The opposing fountains of plasma and particles spanning 23 million light-years are the longest pair of black hole jets ever seen. That’s far enough away to affect the evolution of the universe on a cosmic scale, astronomers report Sept. 18. Nature.
“Traditionally, astronomers believed that all jets remain inside, or at least very close to, their host galaxy,” astrophysicist Martijn Oei of Caltech said at a Sept. 16 press conference. “We present evidence that supermassive black holes not only affect galaxies, but also the cosmic web that surrounds them.”
Astronomers think that all massive galaxies harbor a giant black hole at their center, and some of these galaxies emit high-energy sources of charged plasma into space. Those jets affect the structure and evolution of the galaxy in which they are embedded, slowing or even shutting down star formation. (SN: 10/13/23).
The newly discovered pair, nicknamed Porphyrion after a rebel giant in Greek mythology, were spotted in observations by LOFAR, a network of radio wave detectors in the Netherlands. Porphyry’s incredible size—it outshines the previous record holder by about 7 million light-years—hints that its influence may exceed the limits of ordinary galaxies.
This photo from the LOFAR telescope array shows the longest black hole jets ever observed, seen as faint streaks running diagonally across the image from top left to bottom right.LOFAR, M. Oei/Caltech CollaborationThis photo from the LOFAR telescope array shows the longest black hole jets ever observed, seen as faint streaks running diagonally across the image from top left to bottom right.LOFAR, M. Oei/Caltech Collaboration
The following observations suggest that Porphyry’s home galaxy is embedded in a filament of the cosmic web, the tangled scene of gas and galaxies where most of the universe’s ordinary matter resides. (SN: 3/6/23). Jets also existed in an early era of the universe’s history, about halfway through its current era, when the strands of the cosmic web were closer together than they are today. Oei and colleagues calculate that jets can travel two-thirds of the way through the voids between cosmic strings.
And Porphyrion is not alone. A citizen science effort to identify other large black hole jets has revealed more than 10,000 that span roughly 3 million light-years or more, though none as large as Porphyrion.
“Those massive jet systems with black holes may be less rare than we thought,” Oei said. “So they may have a bigger impact than we expected.”
Imagine Victorian London, but its skies are filled with airplanes. Steam robots crowd the streets, mingling with people in hats and cloaks. This kind of retrofuturistic mash-up is the fantasy realm of steampunk, a genre of literature, film, and other creative media. Theoretical physicist Nicole Yunger Halpern sees her specialty, the field of quantum thermodynamics, as the real-life version of steampunk.
In steampunk, “there’s a strange juxtaposition of old environment and futuristic technology,” says Yunger Halpern. “That’s what we do in quantum thermodynamics.”
Thermodynamics, developed in the 1800s in the context of the Industrial Revolution, describes the physics concepts of heat, work, and energy (SN: 6/12/24). The field arose out of scientific efforts to understand steam engines. Unlike the clatter and clatter of industrial machines, quantum physics describes phenomena at the scale of atoms, electrons, and the like, and has fueled the development of modern technologies such as quantum computers (SN: 28/6/23).
In the past, some physicists didn’t think the idea of quantum thermodynamics made sense. “They saw it as an oxymoron,” says Yunger Halpern.
Now, however, the two concepts collide in quantum engines and other miniature devices. Quantum thermodynamics researchers aim to develop the tools to describe heat, work, cooling, and efficiency in quantum systems and to determine the performance limits of quantum devices. Yunger Halpern, a National Institute of Standards and Technology physicist based at the Joint Center for Quantum Information and Computer Science in College Park, Md., is at the forefront of these efforts.
“She has a vision and follows it,” says quantum physicist Aram Harrow of MIT. “She’s also good at recruiting other people to her vision.”
One of Yunger Halpern’s major contributions has been exploring what the quantum concept behind Heisenberg’s uncertainty principle might mean for thermodynamics.
