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Astronomers have been on the hunt for a new kind of exoplanet in recent years – one especially suited for habitability. They’re called hycean worlds, and they’re characterized by vast liquid water oceans and thick hydrogen-rich atmospheres. The name was coined in 2021 by Cambridge astronomer Nikku Madhusudhan, whose team got a close-up look at one possible hycean world, K2-18b, using the James Webb Space Telescope in 2023. In a newly accepted paper this January, Madhusudhan and coauthor Frances Rigby examined what the internal structure of hycean planets might look like, and what that means for the possibility of finding life within.

Hycean worlds are unlike anything we have seen in our own solar system, expanding the very definition of a habitable planet. They tend to be much bigger than Earth-like planets, earning them the moniker ‘mini-neptunes’. Their size makes them easier to detect than smaller rocky worlds, and their thick atmospheres give them a wider habitable zone.

Those same properties also make them ideal candidates for spectroscopic analysis, where measuring the chemical composition of the atmospheres might reveal biosignatures.

In order to tease out the potential characteristics of a habitable hycean world, Rigby and Madhusudhan used a modeling tool called HyRIS to map out possible planetary structures. They limited their models to only allow for habitable temperatures and pressures at the ocean’s surface, where the water meets the air.

Even with those strict conditions in place, the results showed a wide variety of possible internal structures. The ocean depths of a habitable hycean world could range from 10s of kilometers deep to 1000s of kilometers (for comparison, Earth’s ocean averages about 3.7km deep).

One factor that potentially limits the habitability of these worlds is that they are likely to have a thick layer of ice between the ocean floor and the rocky core of the planet. On Earth, the weathering of the rocky seafloor produces nutrients that are essential to life – ice might inhibit that process. Nonetheless, there is still the possibility that these nutrients could be transported through the ice via convection, or delivered to the planet in other ways, like via comet and asteroid impacts or atmospheric condensation.

The study also looked at several real hycean world candidates, and among them, there are three that stand out as having good chances of habitability.

Although these three candidates orbit red dwarf stars – known for their violent, hostile solar flares – these planets’ stars are comparatively calm. They are TOI-270 d, TOI 1468 c, and TOI-732 c (TOI refers to planets observed by the TESS space telescope).

Each of these three planets is scheduled for observation by James Webb in its second year of observing, meaning we’re about to get a more detailed look at some exciting new exoplanets. Last year’s observation of K2-18b was just the beginning of hycean world research, and this recent paper will help astronomers constrain the possible internal structures of these worlds, and help determine the prospect of finding life on them.

Learn More:

Frances E. Rigby, Nikku Madhusudhan, “On the Ocean Conditions of Hycean Worlds,” ArXiv preprint.

“Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18 b.” NASA, September 2023.

The post If Hycean Worlds Really Exist, What are Their Oceans Like? appeared first on Universe Today.

Intuitive Machines‘ Odysseus lander made space history today — becoming the first commercial spacecraft to survive a descent to the moon, and the first U.S.-built spacecraft to do so since the Apollo 17 mission in 1972. But it wasn’t a trouble-free landing.

Ground controllers had a hard time establishing contact with the robotic lander just after the scheduled touchdown time of 6:23 p.m. ET (2323 UTC). Several minutes passed, and then Intuitive Machines mission director Tim Crain reported that there was a faint signal coming from Odysseus’ high-gain antenna.

“We’re not dead yet,” he said.

Your order was delivered… to the Moon! ?@Int_Machines' uncrewed lunar lander landed at 6:23pm ET (2323 UTC), bringing NASA science to the Moon's surface. These instruments will prepare us for future human exploration of the Moon under #Artemis. pic.twitter.com/sS0poiWxrU

— NASA (@NASA) February 22, 2024

A few minutes later, the IM-1 mission team decided that the signal was evidence enough that Odysseus was still operating.

“What we can confirm without a doubt is our equipment is on the surface of the moon, and we are transmitting,” Crain said. “So, congratulations, IM team, we’ll see how much more we can get from that.”

As mission team members applauded, Intuitive Machines CEO Steve Altemus radioed in with his congratulations. “I know this was a nail-biter, but we are on the surface and we are transmitting,” he said. “Welcome to the moon.”

“Houston, Odysseus has found its new home,” Crain replied.

What Odysseus was designed to do

Odysseus, which is named after a seafaring hero in Greek mythology, was launched from NASA’s Kennedy Space Center on Feb. 15. The mission’s objective was to deliver payloads from NASA and commercial customers to a spot near Malapert A crater in the lunar south polar region. That area of the moon is of high interest because its cratered terrain is thought to hold resources of water ice that could be eventually be used to supply crewed outposts.

NASA is paying Houston-based Intuitive Machines $118 million for the delivery under the terms of its Commercial Lunar Payload Services initiative.

