the disease or pest resistance of domesticated crop plants. Jungle fowl genomes could be similarly valuable for this reason.

“If this trend continues unabated, future human generations may only be able to access the entirety of ancestral genetic diversity of chickens in the form of museum specimens,” Rheindt says, which could hamper chicken breeding efforts using the wild fowl genes.

Some countries such as Singapore, Rheindt says, have started managing jungle fowl populations to reduce interbreeding with chickens.

The worst procrastinators probably won’t be able to read this story. It’ll remind them of what they’re trying to avoid, psychologist Piers Steel says.

Maybe they’re dragging their feet going to the gym. Maybe they haven’t gotten around to their New Year’s resolutions. Maybe they’re waiting just one more day to study for that test.

Procrastination is “putting off to later what you know you should be doing now,” even if you’ll be worse off, says Steel, of the University of Calgary in Canada. But all those tasks pushed to tomorrow seem to wedge themselves into the mind — and it may be harming people’s health.
In a study of thousands of university students, scientists linked procrastination to a panoply of poor outcomes, including depression, anxiety and even disabling arm pain. “I was surprised when I saw that one,” says Fred Johansson, a clinical psychologist at Sophiahemmet University in Stockholm. His team reported the results January 4 in JAMA Network Open.

The study is one of the largest yet to tackle procrastination’s ties to health. Its results echo findings from earlier studies that have gone largely ignored, says Fuschia Sirois, a behavioral scientist at Durham University in England, who was not involved with the new research.

For years, scientists didn’t seem to view procrastination as something serious, she says. The new study could change that. “It’s that kind of big splash that’s … going to get attention,” Sirois says. “I’m hoping that it will raise awareness of the physical health consequences of procrastination.”

Procrastinating may be bad for the mind and body
Whether procrastination harms health can seem like a chicken-and-egg situation.

It can be hard to tell if certain health problems make people more likely to procrastinate — or the other way around, Johansson says. (It may be a bit of both.) And controlled experiments on procrastination aren’t easy to do: You can’t just tell a study participant to become a procrastinator and wait and see if their health changes, he says.
Many previous studies have relied on self-reported surveys taken at a single time point. But a snapshot of someone makes it tricky to untangle cause and effect. Instead, in the new study, about 3,500 students were followed over nine months, so researchers could track whether procrastinating students later developed health issues.

On average, these students tended to fare worse over time than their prompter peers. They were slightly more stressed, anxious, depressed and sleep-deprived, among other issues, Johansson and colleagues found. “People who score higher on procrastination to begin with … are at greater risk of developing both physical and psychological problems later on,” says study coauthor Alexander Rozental, a clinical psychologist at Uppsala University in Sweden. “There is a relationship between procrastination at one time point and having these negative outcomes at the later point.”

The study was observational, so the team can’t say for sure that procrastination causes poor health. But results from other researchers also seem to point in this direction. A 2021 study tied procrastinating at bedtime to depression. And a 2015 study from Sirois’ lab linked procrastinating to poor heart health.

Stress may be to blame for procrastination’s ill effects, data from Sirois’ lab and other studies suggest. She thinks that the effects of chronic procrastinating could build up over time. And though procrastination alone may not cause disease, Sirois says, it could be “one extra factor that can tip the scales.”

No, procrastinators are not lazy
Some 20 percent of adults are estimated to be chronic procrastinators. Everyone might put off a task or two, but chronic procrastinators make it their lifestyle, says Joseph Ferrari, a psychologist at DePaul University in Chicago, who has been studying procrastination for decades. “They do it at home, at school, at work and in their relationships.” These are the people, he says, who “you know are going to RSVP late.”

Though procrastinators may think they perform better under pressure, Ferrari has reported the opposite. They actually worked more slowly and made more errors than non-procrastinators, his experiments have shown. And when deadlines are slippery, procrastinators tend to let their work slide, Steel’s team reported last year in Frontiers in Psychology.

For years, researchers have focused on the personalities of people who procrastinate. Findings vary, but some scientists suggest procrastinators may be impulsive, worriers and have trouble regulating their emotions. One thing procrastinators are not, Ferrari emphasizes, is lazy. They’re actually “very busy doing other things than what they’re supposed to be doing,” he says.

In fact, Rozental adds, most research today suggests procrastination is a behavioral pattern.

And if procrastination is a behavior, he says, that means it’s something you can change, regardless of whether you’re impulsive.

