TL;DR
• A new study has found that galaxies with more neighbors tend to be larger than their counterparts with a similar shape and mass but reside in less dense environments. The team, which used a machine-learning algorithm to analyze millions of galaxies, reports that galaxies found in denser regions of the universe are as much as 25% larger than isolated galaxies. The findings resolve a long-standing debate among astrophysicists over the relationship between a galaxy’s size and its environment but also raise new questions about how galaxies form and evolve over billions of years.
• With 2D cameras and space robotics algorithms, astronautics engineers have created a navigation system able to manage multiple satellites using visual data only. They just tested it in space for the first time.
• Using data from NASA’s James Webb Space Telescope, astronomers have confirmed hydroxyl molecules on the surface of the metallic asteroid Psyche. The presence of hydrated minerals suggests a complex history for Psyche, an important context for the NASA spacecraft en route to this interesting asteroid orbiting the Sun between Mars and Jupiter.
• Scientists say they have identified the main process that formed the moon’s atmosphere and continues to sustain it today. The team reports that the lunar atmosphere is primarily a product of ‘impact vaporization.’
• A new study extends the definition of a habitable zone for planets to include their star’s magnetic field.
Space industry in numbers
The global smart space market size is projected to grow from USD 9.4 billion in 2020 to USD 15.3 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 10.2% during the forecast period. The increasing venture capital funding and growing investments in smart space technology to drive market growth.
Analysts at Morgan Stanley and Goldman Sachs have predicted that economic activity in space will become a multi-trillion-dollar market in the coming decades. Morgan Stanley’s Space Team estimates that the roughly USD 350 billion global space industry could surge to over USD 1 trillion by 2040.
Latest Research
Denser Environments Cultivate Larger Galaxies: A Comprehensive Study beyond the Local Universe with 3 Million Hyper Suprime-Cam Galaxies
by Aritra Ghosh, C. Megan Urry, Meredith C. Powell, Rhythm Shimakawa, Frank C. van den Bosch, Daisuke Nagai, Kaustav Mitra, Andrew J. Connolly in The Astrophysical Journal
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, 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.”
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.”
Starling Formation-Flying Optical Experiment: Initial Operations and Flight Results
by Justin Kruger, Soon S. Hwang, Simone D’Amico in arXiv
Someday, instead of large, expensive individual space satellites, teams of smaller satellites — known by scientists as a “swarm” — will work in collaboration, enabling greater accuracy, agility, and autonomy. Among the scientists working to make these teams a reality are researchers at Stanford University’s Space Rendezvous Lab, who recently completed the first-ever in-orbit test of a prototype system able to navigate a swarm of satellites using only visual information shared through a wireless network.
“It’s a milestone paper and the culmination of 11 years of effort by my lab, which was founded with this goal of surpassing the current state of the art and practice in distributed autonomy in space,” said Simone D’Amico, associate professor of aeronautics and astronautics and senior author of the study. “Starling is the first demonstration ever made of an autonomous swarm of satellites.”
The test is known as Starling Formation-Flying Optical Experiment, or StarFOX. In it, the team successfully navigated four small satellites working in tandem using only visual information gathered from onboard cameras to calculate their trajectories (or orbits). The researchers presented their findings from the initial StarFOX test at a gathering of swarm satellite experts at the Small Satellite Conference in Logan, Utah.
D’Amico described the challenge as one that has driven his team for more than a decade. “Our team has been advocating for distributed space systems since the lab’s inception. Now it has become mainstream. NASA, the Department of Defense, the U.S. Space Force — all have understood the value of multiple assets in coordination to accomplish objectives which would otherwise be impossible or very difficult to achieve by a single spacecraft,” he said. “Advantages include improved accuracy, coverage, flexibility, robustness, and potentially new objectives not yet imagined.”
Robust navigation of the swarm presents a considerable technological challenge. Current systems rely on the Global Navigation Satellite System (GNSS), requiring frequent contact with terrestrial systems. Beyond Earth’s orbit, there is the Deep Space Network, but it is relatively slow and not easily scalable to future endeavors. What’s more, neither system can help satellites avoid what D’Amico calls “non-cooperative objects” like space debris that might knock a satellite out of commission.
The swarm needs a self-contained navigation system that allows a high degree of autonomy and robustness, D’Amico said. Such systems are likewise made more attractive by minimal technical requirements and financial costs of today’s miniaturized cameras and other hardware. The cameras used in the StarFOX test are proven, relatively inexpensive 2D cameras called star-trackers found on any satellite today.
“At its core, angles-only navigation requires no additional hardware even when used on small and inexpensive spacecraft,” D’Amico said. “And exchanging visual information between swarm members provides a new distributed optical navigation capability.”
