Space & Astronomy

Subterms

    More stories

    • 163 Shares199 Views

      in Space & Astronomy

      How Mars rovers have evolved in 25 years of exploring the Red Planet

      by

      Few things are harder than hurling a robot into space — and sticking the landing. On the morning of July 4, 1997, mission controllers at the Jet Propulsion Laboratory in Pasadena, Calif., were hoping to beat the odds and land a spacecraft successfully on the Red Planet.

      Twenty-five years ago that little robot, a six-wheeled rover named Sojourner, made it — becoming the first in a string of rovers built and operated by NASA to explore Mars. Four more NASA rovers, each more capable and complex than the last, have surveyed the Red Planet. The one named Curiosity marked its 10th year of cruising around on August 5. Another, named Perseverance, is busy collecting rocks that future robots are supposed to retrieve and bring back to Earth. China recently got into the Mars exploring game, landing its own rover, Zhurong, last year.

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      Other Mars spacecraft have done amazing science from a standstill, such as the twin Viking landers in the 1970s that were the first to photograph the Martian surface up close and the InSight probe that has been listening for Marsquakes shaking the planet’s innards (SN Online: 2/24/20). But the ability to rove turns a robot into an interplanetary field geologist, able to explore the landscape and piece together clues to its history. Mobility, says Kirsten Siebach, a planetary scientist at Rice University in Houston, “makes it a journey of discovery.”

      Each of the Mars rovers has gone to a different place on the planet, enabling scientists to build a broad understanding of how Mars evolved over time. The rovers revealed that Mars contained water, and other life-friendly conditions, for much of its history. That work set the stage for Perseverance’s ongoing hunt for signs of ancient life on Mars.

      Each rover is also a reflection of the humans who designed and built and drove it. Perseverance carries on one of its wheels a symbol of Mars rover tracks twisted into the double helix shape of DNA. That’s “to remind us, whatever this rover is, it’s of human origin,” says Jennifer Trosper, an engineer at the Jet Propulsion Lab, or JPL, who has worked on all five NASA rovers. “It is us on Mars, and kind of our creation.”

      The little microwave that could

      Sojourner, that first rover, was born in an era when engineers weren’t sure if they even could get a robot to work on Mars. In the early 1990s, then-NASA Administrator Daniel Goldin was pushing the agency to do things “faster, better and cheaper” — a catchphrase that engineers would mock by saying only two of those three things were possible at the same time. NASA had no experience with inter­planetary rovers. Only the Soviet Union had operated rovers — on the moon in 1970 and 1973.

      JPL began developing a Mars rover anyway. Named after the abolitionist Sojourner Truth, the basic machine was the size of a microwave oven. Engineers were limited in where they could send it; they needed a large flat region on Mars because handling a precision landing near mountains or canyons was beyond their abilities. NASA chose Ares Vallis, a broad outflow channel from an ancient flood, and the mission landed there successfully.

      Sojourner spent nearly three months poking around the landscape. It was slow going. Mission controllers had to communicate with Sojourner constantly, telling it where to roll and then assessing whether it had gotten there safely. They made mistakes: One time they uploaded a sequence of computer commands that mistakenly told the rover to shut itself down. They recovered from that stumble and many others, learning to quickly fix problems and move forward.

      In 1997, NASA’s first rover, Sojourner, rolled down a landing ramp and became the first mobile Mars robot. Solar panels provided power throughout its 12-week mission.JPL-CALTECH/NASA

      Although Sojourner was a test mission to show that a rover could work, it managed to do some science with its one X-ray spectrometer. The little machine analyzed the chemical makeup of 15 Martian rocks and tested the friction of the Martian soil.

      After surviving 11 weeks beyond its planned one-week lifetime, Sojourner ultimately grew too cold to operate. Trosper was in mission control when the rover died on September 27, 1997. “You build these things, and even if they’re well beyond their lifetime, you just can’t let go very easily, because they’re part of you,” she says.

      Jennifer Trosper, an engineer at the Jet Propulsion Laboratory, is part of a small group of people who have worked on all five NASA Mars rovers. Here she is in 2021 with a model of Perseverance.CHRISTOPHER MICHEL/WIKIMEDIA COMMONS (CC BY-SA 4.0)

      Twin explorers

      In 1998 and 1999, NASA hurled a pair of spacecraft at Mars; one was supposed to orbit the planet and another was supposed to land near one of the poles. Both failed. Stung from the disappointment, NASA decided to build a rover plus a backup for its next attempt.

      Thus were born the twins Spirit and Opportunity. Each the size of a golf cart, they were a major step up from Sojourner. Each had a robotic arm, a crucial development in rover evolution that enabled the machines to do increasingly sophisticated science. The two had beefed-up cameras, three spectrometers and a tool that could grind into rocks to reveal the texture beneath the surface.