The space agency’s payloads include a camera system that was designed to document the plumes of dust kicked up by the landing, an experimental radio navigation beacon, a radio-based fuel gauge, a laser range finder, a set of laser reflectors and a sensor that will study the moon’s electron plasma environment. Data from the experiments could help NASA plan for the Artemis program’s crewed lunar landings, which could start happening as soon as 2026.

The commercial payloads range from a box of 125 marble-sized moon sculptures and a digital data storage device to a mini-observatory that could capture pictures of the lunar surface and the Milky Way above. There’s also a camera system that was designed to be dropped off during the descent to take “selfie” pictures of the touchdown.

Backup systems come into play

Odysseus reached lunar orbit on Feb. 21, and went through a series of maneuvers today to descend from an altitude of 92 kilometers (57 miles).

NASA’s laser range finder, known as the Navigation Doppler Lidar or NDL, ended up playing a crucial backup role in guiding the descent. Just a couple of hours before landing, Intuitive Machines reported that controllers couldn’t get Odysseus’ own laser range finders to work — so they reprogrammed the lander to use NASA’s NDL system instead.

In the wake of the landing, Intuitive Machines’ mission control team went through a series of procedures aimed at resetting equipment and boosting the signal from Odysseus.

“After troubleshooting communications, flight controllers have confirmed Odysseus is upright and starting to send data,” Intuitive Machines reported in a posting to X / Twitter. “Right now, we are working to downlink the first images from the lunar surface.”

It's getting late over here, but #IM1 @Int_Machines landed on the moon and is alive!!!! Congratulations!??? Somewhat weaker signal than expected, but it's definitely there, switching antennas/radios and calling home. ????? pic.twitter.com/AwlQOvVQ78

— AMSAT-DL (@amsatdl) February 23, 2024

There’s a chance that Odysseus went off track during the final stages of the descent and ended up landing askew. That’s what happened a month ago when Japan’s SLIM spacecraft tumbled into an awkward position on its lunar landing site. SLIM’s off-kilter solar arrays were able to soak up enough power for an abbreviated round of science observations.

Even under the best of circumstances, the solar-powered Odysseus lander is expected to be in operation on the lunar surface for only seven days. The mission is slated to end when the sun drops below the lunar horizon and the circuit-chilling lunar night begins.

Past and future lunar robots

NASA’s deputy associate administrator for exploration, Joel Kearns, noted in advance of the landing that the odds for a completely successful commercial moon landing were slim.

“This is not an easy thing we’ve asked these companies to do, but if they’re successful, the up side for American exploration is just so great we have to try it,” Kearns said.

Last month, Pittsburgh-based Astrobotic missed out on sending its Peregrine lander to the lunar surface, due to a propellant leak that was detected after launch. The past year has also seen moon landing failures by Russia and a Japanese private venture, as well as successes by the Japan Aerospace Exploration Agency’s SLIM team and India’s space agency.

Still more commercial moon landing attempts are on NASA’s calendar: Intuitive Machines is already working on another lander that will drill for ice in the moon’s south polar region. Meanwhile, Astrobotic is getting set to send NASA’s VIPER rover to a spot near the south pole, and Firefly Aerospace is due to deliver 10 NASA payloads to Mare Crisium aboard its Blue Ghost lander.

NASA Administrator Bill Nelson accentuated the positive in a pre-recorded video message that was released on the assumption that Odysseus survived its descent to the surface.

“Today, for the first time in more than half a century, the U.S. has returned to the moon,” Nelson said. “Today, for the first time in the history of humanity, a commercial company, an American company, launched and led the voyage up there. Today is a day that shows the power and promise of NASA’s commercial partnerships. … This feat is a giant leap forward for all of humanity. Stay tuned.”

Stay tuned, indeed.

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It’s a headline straight out of the movies yet the White House has recently confirmed it believes that Russia is building space-based anti-satellite weapon! There seems to be no conclusive evidence what this might be but one option may be a nuclear bomb that would indiscriminately wipe out satellites within a huge volume of space! Not only would it devastate satellites but would cause more problems down on the surface and create a whole load of space junk. 

In a statement, the National Security Council spokesperson John Kirby said that he did not believe the weapon had an ‘active capability’ yet and further went on to say he did not believe it had even been deployed. He went on to say that the White House was monitoring Russian activity and would continue to take it very seriously. 

Launching such a nuclear weapon into space would violate the 1967 Outer Space Treaty which countries of the United Nations, including Russia, signed. It prohibits putting nuclear weapons or weapons of mass destruction into space, on the Moon or on any other celestial object. Such an act would likely prompt sanctions from other nations and further compound the situation faced by Russia following its invasion of Ukraine. Note that such a device wouldn’t even actually need to be used, just deploying it into space would be sufficient to violate the Treaty. 

A spokesperson from Moscow has denied the existence of such a program suggesting it was “malicious fabrication” that has been created by the American political teams. The Kremlin went on to suggest that such a fabrication might coerce the Congress to pass a $97 billion foreign aid bill which includes $60 million for Ukraine. 