Why procrastinators should be kind to themselves
When people put off a tough task, they feel good — in the moment.
Procrastinating is a way to sidestep the negative emotions linked to the task, Sirois says. “We’re sort of hardwired to avoid anything painful or difficult,” she says. “When you procrastinate, you get immediate relief.” A backdrop of stressful circumstances — say, a worldwide pandemic — can strain people’s ability to cope, making procrastinating even easier. But the relief it provides is only temporary, and many seek out ways to stop dawdling.

Researchers have experimented with procrastination treatments that run the gamut from the logistical to the psychological. What works best is still under investigation. Some scientists have reported success with time-management interventions. But the evidence for that “is all over the map,” Sirois says. That’s because “poor time management is a symptom not a cause of procrastination,” she adds.

For some procrastinators, seemingly obvious tips can work. In his clinical practice, Rozental advises students to simply put down their smartphones. Silencing notifications or studying in the library rather than at home can quash distractions and keep people on task. But that won’t be enough for many people, he says.

Hard-core procrastinators may benefit from cognitive behavioral therapy. In a 2018 review of procrastination treatments, Rozental found that this type of therapy, which involves managing thoughts and emotions and trying to change behavior, seemed to be the most helpful. Still, not many studies have examined treatments, and there’s room for improvement, he says.

Sirois also favors an emotion-centered approach. Procrastinators can fall into a shame spiral where they feel uneasy about a task, put the task off, feel ashamed for putting it off and then feel even worse than when they started. People need to short-circuit that loop, she says. Self-forgiveness may help, scientists suggested in one 2020 study. So could mindfulness training.

In a small trial of university students, eight weekly mindfulness sessions reduced procrastination, Sirois and colleagues reported in the January Learning and Individual Differences. Students practiced focusing on the body, meditating during unpleasant activities and discussed the best way to take care of themselves. A little self-compassion may snap people out of their spiral, Sirois says.

“You made a mistake and procrastinated. It’s not the end of the world,” she says. “What can you do to move forward?”

Concerns abound about what’s gone wrong in modern societies. Many scholars explain growing gaps between the haves and the have-nots as partly a by-product of living in dense, urban populations. The bigger the crowd, from this perspective, the more we need power brokers to run the show. Societies have scaled up for thousands of years, which has magnified the distance between the wealthy and those left wanting.

In The Dawn of Everything, anthropologist David Graeber and archaeologist David Wengrow challenge the assumption that bigger societies inevitably produce a range of inequalities. Using examples from past societies, the pair also rejects the popular idea that social evolution occurred in stages.

Such stages, according to conventional wisdom, began with humans living in small hunter-gatherer bands where everyone was on equal footing. Then an agricultural revolution about 12,000 years ago fueled population growth and the emergence of tribes, then chiefdoms and eventually bureaucratic states. Or perhaps murderous alpha males dominated ancient hunter-gatherer groups. If so, early states may have represented attempts to corral our selfish, violent natures.

Neither scenario makes sense to Graeber and Wengrow. Their research synthesis — which extends for 526 pages — paints a more hopeful picture of social life over the last 30,000 to 40,000 years. For most of that time, the authors argue, humans have tactically alternated between small and large social setups. Some social systems featured ruling elites, working stiffs and enslaved people. Others emphasized decentralized, collective decision making. Some were run by men, others by women. The big question — one the authors can’t yet answer — is why, after tens of thousands of years of social flexibility, many people today can’t conceive of how society might effectively be reorganized.
Hunter-gatherers have a long history of revamping social systems from one season to the next, the authors write. About a century ago, researchers observed that Indigenous populations in North America and elsewhere often operated in small, mobile groups for part of the year and crystallized into large, sedentary communities the rest of the year. For example, each winter, Canada’s Northwest Coast Kwakiutl hunter-gatherers built wooden structures where nobles ruled over designated commoners and enslaved people, and held banquets called potlatch. In summers, aristocratic courts disbanded, and clans with less formal social ranks fished along the coast.

Many Late Stone Age hunter-gatherers similarly assembled and dismantled social systems on a seasonal basis, evidence gathered over the last few decades suggests. Scattered discoveries of elaborate graves for apparently esteemed individuals (SN: 10/5/17) and huge structures made of stone (SN: 2/11/21), mammoth bones and other material dot Eurasian landscapes. The graves may hold individuals who were accorded special status, at least at times of the year when mobile groups formed large communities and built large structures, the authors speculate. Seasonal gatherings to conduct rituals and feasts probably occurred at the monumental sites. No signs of centralized power, such as palaces or storehouses, accompany those sites.