      But there were a lot of bugs to work out. Spirit and Opportunity launched several weeks apart in 2003. Spirit got to Mars first, and on its 18th Martian day on the surface it froze up and started sending error messages. It took mission controllers days to sort out the problem — an overloaded flash-memory system — all while Opportunity was barreling toward Mars. Ultimately, engineers fixed the problem, and Opportunity landed safely on the opposite side of the planet from Spirit.

      Both rovers lasted years beyond their expected three-month lifetimes. And both did far more Martian science than anticipated.

      Spirit broke one of its wheels early on and had to drive backward, dragging the broken wheel behind it. But the rover found plenty to do near its landing site of Gusev crater, home to a classic Mars landscape of dust, rock and hills. Spirit found rocks that appeared to have been altered by water long ago and later spotted a pair of iron-rich meteorites. The rover ultimately perished in 2010, stuck in a sand-filled pit. Mission controllers tried to extract it in an effort dubbed “Free Spirit,” but salts had precipitated around the sand grains, making them particularly slippery.

      Opportunity, in contrast, became the Energizer Bunny of rovers, exploring constantly and refusing to die. Immediately after landing in Meridiani Planum, Opportunity had scientists abuzz.

      The pale rock at center, seen beneath the Opportunity rover’s robotic arm in 2013, was one of many at the rover’s landing site that held long-awaited evidence that liquid water once flowed on Mars.
      JPL-CALTECH/NASA, CORNELL UNIV., ARIZONA STATE UNIV.

      “The images that the rover first sent back were just so different from any other images we’d seen of the Martian surface,” says Abigail Fraeman, a planetary scientist at JPL. “Instead of these really dusty volcanic plains, there was just this dark sand and this really bright bedrock. And that was just so captivating and inspiring.”

      Right at its landing site, Opportunity spotted the first definitive evidence of past liquid water on Mars, a much-anticipated and huge discovery (SN: 3/27/04, p. 195). The rover went on to find evidence of liquid water at different times in the Martian past. After years of driving, the rover reached a crater called Endeavour and “stepped into a totally new world,” Fraeman says. The rocks at Endeavour were hundreds of millions of years older than others studied on Mars. They contained evidence of different types of ancient water chemistry.

      Opportunity ultimately drove farther than any rover on any extraterrestrial world, breaking a Soviet rover’s lunar record. In 2015, Opportunity passed 26.2 miles (42.2 km) on its odometer; mission controllers celebrated by putting a marathon medal onto a mock-up of the rover and driving it through a finish line ribbon at JPL. Opportunity finally died in 2019 after an intense dust storm obscured the sun, cutting off solar power, a must-have for the rover to recharge its batteries (SN: 3/16/19, p. 7).

      The twin rovers were a huge advance over Sojourner. But the next rover was an entirely different beast.

      Mission project scientist Ashwin Vasavada stands with several rovers, which learn to traverse various surfaces in the Mars Yard at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.JPL-Caltech/NASA

      The SUV of rovers

      By the mid-2000s, NASA had decided it needed to go big on Mars, with a megarover the size of a sports utility vehicle. The one-ton Curiosity was so heavy that its engineers had to come up with an entirely new way to land on Mars. The “sky crane” system used retro-rockets to hover above the Martian surface and slowly lower the rover to the ground.

      Against all odds, in August 2012, Curiosity landed safely near Mount Sharp, a 5-kilometer-high pile of sediment within the 154-kilometer-wide Gale crater (SN: 8/25/12, p. 5). Unlike the first three Mars rovers, which were solar-powered, Curiosity runs on energy produced by the radioactive decay of plutonium. That allows the rover to travel farther and faster, and to power a suite of sophisticated science instruments, including two chemical laboratories.

      Curiosity introduced a new way of exploring Mars. When the rover arrives in a new area, it looks around with its cameras, then zaps interesting rocks with its laser to identify which ones are worth a closer look. Once up close, the rover stretches out its robotic arm and does science, including drilling into rocks to see what they are made of.

      When Curiosity arrived near the base of Mount Sharp, it immediately spotted rounded pebbles shaped by a once-flowing river, the first close­up look at an ancient river on Mars. Then mission controllers sent the rover rolling away from the mountain, toward an area in the crater known as Yellowknife Bay. There Curiosity discovered evidence of an ancient lake that created life-friendly conditions for potentially many thousands of years.

      Curiosity then headed back toward the foothills of Mount Sharp. Along the way, the rover discovered a range of organic molecules in many different rocks, hinting at environments that had been habitable for millions to tens of millions of years. It sniffed methane gas sporadically wafting within Gale crater, a still-unexplained mystery that could result from geologic reactions, though methane on Earth can be formed by living organisms (SN: 7/7/18, p. 8). The rover measured radiation levels across the surface — helpful for future astronauts who’ll need to gauge their exposure — and observed dust devils, clouds and eclipses in the Martian atmosphere and night sky.

