SPACE
Galaxies in dense environments tend to be larger, settling one cosmic question and raising others
image:
Images of galaxies of a variety of shapes and sizes. New research shows that galaxies with more nearby neighbors tend to be larger.
view moreCredit: NAOJ/NASA/ESA/CSA
Link to release:
https://www.washington.edu/news/2024/08/14/galaxy-size/
FROM: James Urton
University of Washington
206-543-2580
(Note: researcher contact information at the end)
For decades, scientists have known that some galaxies reside in dense environments with lots of other galaxies nearby. Others drift through the cosmos essentially alone, with few or no other galaxies in their corner of the universe.
A new study has found a major difference between galaxies in these divergent settings: Galaxies with more neighbors tend to be larger than their counterparts, which have a similar shape and mass, but reside in less dense environments. In a paper published Aug. 14 in the Astrophysical Journal, researchers at the University of Washington, Yale University, the Leibniz Institute for Astrophysics Potsdam in Germany and Waseda University in Japan report that galaxies found in denser regions of the universe are as much as 25% larger than isolated galaxies.
The research, which used a new machine-learning tool to analyze millions of galaxies, helps resolve a long-standing debate among astrophysicists over the relationship between a galaxy’s size and its environment. The findings also raise new questions about how galaxies form and evolve over billions of years.
“Current theories of galaxy formation and evolution cannot adequately explain the finding that clustered galaxies are larger than their identical counterparts in less dense regions of the universe,” said lead author Aritra Ghosh, a UW postdoctoral researcher in astronomy and an LSST-DA Catalyst Fellow with the UW’s DiRAC Institute. “That’s one of the most interesting things about astrophysics. Sometimes what the theories predict we should find and what a survey actually finds are not in agreement, and so we go back and try to modify existing theories to better explain the observations.”
Past studies that looked into the relationship between galaxy size and environment came up with contradictory results. Some determined that galaxies in clusters were smaller than isolated galaxies. Others came to the opposite conclusion. The studies were generally much smaller in scope, based on observations of hundreds or thousands of galaxies.
In this new study, Ghosh and his colleagues utilized a survey of millions of galaxies conducted using the Subaru Telescope in Hawaii. This endeavor, known as the Hyper Suprime-Cam Subaru Strategic Program, took high-quality images of each galaxy. The team selected approximately 3 million galaxies with the highest-quality data and used a machine learning algorithm to determine the size of each one. Next, the researchers essentially placed a circle — one with a radius of 30 million light years — around each galaxy. The circle represents the galaxy’s immediate vicinity. They then asked a simple question: How many neighboring galaxies lie within that circle?
The answer showed a clear general trend: Galaxies with more neighbors were also on average larger.
There could be many reasons why. Perhaps densely clustered galaxies are simply larger when they first form, or are more likely to undergo efficient mergers with close neighbors. Perhaps dark matter — that mysterious substance that makes up most of the matter in the universe, yet cannot be detected directly by any current means – plays a role. After all, galaxies form within individual “halos” of dark matter and the gravitational pull from those halos plays a critical role in how galaxies evolve.
“Theoretical astrophysicists will have to perform more comprehensive studies using simulations to conclusively establish why galaxies with more neighbors tend to be larger,” said Ghosh. “For now, the best we can say is that we’re confident that this relationship between galaxy environment and galaxy size exists.”
Utilizing an incredibly large dataset like the Hyper Suprime-Cam Subaru Strategic Program helped the team reach a clear conclusion. But that’s only part of the story. The novel machine learning tool they used to help determine the size of each individual galaxy also accounted for inherent uncertainties in the measurements of galaxy size.
“One important lesson we had learned prior to this study is that settling this question doesn’t just require surveying large numbers of galaxies,” said Ghosh. “You also need careful statistical analysis. A part of that comes from machine learning tools that can accurately quantify the degree of uncertainty in our measurements of galaxy properties.”
The machine learning tool that they used is called GaMPEN — or Galaxy Morphology Posterior Estimation Network. As a doctoral student at Yale, Ghosh led development of GaMPEN, which was unveiled in papers published in 2022 and 2023 in the Astrophysical Journal. The tool is freely available online and could be adapted to analyze other large surveys, said Ghosh.
Though this new study focuses on galaxies, it also forecasts the types of research — centered on complex analyses of incredibly large datasets — that will soon take astronomy by storm. When a generation of new telescopes with powerful cameras, including the Vera C. Rubin Observatory in Chile, come online, they will collect massive amounts of data on the cosmos every night. In anticipation, scientists have been developing new tools like GaMPEN that can utilize these large datasets to answer pressing questions in astrophysics.
“Very soon, large datasets will be the norm in astronomy,” said Ghosh. “This study is a perfect demonstration of what you can do with them — when you have the right tools.”
Co-authors on the study are Meg Urry, professor of physics and of astronomy at Yale; Meredith Powell, a research fellow with the Leibniz Institute; Rhythm Shimakawa, associate professor at Waseda University; Frank van den Bosch, a Yale professor of astronomy; Daisuke Nagai, professor of physics and of astronomy at Yale; Kaustav Mitra, a doctoral student at Yale; and Andrew Connolly, professor of astronomy at the UW and faculty member in the DiRAC Institute and the eScience Institute. The research was funded by NASA, the Yale Graduate School of Arts & Sciences, the John Templeton Foundation, the Charles and Lisa Simonyi Fund for Arts and Sciences, the Washington Research Foundation and the UW eScience Institute.
Image of Abell 2218, a dense galactic cluster approximately 2 billion light years from Earth.
