Chinese scientists have found key evidence for the existence of nanohertz gravitational waves. The research was based on pulsar timing observations carried out with the Five-hundred-meter Aperture Spherical Telescope (FAST). The detection of nanohertz gravitational waves can be very challenging due to their extremely low frequency, where the corresponding period can be as long as several years and wavelengths up to several light-years.
WION Video Team|Updated: Jun 30, 2023, 01:00 PM IST
NASA's search for life on the moon is reaching new heights. From probing water & oxygen on the lunar surface. To locating iron & rare earth metals. NASA is looking to develop resources on the moon. According to a scientist, NASA has already taken steps toward excavating moon soil in 2032.
Alexandria, VA – The International Association for Dental, Oral, and Craniofacial Research (IADR) and the American Association for Dental, Oral, and Craniofacial Research (AADOCR) announced today the JDR Clinical & Translational Research (JDR CTR) has received its first Journal Impact Factor™.
JDR CTR has earned a Journal Impact Factor of 3.0, with an Eigenfactor™ of 0.00148, an Immediacy Index of 0.5, and 786 total citations in 2022. This represents a significant achievement and a huge milestone in JDR CTR’s history, which was launched in 2016.
“JDR CTR’s new Impact Factor marks the culmination of years of commitment and dedication on the part of all our authors, contributors, and our entire editorial team,” said JTR CTR Editor-in-Chief Jocelyne Feine. “I am extremely proud of what we’ve achieved since 2016 and look forward to even greater things in the years to come.”
The 2-year Journal Impact Factor is defined as citations to the journal in the Journal Citation Reports™ (Clarivate™, 2023) year to items published in the previous two years, divided by the total number of scholarly items, also known as citable items, including articles and reviews published in the journal in the previous two years.
This year for the first time, all Web of Science Core Collection™ journals that passed the rigorous Web of Science quality criteria and were accepted before January 1, 2023, were eligible to receive an Impact Factor. By expanding the JIF to the Arts and Humanities Citation Index™ (AHCI) and the multidisciplinary Emerging Sources Citation Index™ (ESCI), more than 9,000 journals from more than 3,000 publishers now have a JIF for the first time. This indicator helps the scholarly community more easily identify trustworthy, high-quality journals that have been selected by the Web of Science editorial team. Selection is only granted to journals that have met the high-quality criteria applied on evaluation, with only 15% of journals evaluated passing this bar.
About the JDR Clinical & Translational Research
The JDR Clinical & Translational Research (JDR CTR) is a peer-reviewed, quarterly journal that encompasses all areas of clinical and translational research in the dental, oral, and craniofacial sciences. Launched by IADR and AADOCR, JDR CTR provides a resource for clinicians, scientists, academics, researchers, and policy makers across the entire spectrum of the dental community. Follow JDR CTR on Twitter @JDRClinTransRes!
About IADR The International Association for Dental, Oral, and Craniofacial Research (IADR) is a nonprofit organization with a mission to drive dental, oral, and craniofacial research for health and well-being worldwide. IADR represents the individual scientists, clinician-scientists, dental professionals, and students based in academic, government, non-profit, and private-sector institutions who share our mission. Learn more at www.iadr.org.
About AADOCR
The American Association for Dental, Oral, and Craniofacial Research (AADOCR) is a nonprofit organization with a mission to drive dental, oral, and craniofacial research to advance health and well-being. AADOCR represents the individual scientists, clinician-scientists, dental professionals, and students based in academic, government, non-profit, and private-sector institutions who share our mission. AADOCR is the largest division of IADR. Learn more at www.aadocr.org.
Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
The black wave-like curve plotted here depicts what the variations in timing from pulsars should look like, based on theory. The blue dots (with error bars) depict the actual data collected by NANOGrav, which very closely matches the shape of the theoretical variations. Credit: Gabriella Agazie et al 2023/Astrophysical Journal Letters/NANOGrav Collaboration
"This is the first evidence for gravitational waves at very low frequencies," Dr. Stephen Taylor from Vanderbilt University, who co-led the research with Dr. Vigeland, said in the NANOgrav press release. "After years of work, NANOGrav is opening an entirely new window on the gravitational-wave universe."
An exciting result
Although the group still needs to go through all the data in order to positively identify the sources of these low-frequency gravitational waves, the prospects of what they might find have scientists fairly excited.
As the researchers have pointed out, one potential source is merging supermassive black holes.
As far as we know, at the core of each galaxy is a black hole millions to billions of times the mass of our Sun. Telescopes have captured views of galaxies merging, and galaxies that are in the aftermath of a merger. Thus, the supermassive black holes of these merging galaxies must also merge together.