      Shimmering clouds of ice crystals appear in the sky above Gale crater on Mars, as seen by the Curiosity rover in March 2021. The ability to drive across Mars gives rovers a humanlike ability to interact with the landscape.
      MSSS, JPL-Caltech/NASA

      “We’ve encountered so many unexpectedly rich things,” says Ashwin Vasavada of JPL, the mission’s project scientist. “I’m just glad a place like this existed.”

      Ten years into its mission, Curiosity still trundles on, making new discoveries as it climbs the foothills of Mount Sharp. It recently departed a clay-rich environment and is now entering one that is heavier in sulfates, a transition that may reflect a major shift in the Martian climate billions of years ago.

      In the course of driving more than 28 kilometers, Curiosity has weathered major glitches, including one that shuttered its drilling system for over a year. And its wheels have been banged up more than earthbound tests had predicted. The rover will continue to roll until some unknown failure kills it or its plutonium power wanes, perhaps five years from now.

      Over nearly 10 years of driving on Mars’ rocky surface, Curiosity’s wheels have taken more of a beating than its designers expected.
      MSSS, JPL-Caltech/NASA

      A rover and its sidekick

      NASA’s first four rovers set the stage for the most capable and agile rover ever to visit Mars: Perseverance. Trosper likens the evolution of the machines to the growth of children. “We have a preschooler in Sojourner, and then … your happy-go-lucky teenagers in Spirit and Opportunity,” she says. “Curiosity is certainly a young adult that’s able to do a lot of things on her own, and Perseverance is kind of that high-powered mid­career [person] able to do pretty much anything you ask with really no questions.”

      Perseverance is basically a copy of Curiosity built from its spare parts, but with one major modification: a system for drilling, collecting and storing slender cores of rock. Perseverance’s job is to collect samples of Martian rock for future missions to bring to Earth, in what would be the first robotic sample return from Mars. That would allow scientists to do sophisticated analyses of Martian rocks in their earthbound labs. “It feels, even more than previous missions, that we are doing this for the next generation,” Siebach says.

      The rover is working fast. Compared with Curiosity’s leisurely exploration of Gale crater, Perseverance has been zooming around its landing site, the 45-kilometer-wide Jezero crater, since its February 2021 arrival. It has collected 10 rock cores and is already eyeing where to put them down on the surface for future missions to pick up. “We’re going to bring samples back from a diversity of locations,” says mission project scientist Kenneth Farley of Caltech. “And so we keep to a schedule.”

      Perseverance went to Jezero to study an ancient river delta, which contains layers of sediment that may harbor evidence of ancient Martian life. But the rover slightly missed its target, landing on the other side of a set of impassable sand dunes. So it spent most of its first year exploring the crater floor, which turned out to be made of igneous rocks (SN: 9/11/21, p. 32). The rocks had cooled from molten magma and were not the sedimentary rocks that many had expected.

      Scientists back on Earth will be able to precisely date the age of the igneous rocks, based on the radioactive decay of chemical elements within them, providing the first direct evidence for the age of rocks from a particular place on Mars.

      Perseverance collected its 9th rock core, barely the size of a pinky finger, on July 7. Future missions will return the stored samples to Earth for study.
      JPL-CALTECH/NASA, ARIZONA STATE UNIV.

      Once it finished exploring the crater floor in March, the rover drove quickly toward the delta. Each successive NASA rover has had greater skills in autonomous driving, able to identify hazards, steer around them and keep going without needing constant instructions from mission control.

      Perseverance has a separate computer processor to run calculations for autonomous navigation, allowing it to move faster than Curiosity. (It took Curiosity two and a half years to travel 10 kilometers; Perseverance traveled that far in a little over a year.) “The rover drives pretty much every minute that we can give it,” Farley says.

      In April, Perseverance set a Martian driving record, traveling nearly five kilometers in just 30 Martian days. If all goes well, it will make some trips up and down the delta, then travel to Jezero crater’s rim and out onto the ancient plains beyond.

      Perseverance has a sidekick, Ingenuity, the first helicopter to visit another world. The nimble flier, only half a meter tall, succeeded beyond its designers’ wildest dreams. The helicopter made 29 flights in its first 16 months when it was only supposed to make five in one month. It has scouted paths ahead and scientific targets for the rover (SN Online: 4/19/22). Future rovers are almost certain to carry a little buddy like this.