Imagine a hot cup of tea. Thermodynamics describes how energy moves from the tea to the surrounding air, or how evaporating water molecules escape. Both of these quantities—energy and water molecules—are conserved in this scenario, meaning they can move from one place to another, but the total amount is fixed. The problem of explaining how conserved quantities are exchanged occurs repeatedly in thermodynamics.
Now, what if the tea wasn’t a whole cup, but a packet of just a few atoms? Yunger Halpern wants to know how the exchange would change. In quantum physics, conserved quantities can be mutually exclusive. This means that they cannot be measured simultaneously. Heisenberg’s uncertainty principle, which states that the better you know the position of a quantum object, the worse you know its momentum and vice versa., give a famous example (SN: 1/12/22).
Thermodynamic quantities such as energy or water molecules are exchanged between a system, such as a hot cup of tea (left), and its surroundings. In a system consisting of several quantum particles (right), the quantities that can be exchanged can be incompatible. Incompatible quantities cannot be measured simultaneously.B. PriceThermodynamic quantities such as energy or water molecules are exchanged between a system, such as a hot cup of tea (left), and its surroundings. In a system consisting of several quantum particles (right), the quantities that can be exchanged can be incompatible. Incompatible quantities cannot be measured simultaneously.B. Price
“For many decades, almost nobody thought about what happens when you have a system and environment that exchange quantities that are incompatible,” says Yunger Halpern. It turns out that incompatibility can have a real impact on how the system behaves, she and colleagues noted in a survey of the topic published in 2023 in Nature Reviews Physics. For example, incompatibility can reduce the amount of entropy, or disorder, that is produced in such exchanges. Because the total entropy of an isolated system tends to increase with time, some scientists think that entropy is closely related to an “arrow of time” that distinguishes the future from the past.SN: 7/10/15). In a sense, says Yunger Halpern, this means that incompatible quantities can hinder a system’s ability to experience that arrow of time.
Quantum thermodynamics has led to some neat laboratory demonstrations. For example, a single atom can be turned into a quantum engine that converts heat into work (SN: 14.4.16). Now, Yunger Halpern aims to put quantum thermodynamics to practical use through autonomous quantum machines.
Typical quantum devices, such as single-atom engines, atomic clocks, or the quantum parts that make up quantum computers, require constant prodding by experimenters to operate. Autonomous devices will operate automatically.
Yunger Halpern joined colleagues to bring this idea to reality. The result was an autonomous quantum refrigerator that can automatically cool a quantum particle, the team reported in May 2023 on arXiv.org.
And in a July 2023 arXiv article, she and colleagues laid out the criteria that must be met to create an autonomous quantum machine. For example, these machines must have structural integrity and sufficiently pure quantum states. In addition, their output must be worth the input required to execute them. This means that a quantum motor cannot take in more energy to control it than it puts out. Quantum physicist Marcus Huber worked with Yunger Halpern in developing these criteria. “I found it brilliant, but also mega intense and focused,” says Huber, from TU Wien in Vienna. “She will bombard you with relevant and good questions.”
It’s not just her science that’s in the spotlight—her writing is, too. Yunger Halpern’s book 2022, Quantum Steampunk: Yesterday’s Tomorrow’s Physicsattracted the attention of the public in the field. She is also a science blogger at the website Quantum Frontiers. Writing, says Yunger Halpern, allows him to explore new ideas without the constraints of scientific publishing (fantasy speculations and “out there” ideas aren’t likely to pass peer review). “Thinking really big and wild and so creatively that you feel like thinking on a certain day of the month is helpful for keeping creativity in physics.”
And just as her work juxtaposes old and new, Yunger Halpern often illustrates contrasts, says Shayan Majidy of the University of Waterloo in Canada and soon to join Harvard University, who recently completed his Ph.D. advised by Yunger Halpern. She holds her students to high standards, but is warm and caring as a counselor. Majidy says that when he got married, Yunger Halpern somehow figured out his favorite local ice cream brand — Kawartha Dairy — and sent him a gift card.