Tempting though such a nuclear device might seem to any countries wishing to unleash devastation to other nations, the impacts can be far reaching. The destruction of any object in orbit will create a whole debris field with components ranging from a few millimetres to several centimetres. At the moment, there are several hundreds of millions of pieces of space debris being tracked from Earth. The high velocity items drifting around pose a threat to other satellites still in operation and even the International Space Station which has had to apply course directions to avoid collisions. 

Should Russia have, and launch and subsequently detonate a nuclear device in space, they would not only be putting themselves at risk of more sanctions but also be putting their own satellites at risk! It’s almost impossible to control the path of space debris so a detonation would generate more that would undoubtedly destroy some of Russia’s own satellites. 

It may be some time before we know for certain whether Russia are planning a nuclear capability in space. The one hope is that they recognise the risk to their own, and other supportive countries space assets. Taking out a bunch of US or western satellites is one thing but the subsequent debris taking out their own infrastructures and those of other supportive nations may have repercussions that are quite unpalatable.  Even if the space debris does not knock out other satellites, it is certainly going to make it even harder for us to travel beyond the confines of the Earth due to the sheer volume of high velocity fragments orbiting the planet.

Source : Russia’s space weapon: anti-satellite systems are indiscriminate, posing a risk to everyone’s spacecraft

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Supermassive black holes are messy feeders, and when they’re gorging on too much material, they can hurl high-energy jets into the surrounding Universe. Astronomers have found one of the most powerful eruptions ever seen, emanating from a black hole 3.8 billion light-years away. The powerful jets are blowing out cavities in intergalactic space and triggering the formation of a huge chain of star clusters.

The black hole is part of a massive galaxy cluster, named SDSS J1531, which contains hundreds of individual galaxies, and all these galaxies have huge reservoirs of hot gas and dark matter. Using several telescopes for multiwavelength observations — including the Chandra X-ray Observatory, the Low Frequency Array (LOFAR) radio telescope, the Atacama Large Millimeter and submillimeter Array (ALMA), the Gemini North telescope’s Gemini Multi-Object Spectrograph (GMOS), and the Very Large Array (VLA) — astronomers were able to discern that two of the central galaxies were engaged in a major merger. The merger activated the supermassive black hole in the center of one of the large galaxies, which produced an extremely powerful jet. As the jet moved through space, it pushed the surrounding hot gas away from the black hole, creating a gigantic cavity.

The merger and the resulting jets from the black hole created a remarkable and stunning chain of 19 young stellar superclusters wound the two galaxies like a string of beads.

In their paper, the astronomers said the dynamic environment of SDSS J1531 offers an excellent laboratory to study the interplay between mergers, and their multiwavelength studies allowed them to uncover the origin and evolution of the “beads on a string” star formation complex.

“We’ve reconstructed a likely sequence of events in this cluster that occurred over a vast range of distances and times,” said co-author Grant Tremblay, from the Harvard & Smithsonian Center for Astrophysics CfA). “It began with the black hole a tiny fraction of a light-year across forming a cavity almost 500,000 light-years wide. This single event set in motion the formation of the young star clusters nearly 200 million years later, each a few thousand light-years across.”

A labeled view of the multiwavelength Image of SDSS J1531. Credit: X-ray: NASA/CXC/SAO/O. Omoruyi et al.; Optical: NASA/ESA/STScI/G. Tremblay et al.; Radio: ASTRON/LOFAR; Image Processing: NASA/CXC/SAO/N. Wolk.

Chandra’s X-ray vision allowed the scientists to see wing-shaped emissions in bright X-rays, which traced dense gas near the center of SDSS J1531. The said these wings make up the edge of the cavity, and then LOFAR revealed radio waves from the remains of the jet’s energetic particles filling in the giant cavity. Together, these data provide compelling evidence of an ancient, massive explosion.

Osase Omoruyi, also from CfA who led the study, compared finding this cavity to unearthing a buried fossil.

“We are already looking at this system as it existed four billion years ago, not long after the Earth formed,” she said. “This ancient cavity, a fossil of the black hole’s effect on the host galaxy and its surroundings, tells us about a key event that happened nearly 200 million years earlier in the cluster’s history.”

This Hubble Space Telescope image from 2014 shows two galaxies (yellow, center) from the cluster SDSS J1531 found to be merging into one and a “chain” of young stellar super-clusters are seen winding around the galaxies’ nuclei. The galaxies are surrounded by an egg-shaped blue ring caused by the immense gravity of the cluster bending light from other galaxies beyond it. Credit: NASA/ESA/Grant Tremblay

You can learn more about a Hubble Space Telescope view of this supercluster back in 2014.