This artist's conception drawing shows an array of pulsars being affected by gravitational ripples produced by a supermassive black hole binary in a distant galaxy. Credit: Aurore Simonnet/NANOGrav Collaboration
The process would happen very slowly, over the course of millions of years. However, the timing and scale of such a merger could produce these low-frequency space-time ripples with wavelengths lightyears long.
"We think these systems of black holes exist everywhere in the early universe. If we can get a very precise measurements of the gravitational waves, we can get a better idea of how many of these pairs there are, and how they behave," Dr. Ingrid Stairs, co-founder of NANOgrav and professor of physics and astronomy at UBC, said in the press release. "This in turn could give us more information about some of the processes in the early universe such as galaxy formation."
An artist’s interpretation shows an array of pulsars being affected by gravitational ripples produced by a supermassive black hole binary in a distant galaxy.Handout
Somewhere, far away, the universe is humming, and for the first time, scientists are picking up the tune.
But that hum is not audible; rather, it consists of unimaginably long waves of gravitational energy that alternately stretch and squeeze space as they propagate in all directions. Their suspected source: hundreds of thousands of supermassive black holes swinging around each other like vigorous couples shaking the floor at a cosmic barn dance.
Such is the world of low frequency gravitational wave astronomy – a search for undulations so vast that, even thought they are coming at us at the speed of light, any single wave might take a decade or more to crest as it passes by Earth. The change is so subtle that scientists must employ special techniques just to demonstrate that the waves are there at all.
“These truly are among the lowest notes in the cosmic symphony. It’s an amazing feat to have found evidence for signals like this,” said Ingrid Stairs, an astronomer at the University of British Columbia and member of the NANOGrav collaboration, a North America-wide effort to search for the elusive low frequency waves.
The project’s latest measurements were published Thursday in the Astrophysical Journal Letters, in co-ordination with teams in Europe, India, Australia and China that have been independently looking for the same signal. All the findings are consistent with the existence of low frequency gravitational waves, though NANOGrav team members said the data are close but not yet at the 3.5 million-to-one-certainty level considered the gold standard for reporting new discoveries in physics.
“We’re not saying the word ‘detection,’ ” Dr. Stairs said.
If their interpretation is correct, researchers have used gravity to open up a new window into the unseen depths of the universe and shed light on the formation and evolution of the heaviest objects we know – or it could mean the discovery of something entirely new and unexpected.
Long predicted by Einstein’s theory of general relativity, gravitational waves are disturbances in space that are produced whenever massive objects move very quickly. Their existence was first confirmed in 2015 by the Laser Interferometer Gravitational-Wave Observatory. The U.S.-based facility uses laser light reflecting back and forth between mirrors that are four kilometres apart to pick up slight vibrations that occur when gravitational waves are traversing through the experiment.
Since acquiring the sensitivity to detect the waves, LIGO has recorded many signals that come from colliding black holes a few dozen times the sun’s mass. Those signals appear as short-lived chirps in the data that momentarily jiggle the detector before fading away.
This week, scientists are reporting something quite different: not high-pitched chirps but a deep and continuous drone that permeates all of space. Such a drone would be expected to arise not from one collision but from the collective motion of many of the largest black holes in the universe – each one carrying the mass of millions of suns. Black holes of such extreme mass are known to form at the centres of distant galaxies. And while they may form separately, two such black holes can find themselves bound together in a tight orbit after their host galaxies merge.
Neither LIGO nor any other detector on Earth is large enough to sense the gravitational waves emanating from such a massive duo. However, by checking Earth’s position relative to other objects in space, astronomers have shown that our planet is acting very much like a cork bobbing around in slow motion exactly as would be expected from the low frequency waves.
“This is really compelling evidence for a background of gravitational waves,” said Steve Taylor, an astronomer at Vanderbilt University in Tennessee and current chair of NANOGrav during a briefing on the find. The collaboration harnessed researchers and facilities across North America to search for the effect.
To conduct its search, the team used radio telescopes in multiple locations to carefully monitor pulsars – compact, rotating objects scattered around our Milky Way galaxy that are left behind when stars exhaust their fuel and explode as supernovas. Some pulsars can spin as much as 1000 times per second, which makes then ideal natural timers because their rotations are so precise and consistent. As Earth is buffeted by gravitational waves, the planet’s back and forth motion can be spotted by comparing pulsars in different directions and checking for slight discrepancies in timing. The hitch is that it takes years of measurements to see the gradual change caused by passing low frequency gravitational waves.
Achieving that result reliably “has taken a small army of people to do everything right,” Dr. Stairs said.
Other teams used the same pulsar-timing approach to arrive at comparable results. And while the existence of low frequency gravitational waves has long been suspected, the details include a few puzzles. For example, if the background hum is produced solely by close pairs of supermassive black holes circling each other, then the pairs are more common and somewhat more massive on average than standard theories predict.