      An engineer at NASA’s Jet Propulsion Laboratory measures light on the Perseverance rover during a 2019 test. The rover landed on Mars last year and has been exploring it ever since.JPL-CALTECH/NASA

      China’s debut

      While the United States has led in Mars rover exploration, it is not the only player on the scene. In May 2021, China became the second nation to successfully place a rover on Mars. Its Zhurong rover, named after a mythological fire god, has been exploring part of a large basin in the planet’s northern hemisphere known as Utopia Planitia.

      The landing site lies near a geologic boundary that may be an ancient Martian shoreline. Compared with the other Mars rover locations, Zhurong’s landing site is billions of years younger, “so we are investigating a different world on Mars,” says Lu Pan, a planetary scientist at the University of Copenhagen who has collaborated with Zhurong scientists.

      In many ways, Zhurong resembles Spirit and Opportunity, in size as well as mobility. It carries cameras, a laser spectrometer for studying rocks and ground-penetrating radar to probe underground soil structures (SN Online: 5/19/21).

      After landing, Zhurong snapped pictures of its rock-strewn surroundings and headed south to explore a variety of geologic terrains, including mysterious cones that could be mud volcanoes and ridges that look like windblown dunes. The rover’s initial findings include that the Martian soil at Utopia Planitia is similar to some desert sands on Earth and that water had been present there perhaps as recently as 700 million years ago.

      In May, mission controllers switched Zhurong into dormant mode for the Martian winter and hope it wakes up at the end of the season, in December. It has already traveled nearly two kilometers across the surface, farther than the meager 100 meters that Sojourner managed. (To be fair, Sojourner had to keep circling its lander because it relied on that lander to communicate with Earth.)

      The China National Space Administration released this image on June 11, 2021 of Zhurong with its landing platform on Mars.CNSA/Handout via Xinhua

      From Sojourner to Zhurong, the Mars rovers show what humankind can accomplish on another planet. Future rovers might include the European Space Agency’s ExoMars, although its 2022 launch was postponed after Russia attacked Ukraine (SN: 3/26/22, p. 6). Europe terminated all research collaborations with Russia after the invasion, including launching ExoMars on a Russian rocket.

      Vasavada remembers his sense of awe at the Curiosity launch in 2011: “Standing there in Florida, watching this rocket blasting off and feeling it in your chest and knowing that there’s this incredibly fragile complex machine hurtling on the end of this rocket.… It just gave me this full impression that here we are, humans, blasting these things off into space,” he says. “We’re little tiny human beings sending these things to another planet.” More

    • 150 Shares169 Views

      in Space & Astronomy

      The Windchime experiment could use gravity to hunt for dark matter ‘wind’

      by

      The secret to directly detecting dark matter might be blowin’ in the wind.

      The mysterious substance continues to elude scientists even though it outweighs visible matter in the universe by about 8 to 1. All laboratory attempts to directly detect dark matter — seen only indirectly by the effect its gravity has on the motions of stars and galaxies — have gone unfulfilled.

      Those attempts have relied on the hope that dark matter has at least some other interaction with ordinary matter in addition to gravity (SN: 10/25/16). But a proposed experiment called Windchime, though decades from being realized, will try something new: It will search for dark matter using the only force it is guaranteed to feel — gravity.

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      “The core idea is extremely simple,” says theoretical physicist Daniel Carney, who described the scheme in May at a meeting of the American Physical Society’s Division of Atomic Molecular and Optical Physics in Orlando, Fla. Like a wind chime on a porch rattling in a breeze, the Windchime detector would try to sense a dark matter “wind” blowing past Earth as the solar system whips around the galaxy.  

      If the Milky Way is mostly a cloud of dark matter, as astronomical measurements suggest, then we should be sailing through it at about 200 kilometers per second. This creates a dark matter wind, for the same reason you feel a wind when you stick your hand out the window of a moving car.

      The Windchime detector is based on the notion that a collection of pendulums will swing in a breeze. In the case of backyard wind chimes, it might be metal rods or dangling bells that jingle in moving air. For the dark matter detector, the pendulums are arrays of minute, ultrasensitive detectors that will be jostled by the gravitational forces they feel from passing bits of dark matter. Instead of air molecules bouncing off metal chimes, the gravitational attraction of the particles that make up the dark matter wind would cause distinctive ripples as it blows through a billion or so sensors in a box measuring about a meter per side.

      Within the Windchime detector (illustrated as an array of small pendulums), a passing dark matter particle (red dot) would gravitationally tug on sensors (blue squares) and cause a detectable ripple, much like wind blowing through a backyard wind chime.D. Carney et al/Physical Review D 2020

      While it may seem logical to search for dark matter using gravity, no one has tried it in the nearly 40 years that scientists have been pursuing dark matter in the lab. That’s because gravity is, comparatively, a very weak force and difficult to isolate in experiments. 