Her hobbies tend towards quiet and slow-paced activities: walks, museum visits. Yet she injects intense passion into her work. “She has very old-fashioned interests and tastes,” Majidy says, “but she’s this very young, energetic researcher of rising stars.”
Dust pollution is known to contribute to asthma and heart and lung disease. But dust blowing from the Great Salt Lake in Utah can cause an additional unwanted shock.
Metals in dust and sediments around the Great Salt Lake are more reactive than dust from nearby lake beds, researchers report in November. Atmospheric Environment. When inhaled, the dust has the potential to cause inflammation, although the actual impacts on humans in the area will require further study.
The Great Salt Lake is steadily shrinking as drought, climate change and consumption drain water faster than it can be replenished, leaving over 1,900 square kilometers of the lake bed exposed (SN: 17.4.23). As the lake dries up, it leaves behind dust laden with metals, minerals and sediments that were carried into the lake from upstream.
To better understand the composition of the dust, chemical engineer Kerry Kelly and colleagues aerosolized samples collected from around the lake. They then filtered out any dust particles larger than 10 micrometers, leaving only dust particles small enough to inhale.
Analysis of respirable particles revealed several metals — including manganese, copper, iron and lead — in higher concentrations than dust from other nearby playas. Lithium and arsenic were also present at levels that exceeded the US Environmental Protection Agency’s regional control levels, a benchmark for further risk assessment.
The team also found that the oxidative potential of Great Salt Lake dust, which indicates how likely the dust is to generate reactive oxygen species, is generally higher than that of dust from other nearby lakes. Reactive oxygen species are unstable oxygen-containing molecules that interact with—and sometimes damage—molecules in living cells.
“Our body has all kinds of antioxidants,” says Kelly, of the University of Utah in Salt Lake City. These compounds allow us to breathe and handle reactive oxygen species—up to a point. “However, if we get too many of these reactive particles or reactive species entering our lungs, it can cause an imbalance. Then that can lead to inflammation, and then inflammation leads to a number of negative health effects.”
But experts advise not to draw quick conclusions. “I think it’s good to look at environmental components and look at their potential to have this or that effect,” says David Lo, a biomedical scientist at the University of California, Riverside. “But then you want to ask on the same side, is there any evidence that people are actually being harmed?” Linking exposure to highly oxidative dust to specific public health outcomes would require more data on the extent of exposure and studies linking oxidative potential to specific health concerns, he says.
Kelly agrees. “I don’t mean, ‘the sky is falling, we’re all going to die.'” Rather, she says, the study “shows that dust from the Salt Lake is potentially a significant health concern, so we need to do more work.” Utah has funding for equipment to measure the rate at which dust from the Great Salt Lake blows into nearby cities, she says, but it hasn’t been deployed.
“We also need to get more water into the Great Salt Lake,” Kelly says, “because that’s really the solution.”
While SpaceX’s Starlink satellites are enabling Internet access and mobile communications around the globe, they are also posing a threat to radio astronomy, a new study suggests.
In several wavelength bands, the inadvertent leakage of electromagnetic radiation from the latest generation of satellites is more than 30 times brighter than emissions from earlier versions, Cees Bassa, a radio astronomer at the Netherlands Institute for Radio Astronomy in Dwingeloo and his colleagues report on September 18. IN Astronomy & Astrophysics. Because the latest generation of Starlink satellites will orbit up to 100 kilometers lower than previous satellites, they will appear even brighter to ground-based telescopes. In general, their brightness could easily mask observations of fainter objects such as galaxies or distant stars.
Radio telescopes, instead of collecting visible light, collect lower-energy waves from sources that emit radiation at longer wavelengths. Bassa and his team used six radio telescopes at an observatory near Exloo, the Netherlands, to characterize the emissions from the Starlink satellites during two one-hour sessions in July. Although the satellites passed through the telescopes’ field of view for only 12 and 40 seconds, they were very bright: Compared to the faintest astronomical sources that can be observed by those telescopes, the Starlink satellites are about 10 million times brighter, Bassa and he noted the team.