The astronomers said that some of the hot gas pushed away from the black hole eventually cooled to form cold and warm gas. The team thinks tidal effects from the two merging galaxies compressed the gas along curved paths, leading to the star clusters forming in the bead-like pattern.

Omoruyi and her colleagues could only see radio waves and a cavity from one jet, but black holes usually fire two jets in opposite directions. This led them to surmise that the radio and X-ray signals from the jet in the other direction might have faded to the point that they are undetectable.

“We think our evidence for this huge eruption is strong, but more observations with Chandra and LOFAR would clinch the case,” said Omoruyi. “We hope to learn more about the origin of the cavity we’ve already detected, and find the one expected on the other side of the black hole.”

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The conditions for life throughout the Universe are so plentiful that it seems reasonable to presume there must be extra-terrestrial civilizations in the galaxy. But if that’s true, where are they? The Search for Extra-terrestrial Intelligence (SETI) program and others have long sought to find signals from these civilizations, but so far there has been nothing conclusive. Part of the challenge is that we don’t know what the nature of an alien signal might be. It’s a bit like finding a needle in a haystack when you don’t know what the needle looks like. Fortunately, any alien civilization would still be bound by the same physical laws we are, and we can use that to consider what might be possible. One way to better our odds of finding something would be to focus not on a direct signal from a single world, but the broader echos of an interstellar network of signals.

As noted in a 2022 paper on the arXiv, one physical constraint is that there is a great deal of dust and interstellar gas in the Milky Way. Since radio light penetrates gas and dust better than visible light, the signals sent between stars are likely to be microwave radio signals. Another fact is that if you are traveling between the stars you need to know where you are and where you are going. One way to do this is to use pulsars as navigational beacons. In the paper the author argues that these can be combined as a broadband radio signal from the hub of the alien civilization that contains x-ray pulsar navigation metadata (XNAV).

One of the biggest challenges of detecting stray alien signals is that they would likely be difficult to distinguish from random noise. Even simple signals such as television broadcasts rely upon a known protocol. Without that protocol, we can’t decipher the message. This is similar to the challenge of breaking the Enigma code during World War II. One of the breakthroughs came when it was realized that most messages contained a weather report, so the message likely contained the German word for weather. Metadata in an alien signal could serve a similar role. If we know radio signals should contain XNAV metadata, then we can use this as a starting point. In game theory this is known as a Shelling Point.

A 3-pulsar navigation system for an ET civilization. Credit: Ross Davis (2022)

The author outlines nine steps for how an interstellar civilization might construct a pulsar navigation system, and what the pattern of that network might be. By creating multiple scenarios, we might be able to recognize certain patterns as technosignatures. As the author notes, one limitation of this approach is that any metadata scenario we imagine is still based on how homo sapiens think, which might not be how an alien intelligence sees things.

All of this is speculative, but it’s worth considering. We will only recognize an alien signal if we better understand the forms they might take, and perhaps a few wild ideas like this one are exactly what we need.

Reference: Davis, Ross. “Finding the ET Signal from the Cosmic Noise.” arXiv preprint arXiv:2204.04405 (2022).

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Space debris is a thing.. It seems whether we explore the Earth or space we leave rubbish in our wake. Thankfully, organisations like Astroscale are trying to combat the problem of debris in space with a new commercial debris inspection demonstration satellite. Named ADRAS-J, the satellite – which is now in orbit – is hunting down an old Japanese upper stage rocket body which was launched in 2009.  It will approach to within 30 metres to study the module from every angle and work out how it can be safely de-orbited by a future mission. 

Space debris, or space junk comprises of man made objects orbiting Earth that are no longer needed.  It’s been about 70 years since the launch of Sputnik, the first human made satellite and already, debris in space is a problem and it can be anything from  spent rocket stages to defunct satellites or even fragments that are the results of collisions. Collectively these objects pose a real threat to operational spacecraft due their high speed. Left unchecked, space debris will become a major problem and could even, ultimately, cut off our access to space. 

The Sputnik spacecraft stunned the world when it was launched into orbit on Oct. 4th, 1954. Credit: NASA

The ADRAS-J mission marks the world’s first attempt to safely approach and survey a piece of space debris through the Rendezvous and Proximity Operations (RPO) technique. Designed to approach a Japanese upper stage rocket body, ADRAS-J aims to showcase the technique while capturing images to assess the object’s movement and condition.

ADRAS-J was successfully launched from New Zealand on February 18 and is part of Phase 1 of the Japan Aerospace Exploration Agency’s plan to deal with space debris. Its name gives recognition to that purpose ‘Active Debris Removal by Astroscale-Japan’. Its initial target, the Japanese H2A upper stage rocket body. 

An H-2A rocket, Japan’s primary large-scale launch vehicle. Credit: JAXA

The target object lacks any GPS data making it more tricky for the team to rendezvous but perhaps makes it a more realistic target for testing debris analysis activity. Over the next few weeks, the ADRAS-J team will continue to undertake in-orbit tests and checks before it finally, cautiously approaches the object. They will resort to using ground based observational data to approximate its position to make the approach as safe as possible. The initial approach will then be followed up with closer approachers to fully assess the object. 