      “You’re looking for dark matter to [cause] a gravitational signal in the sensor,” says Carney, of Lawrence Berkeley National Laboratory in California. “And you just ask . . . could I possibly see this gravitational signal? When you first make the estimate, the answer is no. It’s actually going to be infeasibly difficult.”

      That didn’t stop Carney and a small group of colleagues from exploring the idea anyway in 2020. “Thirty years ago, this would have been totally nuts to propose,” he says. “It’s still kind of nuts, but it’s like borderline insanity.”

      The Windchime Project collaboration has since grown to include 20 physicists. They have a prototype Windchime built of commercial accelerometers and are using it to develop the software and analysis that will lead to the final version of the detector, but it’s a far cry from the ultimate design. Carney estimates that it could take another few decades to develop sensors good enough to measure gravity even from heavy dark matter.

      Carney bases the timeline on the development of the Laser Interferometer Gravitational-Wave Observatory, or LIGO, which was designed to look for gravitational ripples coming from black holes colliding (SN: 2/11/16). When LIGO was first conceived, he says, it was clear that the technology would need to be improved by a hundred million times. Decades of development resulted in an observatory that views the sky in gravitational waves. With Windchime, “we’re in the exact same boat,” he says.

      Even in its final form, Windchime will be sensitive only to dark matter bits that are roughly the mass of a fine speck of dust. That’s enormous on the spectrum of known particles — more than a million trillion times the mass of a proton.

      “There is a variety of very interesting dark matter candidates at [that scale] that are definitely worth looking for … including primordial black holes from the early universe,” says Katherine Freese, a physicist at the University of Michigan in Ann Arbor who is not part of the Windchime collaboration. Black holes slowly evaporate, leaking mass back into space, she notes, which could leave many relics formed shortly after the Big Bang at the mass Windchime could detect.

      But if it never detects anything at all, the experiment still stands out from other dark matter detection schemes, says Dan Hooper, a physicist at Fermilab in Batavia, Ill., also not affiliated with the project. That’s because it would be the first experiment that could entirely rule out some types of dark matter.

      Even if the experiment turns up nothing, Hooper says, “the amazing thing about [Windchime] … is that, independent of anything else you know about dark matter particles, they aren’t in this mass range.” With existing experiments, a failure to detect anything could instead be due to flawed guesses about the forces that affect dark matter (SN: 7/7/22).  

      Windchime will be the only experiment yet imagined where seeing nothing would definitively tell researchers what dark matter isn’t. With a little luck, though, it could uncover a wind of tiny black holes, or even more exotic dark matter bits, blowing past as we careen around the Milky Way. More

    • 138 Shares169 Views

      in Space & Astronomy

      A new James Webb telescope image reveals a galactic collision’s aftermath

      by

      It’s not easy being ringed. A newly released image from the James Webb Space Telescope, or JWST, shows the Cartwheel Galaxy still reeling from a run-in with a smaller galaxy 400 million years ago.

      The Cartwheel Galaxy, so called because of its bright inner ring and colorful outer ring, lies about 500 million light-years from Earth. Astronomers think it used to be a large spiral like the Milky Way, until a smaller galaxy smashed through it. In earlier observations with other telescopes, the space between the rings appeared shrouded in dust.

      Now, JWST’s infrared cameras have peered through the dust and found previously unseen stars and structure (SN: 7/11/22). The new image shows sites of intense star formation throughout the galaxy that were triggered by the collision’s aftereffects. Some of those new stars are forming in spokelike patterns between the central ring and the outer ring, a process that is not well understood.

      When the Hubble Space Telescope observed the Cartwheel Galaxy in visible light (left), the spokes between the galaxy’s bright rings were barely visible wisps. JWST’s infrared eyes brought them into vivid focus (right). Near-infrared light (blue, orange and yellow) traces newly forming stars; mid-infrared light (red) highlights the galaxy’s chemistry.Left: Hubble/NASA and ESA; Right: NASA, ESA, CSA, STScI and Webb ERO Production Team

      Ring galaxies are rare, and galaxies with two rings are even more unusual. That strange shape means that the long-ago collision set up multiple waves of gas rippling back and forth in the galaxy left behind. It’s like if you drop a pebble in the bathtub, says JWST project scientist Klaus Pontoppidan of the Space Telescope Science Institute in Baltimore. “First you get this ring, then it hits the walls of your bathtub and reflects back, and you get a more complicated structure.”

      The effect probably means that the Cartwheel Galaxy has a long road to recovery ahead — and astronomers don’t know what it will look like in the end.

      As for the smaller galaxy that caused all this mayhem, it didn’t stick around to get its picture taken. “It’s gone off on its merry way,” Pontoppidan says. More

    • 138 Shares179 Views

      in Space & Astronomy

      Two black holes merged despite being born far apart in space

      by

      Signals buried deep in data from gravitational wave observatories imply a collision of two black holes that were clearly born in different places.