Social flexibility and experimentation, rather than a revolutionary shift, also characterized ancient transitions to agriculture, Graeber and Wengrow write. Middle Eastern village excavations now indicate that the domestication of cereals and other crops occurred in fits and starts from around 12,000 to 9,000 years ago. Ancient Fertile Crescent communities periodically gave farming a go while still hunting, foraging, fishing and trading. Early cultivators were in no rush to treat tracts of land as private property or to form political systems headed by kings, the authors conclude.

Even in early cities of Mesopotamia and Eurasia around 6,000 years ago (SN: 2/19/20), absolute rule by monarchs did not exist. Collective decisions were made by district councils and citizen assemblies, archaeological evidence suggests. In contrast, authoritarian, violent political systems appeared in the region’s mobile, nonagricultural populations at that time.

Early states formed in piecemeal fashion, the authors argue. These political systems incorporated one or more of three basic elements of domination: violent control of the masses by authorities, bureaucratic management of special knowledge and information, and public demonstrations of rulers’ power and charisma. Egypt’s early rulers more than 4,000 years ago fused violent coercion of their subjects with extensive bureaucratic controls over daily affairs. Classic Maya rulers in Central America 1,100 years ago or more relied on administrators to monitor cosmic events while grounding earthly power in violent control and alliances with other kings.

States can take many forms, though. Graeber and Wengrow point to Bronze Age Minoan society on Crete as an example of a political system run by priestesses who called on citizens to transcend individuality via ecstatic experiences that bound the population together.

What seems to have changed today is that basic social liberties have receded, the authors contend. The freedom to relocate to new kinds of communities, to disobey commands issued by others and to create new social systems or alternate between different ones has become a scarce commodity. Finding ways to reclaim that freedom is a major challenge.

These examples give just a taste of the geographic and historical ground covered by the authors. Shortly after finishing writing the book, Graeber, who died in 2020, tweeted: “My brain feels bruised with numb surprise.” That sense of revelation animates this provocative take on humankind’s social journey.

he James Webb Space Telescope has been a long time coming. When it launches later this year, the observatory will be the largest and most complex telescope ever sent into orbit. Scientists have been drafting and redrafting their dreams and plans for this unique tool since 1989.

The mission was originally scheduled to launch between 2007 and 2011, but a series of budget and technical issues pushed its start date back more than a decade. Remarkably, the core design of the telescope hasn’t changed much. But the science that it can dig into has. In the years of waiting for Webb to be ready, big scientific questions have emerged. When Webb was an early glimmer in astronomers’ eyes, cosmological revolutions like the discoveries of dark energy and planets orbiting stars outside our solar system hadn’t yet happened.

“It’s been over 25 years,” says cosmologist Wendy Freedman of the University of Chicago. “But I think it was really worth the wait.”

An audacious plan
Webb has a distinctive design. Most space telescopes house a single lens or mirror within a tube that blocks sunlight from swamping the dim lights of the cosmos. But Webb’s massive 6.5-meter-wide mirror and its scientific instruments are exposed to the vacuum of space. A multilayered shield the size of a tennis court will block light from the sun, Earth and moon.

For the awkward shape to fit on a rocket, Webb will launch folded up, then unfurl itself in space (see below, What could go wrong?).

“They call this the origami satellite,” says astronomer Scott Friedman of the Space Telescope Science Institute, or STScI, in Baltimore. Friedman is in charge of Webb’s postlaunch choreography. “Webb is different from any other telescope that’s flown.”
Its basic design hasn’t changed in more than 25 years. The telescope was first proposed in September 1989 at a workshop held at STScI, which also runs the Hubble Space Telescope.

At the time, Hubble was less than a year from launching, and was expected to function for only 15 years. Thirty-one years after its launch, the telescope is still going strong, despite a series of computer glitches and gyroscope failures (SN Online: 10/10/18).

The institute director at the time, Riccardo Giacconi, was concerned that the next major mission would take longer than 15 years to get off the ground. So he and others proposed that NASA investigate a possible successor to Hubble: a space telescope with a 10-meter-wide primary mirror that was sensitive to light in infrared wavelengths to complement Hubble’s range of ultraviolet, visible and near-infrared.

Infrared light has a longer wavelength than light that is visible to human eyes. But it’s perfect for a telescope to look back in time. Because light travels at a fixed speed, looking at distant objects in the universe means seeing them as they looked in the past. The universe is expanding, so that light is stretched before it reaches our telescopes. For the most distant objects in the universe — the first galaxies to clump together, or the first stars to burn in those galaxies — light that was originally emitted in shorter wavelengths is stretched all the way to the infrared.