This had some researchers this week pointing to even more exotic possibilities for explaining the cause of the gravitational waves, including cosmic strings: hypothetical defects in spacetime that some theories predict could have formed during the Big Bang.
Luis Lehner, a researcher at the Perimeter Institute for Theoretical Physics in Waterloo, Ont., who was not part of the collaboration, said that theorists may have difficulty explaining how pairs of supermassive can get close enough to each other often enough to match what observers are now finding in their data.
“They take too long to merge, but we’re not seeing that,” he said. “Somehow they get together … it’s nature reminding us that it’s always going to be smarter than we are.”
In this artist’s interpretation, a pair of supermassive black holes (top left) emits gravitational waves that ripple through the fabric of space-time. Those gravitational waves compress and stretch the paths of radio waves emitted by pulsars (white). By carefully measuring the radio waves, a team of scientists recently made the first detection of the universe’s gravitational wave background. Credit: Aurore Simonnet for the NANOGrav Collaboration
Following 15 years of data collection in a galaxy-sized experiment, scientists have "heard" the perpetual chorus of gravitational waves rippling through our universe for the first time—and it's louder than expected.
The groundbreaking discovery was made by scientists with the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) who closely observed stars called pulsars that act as celestial metronomes. The newly detected gravitational waves—ripples in the fabric of space-time—are by far the most powerful ever measured: They carry roughly a million times as much energy as the one-off bursts of gravitational waves from black hole and neutron star mergers detected by experiments such as LIGO and Virgo.
Most of the gigantean gravitational waves are probably produced by pairs of supermassive black holes spiraling toward cataclysmic collisions throughout the cosmos, the NANOGrav scientists report in a series of new papers appearing today in The Astrophysical Journal Letters.
"It's like a choir, with all these supermassive black hole pairs chiming in at different frequencies," says NANOGrav scientist Chiara Mingarelli, who worked on the new findings while an associate research scientist at the Flatiron Institute's Center for Computational Astrophysics (CCA) in New York City. "This is the first-ever evidence for the gravitational wave background. We've opened a new window of observation on the universe."
Credit: National Science Foundation
The existence and composition of the gravitational wave background—long theorized but never before heard—presents a treasure trove of new insights into long-standing questions, from the fate of supermassive black hole pairs to the frequency of galaxy mergers.
For now, NANOGrav can only measure the overall gravitational wave background rather than radiation from the individual "singers." But even that brought surprises.
"The gravitational wave background is about twice as loud as what I expected," says Mingarelli, now an assistant professor at Yale University. "It's really at the upper end of what our models can create from just supermassive black holes."
The deafening volume may result from experimental limitations or heavier and more abundant supermassive black holes. But there's also the possibility that something else is generating powerful gravitational waves, Mingarelli says, such as mechanisms predicted by string theory or alternative explanations of the universe's birth. "What's next is everything," she says. "This is just the beginning."
An artist’s rendering of gravitational waves from a pair of close-orbiting black holes (visible on the left in the distance). The waves are passing by several pulsars and the Earth (on the right). Credit: Keyi “Onyx” Li/U.S. National Science Foundation
A galaxy-wide experiment
Getting to this point was a years-long challenge for the NANOGrav team. The gravitational waves they hunted are different from anything previously measured. Unlike the high-frequency waves detected by earthbound instruments such as LIGO and Virgo, the gravitational wave background is made up of ultra-low-frequency waves. A single rise and fall of one of the waves could take years or even decades to pass by. Since gravitational waves travel at the speed of light, a single wavelength could be tens of light-years long.
No experiment on Earth could ever detect such colossal waves, so the NANOGrav team instead looked to the stars. They closely observed pulsars, the ultra-dense remnants of massive stars that went supernova. Pulsars act like stellar lighthouses, shooting beams of radio waves from their magnetic poles. As the pulsars rapidly spin (sometimes hundreds of times a second), those beams sweep across the sky, appearing from our vantage point on Earth as rhythmic pulses of radio waves.
The Very Large Array in New Mexico gathered data that contributed to the detection of the universe’s gravitational wave background. Credit: NRAO/AUI/NSF
The pulses arrive on Earth like a perfectly timed metronome. The timing is so precise that when Jocelyn Bell measured the first pulsar radio waves in 1967, astronomers thought they might be signals from an alien civilization.
As a gravitational wave passes between us and a pulsar, it throws off the radio wave timing. That's because, as Albert Einstein predicted, gravitational waves stretch and compress space as they ripple through the cosmos, changing how far the radio waves have to travel.