      Almost all the spacetime ripples that experiments like the Laser Interferometer Gravitational-Wave Observatory, or LIGO, see come from collisions among black holes and neutron stars that are probably close family members (SN: 1/21/21). They were once pairs of stars born at the same time and in the same place, eventually collapsing to form orbiting black holes or neutron stars in old age.

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      Now, a newly noted marriage of black holes, found in existing data from U.S.–based LIGO and its sister observatory Virgo in Italy, seems to be of an unrelated pair. Evidence for this stems from how they were spinning as they merged into one, researchers report in a paper in press at Physical Review D. Black holes that are born in the same place tend to have their spins aligned, like a pair of toy tops spinning on a table, as they orbit each other. But the pair in this case have no correlation between their respective spins and orbits, implying that they were born in different places.

      “This is telling us we’ve finally found a pair of black holes that must come from the non-grow-old-and-die-together channel,” says Seth Olsen, a physicist at Princeton University.

      Previous events that have turned up in gravitational wave observations show back holes merging that aren’t perfectly aligned, but most are close enough to strongly imply family connections. The new detection, which Olsen and colleagues found by sifting through data that the LIGO-Virgo collaboration released to the public, is different. One of the black holes is effectively spinning upside down.

      That can’t easily happen unless the two black holes come from separate places. They probably met late in their stellar lives, unlike the black hole littermates that seem to make up the bulk of gravitational wave observations.

      In addition to the merger between unrelated black holes, Olsen and his collaborators identified nine other black hole mergers that had slipped through the prior LIGO-Virgo studies (SN: 8/4/21).

      “This is actually the nice thing about this type of analysis,” says LIGO scientific collaboration spokesperson Patrick Brady, a physicist at the University of Wisconsin–Milwaukee who was not affiliated with the new study. “We deliver the data in a format that can be used by other people and then [they] will have access to try out new techniques.”

      To compile so many new signals in data that had already been gone over by other researchers, Olsen’s group lowered the analytical bar a little.

      “Out of the 10 new ones,” Olsen says, “there are about three of them, statistically, that probably come from noise,” rather than being definitive black hole merger detections. Assuming that the merger of black holes strangers is not among the errant signals, it almost certainly tells a tale of black hole histories distinct from the others seen so far.

      “It would be [extremely] unlikely for this to come from two black holes that have been together for their whole lifespan,” Olsen says. “This must have been a capture. That’s cool because we’re finally able to start probing that region of the [black hole] population.”

      Brady notes that “we don’t understand the theory [of black hole mergers] well enough to be able to confidently predict all of these types of things.” But the recent study may point to new and interesting opportunities in gravitational wave astronomy. “Let’s follow this clue to see if it really is reflecting something rare,” he says. “Or if not, well, we’ll learn other things.” More

    • 138 Shares99 Views

      in Space & Astronomy

      Astronauts might be able to use asteroid soil to grow crops

      by

      Astronauts might one day dine on salad grown in asteroid soil.

      Romaine lettuce, chili pepper and pink radish plants all grew in mixtures of peat moss and faux asteroid soil, researchers report in the July Planetary Science Journal.  

      Scientists have previously grown crops in lunar dirt (SN: 5/23/22). But the new study focuses on “carbonaceous chondrite meteorites, known to be rich in volatile sources — water especially,” says astroecologist Sherry Fieber-Beyer of the University of North Dakota in Grand Forks. These meteorites, and their parent asteroids, are also rich in nitrogen, potassium and phosphorus — key agricultural nutrients. Pulverizing these types of asteroids, perhaps as part of space mining efforts, could potentially provide a ready supply of farming material in space.

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      Fieber-Beyer purchased a material that mimics the space rocks’ composition and gave it to her graduate student Steven Russell. “I said, ‘All right, grow me some plants.’”

      Russell, now an astrobiologist at the University of Wisconsin–Madison, chose a type of radish, lettuce and chili pepper — all of which have grown aboard the International Space Station. He, Fieber-Beyer and their colleague Kathryn Yurkonis, also of the University of North Dakota, compared how the plants grew in only faux asteroid soil, only peat moss and various mixes of the two.

      Peat moss keeps soil loose and improves water retention. In all mixtures with peat moss, the plants grew. Faux asteroid soil on its own, however, compacted and couldn’t retain water, and so plants couldn’t grow.

      Next, Fieber-Beyer will try growing hairy vetch seeds in that faux asteroid dirt, let the plants decay and then mix the dead plant matter throughout the soil. That, she says, could ensure that the soil doesn’t compact. Plus, seeds weigh a lot less than peat moss, making them easier to carry to space to help with any future farming attempts. More

    • 150 Shares169 Views

      in Space & Astronomy

      Amateur astronomers’ images of a rare double aurora may unlock its secrets

      by

      What happens when two different kinds of auroras get together? One spills the other’s secrets.