Giacconi and his collaborators dreamed of a telescope that would detect that stretched light from the earliest galaxies. When Hubble started sharing its views of the early universe, the dream solidified into a science plan. The galaxies Hubble saw at great distances “looked different from what people were expecting,” says astronomer Massimo Stiavelli, a leader of the James Webb Space Telescope project who has been at STScI since 1995. “People started thinking that there is interesting science here.”

In 1995, STScI and NASA commissioned a report to design Hubble’s successor. The report, led by astronomer Alan Dressler of the Carnegie Observatories in Pasadena, Calif., suggested an infrared space observatory with a 4-meter-wide mirror.

The bigger a telescope’s mirror, the more light it can collect, and the farther it can see. Four meters wasn’t that much larger than Hubble’s 2.4-meter-wide mirror, but anything bigger would be difficult to launch.

Dressler briefed then-NASA Administrator Dan Goldin in late 1995. In January 1996 at the American Astronomical Society’s annual meeting, Goldin challenged the scientists to be more ambitious. He called out Dressler by name, saying, “Why do you ask for such a modest thing? Why not go after six or seven meters?” (Still nowhere near Giacconi’s pie-in-the-sky 10-meter wish.) The speech received a standing ovation.

Six meters was a larger mirror than had ever flown in space, and larger than would fit in available launch vehicles. Scientists would have to design a telescope mirror that could fold, then deploy once it reached space.

The telescope would also need to cool itself passively by radiating heat into space. It needed a sun shield — a big one. The origami telescope was born. It was dubbed James Webb in 2002 for NASA’s administrator from 1961 to 1968, who fought to support research to boost understanding of the universe in the increasingly human-focused space program. (In response to a May petition to change the name, NASA investigated allegations that James Webb persecuted gay and lesbian people during his government career. The agency announced on September 27 that it found no evidence warranting a name change.)
Goldin’s motto at NASA was “Faster, better, cheaper.” Bigger was better for Webb, but it sure wasn’t faster — or cheaper. By late 2010, the project was more than $1.4 billion over its $5.1 billion budget (SN: 4/9/11, p. 22). And it was going to take another five years to be ready. Today, the cost is estimated at almost $10 billion.

The telescope survived a near-cancellation by Congress, and its timeline was reset for an October 2018 launch. But in 2017, the launch was pushed to June 2019. Two more delays in 2018 pushed the takeoff to May 2020, then to March 2021. Some of those delays were because assembling and testing the spacecraft took longer than NASA expected.

Other slowdowns were because of human errors, like using the wrong cleaning solvent, which damaged valves in the propulsion system. Recent shutdowns due to the coronavirus pandemic pushed the launch back a few more months.

“I don’t think we ever imagined it would be this long,” says University of Chicago’s Freedman, who worked on the Dressler report. But there’s one silver lining: Science marched on.

The age conflict
The first science goal listed in the Dressler report was “the detailed study of the birth and evolution of normal galaxies such as the Milky Way.” That is still the dream, partly because it’s such an ambitious goal, Stiavelli says.

“We wanted a science rationale that would resist the test of time,” he says. “We didn’t want to build a mission that would do something that gets done in some other way before you’re done.”

Webb will peek at galaxies and stars as they were just 400 million years after the Big Bang, which astronomers think is the epoch when the first tiny galaxies began making the universe transparent to light by stripping electrons from cosmic hydrogen.

But in the 1990s, astronomers had a problem: There didn’t seem to be enough time in the universe to make galaxies much earlier than the ones astronomers had already seen. The standard cosmology at the time suggested the universe was 8 billion or 9 billion years old, but there were stars in the Milky Way that seemed to be about 14 billion years old.

“There was this age conflict that reared its head,” Freedman says. “You can’t have a universe that’s younger than the oldest stars. The way people put it was, ‘You can’t be older than your grandmother!’”
In 1998, two teams of cosmologists showed that the universe is expanding at an ever-increasing rate. A mysterious substance dubbed dark energy may be pushing the universe to expand faster and faster. That accelerated expansion means the universe is older than astronomers previously thought — the current estimate is about 13.8 billion years old.

“That resolved the age conflict,” Freedman says. “The discovery of dark energy changed everything.” And it expanded Webb’s to-do list.

Dark energy
Top of the list is getting to the bottom of a mismatch in cosmic measurements. Since at least 2014, different methods for measuring the universe’s rate of expansion — called the Hubble constant — have been giving different answers. Freedman calls the issue “the most important problem in cosmology today.”

The question, Freedman says, is whether the mismatch is real. A real mismatch could indicate something profound about the nature of dark energy and the history of the universe. But the discrepancy could just be due to measurement errors.