And the problem is likely to get worse: SpaceX is launching about 40 second-generation Starlink satellites every week, researchers note, with more than 6,000 already out there (SN: 3/3/23). Bassa and his colleagues have discovered that other companies’ satellites are also detectable by radio telescopes, and they are also working to measure those emissions.
Bassa and his colleagues hope their continued observations will prompt the developers of such satellites to redesign their equipment where possible to reduce unwanted radio emissions.
Bhavin Shastri still gets excited when he sees a laser pointer and has been fascinated by them since he was about 10 years old. “I was amazed that a beam of light could retain its brightness, concentrated in a small spot even after traveling a great distance,” says Shastri. “A laser pointer in my hand felt like a lightsaber Star Wars.”
Now a physicist and engineer at Queen’s University in Kingston, Canada, Shastri wants to create light- or photonic-based computers. And he wants them to mimic the human brain.
Standard computers rely on electricity, using wires to transmit data via electrical currents. Photonic computers instead rely on light in the form of laser beams. Filters along the way change the intensity of the light to perform the calculations.
Although researchers have used light to transmit, store and process data in the laboratory, photonic computing is still in its infancy. Shastri has begun to push those boundaries. Its photonic computer chips are packaged together and connect photonic components that behave like brain neurons, creating a physical neural network on a chip. “Physics mimics biology,” says Shastri.
These types of chips are more powerful for certain applications and can be a big help for AI.
Shastri’s chips are built to package photonic components together to look and function like the human brain.Hugh Morrison
Modeling computers as brains
Shastri’s interest in light began young. He recalls an experiment he saw as a child: A plastic water bottle was punctured near its base so that a steady stream of water flowed out and down under the force of gravity. A laser shone through the hole in the bottle and, to Shastri’s surprise, it did not continue on a horizontal path. Instead, the beam bent down with the flow of water. “I was completely blown away by this experiment,” he says.
Since then, Shastri has been thinking about how light can be manipulated, while also exploring other research interests. In college, he worked with a professor who was researching machine learning and artificial intelligence, which sparked a new passion. Later, as a postdoc at Princeton University, Shastri met optical physicist Paul Prucnal, who would serve as Shastri’s advisor.
Prucnal told Shastri about his research creating “a laser that behaves like a biological neuron,” Shastri says, and how the team was looking to use such a laser to compute with light. This idea caught Shastri’s attention.
Shastri was “the first to connect the dots,” Prucnal says, when he realized that photonics could overcome some serious limitations of electronics.
Standard computers are “reaching their fundamental limits,” says Shastri. When most modern computers do computations, they cannot access much of their memory, and when they retrieve information from memory, they cannot compute. This makes computers slow and difficult for AI, image processing and other processing-intensive calculations. Training and running today’s AI algorithms consumes a huge amount of energy — collectively, it’s predicted to require as much as Japan’s total electricity consumption by 2026. Computers with brain-mimicking architectures, or neuromorphic computers , promise to be faster and use less energy.
“We want to build machines that will be much more energy efficient and much faster than other computers,” says Shastri.
But packing enough wires onto a chip to form a brain-like network of connections for use in an electronic computer is not easy. Electrical currents in close proximity will exert unwanted magnetic forces on each other, resulting in overheating and erratic performance. Light, however, usually does not interact with other light. Thus, countless light rays of different wavelengths can pass through the same path at the same time without any problem.
Prucnal notes that Shastri was the first to successfully create neuromorphic photonic computers on a chip. “Bhavin pioneered a way of thinking,” he says.
The study of light
A self-described “strong experimentalist,” Shastri designs, engineers, builds, and conducts experiments on chip-sized photonic devices. His team began by studying simpler devices similar to a single neuron, analyzing how they could mimic the function of a biological neuron. Years later, in as-yet-unpublished work, researchers have tentatively demonstrated that a chip with 100,000 neuron-like components can perform 120 billion operations per second, Shastri says—about 40 times faster than an average electronic computer.