      Amateur astronomers have captured a strange combination of red and green auroras on camera, and physicists — who had never seen such a thing before — have now used these images to learn what may trigger the more mysterious part of the lightshow.

      Photographer Alan Dyer was in his backyard in Strathmore, Canada, when he saw the lights dancing overhead and started filming. “I knew I had something interesting,” says Dyer, who also writes about astronomy. What he didn’t know was that he had just made the most complete recording of this rare phenomenon.

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      At a glance, Dyer’s video looks like a celestial watermelon. The rind, a rippling green aurora, is well understood: It appears when the solar wind energizes protons trapped within Earth’s magnetic field, which then rain down and knock electrons and atoms around (SN: 12/10/03).  

      The swath of fruity magenta is more mysterious: Though scientists have known about these “stable auroral red arcs” for decades, there’s no widely accepted proof of how they form. One popular theory is that part of Earth’s magnetic field can heat up the atmosphere and, like proton rain, jostle particles.   

      But until now, researchers had never seen both of these red and green auroras side by side, says Toshi Nishimura, a space physicist at Boston University. “This strange combination,” he says, “was something beyond our expectations.”

      [embedded content]
      Alan Dyer’s footage of this rare double aurora, a time lapse captured over 33 minutes on October 12, 2021, is helping physicists tease out clues to what causes the red glow.

      Along with satellite observations, Dyer’s images and similar ones captured by other amateur astronomers in Canada and Finland show that the two phenomena are related, Nishimura’s team reports in the July JGR Space Physics. Thin rays in the red aurora are the smoking gun as to how. Those lines trace the paths of electrons as they fall along the Earth’s magnetic field. So just as proton rain triggers the green aurora, electron rain appears to trigger the red one, with the solar wind powering both at the same time. Since the electrons carry less energy than the protons, they make for a more reddish color. 

      But electron rain might not be the only way to produce these red glows, cautions Brian Harding, a space physicist at the University of California, Berkeley. Either way, he says, the results are exciting because they show what’s going on is more complicated than researchers thought.

      Those complications are important to understand. The auroras Dyer saw, though beautiful, are danger zones for radio communication and GPS systems (SN: 8/13/17). As Nishimura puts it: If you were driving under a subauroral red arc, your GPS might tell you to veer into a field.

      Until scientists better understand these red glows, they won’t be able to forecast space weather like they do normal weather, Harding explains. “You want to make sure that you can predict stuff like this,” he says.

      The new results would not have been possible without the citizen scientists who took the photos, Nishimura says. “This is a new way of doing research…. When they take more and more cool images, they find more and more things that we don’t know about.”

      According to Dyer, more photos are exactly what’s coming. “We can make a unique contribution to science,” he says.  After all, “you never know what’s going to appear.” More

    • 175 Shares189 Views

      in Space & Astronomy

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

      by

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

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

      The previous record holder was a neutron star in the northern constellation Camelopardalis named PSR J0740+6620, which tipped the scales at about 2.08 times as massive as the sun. If a neutron star grows too massive, it collapses under its own weight and becomes a black hole. These measurements of hefty neutron stars are of interest because no one knows the exact mass boundary between neutron stars and black holes.

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      That dividing line drives the quest to find the most massive neutron stars and determine just how massive they can be, Romani says. “It’s defining the boundary between the visible things in the universe and the stuff that is forever hidden from us inside of a black hole,” he says. “A neutron star that’s on the hairy edge of becoming a black hole — just about heavy enough to collapse — has at its center the very densest material that we can access in the entire visible universe.”

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

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

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

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

    • 125 Shares119 Views

      in Space & Astronomy

      How James Webb Space Telescope data have already revealed surprises

      by

      Massimo Pascale wasn’t planning to study the galaxy cluster SMACS 0723. But as soon as he saw the cluster glittering in the first image from the James Webb Space Telescope, or JWST, he and his colleagues couldn’t help themselves.

      “We were like, we have to do something,” says Pascale, an astronomer at the University of California, Berkeley. “We can’t stop ourselves from analyzing this data. It was so exciting.”

      Pascale’s team is one of several groups of scientists who saw the first JWST images and immediately rolled up their sleeves. In the first few days after images and the data used to create them were made public, scientists have estimated the amount of mass the cluster contains, uncovered a violent incident in the cluster’s recent past and estimated the ages of the stars in galaxies far beyond the cluster itself.

      “We’ve been preparing for this for a long time. Myself, I’ve been preparing for years, and I’m not very old,” says Pascale, who is in his fourth year of graduate school.  JWST “is really going to define a new generation of astronomers and a new generation of science as a whole.”