Webb can help settle the debate. One common way to determine the Hubble constant is by measuring the distances and speeds of far-off galaxies. Measuring cosmic distances is difficult, but astronomers can estimate them using objects of known brightness, called standard candles. If you know the object’s actual brightness, you can calculate its distance based on how bright it seems from Earth.

Studies using supernovas and variable stars called Cepheids as candles have found an expansion rate of 74.0 kilometers per second for approximately every 3 million light-years, or megaparsec, of distance between objects. But using red giant stars, Freedman and colleagues have gotten a smaller answer: 69.8 km/s/Mpc.

Other studies have measured the Hubble constant by looking at the dim glow of light emitted just 380,000 years after the Big Bang, called the cosmic microwave background. Calculations based on that glow give a smaller rate still: 67.4 km/s/Mpc. Although these numbers may seem close, the fact that they disagree at all could alter our understanding of the contents of the universe and how it evolves over time. The discrepancy has been called a crisis in cosmology (SN: 9/14/19, p. 22).

In its first year, Webb will observe some of the same galaxies used in the supernova studies, using three different objects as candles: Cepheids, red giants and peculiar stars called carbon stars.

The telescope will also try to measure the Hubble constant using a distant gravitationally lensed galaxy. Comparing those measurements with each other and with similar ones from Hubble will show if earlier measurements were just wrong, or if the tension between measurements is real, Freedman says.

Without these new observations, “we were just going to argue about the same things forever,” she says. “We just need better data. And [Webb] is poised to deliver it.”
Exoplanets
Perhaps the biggest change for Webb science has been the rise of the field of exoplanet explorations.

“When this was proposed, exoplanets were scarcely a thing,” says STScI’s Friedman. “And now, of course, it’s one of the hottest topics in all of science, especially all of astronomy.”

The Dressler report’s second major goal for Hubble’s successor was “the detection of Earthlike planets around other stars and the search for evidence of life on them.” But back in 1995, only a handful of planets orbiting other sunlike stars were even known, and all of them were scorching-hot gas giants — nothing like Earth at all.

Since then, astronomers have discovered thousands of exoplanets orbiting distant stars. Scientists now estimate that, on average, there is at least one planet for every star we see in the sky. And some of the planets are small and rocky, with the right temperatures to support liquid water, and maybe life.

Most of the known planets were discovered as they crossed, or transited, in front of their parent stars, blocking a little bit of the parent star’s light. Astronomers soon realized that, if those planets have atmospheres, a sensitive telescope could effectively sniff the air by examining the starlight that filters through the atmosphere.

The infrared Spitzer Space Telescope, which launched in 2003, and Hubble have started this work. But Spitzer ran out of coolant in 2009, keeping it too warm to measure important molecules in exoplanet atmospheres. And Hubble is not sensitive to some of the most interesting wavelengths of light — the ones that could reveal alien life-forms.

That’s where Webb is going to shine. If Hubble is peeking through a crack in a door, Webb will throw the door wide open, says exoplanet scientist Nikole Lewis of Cornell University. Crucially, Webb, unlike Hubble, will be particularly sensitive to several carbon-bearing molecules in exoplanet atmospheres that might be signs of life.

“Hubble can’t tell us anything really about carbon, carbon monoxide, carbon dioxide, methane,” she says.

If Webb had launched in 2007, it could have missed this whole field. Even though the first transiting exoplanet was discovered in 1999, their numbers were low for the next decade.

Lewis remembers thinking, when she started grad school in 2007, that she could make a computer model of all the transiting exoplanets. “Because there were literally only 25,” she says.
Between 2009 and 2018, NASA’s Kepler space telescope raked in transiting planets by the thousands. But those planets were too dim and distant for Webb to probe their atmospheres.

So the down-to-the-wire delays of the last few years have actually been good for exoplanet research, Lewis says. “The launch delays were one of the best things that’s happened for exoplanet science with Webb,” she says. “Full stop.”

That’s mainly thanks to NASA’s Transiting Exoplanet Survey Satellite, or TESS, which launched in April 2018. TESS’ job is to find planets orbiting the brightest, nearest stars, which will give Webb the best shot at detecting interesting molecules in planetary atmospheres.

If it had launched in 2018, Webb would have had to wait a few years for TESS to pick out the best targets. Now, it can get started on those worlds right away. Webb’s first year of observations will include probing several known exoplanets that have been hailed as possible places to find life. Scientists will survey planets orbiting small, cool stars called M dwarfs to make sure such planets even have atmospheres, a question that has been hotly debated.