Whilst it is of course great to see some real movement to resolve the issue of space debris, the problem will simply keep growing until efforts are made to stem the increasing amount of debris. On more than one occasion now the occupants to the International Space Station have had to evacuate due to risks over space debris impact. Yet over 300 commercial and government groups have announced that there are plans to launch around half a million more satellites by 2030! That’s almost half a million more objects to track and keep managed so they do not lead to more and more debris. The challenge is hard but is not surmountable, as long as we act now.

Source : Astroscale Successfully Launches World’s First Debris Inspection Spacecraft, ADRAS-J

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For over a century, people have dreamed of the day when humanity (as a species) would venture into space. In recent decades, that dream has moved much closer to realization, thanks to the rise of the commercial space industry (NewSpace), renewed interest in space exploration, and long-term plans to establish habitats in Low Earth Orbit (LEO), on the lunar surface, and Mars. Based on the progression, it is clear that going to space exploration will not be reserved for astronauts and government space agencies for much longer.

But before the “Great Migration” can begin, there are a lot of questions that need to be addressed. Namely, how will prolonged exposure to microgravity and space radiation affect human health? These include the well-studied aspects of muscle and bone density loss and how time in space can impact our organ function and cardiovascular and psychological health. In a recent study, an international team of scientists considered an often-overlooked aspect of human health: our microbiome. In short, how will time in space affect our gut bacteria, which is crucial to our well-being?

The team consisted of biomedical researchers from the Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC) at the Shiraz University of Medical Sciences (SUMS), the Lebanese International University, the International University of Beirut, the MVLS College at The University of Glasgow, the Center for Applied Mathematics and Bioinformatics (CAMB) at Gulf University in Kuwait, the Nuclear Physics Institute (NPI) of the Czech Academy of Sciences (CAS), and the Technische Universität Wien Atominstitut in Vienna. The paper that describes their findings recently appeared in Frontiers of Microbiology.

Artist’s impression of the Space Launch System (SLS) taking off. Credit: NASA

A microbiome is the collection of all microbes that live on and within our bodies, including bacteria, fungi, viruses, and their respective genes. These microbes are key to how our body interacts with the surrounding environment since they can affect how we respond to the presence of foreign bodies and substances. In particular, some microbes alter foreign bodies in ways that make them more harmful, while others act as a buffer that mitigates the effects of toxins. As they note in their study, the microbiota of astronauts will encounter elevated stress from microgravity and space radiation, including Galactic Cosmic Rays (GCR).

Cosmic rays are a high-energy form of radiation that consists primarily of protons and atomic nuclei stripped of their electrons that have been accelerated to close to the speed of light. When these rays are generated from elements heavier than hydrogen or helium, their high-energy nuclei components are known as HZE ions, which are particularly hazardous. When these impact our atmosphere or protective shielding aboard spacecraft or the International Space Station (ISS), they result in showers of secondary particles.

While Earth’s protective magnetosphere and atmosphere prevent most of these particles from reaching the surface, astronauts in space are exposed to them regularly. As the authors noted, previous research has shown how this exposure could potentially enhance astronaut resilience to radiation, a process known as radio-adaptation. However, they also noted that the extent to which astronauts adapted varied from one astronaut to the next, with some experiencing adverse biological effects before embarking on a deep space mission.

For this reason, they recommend conducting further research to determine the risks associated with the space environment, as it mostly consists of protons, which astronauts will be exposed to before encountering HZE particles. Third, NASA’s Multi-Mission Model suggests that an astronaut’s first mission can be an adapting dose. However, the team notes that current research suggests that a second spaceflight does not necessarily increase the chances of genetic abnormalities as much as expected. This could mean that the body may have a natural radio-adaptive defense mechanism.

Making medical diagnoses aboard the International Space Station can be a tricky business Credit: NASA

In terms of recommendations, the team lauded the ISS as the ideal environment for testing the human microbiome response to space radiation and microgravity. They also address the shortage of research in this area and how the long-term effects of radiation on microbiomes and environmental bacteria are poorly understood:

“The International Space Station (ISS) is a unique and controlled system to study the interplay between the human microbiome and the microbiome of their habitats. The ISS is a hermetically sealed closed system, yet it harbors many microorganisms… In this context, NASA scientists did not consider that adaptation is not limited to astronauts and radiation exposure to bacteria inside an astronaut’s body or that bacteria inside the space station could induce resistance not only to high levels of DNA damage caused by HZEs but also to other bacterial activity-threatening factors such as antibiotics.”