Image URL: https://esahubble.org/images/heic0814a/
For more information, contact Ghosh at aritrag@uw.edu.
Grant numbers
- NASA: 80NSSC23K0488
- John Templeton Foundation: 62192
Journal
The Astrophysical Journal
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Denser Environments Cultivate Larger Galaxies: A Comprehensive Study beyond the Local Universe with 3 Million Hyper Suprime-Cam Galaxies
UAF scientists discover phenomenon impacting Earth’s radiation belts
University of Alaska Fairbanks
Two University of Alaska Fairbanks scientists have discovered a new type of “whistler,” an electromagnetic wave that carries a substantial amount of lightning energy to the Earth’s magnetosphere.
The research is published today in Science Advances.
Vikas Sonwalkar, a professor emeritus, and Amani Reddy, an assistant professor, discovered the new type of wave. The wave carries lightning energy, which enters the ionosphere at low latitudes, to the magnetosphere. The energy is reflected upward by the ionosphere’s lower boundary, at about 55 miles altitude, in the opposite hemisphere.
It was previously believed, the authors write, that lightning energy entering the ionosphere at low latitudes remained trapped in the ionosphere and therefore was not reaching the radiation belts. The belts are two layers of charged particles surrounding the planet and held in place by Earth's magnetic field.
“We as a society are dependent on space technology,” Sonwalkar said. “Modern communication and navigation systems, satellites, and spacecraft with astronauts aboard encounter harmful energetic particles of the radiation belts, which can damage electronics and cause cancer.
“Having a better understanding of radiation belts and the variety of electromagnetic waves, including those originating in terrestrial lightning, that impact them is vital for human operations in space,” he said.
Sonwalkar and Reddy’s discovery is a type of whistler wave they call a “specularly reflected whistler.” Whistlers produce a whistling sound when played through a speaker.
Lightning energy entering the ionosphere at higher latitudes reaches the magnetosphere as a different type of whistler called a magnetospherically reflected whistler, which undergoes one or more reflections within the magnetosphere.
The ionosphere is a layer of Earth's upper atmosphere characterized by a high concentration of ions and free electrons. It is ionized by solar radiation and cosmic rays, making it conductive and crucial for radio communication because it reflects and modifies radio waves.
Earth's magnetosphere is a region of space surrounding the planet and created by Earth's magnetic field. It provides a protective barrier that prevents most of the solar wind's particles from reaching the atmosphere and harming life and technology.
Sonwalkar and Reddy’s research shows that both types of whistlers — specularly reflected whistlers and magnetospherically reflected whistlers — coexist in the magnetosphere.
In their research, the authors used plasma wave data from NASA’s Van Allen Probes, which launched in 2012 and operated until 2019, and lightning data from the World Wide Lightning Detection Network.
They developed a wave propagation model that, when considering specularly reflected whistlers, showed the doubling of lightning energy reaching the magnetosphere.
Review of plasma wave data from the Van Allen Probes showed that specularly reflected whistlers are a common magnetospheric phenomenon.
A majority of lightning occurs at the low latitudes, which are tropical and subtropical regions prone to thunderstorm development.
“This implies that specularly reflected whistlers probably carry a greater part of lightning energy to the magnetosphere relative to that carried by magnetospherically reflected whistlers,” Sonwalkar said.
The impact of lightning-generated whistler waves on radiation belt physics and their use in remote sensing of magnetospheric plasma have been researched since the 1950s.
Sonwalkar and Reddy are with the Department of Electrical and Computer Engineering in the UAF College of Engineering and Mines. Reddy is also affiliated with the UAF Geophysical Institute.
Sonwalkar and Reddy’s research is supported by grants from the National Science Foundation and NASA EPSCoR, the Established Program to Stimulate Competitive Research.
CONTACTS:
• Vikas Sonwalkar, University of Alaska Fairbanks vssonwalkar@alaska.edu
• Rod Boyce, University of Alaska Fairbanks Geophysical Institute, 907-474-7185, rcboyce@alaska.edu
Two University of Alaska Fairbanks scientists have discovered a new type of “whistler,” an electromagnetic wave that carries a substantial amount of lightning energy to the Earth’s magnetosphere.
The research is published today in Science Advances.
Vikas Sonwalkar, a professor emeritus, and Amani Reddy, an assistant professor, discovered the new type of wave. The wave carries lightning energy, which enters the ionosphere at low latitudes, to the magnetosphere. The energy is reflected upward by the ionosphere’s lower boundary, at about 55 miles altitude, in the opposite hemisphere.
It was previously believed, the authors write, that lightning energy entering the ionosphere at low latitudes remained trapped in the ionosphere and therefore was not reaching the radiation belts. The belts are two layers of charged particles surrounding the planet and held in place by Earth's magnetic field.
“We as a society are dependent on space technology,” Sonwalkar said. “Modern communication and navigation systems, satellites, and spacecraft with astronauts aboard encounter harmful energetic particles of the radiation belts, which can damage electronics and cause cancer.
“Having a better understanding of radiation belts and the variety of electromagnetic waves, including those originating in terrestrial lightning, that impact them is vital for human operations in space,” he said.
Sonwalkar and Reddy’s discovery is a type of whistler wave they call a “specularly reflected whistler.” Whistlers produce a whistling sound when played through a speaker.
Lightning energy entering the ionosphere at higher latitudes reaches the magnetosphere as a different type of whistler called a magnetospherically reflected whistler, which undergoes one or more reflections within the magnetosphere.