If a sign of life does show up on any of these planets, that result will be fiercely debated, too, Lewis says. “There will be a huge kerfuffle in the literature when that comes up.” It will be hard to compare planets orbiting M dwarfs with Earth, because these planets and their stars are so different from ours. Still, “let’s look and see what we find,” she says.

A limited lifetime
With its components assembled, tested and folded at Northrop Grumman’s facilities in California, Webb is on its way by boat through the Panama Canal, ready to launch in an Ariane 5 rocket from French Guiana. The most recent launch date is set for December 18.

For the scientists who have been working on Webb for decades, this is a nostalgic moment.

“You start to relate to the folks who built the pyramids,” Stiavelli says.

Other scientists, who grew up in a world where Webb was always on the horizon, are already thinking about the next big thing.

“I’m pretty sure, barring epic disaster, that [Webb] will carry my career through the next decade,” Lewis says. “But I have to think about what I’ll do in the next decade” after that.

Unlike Hubble, which has lasted decades thanks to fixes by astronauts and upgrade missions, Webb has a strictly limited lifetime. Orbiting the sun at a gravitationally fixed point called L2, Webb will be too far from Earth to repair, and will need to burn small amounts of fuel to stay in position. The fuel will last for at least five years, and hopefully as much as 10. But when the fuel runs out, Webb is finished. The telescope operators will move it into retirement in an out-of-the-way orbit around the sun, and bid it farewell.

Squabbling sibling planets may have hurled space rocks when they were young.

Simulations suggest that space rocks the size of baby planets struck both the newborn Earth and Venus, but many of the rocks that only grazed Earth went on to hit — and stick — to Venus. That difference in early impacts could help explain why Earth and Venus are such different worlds today, researchers report September 23 in the Planetary Science Journal.

“The pronounced differences between Earth and Venus, in spite of their similar orbits and masses, has been one of the biggest puzzles in our solar system,” says planetary scientist Shigeru Ida of the Tokyo Institute of Technology, who was not involved in the new work. This study introduces “a new point that has not been raised before.”

Scientists have typically thought that there are two ways that collisions between baby planets can go. The objects could graze each other and each continue on its way, in a hit-and-run collision. Or two protoplanets could stick together, or accrete, making one larger planet. Planetary scientists often assume that every hit-and-run collision eventually leads to accretion. Objects that collide must have orbits that cross each other’s, so they’re bound to collide again and again, and eventually should stick.
But previous work from planetary scientist Erik Asphaug of the University of Arizona in Tucson and others suggests that isn’t so. It takes special conditions for two planets to merge, Asphaug says, like relatively slow impact speeds, so hit-and-runs were probably much more common in the young solar system.

Asphaug and colleagues wondered what that might have meant for Earth and Venus, two apparently similar planets with vastly different climates. Both worlds are about the same size and mass, but Earth is wet and clement while Venus is a searing, acidic hellscape (SN: 2/13/18).

“If they started out on similar pathways, somehow Venus took a wrong turn,” Asphaug says.

The team ran about 4,000 computer simulations in which Mars-sized protoplanets crashed into a young Earth or Venus, assuming the two planets were at their current distances from the sun. The researchers found that about half of the time, incoming protoplanets grazed Earth without directly colliding. Of those, about half went on to collide with Venus.

Unlike Earth, Venus ended up accreting most of the objects that hit it in the simulations. Hitting Earth first slowed incoming objects down enough to let them stick to Venus later, the study suggests. “You have this imbalance where things that hit the Earth, but don’t stick, tend to end up on Venus,” Asphaug says. “We have a fundamental explanation for why Venus ended up accreting differently from the Earth.”

If that’s really what happened, it would have had a significant effect on the composition of the two worlds. Earth would have ended up with more of the outer mantle and crust material from the incoming protoplanets, while Venus would have gotten more of their iron-rich cores.

The imbalance in impacts could even explain some major Venusian mysteries, like why the planet doesn’t have a moon, why it spins so slowly and why it lacks a magnetic field — though “these are hand-waving kind of conjectures,” Asphaug says.

Ida says he hopes that future work will look into those questions more deeply. “I’m looking forward to follow-up studies to examine if the new result actually explains the Earth-Venus difference,” he says.

The idea fits into a growing debate among planetary scientists about how the solar system grew up, says planetary scientist Seth Jacobson of Michigan State University in East Lansing. Was it built violently, with lots of giant collisions, or calmly, with planets growing smoothly via pebbles sticking together?

“This paper falls on the end of lots of giant impacts,” Jacobson says.