For 15 years, NANOGrav scientists from the United States and Canada closely timed the radio wave pulses from dozens of millisecond pulsars in our galaxy using the Arecibo Observatory in Puerto Rico, the Green Bank Telescope in West Virginia and the Very Large Array in New Mexico. The new findings are the result of a detailed analysis of an array of 67 pulsars.
"Pulsars are actually very faint radio sources, so we require thousands of hours a year on the world's largest telescopes to carry out this experiment," says Maura McLaughlin of West Virginia University, co-director of the NANOGrav Physics Frontiers Center. "These results are made possible through the National Science Foundation's (NSF's) continued commitment to these exceptionally sensitive radio observatories."
Detecting the background
In 2020, with just over 12 years of data, NANOGrav scientists began to see hints of a signal, an extra "hum" common to the timing behavior of all pulsars in the array. Now, three years of additional observations later, they have accumulated concrete evidence for the existence of the gravitational wave background.
"Now that we have evidence for gravitational waves, the next step is to use our observations to study the sources producing this hum," says Sarah Vigeland of the University of Wisconsin-Milwaukee, chair of the NANOGrav detection working group.
The likeliest sources of the gravitational wave background are pairs of supermassive black holes caught in a death spiral. Those black holes are truly colossal, containing billions of suns' worth of mass. Nearly all galaxies, including our own Milky Way, have at least one of the behemoths at their core. When two galaxies merge, their supermassive black holes can meet up and begin orbiting one another. Over time, their orbits tighten as gas and stars pass between the black holes and steal energy.
Eventually, the supermassive black holes get so close that the energy theft stops. Some theoretical studies have argued for decades that the black holes then stall indefinitely when they're around 1 parsec apart (roughly three light-years). This close-but-no-cigar theory became known as the final parsec problem. In this scenario, only rare groups of three or more supermassive black holes result in mergers.
Supermassive black hole pairs could have a trick up their sleeves, though. They could emit energy as powerful gravitational waves as they orbit one another until eventually they collide in a cataclysmic finale. "Once the two black holes get close enough to be seen by pulsar timing arrays, nothing can stop them from merging within just a few million years," says Luke Kelley of the University of California, Berkeley, chair of NANOGrav's astrophysics group.
Pulsars are fast-spinning neutron stars that emit narrow, sweeping beams of radio waves. Credit: NASA’s Goddard Space Flight Center
The existence of the gravitational wave background found by NANOGrav seems to back up this prediction, potentially putting the final parsec problem to rest.
Since supermassive black hole pairs form due to galaxy mergers, the abundance of their gravitational waves will help cosmologists estimate how frequently galaxies have collided throughout the universe's history. Mingarelli, postdoctoral researcher Deborah C. Good of the CCA and the University of Connecticut, and their colleagues studied the intensity of the gravitational wave background. They estimate that hundreds of thousands or maybe even a million or more supermassive black hole binaries inhabit the universe.
Alternative sources
Not all the gravitational waves detected by NANOGrav are necessarily from supermassive black hole pairs, though. Other theoretical proposals also predict waves in the ultra-low-frequency range. String theory, for instance, predicts that one-dimensional defects called cosmic strings may have formed in the early universe. These strings could dissipate energy by emitting gravitational waves. Another proposal suggests that the universe didn't start with the Big Bang but with a Big Bounce as a precursor universe collapsed in on itself before expanding back outward. In such an origin story, gravitational waves from the incident would still be rippling through space-time.
There's also a chance that pulsars aren't the perfect gravitational wave detectors scientists think they are, and that they instead might have some unknown variability that's skewing NANOGrav's results. "We can't walk over to the pulsars and turn them on and off again to see if there's a bug," Mingarelli says.
The NANOGrav team hopes to explore all the potential contributors to the newfound gravitational wave background as they continue monitoring the pulsars. The group plans to break down the background based on the waves' frequency and origin in the sky.
An international effort
Luckily, the NANOGrav team isn't alone in its quest. Several papers released today by collaborations using telescopes in Europe, India, China and Australia report hints of the same gravitational wave background signal in their data. Through the International Pulsar Timing Array consortium, the individual groups are pooling their data to better characterize the signal and identify its sources.
"Our combined data will be much more powerful," says Stephen Taylor of Vanderbilt University, who co-led the new research and currently chairs the NANOGrav collaboration. "We're excited to discover what secrets they will reveal about our universe."
More information:
The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background, The Astrophysical Journal Letters (2023). DOI: 10.3847/2041-8213/acdac6
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NASA is looking to develop resources on the moon that initially include oxygen and water, and eventually may expand to iron and rare earths, and has already taken steps toward excavating moon soil in 2032, a scientist said on Wednesday.
The U.S. space agency plans to return Americans to the moon as part of its Artemis mission, including the first woman and person of colour by 2025, and to learn from the mission to facilitate a trip to Mars.