The ionosphere is a layer of Earth's upper atmosphere characterized by a high concentration of ions and free electrons. It is ionized by solar radiation and cosmic rays, making it conductive and crucial for radio communication because it reflects and modifies radio waves.
Earth's magnetosphere is a region of space surrounding the planet and created by Earth's magnetic field. It provides a protective barrier that prevents most of the solar wind's particles from reaching the atmosphere and harming life and technology.
Sonwalkar and Reddy’s research shows that both types of whistlers — specularly reflected whistlers and magnetospherically reflected whistlers — coexist in the magnetosphere.
In their research, the authors used plasma wave data from NASA’s Van Allen Probes, which launched in 2012 and operated until 2019, and lightning data from the World Wide Lightning Detection Network.
They developed a wave propagation model that, when considering specularly reflected whistlers, showed the doubling of lightning energy reaching the magnetosphere.
Review of plasma wave data from the Van Allen Probes showed that specularly reflected whistlers are a common magnetospheric phenomenon.
A majority of lightning occurs at the low latitudes, which are tropical and subtropical regions prone to thunderstorm development.
“This implies that specularly reflected whistlers probably carry a greater part of lightning energy to the magnetosphere relative to that carried by magnetospherically reflected whistlers,” Sonwalkar said.
The impact of lightning-generated whistler waves on radiation belt physics and their use in remote sensing of magnetospheric plasma have been researched since the 1950s.
Sonwalkar and Reddy are with the Department of Electrical and Computer Engineering in the UAF College of Engineering and Mines. Reddy is also affiliated with the UAF Geophysical Institute.
Sonwalkar and Reddy’s research is supported by grants from the National Science Foundation and NASA EPSCoR, the Established Program to Stimulate Competitive Research.
CONTACTS:
• Vikas Sonwalkar, University of Alaska Fairbanks vssonwalkar@alaska.edu
• Rod Boyce, University of Alaska Fairbanks Geophysical Institute, 907-474-7185, rcboyce@alaska.edu
Journal
Science Advances
Science Advances
DOI
Article Title
Specularly reflected whistler: A low-latitude channel to couple lightning energy to the magnetosphere
Specularly reflected whistler: A low-latitude channel to couple lightning energy to the magnetosphere
Article Publication Date
16-Aug-2024
16-Aug-2024
Chicxulub impactor was a carbonaceous-type asteroid from beyond Jupiter
American Association for the Advancement of Science (AAAS)
Scientists have pinpointed the origin and composition of the asteroid that caused the mass extinction 66 million years ago, revealing it was a rare carbonaceous asteroid from beyond Jupiter, according to a new study. The findings help resolve long-standing debates about the nature of Chicxulub impactor, reshaping our understanding of Earth's history and the extraterrestrial rocks that have collided with it. Earth has experienced several mass extinction events. The most recent event occurred 66 million years ago at the boundary between the Cretaceous and Paleogene eras (K-Pg boundary) and resulted in the loss of roughly 60% of the planet’s species, including non-avian dinosaurs. The Chicxulub impactor, a massive asteroid that collided with Earth in what is now the Gulf of Mexico, is thought to have played a key role in this extinction event. Evidence includes high levels of platinum-group elements (PGEs) like iridium, ruthenium, osmium, rhodium, platinum, and palladium in K-Pg boundary layers, which are rare on Earth but common in meteorites. These elevated PGE levels have been found globally, suggesting the impact spread debris worldwide. While some propose large-scale volcanic activity from the Deccan Traps igneous province as an alternative source of PGEs, the specific PGE ratios at the K-Pg boundary align more with asteroid impacts than volcanic activity. However, much about the nature of the Chicxulub impactor – its composition and extraterrestrial origin – is poorly understood.
To address these questions, Mario Fischer-Gödde and colleagues evaluated ruthenium (Ru) isotopes in samples taken from the K-Pg boundary. For comparison, they also analyzed samples from five other asteroid impacts from the last 541 million years, samples from ancient Archaean-age (3.5 – 3.2 billion-years-old) impact-related spherule layers, and samples from two carbonaceous meteorites. Ficher-Gödde et al. found that the Ru isotope signatures in samples from the K-Pg boundary were uniform and closely matched those of carbonaceous chondrites (CCs), not Earth or other meteorite types, suggesting that the Chicxulub impactor likely came from a C-type asteroid that formed in the outer Solar System. They also rule out a comet as the impactor. Ancient Archean samples also suggest impactors with a CC-like composition, indicating a similar outer Solar System origin and perhaps representing material that impacted during Earth’s final stages of accretion. In contrast, other impact sites from different periods showed Ru isotope compositions consistent with S-type (salicaceous) asteroids from the inner Solar System.
Podcast: A segment of Science's weekly podcast, related to this research, will be available on the Science.org podcast landing page after the embargo lifts. Reporters are free to make use of the segments for broadcast purposes and/or quote from them – with appropriate attribution (i.e., cite "Science podcast"). Please note that the file itself should not be posted to any other Web site.
Journal
Science
Article Title
Ruthenium isotopes show the Chicxulub impactor was a carbonaceous-type asteroid
Article Publication Date
16-Aug-2024
Tracking down the asteroid that sealed the fate of the dinosaurs
University of Cologne
Geoscientists from the University of Cologne have led an international study to determine the origin of the huge piece of rock that hit the Earth around 66 million years ago and permanently changed the climate. The scientists analysed samples of the rock layer that marks the boundary between the Cretaceous and Paleogene periods. This period also saw the last major mass extinction event on Earth, in which around 70 percent of all animal species became extinct. The results of the study published in Science indicate that the asteroid formed outside Jupiter’s orbit during the early development of our solar system.