Each rocky planet in the solar system should have very different chemistry and structure depending on which scenario is true. But scientists know the chemistry and structure of only one planet with any confidence: Earth. And Earth’s early history has been overwritten by plate tectonics and other geologic activity. “Venus is the missing link,” Jacobson says. “Learning more about Venus’ chemistry and interior structure is going to tell us more about whether it had a giant impact or not.”

Three missions to Venus are expected to launch in the late 2020s and 2030s (SN: 6/2/21). Those should help, but none are expected to take the kind of detailed composition measurements that could definitively solve the mystery. That would take a long-lived lander, or a sample return mission, both of which would be extremely difficult on hot, hostile Venus.

“I wish there was an easier way to test it,” Jacobson says. “I think that’s where we should concentrate our energy as terrestrial planet formation scientists going forward.”

Fleets of private satellites orbiting Earth will be visible to the naked eye in the next few years, sometimes all night long.

Companies like SpaceX and Amazon have launched hundreds of satellites into low orbits since 2019, with plans to launch thousands more in the works — a trend that’s alarming astronomers. The goal of these satellite “mega-constellations” is to bring high-speed internet around the globe, but these bright objects threaten to disrupt astronomers’ ability to observe the cosmos (SN: 3/12/20). “For astronomers, this is kind of a pants-on-fire situation,” says radio astronomer Harvey Liszt of the National Radio Astronomical Observatory in Charlottesville, Va.

Now, a new simulation of the potential positions and brightness of these satellites shows that, contrary to earlier predictions, casual sky watchers will have their view disrupted, too. And parts of the world will be affected more than others, astronomer Samantha Lawler of the University of Regina in Canada and her colleagues report in a paper posted September 9 at arXiv.org.

“How will this affect the way the sky looks to your eyeballs?” Lawler asks. “We humans have been looking up at the night sky and analyzing patterns there for as long as we’ve been human. It’s part of what makes us human.” These mega-constellations could mean “we’ll see a human-made pattern more than we can see the stars, for the first time in human history.”
Flat, smooth surfaces on satellites can reflect sunlight depending on their position in the sky. Earlier research had suggested that most of the new satellites would not be visible with the naked eye.

Lawler, along with Aaron Boley of the University of British Columbia and Hanno Rein of the University of Toronto at Scarborough in Canada, started building their simulation with public data about the launch plans of four companies — SpaceX’s Starlink, Amazon’s Kuiper, OneWeb and StarNet/GW — that had been filed with the U.S. Federal Communications Commission and the International Telecommunications Union. The filings detailed the expected orbital heights and angles of 65,000 satellites that could be launched over the next few years.

“It’s impossible to predict the future, but this is realistic,” says astronomer Meredith Rawls of the University of Washington in Seattle, who was not involved in the new study. “A lot of times when people make these simulations, they pick a number out of a hat. This really justifies the numbers that they pick.”

There are currently about 7,890 objects in Earth orbit, about half of which are operational satellites, according to the U.N. Office for Outer Space Affairs. But that number is increasing fast as companies launch more and more satellites (SN: 12/28/20). In August 2020, there were only about 2,890 operational satellites.

Next, the researchers computed how many satellites will be in the sky at different times of year, at different hours of the night and from different positions on Earth’s surface. They also estimated how bright the satellites were likely to be at different hours of the day and times of the year.

That calculation required a lot of assumptions because companies aren’t required to publish details about their satellites like the materials they’re made of or their precise shapes, both of which can affect reflectivity. But there are enough satellites in orbit that Lawler and colleagues could compare their simulated satellites to the light reflected down to Earth by the real ones.

The simulations showed that “the way the night sky is going to change will not affect all places equally,” Lawler says. The places where naked-eye stargazing will be most affected are at latitudes 50° N and 50° S, regions that cross lower Canada, much of Europe, Kazakhstan and Mongolia, and the southern tips of Chile and Argentina, the researchers found.
“The geometry of sunlight in the summer means there will be hundreds of visible satellites all night long,” Lawler says. “It’s bad everywhere, but it’s worse there.” For her, this is personal: She lives at 50° N.

Closer to the equator, where many research observatories are located, there is a period of about three hours in the winter and near the time of the spring and fall equinoxes with few or no sunlit satellites visible. But there are still hundreds of sunlit satellites all night at these locations in the summer.

A few visible satellites can be a fun spectacle, Lawler concedes. “I think we really are at a transition point here where right now, seeing a satellite, or even a Starlink train, is cool and different and wow, that’s amazing,” she says. “I used to look up when the [International Space Station] was overhead.” But she compares the coming change to watching one car go down the road 100 years ago, versus living next to a busy freeway now.