A key part of the mission is advancing commercial opportunities in space. The agency is looking to quantify potential resources, including energy, water and lunar soil, as a goal to attract commercial investment, said Gerald Sanders, a rocket scientist at NASA’s Johnston Space Centre for 35 years.
Developing access to resources on the moon will be key to cutting costs and developing a circular economy, Sanders said.
“We are trying to invest in the exploration phase, understand the resources... to [lower] risk such that external investment makes sense that could lead to development and production,” he told a mining conference in Brisbane.
“We are literally just scratching the surface,” he said. NASA will at the end of the month send a test drill rig to the moon and plans a larger-scale excavation of moon soil, or regolith, and a pilot processing plant in 2032.
The first customers are expected to be commercial rocket companies who could use the moon’s resources for fuel or oxygen.
The Australian Space Agency is involved in developing a semi-autonomous rover that will take regolith samples on a NASA mission as early as 2026, said Samuel Webster, an assistant director at the agency.
The rover will demonstrate the collection of lunar soil that contains oxygen in the form of oxides.
Using separate equipment sent to the moon with the rover, NASA will aim to extract that oxygen, he said.
“This ... is a key step towards establishing a sustainable human presence on the moon, as well (as) supporting future missions to Mars,” he said at the conference.
Images from the James Webb Space Telescope show a part of the Orion Nebula where methyl cation was detected in a young star system, shown in the lower right segment.ESA/Webb, NASA, CSA, M. Zamani (ESA/Webb), and the PDRs4All ERS Team
NASA's James Webb Space Telescope has detected a key carbon molecule in space for the first time: methyl cation (pronounced cat-eye-on).
The methyl cation, or CH3+, molecule can promote chemical reactions that form more complex carbon molecules — crucial building blocks for life.
Scientists have theorized that methyl cation could lay the foundations for organic chemistry, and possibly life, across the universe.
But nobody had detected the molecule beyond our solar system until scientists pointed the Webb telescope at a young star system in the Orion Nebula, a giant star-forming region located 1,350 light-years from Earth.
A wide shot of the Orion Nebula, revealing it's iconic shape.Eric Teske/Stellar Neophyte
There, in a ring of gas, dust, and rock orbiting a star — material that may someday coalesce into a planet — Webb spotted the first alien methyl cation known to science.
"While we have hypothesized for some time methyl cation existed in the universe, it was purely theoretical until now," Els Peeters, an astrophysicist at Western University, an expert in interstellar molecules and star formation, and a member of the team that made this discovery, said in a press release.
Webb's sensitivity to light helps it detect new molecules
An artist's impression of the James Webb Space Telescope.NASA
The Orion Nebula is visible to the unaided eye under very dark skies, but it takes a powerful telescope to identify the molecules that make it.
While scientists have used other telescopes, including Hubble, to study the Orion Nebula, only Webb has the power to detect methyl cation. That's because Webb analyzes wavelengths of a type of electromagnetic radiation called infrared light coming from distant objects in space.
That's a treasure trove of information for astronomers, because each chemical element emits and absorbs light at specific wavelengths. By picking apart the infrared light shining from a star or nebula, Webb can tell scientists exactly what chemicals are present there. That's how it can detect water vapor, for example, or sand-like particles in a distant planet's atmosphere.
An international team of scientists spotted the signature of methyl cation in the wavelengths Webb captured from this distant star in the Orion Nebula. They published their findings in the journal Nature on Monday.
"This detection not only validates the incredible sensitivity of Webb but also confirms the postulated central importance of CH3+ in interstellar chemistry," Marie-Aline Martin-Drumel, a researcher at the University of Paris-Saclay and another co-author on the paper, said in a NASA press release.
Destructive UV radiation may actually help the early chemistry of life
The young star system in the center of this image contains a protoplanetary disk named d203-506.ESA/Webb, NASA, CSA, M. Zamani (ESA/Webb), and the PDRs4All ERS Team
Some scientists wouldn't have expected to find methyl cation in the ring of material, or "protoplanetary disk," where Webb spotted the critical carbon molecule.
That's because, according to NASA, the region is being constantly bombarded with powerful UV radiation, which is known to destroy complex organic molecules.
The discovery of methyl cation there suggests that UV radiation may actually be the source of energy needed to form this particular molecule in the first place. Then, eons later, the methyl cation could help form the more UV-sensitive complex carbon molecules needed for life.
That could explain how the building blocks of life appeared on our planet. Long ago, when Earth was just a protoplanetary disk, it too was bombarded with heavy UV radiation.
"This clearly shows that ultraviolet radiation can completely change the chemistry of a protoplanetary disk. It might actually play a critical role in the early chemical stages of the origins of life," said lead author of the study, Olivier Berné of the French National Centre for Scientific Research in Toulouse.