According to a widely accepted theory, the mass extinction at the Cretaceous-Paleogene boundary was triggered by the impact of an asteroid at least 10 kilometres in diameter near Chicxulub on the Yucatán Peninsula in Mexico. On impact, the asteroid and large quantities of earth rock vaporized. Fine dust particles spread into the stratosphere and obscured the sun. This led to dramatic changes in the living conditions on the planet and brought photosynthetic activity to a halt for several years.
The dust particles released by the impact formed a layer of sediment around the entire globe. This is why the Cretaceous-Paleogene boundary can be identified and sampled in many places on Earth. It contains high concentrations of platinum-group metals, which come from the asteroid and are otherwise extremely rare in the rock that forms the Earth’s crust.
By analysing the isotopic composition of the platinum metal ruthenium in the cleanroom laboratory of the University of Cologne’s Institute of Geology and Mineralogy, the scientists discovered that the asteroid originally came from the outer solar system. “The asteroid’s composition is consistent with that of carbonaceous asteroids that formed outside of Jupiter’s orbit during the formation of the solar system,” said Dr Mario Fischer-Gödde, first author of the study.
The ruthenium isotope compositions were also determined for other craters and impact structures of different ages on Earth for comparison. This data shows that within the last 500 million years, almost exclusively fragments of S-type asteroids have hit the Earth. In contrast to the impact at the Cretaceous-Paleogene boundary, these asteroids originate from the inner solar system. Well over 80 percent of all asteroid fragments that hit the Earth in the form of meteorites come from the inner solar system. Professor Dr Carsten Münker, co-author of the study, added: “We found that the impact of an asteroid like the one at Chicxulub is a very rare and unique event in geological time. The fate of the dinosaurs and many other species was sealed by this projectile from the outer reaches of the solar system.”
Journal
Science
Article Title
Ruthenium isotopes show the Chicxulub impactor was a carbonaceous-type asteroid
Article Publication Date
16-Aug-2024
Nanohertz gravitational waves are cool but not supercool
A new study sheds light on the origin of low-frequency space-time ripples
Xi'an Jiaotong-Liverpool University
image:
This illustration shows a stage in the merger of two galaxies that forms a single galaxy with two centrally located supermassive black holes surrounded by disks of hot gas. The black holes orbit each other for hundreds of millions of years before they merge to form a single supermassive black hole that sends out intense gravitational waves.
view moreCredit: NASA/CXC/A.Hobart, Public domain, via Wikimedia Commons
Similar to the ripples produced from dropping a stone in water, the collision of large celestial objects, such as black holes, generates gravitational waves – ripples in the fabric of space-time.
A specific type, nanohertz gravitational waves, was identified in 2023. These waves have such a low frequency that it took scientists over 10 years to see a complete cycle. However, how these waves are generated is still unclear.
Some scientists thought they came from a first-order phase transition – a change in the universe's structure as it expands and cools down. Yet a new study published in Physical Review Letters challenges that theory.
Dr Andrew Fowlie, Assistant Professor at Xi'an Jiaotong-Liverpool University (XJTLU), China, and an author of the paper, says: "Theorists and experimentalists have speculated nanohertz gravitational waves originated from a known transition that happened very soon after the big bang – a change that generated the masses of all the known fundamental particles.
"However, our work uncovers serious problems with that otherwise appealing explanation of their origin."
Incomplete transitions
"We found that to have created waves with such tiny frequencies, the transition would have to be supercool," says Dr Fowlie.
We can understand supercooled transitions by thinking about ice and water. We all know that water changes to ice as temperature cools below freezing. Water may, however, become stuck in the liquid phase, even below the freezing point, slowing down the transition to ice.
However, Dr Fowlie explains why his research team believes nanohertz gravitational waves are not produced by supercooled first-order phase transitions. "These slow transitions would struggle to finish, as the transition rate is slower than the cosmic expansion rate of the universe.
"What if the transition sped up at the end? We calculated that even if this helped the transition to end, it would shift the frequency of the waves away from nanohertz.
"Thus, although nanohertz gravitational waves are cool, they are probably not supercool in origin.
"If these gravitational waves do come from first-order phase transitions, we now know that there must be some new, much richer physics going on – physics we don't know about yet."
Mysteries remain
Dr Fowlie and co-authors say their results show that more care is needed when studying supercool transitions.
"Because these are necessarily slow transitions, the usual simplifications of whether transitions complete or not won't work.
"There are a lot of subtleties in the connections between the energy scale of the transitions and the frequency of the waves, so we need more careful and sophisticated techniques when considering gravitational waves and supercool transitions."
"Understanding this field will help us understand the most fundamental questions about the origin of the universe.
"It also has links to applications that are closer to home, such as understanding how water flows through a rock, the best ways to percolate coffee, and how wildfires spread."
Dr Fowlie's interest in gravitational waves was sparked when they were first detected in 2015; he was working at Monash University, Australia, where they were quick to develop their investigations using this new breakthrough.
"I was lucky enough to be in the right place when it was still relatively early to be working in this field, so we could be ready to think about the impact that the phenomenology of gravitational waves and their detection can have on current models of physics."
Journal
Physical Review Letters
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Can Supercooled Phase Transitions Explain the Gravitational Wave Background Observed by Pulsar Timing Arrays?
Study: Rocks from Mars’ Jezero Crater, which likely predate life on Earth, contain signs of water
The presence of organic matter is inconclusive, but the rocks could be scientists’ best chance at finding remnants of ancient Martian life.