Daniel Brunner, a machine learning and computing researcher at the FEMTO-ST Institute in France, who met Shastri when they were both postdocs, praised Shastri’s groundbreaking work. “I can’t even count the publications where he laid the groundwork” for using photonics to create physical neural networks, Brunner says.
And Shastri’s brilliance goes beyond his “incredible energy” and “incredible ability,” says Prucnal: Shastri is able to bring people together. “It’s not just about being likable, it’s about having a vision of how to do it [unite] these different fields”, he adds.
Don’t expect a photonic neuromorphic computer in your home anytime soon, though. These computers are best suited for specific research or industry applications. In addition to AI, Shastri and his colleagues are working on applications involving old problems in radio signal optimization and image processing.
Shastri may be committed to transforming computers, but his work is motivated by a decades-long fascination with light and its properties. “I’ve been very lucky to be able to do something,” he says, “it’s always been my childhood dream.”
A red dwarf star known as Barnard’s Star, located just six light-years from our solar system, has at least one — and possibly a handful — of small rocky planets orbiting it, a new study suggests. .
Barnard’s Star, which is about one-sixth the mass of our sun, is the closest individual star to our solar system. Only three stars in the Alpha Centauri system are closer. Because of its proximity to Earth, Barnard’s star has long been a target of astronomers searching for exoplanets (SN: 12/1/73, SN: 12/7/23).
Now, after several false starts over the decades, researchers may have finally hit the dirt. Jonay González Hernández, an astrophysicist at the Instituto de Astrofísica de Canarias in Tenerife, Spain, and his team reviewed more than 150 observations made by a telescope in South America over four years. Specifically, they looked for tiny wobbles that would betray the presence of planets gravitationally pulling the star back and forth as they orbited.
The strongest wobbles occur every 3.15 days, the team reports online Oct. 1 Astronomy & Astrophysics. It’s probably caused by the near-circular orbit of a small rocky planet about three times the mass of Mars, says González Hernández.
The researchers have done a good job of ruling out other possible sources of the wobble, such as the rotation of the star or the movement of the telescope during the observations, says astronomer Jennifer Burt. Those efforts, plus the high precision of the instruments used to collect the team’s data, “will convince scientists that this discovery is real,” notes Burt, of NASA’s Jet Propulsion Laboratory in Pasadena, California. . This, in turn, should inspire other teams to revisit all past observations they’ve made of Barnard’s star.
Indeed, the new study suggests there are more discoveries to be made. González Hernández and his colleagues have observed smaller oscillations that are superimposed on the larger oscillation. Although they have not yet been confirmed, they likely represent the presence of three smaller orbs that circle the star at periods of 2.34 days, 4.12 days, and 6.74 days. All four of these putative planets are too close to Barnard’s star to support life as we know it, the researchers suggest.
An asteroid heading toward Earth can be deflected without ever touching a spacecraft.
The trick is to use X-rays to deflect the space rock, researchers report Sept. 23 Nature Physics. In laboratory experiments, scientists heated the surfaces of free-falling artificial asteroids with X-ray radiation, producing steam plumes that blew the objects away. Later computer simulations showed that X-rays emitted from a distant nuclear explosion could deflect several asteroids that are roughly as wide as the National Center in Washington, DC, is tall.
“There is only one method that has been proposed that has enough energy to deflect the most threatening asteroids, the largest asteroids, or in some cases even smaller asteroids where the warning time is short, maybe a year or less.” , says physicist Nathan. Moore of Sandia National Laboratories in Albuquerque. “The consensus in the planetary defense community is that X-rays from a nuclear device would be the only option in those scenarios.”
Such explosions would, in theory, occur at safe distances from Earth.
Two years ago, NASA deliberately rammed a spacecraft into the asteroid Dimorphos, changing the space rock’s orbit around a larger asteroid (SN: 26.9.22; SN: 10/11/22). It was a watershed moment for the planetary defense community. But such impacts only work if the asteroid is small and has enough time to change its trajectory, Moore says. So he and colleagues set out to test the defective X-ray noise.