Astronomers have detected for the first time in space a carbon molecule thought to be a crucial ingredient for all known life.
A team of scientists found this Holy Grail compound in the Orion Nebula, a baby star nursery about 1,350 light-years away. That may seem absurdly far, but it's actually the closest large star-forming region to Earth.
Using the James Webb Space Telescope, a preeminent cosmic observatory led by NASA and the European and Canadian space agencies, the researchers not only captured a vibrant new picture of the celestial region — blowing the socks off Hubble's version — but found the new molecule lurking in a young star system, known as d203-506(opens in a new tab). This system has a protoplanetary disk, a sort of Lazy Susan of gas and dust rotating around the core.
Astronomers are on a quest to find signals of carbon compounds in the greater universe because this chemistry is at the root of all life, at least as far as we understand it on Earth. Coincidentally, ancient Mayan culture referred to the Orion Nebula as the cosmic fire of creation(opens in a new tab).
The mysterious signal turned out to be methyl cation, a molecule that until this week was relatively unknown to the layperson. With the announcement, NASA went so far as to provide a pronunciation guide(opens in a new tab) for the term. (For the record, it sounds like "CAT-eye-on," not the last two syllables of "vacation.") Organic chemists say methyl cation assists with the formation of more complex carbon-based molecules.
Since the 1970s, scientists have predicted this substance was a missing link between simple molecules and more complex organic molecules. But direct evidence of its existence in space had eluded them — until now. NASA likens the role of methyl cation to a train station(opens in a new tab), where a molecule can remain for a time before routing in one of many different directions to react with other molecules.
"This detection not only validates the incredible sensitivity of Webb but also confirms the postulated central importance of (methyl cation) in interstellar chemistry," said Marie-Aline Martin-Drumel, one of the coauthors on the new study, in a statement(opens in a new tab).
The molecule, which was detected around a small red dwarf star, comes from a region with high levels of ultraviolet light.Credit: ESA / Webb / NASA / CSA / M. Zamani (ESA/Webb) / PDRs4ALL ERS Team
NASA likens the role of methyl cation to a train station, where a molecule can remain for a time before routing in one of many different directions to react with other molecules.
The molecule was found in an enormous cloud of dust and gas that hosts a multitude of stars under construction. At its center are four massive stars collectively known as the Trapezium(opens in a new tab) because they are arranged in a trapezoidal shape. The molecule, which was detected around a small red dwarf star, comes from a region with high levels of ultraviolet light from the Trapezium.
Scientists speculate that most planet-forming disks experience intense ultraviolet radiation for a time, because stars tend to form in groups that include massive UV-producing stars. The odd plot twist, however, is that UV radiation tends to destroy complex organic molecules. The research team thinks in this instance the radiation might be what's providing the needed energy for it to form.
Despite finding this key molecule for life, the team noted the absence of another more well-known ingredient from the star system: water. This leaves more questions about ultraviolet radiation for astronomers, said Olivier Berné, lead author of the study, in a statement.
"It might actually play a critical role in the early chemical stages of the origins of life," he said.
image: Zhurong rover and its magnetometers (left); Zhurong’s landing area and the relevant geologic context (middle); Measured crustal magnetic field along Zhurong’s traverse (right)view more
Credit: Prof. DU Aimin’s group
A joint research team led by Prof. DU Aimin from the Institute of Geology and Geophysics of the Chinese Academy of Sciences (IGGCAS) has found extremely weak magnetic fields during the Zhurong rover's first 1-km traverse on Mars. This indicates no detectable magnetization anomalies below Zhurong's landing site.
The researchers utilized two fluxgate magnetometers aboard the Zhurong rover to conduct the first magnetic field survey in the Utopia Basin on the Martian surface. "The intensity of the magnetic field was surprisingly weak in the Utopia Basin," said Prof. DU Aimin, first and corresponding author of the study.
Results from NASA's Mars' lander InSight, which landed about 2,000 km southeast of Zhurong, have revealed that the crustal magnetic field at InSight's landing site was an order stronger than that inferred from orbital measurement. Measurements from Zhurong, however, revealed the opposite result, with the average intensity an order less than that inferred from orbit.
How to obtain highly precise planetary surface magnetic measurements is a great challenge in planetary exploration. Zhurong is the first rover equipped with magnetometers. The researchers conducted along-track calibration to separate the Martian magnetic field and rover interference field using rover rotations and mast rotations. The accuracy of multi-point in-situ measurement of the Martian surface has reached the order of nanoteslas.
The extremely weak magnetic fields detected by Zhurong imply that either the crust beneath Utopia Basin may have remained unmagnetized since its formation about 4 billion years ago or it was demagnetized by a later sizable impact in the early Hesperian. This new constraint on the timeline of the Martian dynamo sheds further light on the interconnected magnetic, climatic, and interior history of early Mars.