“Every sixteenth star will actually be moving,” she says. “I hope I’m wrong. I’ve never wanted to be wrong about a simulation more than this. But without mitigation, this is what the sky will look like in a few years.”

Astronomers have been meeting with representatives from private companies, as well as space lawyers and government officials, to work out compromises and mitigation strategies. Companies have been testing ways to reduce reflectivity, like shading the satellites with a “visor.” Other proposed strategies include limiting the satellites to lower orbits, where they move faster across the sky and leave a fainter streak in telescope images. Counterintuitively, lower satellites may be better for some astronomy research, Rawls says. “They move out of the way quick.”

But that lower altitude strategy will mean more visible satellites for other parts of the world, and more that are visible to the naked eye. “There’s not some magical orbital altitude that solves all our problems,” Rawls says. “There are some latitudes on Earth where no matter what altitude you put your satellites at, they’re going to be all over the darn place. The only way out of this is fewer satellites.”

There are currently no regulations concerning how bright a satellite can be or how many satellites a private company can launch. Scientists are grateful that companies are willing to work with them, but nervous that their cooperation is voluntary.

“A lot of the people who work on satellites care about space. They’re in this industry because they think space is awesome,” Rawls says. “We share that, which helps. But it doesn’t fix it. I think we need to get some kind of regulation as soon as possible.” (Representatives from Starlink, Kuiper and OneWeb did not respond to requests for comment.)

Efforts are under way to bring the issue to the attention of the United Nations and to try to use existing environmental regulations to place limits on satellite launches, says study coauthor Boley (who also lives near 50° N).

Analogies to other global pollution problems, like space junk, can provide inspiration and precedents, he says. “There are a number of ways forward. We shouldn’t just lose hope. We can do things about this.”

The Perseverance rover has captured its first two slices of Mars.

NASA’s latest Mars rover drilled into a flat rock nicknamed Rochette on September 1 and filled a roughly finger-sized tube with stone. The sample is the first ever destined to be sent back to Earth for further study. On September 7, the rover snagged a second sample from the same rock. Both are now stored in airtight tubes inside the rover’s body.

Getting pairs of samples from every rock it drills is “a little bit of an insurance policy,” says deputy project scientist Katie Stack Morgan of NASA’s Jet Propulsion Lab in Pasadena, Calif. It means the rover can drop identical stores of samples in two different places, boosting chances that a future mission will be able to pick up at least one set.

The successful drilling is a comeback story for Perseverance. The rover’s first attempt to take a bit of Mars ended with the sample crumbling to dust, leaving an empty tube (SN: 8/19/21). Scientists think that rock was too soft to hold up to the drill.
Nevertheless, the rover persevered.

“Even though some of its rocks are not, Mars is hard,” said Lori Glaze, director of NASA’s planetary science division, in a September 10 news briefing.

Rochette is a hard rock that appears to have been less severely eroded by millennia of Martian weather (SN: 7/14/20). (Fun fact: All the rocks Perseverance drills into will get names related to national parks; the region on Mars the rover is now exploring is called Mercantour, so the name Rochette — or “Little Rock” — comes from a village in France near Mercantour National Park.)

Rover measurements of the rock’s texture and chemistry suggests that it’s made of basalt and may have been part of an ancient lava flow. That’s useful because volcanic rocks preserve their ages well, Stack Morgan says. When scientists on Earth get their hands on the sample, they’ll be able to use the concentrations of certain elements and isotopes to figure out exactly how old the rock is — something that’s never been done for a pristine Martian rock.

Rochette also contains salt minerals that probably formed when the rock interacted with water over long time periods. That could suggest groundwater moving through the Martian subsurface, maybe creating habitable environments within the rocks, Stack Morgan says.

“It really feels like this rich treasure trove of information for when we get this sample back,” Stack Morgan says.

Once a future mission brings the rocks back to Earth, scientists can search inside those salts for tiny fluid bubbles that might be trapped there. “That would give us a glimpse of Jezero crater at the time when it was wet and was able to sustain ancient Martian life,” said planetary scientist Yulia Goreva of JPL at the news briefing.

Scientists will have to be patient, though — the earliest any samples will make it back to Earth is 2031. But it’s still a historic milestone, says planetary scientist Meenakshi Wadhwa of Arizona State University in Tempe.

“These represent the beginning of Mars sample return,” said Wadhwa said at the news briefing. “I’ve dreamed of having samples back from Mars to analyze in my lab since I was a graduate student. We’ve talked about Mars sample return for decades. Now it’s starting to actually feel real.”