The experiment began in a vacuum chamber that held a cranberry-sized simulated asteroid made of quartz — a mineral made up of the common asteroid component silica. Using the world’s most powerful X-ray generator, the team blasted the chamber in 6.6 nanoseconds. The pulse vaporized the lamellar supports that suspend the quartz, releasing the mineral in free fall. It also heated and vaporized the surface of the falling ore, generating a gas plume.
The expanding plume propelled the quartz like the discharge of a rocket, Moore says, pushing the mineral away from the X-ray source at approximately 250 kilometers per hour. Tests with fused silica gave similar results.
Assessing the viability of the planetary protection scheme requires incorporating experimental results into computer simulations. X-rays from a nuclear explosion several kilometers away can deflect an asteroid of similar composition that is up to 4 kilometers across, the team found.
The researchers hope to perform similar experiments with iron and other asteroid components. “Asteroids come in many flavors, made up of different types of minerals,” he says. “This is just a starting point.”
Some tadpoles do not poop in the first weeks of their lives. At least, this is the case for Eiffinger’s tree frogs (Kurixalus eiffingeri), scientists report on September 22 at Ecology.
Eiffinger tree frogs are small frogs that live in Taiwan and two Japanese islands: Ishigaki and Iriomote. Tree-dwelling amphibians lay their eggs in small pools, which are often found in plant stems, tree hollows, and bamboo trunks.
After the chicks hatch, they spend their early life in these ponds. However, in pools as small as these, there isn’t much water to dilute the ammonia – a toxic chemical that animals release when they urinate or defecate.
Bun Ito and Yasukazu Okada, biologists from Nagoya University in Japan, have now discovered chickens’ secret hygiene strategy – self-induced constipation. Tadpoles store their excrement in a gut pouch until they begin to metamorphose into full-fledged frogs.
Eiffinger’s tree frog tadpoles (Kurixalus eiffingeri) spend the first weeks of life in small pools of water located inside tree hollows and bamboo trunks.Ito Bun
Ito and Okada raised tadpoles from four different species of frogs in makeshift nurseries. After the experiment began, they moved the chickens to smaller cribs, plastic boxes with little more than a tablespoon of water. The team measured and compared how much ammonia each species emitted. They also measured the amount of ammonia stored in the guts of each species.
Eiffinger tree frog tadpoles released on average less than half the amount of ammonia as the highest emitting species. And compared to two of the other species, chickens carried more ammonia in their guts. The researchers note that unlike Eiffinger’s tree frogs, other species typically lay their eggs in open ponds where ammonia easily dilutes.
“The behavior likely serves to prevent pollution of small bodies of water,” says Ito. Some ammonia still seeped into the tree frogs’ water, potentially through their urine.
It turns out that Eiffinger tree frog tadpoles have another superpower: Experiments showed that they can survive higher concentrations of ammonia than any of the other species included in the study. Dryophytes japonicus, better known as the Japanese tree frog. While this may seem counterintuitive, given the no-lunch period of shrews, Ito notes that chickens sometimes share their beds with other animals, such as mosquito larvae, which also release ammonia.
“We hypothesize that chickens have developed a tolerance to ammonia as a dual defense mechanism,” says Ito, “both against ammonia produced by other organisms and ammonia they produce themselves.”
NASA’s Europa Clipper spacecraft is on its way to help solve a quarter-century-old mystery: Could anything live in the ocean lurking beneath the icy shell of Jupiter’s moon Europa?
“This is a mission we’ve dreamed about for 25 years now, since I was in graduate school,” says planetary geologist Cynthia Phillips of NASA’s Jet Propulsion Laboratory in Pasadena, California. “It’s a generational mission.”
An Oct. 10 launch from the Kennedy Space Center in Florida was canceled because of Hurricane Milton, but on Oct. 14, the spacecraft lifted off just after noon ET and began its five-and-a-half-year journey to Jupiter.