StarFOX combines visual measurements from single cameras mounted on each satellite in a swarm. Similar to a mariner of old navigating the high seas with a sextant, the field of known stars in the background is used as reference to extract bearing angles to the swarming satellites. These angles are then processed onboard through accurate physics-based force models to estimate the position and velocity of the satellites with respect to the orbited planet — in this case, Earth, but the moon, Mars, or other planetary objects would work as well.
StarFOX employs the Space Rendezvous Lab’s angles-only Absolute and Relative Trajectory Measurement System — ARTMS, for short — which integrates three new space robotics algorithms. An Image Processing algorithm detects and tracks multiple targets in images and computes target-bearing angles — the angles at which objects, including space debris, are moving toward or away from each other. The Batch Orbit Determination algorithm then estimates each satellite’s coarse orbit from these angles. Last but not least, the Sequential Orbit Determination algorithm refines swarm trajectories with the processing of new images through time to potentially feed autonomous guidance, control, and collision avoidance algorithms onboard.
Data is shared over an inter-satellite communication link (or wireless network). It is all used to calculate robust absolute and relative position and velocity to a remarkable degree of accuracy without GNSS. Under the most challenging conditions, using just a single observer satellite, StarFOX was able to calculate relative position — the position of individual satellites to one another — to within 0.5% of their distance. When multiple observers were added in, those error rates dropped to just 0.1%.
The Starling test was deemed promising enough that NASA has extended the project, now known as StarFOX+, through 2025 to further explore these improved capabilities and pave the way for future space situational awareness and positioning technologies.
Estimate of water and hydroxyl abundance on asteroid (16) Psyche from JWST data
by Stephanie G. Jarmak, Tracy M. Becker, Charles E. Woodward, Casey I. Honniball, Andrew S. Rivkin, Margaret M. McAdam, Zoe A. Landsman, Saverio Cambioni, Thomas G. Müller, Driss Takir, Kurt D. Retherford, Anicia Arredondo, Linda T. Elkins-Tanton in Planetary Science Journal
Using data from NASA’s James Webb Space Telescope, a Southwest Research Institute-led team has confirmed hydroxyl molecules on the surface of the metallic asteroid Psyche. The presence of hydrated minerals suggests a complex history for Psyche, important context for the NASA spacecraft en route to this interesting asteroid orbiting the Sun between Mars and Jupiter.
At about 140 miles in diameter, Psyche is one of the most massive objects in the main asteroid belt. Previous observations indicate that Psyche is a dense, largely metallic object that could be a leftover core from a planet that experienced a catastrophic collision. On Oct. 13, 2023, NASA launched the Psyche spacecraft, which is traveling 2.2 billion miles to arrive at the asteroid in August 2029.
“Using telescopes at different wavelengths of infrared light, the SwRI-led research will provide different but complementary information to what the Psyche spacecraft is designed to study,” said SwRI’s Dr. Tracy Becker, second author.
“Our understanding of solar system evolution is closely tied to interpretations of asteroid composition, particularly the M-class asteroids that contain higher concentrations of metal,” said Center for Astrophysics | Harvard & Smithsonian’s Dr. Stephanie Jarmak, the paper’s lead author, who conducted much of this research while at SwRI. “These asteroids were initially thought to be the exposed cores of differentiated planetesimals, a hypothesis based on their spectral similarity to iron meteorites.”
The Webb data point to hydroxyl and perhaps water on Psyche’s surface. The hydrated minerals could result from external sources, including impactors. If the hydration is native or endogenous, then Psyche may have a different evolutionary history than current models suggest.
“Asteroids are leftovers from the planetary formation process, so their compositions vary depending on where they formed in the solar nebula,” said SwRI’s Dr. Anicia Arredondo, another co-author. “Hydration that is endogenous could suggest that Psyche is not the remnant core of a protoplanet. Instead, it could suggest that Psyche originated beyond the ‘snow line,’ the minimum distance from the Sun where protoplanetary disc temperatures are low enough for volatile compounds to condense into solids, before migrating to the outer main belt.”
However, the paper found the variability in the strength of the hydration features across the observations implies a heterogeneous distribution of hydrated minerals. This variability suggests a complex surface history that could be explained by impacts from carbonaceous chondrite asteroids thought to be very hydrated.
Understanding the location of asteroids and their compositions tells us how materials in the solar nebula were distributed and have evolved since formation. How water is distributed in our solar system will provide insight into the distribution of water in other solar systems and, because water is necessary for all life on Earth, will drive where to look for potential life, both in our solar system and beyond.