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      Cluster collision

      When the image of SMACS 0723 was released in a White House briefing on July 11, most of the focus went to extremely distant galaxies in the background (SN: 7/11/22). But smack in the middle of the image is SMACS 0723 itself, a much closer cluster of galaxies about 4.6 billion light-years from Earth. Its mass bends light from even farther away, making more distant objects appear magnified, as if their light had traveled through the lens of another cosmic-sized telescope.

      The light from the most distant galaxy in this image started its journey to JWST about 13.3 billion years ago — “almost at the dawn of the universe,” says astrophysicist Guillaume Mahler of Durham University in England, who is already using the picture as his Zoom background.

      But the image can also fill in the history of the intervening galaxy cluster itself. “People sometimes forget about that — the galaxy cluster is also very important,” Pascale says.

      Pascale’s and Mahler’s teams each started by taking inventory of the distant galaxies that appear stretched and distorted in the image. The light from some of those galaxies is warped such that multiple images of the same galaxy appear in different places. Mapping those multiply imaged galaxies is a sensitive probe of the way mass is spread around the cluster. That, in turn, can reveal where the cluster contains dark matter, the invisible, mysterious substance that makes up the majority of the mass in the universe (SN: 9/10/20).

      Both teams found that SMACS 0723 is more elongated than it appeared in previous observations. They also found a faint glow, called intracluster light, inside the cluster from stars that don’t belong to any particular galaxy. Together, those features suggest that SMACS 0723 is still recovering from a relatively recent smash-up with another galaxy cluster, the teams report separately in a pair of papers submitted to arXiv.org on July 14.

      A galaxy cluster that has been sitting on its own for eons should have a rounder distribution of matter and intracluster light, rather than SMACS 0723’s oblong shape. The stars that emit the intracluster light were probably ripped from their home galaxies by gravitational forces during the collision.

      “Two separate clusters have merged together, and it looks to us as if it’s not totally settled yet,” Pascale says. “What we might be looking at is an ongoing merger.”

      Three examples of multiply imaged galaxies — marked with white, red and yellow arrows — popped out of this small region of the first JWST image. The gravity from a foreground galaxy cluster distorted the light from these galaxies, making them appear in at least two places at once.Reproduced from M. Pascale et al/arXiv.org 2022

      Far-flung galaxies

      Mapping out mass in the cluster is also essential to decoding the properties of the more distant galaxies in the background of the image, Mahler says. “You need to understand the cluster and its magnification power to understand what’s behind.”

      Some scientists are already investigating those distant galaxies in detail. The first JWST data include not just pretty pictures but also spectra, measurements of how much light an object emits at various wavelengths. Spectra allow scientists to determine how much a distant object’s light has been stretched — or redshifted — by the expansion of the universe, which is a proxy for its distance. Such data can also help reveal a galaxy’s composition and the ages of its stars.

      “The main thing that limits the study of star formation in galaxies is the quality of the data,” says astrophysicist Adam Carnall of the University of Edinburgh. But with the vastly improved data from JWST, he says, he and his team were able to measure the ages of stars in those remote galaxies.

      Carnall and colleagues turned their attention to the spectra of the distant galaxies just a few days after the SMACS image was released. They measured the redshifts of 10 galaxies, five of which were particularly distant, the team reports in a paper submitted to arXiv.org on July 18. One had already been highlighted as one of the most distant galaxy ever seen, with light that was emitted just 500 million years after the Big Bang 13.8 billion years ago. The other four shone as late as 1.1 billion years after the Big Bang.

      All 10 galaxies were relatively young when they emitted the light captured by JWST, Carnall says. They had all switched on their star formation just a few million years earlier. That’s not especially surprising, but it is interesting.

      “The ability to look at these small, faint galaxies … gives you a sense of how all galaxies must look when they start forming stars,” Carnall says.

      Scientists hope to use JWST to find the first instances of star formation ever. Other early results suggest they’re already getting close.

      Some galaxies in a JWST image of another cluster may hearken from an even earlier time, as early as 300 million years after the Big Bang, two research teams report in a pair of papers submitted to arXiv.org on July 19. One of those galaxies seems to have already built up a spiral disk about a billion times the mass of the sun, which is surprisingly mature for such an early galaxy.

      And a tally of galaxies seen in the SMACS 0723 image suggests that galaxies with mature disks, rather than disorganized blobs or ones made up mostly of dark matter, may have been more common in the very early universe than previously thought, another team reports in an arXiv.org paper submitted July 19. That means those early disks might not be outliers.

      “Definitely these galaxies are a big deal, but it remains to be seen how exciting they will look in the context of a few months’ progress with JWST,” Carnall says. The best is yet to come.

      [embedded content]
      Exploded stars, colliding galaxies, and beautiful clouds feature in the first space photos released by The James Webb Space Telescope July 12. More