Increased resistance to antibiotics could be life-threatening for astronauts, who face risks of injury and infection during long-duration missions. Furthermore, they emphasize how space travel and prolonged exposure to microgravity can weaken the immune system, reducing astronauts’ natural resistance to microbes – especially those with high levels of resistance to radiation, heat, UV, and desiccation, and can therefore survive in a space environment. As they summarize it:

“In a competition between astronauts and their microbiomes to adapt to the harsh space environment, microorganisms may emerge as the winners because they can evolve and adapt more quickly than humans by rapid acquisition of microbial genes. Microorganisms have a much shorter generation time, enabling them to produce many more offspring, each with unique genetic mutations that can help them survive in the space environment.”

Flight Engineer Anne McClain in the cupola holding biomedical gear for MARROW. Credit: NASA

For this reason, the research team stresses that additional research is needed to estimate the magnitude of adaptation in microorganisms before missions are mounted. This could be crucial for identifying potential risks and developing mitigation strategies, novel therapies, and interventions. They also recommend that astronauts undergo regular cytogenetic tests to measure their adaptive response and that only those who show a high adaptive response to low doses of radiation be selected for missions where they would be exposed to higher doses.

They also acknowledge that studying astronaut microbiomes in space presents several challenges. These include the difficulty of conducting experiments in the microgravity environment, which can affect the growth and behavior of microorganisms, making it challenging to obtain accurate and reliable data. There’s also the potential hazard of spreading pathogens in a closed environment with recycled air systems. However, this is research that needs to be conducted before crewed deep-space exploration can be realized, as it has the potential to identify potential pathogens and develop strategies to prevent their spread during missions.

Further Reading: Frontiers in Microbiology

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Cosmologists are wrestling with an interesting question: how much clumpiness does the Universe have? There are competing but not compatible measurements of cosmic clumpiness and that introduces a “tension” between the differing measurements. It involves the amount and distribution of matter in the Universe. However, dark energy and neutrinos are also in the mix. Now, results from a recent large X-ray survey of galaxy clusters may help “ease the tension”.

The eROSITA X-ray instrument orbiting beyond Earth performed an extensive sky survey of galaxy clusters to measure matter distribution (clumpiness) in the Universe. Scientists at the Max Planck Institute for Extraterrestrial Physics recently shared their analysis of its cosmologically important data.

“eROSITA has now brought cluster evolution measurement as a tool for precision cosmology to the next level,” said Dr. Esra Bulbul (MPE), the lead scientist for eROSITA’s clusters and cosmology team. “The cosmological parameters that we measure from galaxy clusters are consistent with state-of-the-art cosmic microwave background, showing that the same cosmological model holds from soon after the Big Bang to today.”

eROSITA, the Standard Cosmological Model, and Clumpiness

To get a better feel for what this means, let’s look at what the team is trying to confirm. The idea is to figure out just what the Universe has been like through time. That means understanding matter, its distribution (or clumpiness), and what role dark matter and dark energy have played. It all began just after the Big Bang when the Universe was in a hot, dense state. The only things existing were photons and particles. The Universe expanded and began to condense into regions of higher density. Think of these as density variations, or areas of more or less clumpiness in the primordial soup. As things cooled and expanded, the denser clumps in the soup became galaxies and eventually galaxy clusters. The clumpiness was smoother (or “isotropic”) than expected. That raises questions about the role of dark matter and dark energy, among other things.

eROSITA’s observations of galaxy clusters and distribution of matter showed several interesting results. First, both dark matter and visible matter (baryonic matter), make up about 29 percent of the total energy density of the Universe. Presumably, the rest consists of dark energy, which we don’t know much about, yet. Energy density is the amount of energy stored in a region of space as a function of volume. In cosmology, it also includes any mass in that volume of space.

This plot shows the constraints put on the total matter density in the Universe and the S8 “tension”. Constraints from eROSITA galaxy clusters are in orange, from the Cosmic Microwave Background (Planck) in blue, from weak lensing (DES+KiDS) in grey, and from cluster number counts (SPT) in black. Credit: MPE, V. Ghirardini for the eROSITA consortium

The measurement of energy density agrees with measurements of the cosmic microwave background radiation—also known as the CMB. Think of that as a map of the density variations in the early Universe. It’s made up of microwave radiation that permeates the Universe. That radiation is not completely smooth or uniform. That’s the variability in density that eventually became the seeds of the first galaxies.

Measuring Clumpiness

eROSITA’s goal is to measure the assembly of galaxy clusters over cosmic time. By tracing their evolution via the X-rays emitted by hot gas, the instrument traced both the total amount of matter in the Universe and its clumpiness. Those measurements solve the “tension” or discrepancy between past clumpiness measurements that used different techniques. Those included the CMB and observations of weak gravitational lensing.

A computer simulation of what gas and stars in a galaxy cluster look like, and how they look embedded in the cosmic web. The assembly of galaxy clusters has implications for the clumpiness of the Universe throughout time. Credit: Yannick Bahé.