Once there, Clipper will be placed into orbit around the giant planet in April 2030, repeatedly passing the icy moon to take pictures of its frozen terrain, measure the surface’s chemistry and deduce internal structure of the moon.
“We think ocean worlds may actually be a common type of world outside our solar system,” NASA’s planetary science chief Gina DiBraccio said at a Sept. 17 press conference. “Clipper will be the first in-depth mission that will allow us to characterize habitability on what may be the most common type of habitable world in our universe.”
Planetary scientists have become increasingly confident that Europa hosts a subsurface ocean since NASA’s Galileo spacecraft visited Jupiter in the 1990s.SN: 18.2.02).
“During the Galileo mission, it was like a detective story,” says Phillips. Constructed data. The lack of craters suggests that the surface is always moving and changing. Lines, cracks and pits, suggesting uplift from below. Regions known as “chaos terrain”, which look like tilted icebergs in a sloping sea (SN: 11/16/11).
And finally, the measurement of an internal magnetic field caused by Jupiter’s external one. This was the “coup d’état,” says Phillips. The only geologically plausible material that can sustain this magnetic field is salt water.
On Earth, water means life. But the findings in Europa were not enough to declare it a habitable world (SN: 19.4.24). Many mysteries remained: How deep is the ocean? How thick is the ice shell? And more importantly, how do they interact? Could material from the surface sink into the salty depths to provide food for the microbes that wait?
The Europa Clipper, named for the fast clipper ships of the 19th century, is poised to pick up where Galileo left off. The spacecraft is tasked with investigating the habitability of Europa by searching for three main ingredients: water, energy and organic compounds.
The spacecraft will not directly orbit Europa. The moon is located within Jupiter’s punishing radiation environment, where high-energy charged particles accelerated by the planet’s magnetic field can fry spacecraft components (SN: 11/9/20). Instead, Clipper will dip in and out of that radiation zone to fly past Europa at least 49 times — aiming all nine of its instruments at the Moon at once — each time retreating to quieter territory to process the data and send it back to Earth. .
To reach Jupiter, Europa Clipper will pass by Mars and Earth, using the gravity of both planets to shape its trajectory and increase speed. It will enter Jupiter’s orbit on April 11, 2030, if all goes well.JPL-Caltech/NASATo reach Jupiter, Europa Clipper will pass by Mars and Earth, using the gravity of both planets to shape its trajectory and increase speed. It will enter Jupiter’s orbit on April 11, 2030, if all goes well.JPL-Caltech/NASA
One of the first things Clipper will do when it arrives is confirm — or perhaps disprove — the presence of the subsurface ocean. The way the moon gravitationally pulls the spacecraft will immediately reveal the details of its interior, JPL’s deputy project scientist Bonnie Buratti said at the press conference.
The pictures will come next. Galileo’s antenna was never positioned properly, so its images weren’t as sharp as they could have been, Phillips says. Galileo’s spectrometer wasn’t designed to work on Europa either, so scientists tried to find out the composition of anything that wasn’t ice on the surface. Clipper’s images and spectra will reveal clues about surface and possibly subsurface chemistry that Galileo never could.
Finally, Clipper will delve into details like the thickness of the crust, the depth of the ocean, and how they interact.
There are some limitations. Clipper’s gaze will not reach the bottom of the ocean, where rock and water meet. This may be the most likely place for microbial ecosystems to take shelter, similar to seafloor vents on Earth. But Clipper won’t be able to sense them directly.
However, there is strong circumstantial evidence that water sometimes rises to the surface, either in plumes of steam or in slower-flowing streams or lakes, and may deposit any other material it carries in the ice.SN: 14.5.18). Clipper will search for chemicals on the surface and find out what might be brewing in the dark depths.
“The holy grail would be if we could see something like an amino acid on the surface,” says Buratti. “But only by looking at many organic molecules will there be good evidence that we have all the conditions for life.”