Massachusetts Institute of Technology
image:
NASA’s Perseverance rover puts its robotic arm to work around a rocky outcrop called “Skinner Ridge” in Mars’ Jezero Crater. Composed of multiple images, this mosaic shows layered sedimentary rocks in the face of a cliff in the delta, as well as one of the locations where the rover abraded a circular patch to analyze a rock’s composition.
view moreCredit: NASA/JPL-Caltech/ASU/MSSS
In a new study appearing today in the journal AGU Advances, scientists at MIT and NASA report that seven rock samples collected along the “fan front” of Mars’ Jezero Crater contain minerals that are typically formed in water. The findings suggest that the rocks were originally deposited by water, or may have formed in the presence of water.
The seven samples were collected by NASA’s Perseverance rover in 2022 during its exploration of the crater’s western slope, where some rocks were hypothesized to have formed in what is now a dried-up ancient lake. Members of the Perseverance science team, including MIT scientists, have studied the rover’s images and chemical analyses of the samples, and confirmed that the rocks indeed contain signs of water, and that the crater was likely once a watery, habitable environment.
Whether the crater was actually inhabited is yet unknown. The team found that the presence of organic matter — the starting material for life — cannot be confirmed, at least based on the rover’s measurements. But judging from the rocks’ mineral content, scientists believe the samples are their best chance of finding signs of ancient Martian life once the rocks are returned to Earth for more detailed analysis.
“These rocks confirm the presence, at least temporarily, of habitable environments on Mars,” says the study’s lead author, Tanja Bosak, professor of geobiology in MIT’s Department of Earth, Atmospheric, and Planetary Sciences (EAPS). “What we’ve found is that indeed there was a lot of water activity. For how long, we don’t know, but certainly for long enough to create these big sedimentary deposits.”
What’s more, some of the collected samples may have originally been deposited in the ancient lake more than 3.5 billion years ago — before even the first signs of life on Earth.
“These are the oldest rocks that may have been deposited by water, that we’ve ever laid hands or rover arms on,” says co-author Benjamin Weiss, the Robert R. Shrock Professor of Earth and Planetary Sciences at MIT. “That’s exciting, because it means these are the most promising rocks that may have preserved fossils, and signatures of life.”
The study’s MIT co-authors include postdoc Eva Scheller, and research scientist Elias Mansbach, along with members of the Perseverance science team.
At the front
The new rock samples were collected in 2022 as part of the rover’s Fan Front Campaign — an exploratory phase during which Perseverance traversed Jezero Crater’s western slope, where a fan-like region contains sedimentary, layered rocks. Scientists suspect that this “fan front” is an ancient delta that was created by sediment that flowed with a river and settled into a now bone-dry lakebed. If life existed on Mars, scientists believe that it could be preserved in the layers of sediment along the fan front.
In the end, Perseverance collected seven samples from various locations along the fan front. The rover obtained each sample by drilling into the Martian bedrock and extracting a pencil-sized core, which it then sealed in a tube to one day be retrieved and returned to Earth for detailed analysis.
Prior to extracting the cores, the rover took images of the surrounding sediments at each of the seven locations. The science team then processed the imaging data to estimate a sediment’s average grain size and mineral composition. This analysis showed that all seven collected samples likely contain signs of water, suggesting that they were initially deposited by water.
Specifically, Bosak and her colleagues found evidence of certain minerals in the sediments that are known to precipitate out of water.
“We found lots of minerals like carbonates, which are what make reefs on Earth,” Bosak says. “And it’s really an ideal material that can preserve fossils of microbial life.”
Interestingly, the researchers also identified sulfates in some samples that were collected at the base of the fan front. Sulfates are minerals that form in very salty water — another sign that water was present in the crater at one time — though very salty water, Bosak notes, “is not necessarily the best thing for life.” If the entire crater was once filled with very salty water, then it would be difficult for any form of life to thrive. But if only the bottom of the lake were briny, that could be an advantage, at least for preserving any signs of life that may have lived further up, in less salty layers, that eventually died and drifted down to the bottom.
“However salty it was, if there were any organics present, it's like pickling something in salt,” Bosak says. “If there was life that fell into the salty layer, it would be very well-preserved.”
Fuzzy fingerprints
But the team emphasizes that organic matter has not been confidently detected by the rover’s instruments. Organic matter can be signs of life, but can also be produced by certain geological processes that have nothing to do with living matter. Perseverance’s predecessor, the Curiosity rover, had detected organic matter throughout Mars’ Gale Crater, which scientists suspect may have come from asteroids that made impact with Mars in the past.
And in a previous campaign, Perseverance detected what appeared to be organic molecules at multiple locations along Jezero Crater’s floor. These observations were taken by the rover’s Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument, which uses ultraviolet light to scan the Martian surface. If organics are present, they can glow, similar to material under a blacklight. The wavelengths at which the material glows act as a sort of fingerprint for the kind of organic molecules that are present.
In Perseverance’s previous exploration of the crater floor, SHERLOC appeared to pick up signs of organic molecules throughout the region, and later, at some locations along the fan front. But a careful analysis, led by MIT’s Eva Scheller, has found that while the particular wavelengths observed could be signs of organic matter, they could just as well be signatures of substances that have nothing to do with organic matter.
“It turns out that cerium metals incorporated in minerals actually produce very similar signals as the organic matter,” Scheller says. “When investigated, the potential organic signals were strongly correlated with phosphate minerals, which always contain some cerium.”