The study was conducted in collaboration with the China University of Geosciences (Wuhan), the National Astronomical Observatories of CAS, the National Space Science Center of CAS, Southern University of Science and Technology, the Beijing Institute of Spacecraft System Engineering, Macau University of Science and Technology, the Harbin Institute of Technology, the Space Research Institute of the Austrian Academy of Sciences, and the University of Leeds.
Journal
Nature Astronomy
Article Title
Ground magnetic survey on Mars from the Zhurong rover
Article Publication Date
19-Jun-2023
Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
The largest shark alive today, reaching up to 20 meters long, is the whale shark, a sedate filter feeder. As recently as 4 million years ago, however, sharks of that scale likely included the fast-moving predator megalodon, famous for its utterly enormous jaws and correspondingly huge teeth.
Because of incomplete fossil data, we're not entirely sure how large megalodon was and can only make inferences based on some of its living relatives, like the great white and mako sharks. But thanks to some new research on its fossilized teeth, we're now fairly confident that it shared something else with these relatives: it wasn't entirely cold-blooded and apparently kept its body temperature above that of the surrounding ocean.
Taking a temperature
Most sharks, like most fish, are ectothermic, meaning that their body temperatures match those of the surrounding water. But a handful of species, part of a group termed mackerel sharks, have a specialized pattern of blood circulation that helps retain some of the heat their muscles produce. This enables them to keep some body parts at a higher temperature than their surroundings. A species called the salmon shark can maintain a body temperature that's 20° C warmer than the sub-Arctic waters that it occupies.
Megalodon is also a mackerel shark, and some scientists have suggested that it, too, must have been at least partially endothermic to have maintained its growth rates in the varied environments that it inhabited. But, as we mentioned, the megalodon remains we have aren't even sufficient to let us know how large the animal was, much less whether it had the sort of specialized circulatory structure needed for shark endothermy.
So, a team of researchers decided to directly test whether there were signs it regulated its body temperature using things we actually do have: its teeth.
The work relies on a phenomenon known as isotope clumping. If an environment is warm enough, the small weight differences between atomic isotopes don't matter, as the heat is warm enough to thoroughly mix isotopes within a material. But as things cool down, heavier isotopes tend to pool together, forming clumps within a material. We now have equipment that can track the distribution of isotopes within a material at high resolution, allowing a direct measure of its clumpiness. That, in turn, can be used to generate an estimate of the temperature at which the material formed.
The new work relied on fossil beds that contained at least three distinct types of fossils. One was obviously megalodon teeth. But the others were needed to provide some degree of outside reference for the estimates obtained from the sharks. These include the bones of known cold-blooded fish, which provided a baseline for the environmental temperatures. They also obtained samples of the ear bones of whales to have a known warm-blooded control. Critically, they obtained these samples from widely distributed sites in the Atlantic and Pacific Oceans, ensuring that any differences weren't simply a matter of local environmental conditions.
Heat up, move fast
The samples of ectotherms showed the sorts of regional variations you'd expect from seawater temperatures, with estimates ranging from a low of 17° C in California to a high of 23° C in the Mediterranean. The megalodon samples, in contrast, were consistently warmer, with an average temperature difference of about 7° C compared to the cold-blooded samples.
This isn't as warm as the whale samples. But, as the researchers point out, the whale samples came from their inner ears, which are fairly removed from the environment, and so likely to reflect the animal's internal temperature. In sharks, in contrast, the teeth are relatively exposed to the environment and so may be intermediate between the typical body temperature and that of the outside world. The temperature of mackerel sharks also tends to vary across different body parts.
So why might an elevated body temperature have been selected for in megalodon? There are two potential reasons. One is, as noted above, that the temperatures might have been essential to maintain the growth rates needed to allow something as big as megalodon to develop in non-tropic environments. The second is speed. Warm muscles could be necessary to power the animal through the water quickly enough to be an effective predator. The mako shark, for example, is the fastest shark and partly endothermic.
Megalodon's large body size might have also made heat retention somewhat easier, as it increases the ratio of body volume to surface area, meaning there's less surface to lose heat compared to the amount of muscle generating it.
The authors of the new paper, however, suggest that might also have left megalodon vulnerable to climate change. The high metabolic demands involved in maintaining its endothermy could have made megalodon sensitive to changes in the ecosystem. And, near the time of its extinction, the Earth generally got cooler, causing sea levels to fall, which would have disrupted coastal ecosystems. And megalodon seems to have relied on coastal nurseries during its early years.