What Clipper won’t do is search directly for life. “We don’t have a tricorder that we can point from Europa and say, ‘It’s life, Jim!'” like in Star Trek, Phillips says. “It will again be multiple lines of indirect evidence.”
“To do a life detection mission,” she says, “you’re going to have to touch that surface.” Or maybe it falls under it (SN: 5/2/14).
As long as he’s had to wait to get to Europe, Phillips doesn’t expect to see that mission for himself. But she hopes scientists won’t have to wait another 25 years.
“I hope this momentum will grow,” she says. “I accept that I probably won’t see that Europa submarine, but I hope my children or maybe my grandchildren will.”
As dust from the Sahara blows thousands of kilometers across the Atlantic Ocean, it becomes progressively more nutritious for marine microbes, a new study suggests.
Chemical reactions in the atmosphere grind iron minerals into dust, making them more soluble in water and creating an essential nutrient source for iron-starved seas, researchers report Sept. 20. Frontiers in Marine Science.
Dust clouds settling in the Atlantic can create phytoplankton blooms that support marine ecosystems, says Timothy Lyons, a biogeochemist at the University of California, Riverside. “Iron is incredibly important for life,” he says. Phytoplankton requires it to convert carbon dioxide into sugars during photosynthesis.
By further studying dust transport and chemical reactions in the atmosphere, scientists can better understand why parts of the ocean are biological hotspots for phytoplankton and fish.
Over 240 million metric tons of Saharan dust blows over the Atlantic Ocean each year. In Bermuda, the Bahamas and other islands, the earth turns red. But most of it settles in the ocean, providing a major source of iron in areas too far from land to get it from rivers.
Lyons and marine geologist Jeremy Owens, then also at UC Riverside, tried to answer another dust question: Have the types of dust settling in the Atlantic changed over the past 120,000 years? They analyzed the minerals that flowed from the dust in four cores ripped from the muddy sea floor – two in the eastern Atlantic near Africa and two from farther west near North America.
What they found prompted another line of inquiry.
In dust and soils around the world, approximately 40 percent of the iron is typically present within “reactive” minerals such as pyrite or carbonates. This type of iron can be decomposed by weak acids and can be used by life. In core samples from the bottom of the Atlantic, only about 9 percent of the iron in dust ores sampled farther west consisted of reactive iron ores, compared with about 18 percent in dust ores sampled from closer to Africa. That, Lyons says, was “the big surprise.”
He and Owens, now at Florida State University in Tallahassee, concluded that during the dust’s several-day flight across the Atlantic, more and more of its reactive iron was altered—attacked by acids and ultraviolet radiation, which separated the minerals.
“There are photochemical transformations that tend to make iron more soluble” in water, Lyons says. As the modified iron later settles into the ocean, it is dissolved—and ingested—by phytoplankton. The only reactive iron that reaches the bottom of the sea is the stuff that wasn’t altered during air transport and wasn’t ingested later. Their results suggest that the farther the desert dust flies, the less iron remains.
By spawning phytoplankton blooms, iron leaching from the dust can also feed small fish and other animals that graze on the plankton, as well as predators that eat the grazers. A recent study suggested that Atlantic tuna, an important commercial fish, is attracted to areas where the Saharan dust has settled.
The new results are plausible because previous studies have shown that iron minerals react in the atmosphere, says Natalie Mahowald, an atmospheric scientist who studies dust at Cornell University. Their conclusion “matches what I thought was going on,” she says.
But she points out that Saharan dust isn’t the only possible source of that iron: The samples came from far enough north in the Atlantic that some of their iron could have come from smoke from fires in North America over 120,000 years. the last one. she says.
Determining a dust source buried deep on the sea floor can be challenging. But Owens and Lyons tried to identify dust fingerprints by measuring the ratios of iron to aluminum and the ratio of light iron atoms to heavy iron atoms in their samples. Both measurements were roughly consistent with the type of dust coming from the Sahara, they found. It may be possible, in the future, to analyze sediment from more places in the Atlantic, providing a clearer picture of how dust has blown across the ocean and changed chemically.