Scheller’s work shows that the rover’s measurements cannot be interpreted definitively as organic matter.
“This is not bad news,” Bosak says. “It just tells us there is not very abundant organic matter. It’s still possible that it’s there. It’s just below the rover’s detection limit.”
When the collected samples are finally sent back to Earth, Bosak says laboratory instruments will have more than enough sensitivity to detect any organic matter that might lie within.
“On Earth, once we have microscopes with nanometer-scale resolution, and various types of instruments that we cannot staff on one rover, then we can actually attempt to look for life,” she says.
This work was supported in part by NASA.
###
Written by Jennifer Chu, MIT News
Paper: “Astrobiological potential of rocks acquired by the Perseverance rover at a sedimentary fan front in Jezero crater, Mars”
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024AV001241
Journal
AGU Advances
Article Title
“Astrobiological potential of rocks acquired by the Perseverance rover at a sedimentary fan front in Jezero crater, Mars”
Rocks collected on Mars hold key to water and perhaps life on the planet. Bring them back to Earth.
Only Earth-based analysis of sediments gathered by rover can retrieve clues to Mars' water history
image:
Red hexagons mark the four sites where the Perseverance rover collected rock samples around the sediment fan in Jezero crater in 2022.
view moreCredit: NASA
Over the course of nearly five months in 2022, NASA's Perseverance rover collected rock samples from Mars that could rewrite the history of water on the Red Planet and even contain evidence for past life on Mars.
But the information they contain can't be extracted without more detailed analysis on Earth, which requires a new mission to the planet to retrieve the samples and bring them back. Scientists hope to have the samples on Earth by 2033, though NASA's sample return mission may be delayed.
"These samples are the reason why our mission was flown," said paper co-author David Shuster, professor of earth and planetary science at the University of California, Berkeley, and a member of NASA’s science team for sample collection. "This is exactly what everyone was hoping to accomplish. And we've accomplished it. These are what we went looking for."
The critical importance of these rocks, sampled from river deposits in a dried-up lake that once filled a crater called Jezero, is detailed in a study to be published Aug. 14 in AGU Advances, a journal of the American Geophysical Union.
"These are the first and only sedimentary rocks that have been studied and collected from a planet other than Earth," said paper co-author David Shuster, professor of earth and planetary science at the University of California, Berkeley, and a member of NASA’s science team for sample collection. "Sedimentary rocks are important because they were transported by water, deposited into a standing body of water and subsequently modified by chemistry that involved liquid water on the surface of Mars at some point in the past. The whole reason that we came to Jezero was to study this sort of rock type. These are absolutely fantastic samples for the overarching objectives of the mission."
Shuster is co-author of the paper with first author Tanja Bosak, a geobiologist at the Massachusetts Institute of Technology (MIT) in Cambridge.
"These rock cores are likely the oldest materials sampled from any known environment that may have supported life," Bosak said. "When we bring them back to Earth, they can tell us so much about when, why and for how long Mars contained liquid water, and whether some organic, prebiotic and potentially even biological evolution may have taken place on that planet."
Significantly, some of the samples contain very fine-grained sediments that are the most likely type of rock to retain evidence of past microbial life on Mars — if there ever was or is life on the planet.
"Liquid water is a key element in all of this because it is the key ingredient for biological activity, as far as we understand it," said Shuster, a geochemist. "Fine-grained sedimentary rocks on Earth are those that are most likely to preserve signatures of past biological activity, including organic molecules. That's why these samples are so important."
NASA announced on July 25 that Perseverance had collected new rock samples from an outcrop named Cheyava Falls that also might contain signs of past life on Mars. The rover's scientific instruments detected evidence of organic molecules, while "leopard spot" inclusions in the rocks are similar to features that on Earth are often associated with fossilized microbial life.
In a statement, Ken Farley, Perseverance project scientist at Caltech, said, “Scientifically, Perseverance has nothing more to give. To fully understand what really happened in that Martian river valley at Jezero crater billions of years ago, we’d want to bring the Cheyava Falls sample back to Earth, so it can be studied with the powerful instruments available in laboratories.”
Sediments hold the answers
Shuster noted that Jezero and the fan of sediments left behind by the river that once flowed into it likely formed 3.5 billion years ago. That abundant water is now gone, either trapped underground or lost to space. But Mars was wet at a time when life on Earth — in the form of microbes — was already everywhere.
"Life was doing its thing on Earth at that point in time, 3.5 billion years ago," he said. "The basic question is: Was life also doing its thing on Mars at that point in time?"
"Anywhere on Earth over the last 3.5 billion years, if you give me the scenario of a river flowing into a crater transporting materials to a standing body of water, biology would have taken hold there and left its mark, in one way or another," Shuster said. "And in the fine-grained sediment, specifically, we would have a very good chance of recording that biology in the laboratory observations that we can make on that material on Earth."
Shuster and Bosak acknowledge that the organic analysis equipment aboard the rover did not detect organic molecules in the four samples from the sedimentary fan. Organic molecules are used and produced by the type of life we're familiar with on Earth, though their presence is not unequivocal evidence of life.
"We did not clearly observe organic compounds in these key samples," Shuster said. "But just because that instrument did not detect organic compounds does not mean that they are not in these samples. It just means they weren't at a concentration detectable by the rover instrumentation in those particular rocks."
To date, Perseverance has collected a total of 25 samples, including duplicates and atmospheric samples, plus three "witness tubes" that capture possible contaminants around the rover. Eight duplicate rock samples plus an atmospheric sample and witness tube were deposited in the so-called Three Forks cache on the surface of Jezero as a backup in case the rover suffers problems and the onboard samples can't be retrieved. The other 15 samples — including the Cheyava Falls sample collected July 21 — remain aboard the rover awaiting recovery.