NASA’s Webb telescope, developed in partnership with the European and Canadian space agencies, is part of the Space Telescope Science Institute, operated by the Association of Universities for Research in Astronomy. The Psyche mission is led by Arizona State University. NASA’s Jet Propulsion Laboratory is responsible for mission management, operations and navigation.
Lunar soil record of atmosphere loss over eons
by Nicole X. Nie, Nicolas Dauphas, Zhe J. Zhang, Timo Hopp, Menelaos Sarantos in Science Advances
While the moon lacks any breathable air, it does host a barely-there atmosphere. Since the 1980s, astronomers have observed a very thin layer of atoms bouncing over the moon’s surface. This delicate atmosphere — technically known as an “exosphere” — is likely a product of some kind of space weathering. But exactly what those processes might be has been difficult to pin down with any certainty.
Now, scientists at MIT and the University of Chicago say they have identified the main process that formed the moon’s atmosphere and continues to sustain it today. In a study, the team reports that the lunar atmosphere is primarily a product of “impact vaporization.”
In their study, the researchers analyzed samples of lunar soil collected by astronauts during NASA’s Apollo missions. Their analysis suggests that over the moon’s 4.5-billion-year history its surface has been continuously bombarded, first by massive meteorites, then more recently, by smaller, dust-sized “micrometeoroids.” These constant impacts have kicked up the lunar soil, vaporizing certain atoms on contact and lofting the particles into the air. Some atoms are ejected into space, while others remain suspended over the moon, forming a tenuous atmosphere that is constantly replenished as meteorites continue to pelt the surface.
The researchers found that impact vaporization is the main process by which the moon has generated and sustained its extremely thin atmosphere over billions of years.
“We give a definitive answer that meteorite impact vaporization is the dominant process that creates the lunar atmosphere,” says the study’s lead author, Nicole Nie, an assistant professor in MIT’s Department of Earth, Atmospheric, and Planetary Sciences. “The moon is close to 4.5 billion years old, and through that time the surface has been continuously bombarded by meteorites. We show that eventually, a thin atmosphere reaches a steady state because it’s being continuously replenished by small impacts all over the moon.”
Nie’s co-authors are Nicolas Dauphas, Zhe Zhang, and Timo Hopp at the University of Chicago, and Menelaos Sarantos at NASA Goddard Space Flight Center.
In 2013, NASA sent an orbiter around the moon to do some detailed atmospheric reconnaissance. The Lunar Atmosphere and Dust Environment Explorer (LADEE, pronounced “laddie”) was tasked with remotely gathering information about the moon’s thin atmosphere, surface conditions, and any environmental influences on the lunar dust. LADEE’s mission was designed to determine the origins of the moon’s atmosphere. Scientists hoped that the probe’s remote measurements of soil and atmospheric composition might correlate with certain space weathering processes that could then explain how the moon’s atmosphere came to be.
Researchers suspect that two space weathering processes play a role in shaping the lunar atmosphere: impact vaporization and “ion sputtering” — a phenomenon involving solar wind, which carries energetic charged particles from the sun through space. When these particles hit the moon’s surface, they can transfer their energy to the atoms in the soil and send those atoms sputtering and flying into the air.
“Based on LADEE’s data, it seemed both processes are playing a role,” Nie says. “For instance, it showed that during meteorite showers, you see more atoms in the atmosphere, meaning impacts have an effect. But it also showed that when the moon is shielded from the sun, such as during an eclipse, there are also changes in the atmosphere’s atoms, meaning the sun also has an impact. So, the results were not clear or quantitative.”
To more precisely pin down the lunar atmosphere’s origins, Nie looked to samples of lunar soil collected by astronauts throughout NASA’s Apollo missions. She and her colleagues at the University of Chicago acquired 10 samples of lunar soil, each measuring about 100 milligrams — a tiny amount that she estimates would fit into a single raindrop.
Nie sought to first isolate two elements from each sample: potassium and rubidium. Both elements are “volatile,” meaning that they are easily vaporized by impacts and ion sputtering. Each element exists in the form of several isotopes. An isotope is a variation of the same element, that consists of the same number of protons but a slightly different number of neutrons. For instance, potassium can exist as one of three isotopes, each one having one more neutron, and there being slightly heavier than the last. Similarly, there are two isotopes of rubidium.
The team reasoned that if the moon’s atmosphere consists of atoms that have been vaporized and suspended in the air, lighter isotopes of those atoms should be more easily lofted, while heavier isotopes would be more likely to settle back in the soil. Furthermore, scientists predict that impact vaporization, and ion sputtering, should result in very different isotopic proportions in the soil. The specific ratio of light to heavy isotopes that remain in the soil, for both potassium and rubidium, should then reveal the main process contributing to the lunar atmosphere’s origins.