CHAPEA 1 will simulate a year-long stay on the red planet — minus the low gravity, Mars time and the vacuum of space
There's no place like Mars: Four astronauts will spend the next year in this simulated Mars habitat.Photo by NASA
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The mission patch for NASA’s newest endeavour looks like it’s for the first humans to set foot on the Mars. There are four astronauts’ names surrounding a crimson landscape beneath a dome of stars, and a mission name, CHAPEA 1.
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But the Latin inscription looks a little off. “Ad Martus A Domo,” it reads. “To Mars, from home.” Astronauts Ross Brockwell, Kelly Haston, Nathan Jones and Anca Selariu are going to Mars. But they’re also not leaving the Johnson Space Center in Houston.
The CHAPEA 1 mission, or Crew Health and Performance Exploration Analog, is just the latest attempt by the space agency to replicate the rigours of an extended stay on the red planet. The astronauts — technically, “analog astronauts” — entered their 158-square-metre (1,700-square-foot) living space on Sunday evening, and will not emerge until July 7, 2024.
The four volunteers will eat, sleep and work in the 3D-printed structure, dubbed “Mars Dune Alpha,” for the next 378 days. The only time they will leave the habitat will be to spend time on the “Martian surface,” a 1,200-square-foot sandbox filled with simulated Mars regolith.
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The surface of Mars will be this 1,200-square-foot sandbox.Photo by NASA
Suzanne Bell, who heads NASA’s Behavioral Health and Performance Laboratory in Houston, told the website collectSPACE.com that the length of the mission, the first of three, was notable. “We also do analogs in something called HERA, the Human Exploration Research Analog, and our missions there have been 45 days,” she said. “And then we collect data at other analogs, too, with varying lengths, but this will be three, over one-year-long missions, which is a really great extended isolation.”
The four crew members may not be “real” astronauts, but the selection process included the same physical and psychological testing as other astronaut candidates, and requirements included a degree in one of the STEM fields (science, technology, engineering or mathematics) as well as professional, piloting or military experience.
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Mission commander Haston is a research scientist studying human disease. Brockwell, a structural engineer, is the crew’s flight engineer. Jones is the medical officer, having been an emergency medicine physician. And Selariu, a microbiologist in the U.S. Navy, is the crew’s science officer.
“What CHAPEA is really about is Mars-realistic conditions in terms of resource restrictions,” Bell said. “Isolation confined with the living space being one of them. But we’re also restricting the crew to a spaceflight food system, time-delayed communications, mission-relevant timelines, contingency situations and other resource restrictions.”
That means that any crew communications will take 22 minutes to reach mission control, duplicating the maximum time for radio waves to travel between Earth and Mars. The crew will be eating freeze-dried, thermo-stablized and shelf-stable foods.
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Since there’s no way to duplicate the red planet’s gravity (38 per cent of Earth’s), the crew won’t experience that aspect of Martian life. They’ll also remain on Earth time, counting days (24 hours) rather than sols — Martian days are roughly 40 minutes longer than ours. And they’ll be spared the months-long journey in what would presumably be even more cramped quarters.
In addition to being the newest and one of the longest Mars analog missions, CHAPEA 1 is also one of the most accessible. Mars analogs are often set up in remote locations, the better to replicate the harsh Martian environment.
NASA’s Hawaii Space Exploration Analog and Simulation, or HI-SEAS, sits 2,400 metres above sea level on the side of a dormant volcano. The space agency also runs the NASA Extreme Environment Mission Operations, or NEEMO.
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Meanwhile, Space advocacy group The Mars Society has an analog station in the desert in Utah and another on Devon Island in Nunavut, whose extreme latitude (75 degrees North) means it receives about the same amount of sunlight as the equatorial regions of Mars. And, like the red planet, Devon Island is cold and uninhabited.
Perhaps the most intense Mars analog mission to date was MARS-500, conduced by Russia, the European Space Agency and China beginning in 2007. The 19,000-square-foot (550-square-metre) mockup included a main spacecraft, a smaller landing craft and an “outdoor” Martian landscape. The mission lasted a total of 520 days.
Fox is airing Stars on Mars, a reality show set in a simulated Martian base in Australia.Photo by FOX
In a lighter (and less scientifically accurate) vein is Stars on Mars, a reality TV show that debuted on Fox this month and places 12 celebrities in a Mars-lookalike landscape in a remote part of South Australia. Contestants include cyclist Lance Armstrong (no relation to Neil), actor Christopher Mintz-Plasse, Super Bowl champion Marshawn Lynch (note the first name) and pro wrestler Ronda Rousey.
“This is the most realistic celebrity Mars colony simulation ever created,” says host William Shatner in the trailer for the show, his wiggle words making it hard to argue with the statement. Unlike more serious-minded analogs, however, Stars on Mars will send one astronaut “back to Earth” each week until only one remains.
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