Shuster was part of a team that analyzed the first eight rock samples collected, two from each site on the crater floor, all of which were igneous rocks likely created when a meteor impact smashed into the surface and excavated the crater. Those results were reported in a 2023 paper, based on analyses by the instruments aboard Perseverance.
The new paper is an analysis of seven more samples, three of them duplicates now cached on Mars' surface, collected between July 7 and November 29 of 2022 from the front of the western sediment fan in Jezero. Bosak, Shuster and their colleagues found the rocks to be composed mostly of sandstone and mudstone, all created by fluvial processes.
"Perseverance encountered aqueously deposited sedimentary rocks at the front, top and margin of the western Jezero fan and collected a sample suite composed of eight carbonate-bearing sandstones, a sulfate-rich mudstone, a sulfate-rich sandstone, a sand-pebble conglomerate," Bosak said. "The rocks collected at the fan front are the oldest, whereas the rocks collected at the fan top are likely the youngest rocks produced during aqueous activity and sediment deposition in the western fan."
While Bosak is most interested in possible biosignatures in the fine-grained sediments, the coarse-grained sediments also contain key information about water on Mars, Shuster said. Though less likely to preserve organic matter or potential biological materials, they contain carbonate materials and detritus washed from upstream by the now-vanished river. They thus could help determine when water actually flowed on Mars, the main emphasis of Shuster's own research.
"With lab analysis of those detrital minerals, we could make quantitative statements about when the sediments were deposited and the chemistry of that water. What was the pH (acidity) of that water when those secondary phases precipitated? At what point in time was that chemical alteration taking place?" he said. "We have this combination of samples now in the sample suite that are going to enable us to understand the environmental conditions when the liquid water was flowing into the crater. When was that liquid water flowing into the crater? Was it intermittent?"
Answers to these questions rely upon analyses of the returned materials in terrestrial laboratories to uncover the organic, isotopic, chemical, morphological, geochronological and paleomagnetic information they record, the researchers emphasized.
"One of the most important planetary science objectives is to bring these samples back," Shuster said.
Journal
AGU Advances
Article Title
● Astrobiological potential of rocks acquired by the Perseverance rover at a sedimentary fan front in Jezero crater, Mars
Article Publication Date
14-Aug-2024
A 76m per pixel global color image dataset and map of Mars by Tianwen-1 has been released
image:
A true color Mars global image map in Robinson projection is created with Tianwen-1 MoRIC image data, the resolution of the original data is ~76 m per pixel, and the horizontal accuracy is 68 m.
view moreCredit: ©Science China Press
Remote-sensing images of Mars contain rich information about its surface morphology, topography, and geological structure. These data are fundamental for scientific research and exploration missions of Mars. Prior to China's first Mars exploration mission, data from six advanced optical imaging systems of different missions in the Martian orbit have been used to generate Mars global/near-global image datasets with spatial resolutions better than 1 km. However, in terms of global color images, the best version of Mars Viking Colorized Global Mosaic has a resolution of ~232 m/pixel. There is a lack of global color images of Mars at the hundred-meter scale and higher resolution.
New data obtained by Tianwen-1 mission have laid the foundation for the development of a high-resolution global color-image map of Mars with high positioning accuracy. As of July 25, 2022, Tianwen-1 Moderate Resolution Imaging Camera (MoRIC) had completed imaging over 284 orbits during its remote-sensing mission period, acquiring 14,757 images with spatial resolutions between 57 and 197 m. The collected images achieved global coverage of the Martian surface. At almost the same time, a total of 325 strips of data in the visible and near-infrared bands were obtained by Tianwen-1 Mars Mineralogical Spectrometer, with spatial resolutions varying from 265–800 m.
With above mentioned data, Professor Li Chunlai at National Astronomical Observatory of the Chinese Academy of Sciences, and Professor Zhang Rongqiao at Lunar Exploration and Space Engineering Center, have led the Tianwen-1 science team and collaborators to conduct the research of image data processing and global mapping of Mars. This study used the bundle adjustment technology to optimize the original orbit measurement data by treating Mars as a unified adjustment network, reduce the position deviation between individual MoRIC images to under 1 pixel, and achieve pixel-level “seamless” global image mosaicking. Brightness and color consistency of the global images was ensured through color correction and global color uniformity. The true colors of the Martian surface were measured using the MMS onboard the Tianwen-1 orbiter, and a true-color reference for the Martian surface was established for true color restoration. Through this study, A global color image dataset and map of Mars (Tianwen-1 Mars Global Color Orthomosaic 76 m v1), with a resolution of 76 m and a horizontal accuracy of 68 m was produced and released.
The Tianwen-1 Mars Global Color Orthomosaic data products fill the gap in the high-precision positioning of Mars global color-image data products at a scale of tens of meters. It is currently the highest resolution global true-color image map of Mars, and significantly improves the resolution and color authenticity of commonly used global Mars images. This mapping product can serve as a new Mars global base map, providing a higher-quality geographic reference for international peers to conduct Mars image mapping at scales of tens of meters, meters, and submeters, as well as supporting subsequent Mars exploration missions and scientific research.