The eROSITA data shows the distribution of matter is actually in good agreement with previous measurements of the CMB. That’s good news because cosmologists were afraid they’d have to invoke “new physics” to explain the tension between measurements. “eROSITA tells us that the Universe behaved as expected throughout cosmic history,” says Dr. Vittorio Ghirardini, the postdoctoral researcher at MPE who led cosmology study. “There’s no tension with the CMB. Maybe the cosmologists can relax a bit now.”

But Wait, There are Neutrinos to Worry About!

Interestingly, the eROSITA measurements of galaxy clusters and other large structures also provide information about neutrinos. They’re the most abundant particles with mass that we know of in the Universe. They come from the Sun and supernovae (for example), but also originated in the Big Bang. eROSITA’s survey offers new information about the mass of neutrinos and their prevalence. “We have obtained tight constraints on the mass of the lightest known particles from the abundance of the largest objects in the Universe,” said Ghirardini.

Computer simulations show how neutrinos can form cosmic clumpiness. Credit: Yoshikawa, Kohji, et al

Neutrinos may be small and tough to “see”, but they have mass that contributes to the total density of matter in the Universe. Cosmologists describe them as “hot”, which means they travel at nearly the speed of light. Therefore, they tend to smooth out the distribution of matter—which can be probed by analyzing the evolution of galaxy clusters in the Universe. And, there’s a good chance that eROSITA may help solve the mystery of neutrino mass. “We are even on the brink of a breakthrough to measure the total mass of neutrinos when combined with ground-based neutrino experiments,” added Ghirardini.

How eROSITA Did It

There’s a lot more to explore in the eROSITA data, but it’s also fascinating to look at the extent of the survey data. It comprises one of the most extensive catalogs of clusters of galaxies done so far. The so-called “Western Galactic half” of the all-sky survey contains 12,247 optically identified X-ray galaxy clusters. “Of these, 8,361 represent new discoveries – almost 70%,” said Matthias Kluge, a postdoctoral researcher at MPE who is responsible for the optical identification of the detected clusters. “This shows the huge discovery potential of eROSITA.”

All that data can be charted in three dimensions, and when scientists do that, galaxy clusters show up as intersections of the cosmic web. In addition, there’s a supercluster catalog, which also shows connected clusters and the filaments of matter between them. “We find more than 1,300 supercluster systems, which makes this the largest-ever X-ray supercluster sample,” said Ang Liu, a postdoctoral researcher at MPE.

This new look at clumpiness in the Universe comes from the first release of data from eROSITA. The instrument completed additional surveys in early 2022. Once those data are analyzed, astronomers expect to be probing even deeper into the distribution of matter in the Universe and testing their models against reality. “When the full data are analyzed,” said Esra Bulbul, “eROSITA will again put our cosmological models to the most stringent test ever conducted through a cluster survey.”

For More Information

eROSITA Relaxes Cosmological Tension
The SRG/eROSITA All-Sky Survey: Cosmology Constraints from Cluster Abundances in the Western Galactic Hemisphere

About eROSITA

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Astronomers say there’s a wave rippling through our galactic neighborhood that’s playing a part in the birth and death of stars — and perhaps in Earth’s history as well.

The cosmic ripple, known as the Radcliffe Wave, was identified in astronomical data four years ago — but in a follow-up study published today by the journal Nature, a research team lays out fresh evidence that the wave is actually waving, like the wave that fans in a sports stadium create by taking turns standing up and sitting down.

“Similar to how fans in a stadium are being pulled back to their seats by the Earth’s gravity, the Radcliffe Wave oscillates due to the gravity of the Milky Way,” study lead author Ralf Konietzka, a researcher at Harvard and the Harvard-Smithsonian Center for Astrophysics, or CfA, said in a news release. 

The wave — which is named in honor of Harvard Radcliffe Institute, where the undulation was discovered — consists of a string of star clusters spread out over a stretch of the Milky Way measuring about 9,000 light-years in length.

Astronomers reported in 2020 that they identified the wavy pattern by correlating the 3-D locations of the clusters in data from the European Space Agency’s Gaia space telescope, plus observations of dust and gas clouds in the same region.

“It’s the largest coherent structure that we know of, and it’s really, really close to us,” said study co-author Catherine Zucker, an astrophysicist with the Smithsonian Astrophysical Observatory at the CfA. “It’s been there the whole time. We just didn’t know about it, because we couldn’t build these high-resolution models of the distribution of gaseous clouds near the sun, in 3-D.”

At the time, the astronomers didn’t have enough data to determine whether the peak of the wave was rolling down the line. That’s what’s known as a traveling wave, as opposed to a stationary wave — the kind of wave that’s set off, for example, by a vibrating guitar string.

Since then, additional readings about the motion of the star clusters have led the astronomers to conclude that the Radcliffe Wave is indeed a traveling wave that rises to a maximum height of more than 700 light-years and has a mean wavelength of roughly 6,500 light-years.