With all that in mind, Nie analyzed the Apollo samples by first crushing the soils into a fine powder, then dissolving the powders in acids to purify and isolate solutions containing potassium and rubidium. She then passed these solutions through a mass spectrometer to measure the various isotopes of both potassium and rubidium in each sample.
In the end, the team found that the soils contained mostly heavy isotopes of both potassium and rubidium. The researchers were able to quantify the ratio of heavy to light isotopes of both potassium and rubidium, and by comparing both elements, they found that impact vaporization was most likely the dominant process by which atoms are vaporized and lofted to form the moon’s atmosphere.
“With impact vaporization, most of the atoms would stay in the lunar atmosphere, whereas with ion sputtering, a lot of atoms would be ejected into space,” Nie says. “From our study, we now can quantify the role of both processes, to say that the relative contribution of impact vaporization versus ion sputtering is about 70:30 or larger.” In other words, 70 percent or more of the moon’s atmosphere is a product of meteorite impacts, whereas the remaining 30 percent is a consequence of the solar wind.
“The discovery of such a subtle effect is remarkable, thanks to the innovative idea of combining potassium and rubidium isotope measurements along with careful, quantitative modeling,” says Justin Hu, a postdoc who studies lunar soils at Cambridge University, who was not involved in the study. “This discovery goes beyond understanding the moon’s history, as such processes could occur and might be more significant on other moons and asteroids, which are the focus of many planned return missions.”
“Without these Apollo samples, we would not be able to get precise data and measure quantitatively to understand things in more detail,” Nie says. “It’s important for us to bring samples back from the moon and other planetary bodies, so we can draw clearer pictures of the solar system’s formation and evolution.”
Exploring the Effects of Stellar Magnetism on the Potential Habitability of Exoplanets
by Anthony S. Atkinson, David Alexander, Alison O. Farrish in The Astrophysical Journal
Interest in Earth-like planets orbiting within the habitable zone of their host stars has surged, driven by the quest to discover life beyond our solar system. But the habitability of such planets, known as exoplanets, is influenced by more than just their distance from the star.
A new study by Rice University’s David Alexander and Anthony Atkinson extends the definition of a habitable zone for planets to include their star’s magnetic field. This factor, well studied in our solar system, can have significant implications for life on other planets, according to the research.
The presence and strength of a planet’s magnetic field and its interaction with the host star’s magnetic field are pivotal factors in a planet’s ability to support life. An exoplanet needs a strong magnetic field to protect it from stellar activity, and it must orbit far enough from its star to avoid a direct and potentially catastrophic magnetic connection.
“The fascination with exoplanets stems from our desire to understand our own planet better,” said Alexander, professor of physics and astronomy, director of the Rice Space Institute and member of the Texas Aerospace Research and Space Economy Consortium. “Questions about the Earth’s formation and habitability are the key drivers behind our study of these distant worlds.”
Traditionally, scientists have focused on the “Goldilocks Zone,” the area around a star where conditions are just right for liquid water to exist. By adding the star’s magnetic field to the habitability criteria, Alexander’s team offers a more nuanced understanding of where life might thrive in the universe.
The investigation focused on the magnetic interactions between planets and their host stars, a concept known as space weather. On Earth, space weather is driven by the sun and affects our planet’s magnetic field and atmosphere. For the study, the researchers simplified the complex modeling usually required to understand these interactions.
The researchers characterized stellar activity using a measure of a star’s activity known as the Rossby number (Ro): the ratio of the star’s rotation period to its convective turnover time. This helped them estimate the star’s Alfvén radius — the distance at which the stellar wind effectively becomes decoupled from the star.
Planets within this radius would not be viable candidates for habitability because they would be magnetically connected back to the star, leading to rapid erosion of their atmosphere.
By applying this approach, the team examined 1,546 exoplanets to determine if their orbits lay inside or outside their star’s Alfvén radius. The study found that only two planets, K2–3 d and Kepler-186 f, of the 1,546 examined met all the conditions for potential habitability. These planets are Earth-sized, orbit at a distance conducive to the formation of liquid water, lie outside their star’s Alfvén radius and have strong enough magnetic fields to protect them from stellar activity.
“While these conditions are necessary for a planet to host life, they do not guarantee it,” said Atkinson, a graduate student of physics and astronomy and lead author of the study. “Our work highlights the importance of considering a wide range of factors when searching for habitable planets.”
The study also underscores the need for continued exploration and observation of exoplanetary systems, drawing lessons from the sun-Earth system. By expanding the criteria for habitability, the researchers provide a framework for future studies and observations to work toward determining whether we are alone in the universe.
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