Exploration illustration of the MoRIC and MMS
The optical camera (MoRIC) and imaging spectrometer (MMS) onboard the Tianwen-1 orbiter were used to obtain remote-sensing images of the entire Martian surface. MoRIC employs a step-starting frame imaging technique with a color-imaging sensor and obtains Martian surface image data along the flight direction when the orbital arc is below an altitude of 800 km at the periareion. At an orbital altitude of 265 km near the periareion, the imaging swath was 265 km and the resolution was 65 m/pixel. MMS is a linear array push-broom imaging spectrometer that collects spectral images in the visible and near-infrared wavelengths. The imaging swath was 55 km at an orbital altitude of 265 km near the periareion, and the spatial resolution was 265 m/pixel. The MMS obtains spectral data simultaneously while the MoRIC is operating.
Comparison of the MoRIC images before/after
several correction processing
(a) Level 2C data product as the input, (b) image corrected by atmospheric correction, (c) image corrected by photometric correction, and (d) image corrected after color correction.
Credit
©Science China Press
https://doi.org/10.1016/j.scib.2024.04.045
https://clpds.bao.ac.cn/web/enmanager/mars1.
Journal
Science Bulletin
DOI
Science in Space to Cure Disease on Earth—the International Space Station National Lab and NASA announce new funding opportunity
Joint solicitation will award up to $4 million for biomedical R&D leveraging the orbiting laboratory
International Space Station U.S. National Laboratory
KENNEDY SPACE CENTER (FL), August 15, 2024—The International Space Station (ISS) National Laboratory is collaborating with NASA on a solicitation for space-based research addressing some of the most significant diseases of our time—such as cancer, cardiovascular disease, and neurodegenerative disease. ISS National Lab Research Announcement (NLRA) 2024-09: Igniting Innovation: Science in Space to Cure Disease on Earth, released in partnership with NASA’s Biological and Physical Sciences division, is aimed at overcoming challenges hindering progress in disease prevention, diagnosis, and treatment. This NLRA will offer up to $4 million in total funding for an expected two to three awards for multiflight translational and transformative research and technology development.
Through this joint solicitation, the ISS National Lab and NASA seek projects that leverage the space environment to improve existing or develop new technologies that help solve health problems on Earth. Therapies for cancer and cardiovascular, immune, muscle and bone, and neurodegenerative diseases face obstacles that thwart scientific advancements and the translation of research findings into clinical applications. These challenges frequently overlap and share common elements, despite the complexity and variability of mechanisms within and among these diseases. Many of these challenges can be mitigated using accelerated disease models in microgravity through ISS National Lab resources.
This NLRA aims to foster collaboration between academia, industry, and government to develop innovative, commercially viable products and technologies to improve medical outcomes on Earth. Below are topics of particular interest for this NLRA:
- Enhanced Models to Study Disease Mechanisms: It is difficult to unravel the intricate dynamics of disease onset and progression and to identify effective therapeutic targets. Leveraging microgravity to improve cell-based models like tissue chips and organoids could deepen understanding of disease mechanisms and lead to personalized therapies.
- Population and Disease Heterogeneity: Population and disease heterogeneity pose significant obstacles to drug Variability in genetic and demographic factors, such as age and sex, leads to differing treatment responses across individuals. Genetic and phenotypic diversity in diseases themselves must also be considered.
- Drug Screening and Development: Microgravity enables high-throughput drug screening in 3D cell cultures and tissue models that more accurately simulate the human body. Innovative approaches and technologies to identify preclinical drug candidates are needed to accelerate development of new, more effective therapeutics.
- Drug Delivery: Innovation in drug delivery, such as nanotechnology and targeted therapies, is vital to enhance treatment precision and reduce side effects. Additionally, the absence of well-defined biomarkers complicates treatment selection, and innovative strategies for biomarker discovery are needed to improve treatment outcomes.
- Drug Resistance and Toxicity: Drug resistance poses significant challenges in treating many diseases. For example, cancer cells can become resistant due to genetic mutations or changes in signaling pathways, decreasing drug efficacy. Additionally, the toxicity of treatments like chemotherapy requires careful balancing of efficacy and adverse effects.
Last month, at the annual ISS Research and Development Conference in Boston, the ISS National Lab and NASA announced five projects selected through the inaugural Igniting Innovation NLRA, which sought to harness the unique space environment to advance cancer research to benefit patients on Earth.
“We are proud to collaborate again this year with NASA’s Biological and Physical Sciences division on this important initiative to bring the transformative power of space-based inquiry into the fight against diseases that touch all of our lives,” said ISS National Lab Chief Scientific Officer Michael Roberts. “Our inaugural solicitation in 2023 resulted in the selection of five innovative concepts to leverage microgravity and the space station to benefit patients on Earth. We look forward to enabling access to even more ideas that ignite innovation and fuel research and development for the benefit of humanity.”
“Space-based research has a long history of contributing to advancements on Earth,” said Lisa Carnell, director of NASA’s Biological and Physical Sciences division. “Continuing the Igniting Innovation solicitation could contribute to the next big leap in disease therapies. We are excited to collaborate with the ISS National Lab on this endeavor to help address some of the biggest health challenges facing the world today.”
This research announcement will follow a three-step proposal submission process (Step 1A: Concept Summary, Step 1B: Technology Roadmap, and Step 2: Full Proposal). Step 1A: Concept Summaries must be submitted by end of day on September 26, 2024.
Those interested in learning more about this research announcement can register for a webinar hosted by the ISS National Lab on August 22, 2024, at 1 p.m. EDT.
For more information on this funding opportunity and how the space-based environment can accelerate research and technology development for the benefit of life on Earth, please visit the official solicitation page.
Download a high-resolution photo: Igniting Innovation 2024
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