“Now we can go and test all these different theories for why the wave formed in the first place,” Zucker said.

Konietzka said the potential explanations range from “explosions of massive stars, called supernovae, to out-of-galaxy disturbances like a dwarf satellite galaxy colliding with our Milky Way.”

Astronomers say the wave’s rippling effect could in turn trigger bursts of supernovae and swarms of star formation within the gas and dust clouds of the interstellar medium. In earlier research, Zucker and other astronomers suggested that sometime around 14 million years ago, just such a burst gave rise to the “Local Bubble,” a star-forming shell that surrounds our own solar system. 

Other researchers have proposed that the long-lasting fallout from all those supernovae could have affected Earth’s geology and climate — for example, by showering our planet with radioactive dust or perhaps even triggering an ice age.

The Radcliffe Wave is currently about 980 light-years away from our own solar system, and appears to be drifting outward at a speed of about 11,000 mph (5 km/sec). “The measured drift of the Radcliffe Wave radially outward from the galactic center suggests that the cluster whose supernovae ultimately created today’s expanding Local Bubble may have been born in the Radcliffe Wave,” authors of the newly published paper say.

Study co-author Alyssa Goodman, an astronomer at the CfA, said the evidence supports the case for claiming that the Radcliffe Wave had an effect on Earth and its cosmic neighborhood. 

“Passage of the sun through over-dense material like the Radcliffe Wave and the Local Bubble does affect the heliosphere,” she wrote in an email, “and the timing does work out that some of the peaks in radioactivity on Earth (e.g., iron-60) line up time-wise with when the sun would have crossed the RadWave, Local Bubble surface, and other ‘Local Fluff’ clouds as well.”

Now the study’s authors are wondering whether the Radcliffe Wave is merely a local phenomenon. Could such waves be common? “The question is, what caused the displacement giving rise to the waving we see?” Goodman said. “And does it happen all over the galaxy? In all galaxies? Does it happen occasionally? Does it happen all the time?”

In addition to Konietzka, Goodman and Zucker, authors of the Nature paper, titled “The Radcliffe Wave Is Oscillating,” include Andreas Burkert, João Alves, Michael Foley, Cameren Swiggum, Maria Koller and Núria Miret-Roig. The research is the focus of a BornCurious podcast titled “Riding the Radcliffe Wave,” as well an online 3-D interactive presented by Cosmic Data Stories and WorldWide Telescope.

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The gigantic galaxies we see in the Universe today, including our own Milky Way galaxy, started out far smaller. Mergers throughout the Universe’s 13.7 billion years gradually assembled today’s massive galaxies. But they may have begun as mere star clusters.

In an effort to understand the earliest galaxies, the JWST has examined their ancient light for clues as to how they became so massive.

The JWST can effectively see back in time to when the Universe was only about 5% as old as it is now. In that distant past, structures that would eventually become as massive as the Milky Way, and even larger, were only about 1/10,000th as massive as they are now. What clues can the powerful infrared space telescope uncover that show us how galaxies grew so large?

A new paper presents JWST observations of a galaxy at redshift z~8.3. At that redshift, the light has been travelling for over 13 billion years and began its journey only 600 million years after the Big Bang. The galaxy, called the Firefly Sparkle, contains a network of massive star clusters that are evidence of how galaxies grow.

The paper is “The Firefly Sparkle: The Earliest Stages of the Assembly of A Milky Way-type Galaxy in a 600 Myr Old Universe.” The lead author is Lamiya Mowla, an observational astronomer and assistant professor of Physics and Astronomy at Wellesley College. The paper is in pre-print and hasn’t yet been peer-reviewed.

“The Firefly Sparkle provides an unprecedented case study of a Milky Way-like galaxy in the earliest stages of its assembly in only a 600 million-year-old Universe,”

From Mowla et al. 2024

Despite the JWST’s power, this distant, ancient galaxy is only visible through the gravitational lensing of a massive cluster of foreground galaxies. The lensing makes the Firefly Sparkle appear as an arc. Two other galaxies are also in the vicinity, called Firefly BF (Best Friend) and Firefly NBF (New Best Friend.)

This image shows the Firefly Sparkle galaxy and its two neighbours, BF and NBF. The Firefly Sparkle’s mass is concentrated in 10 clusters that contain up to 57% of its entire mass. Image Credit: Mowla et al. 2024.

“The Firefly Sparkle exhibits the hallmarks expected of a future Milky Way-type galaxy captured during its
earliest and most gas-rich stage of formation,” the authors write. The young galaxy’s mass is concentrated in 10 clusters, which range from about 200,000 solar masses to 630,000 solar masses. According to the authors, these clusters “straddle the boundary between low-mass galaxies and high-mass globular clusters.”

These clusters are significant because they’re clues to how the galaxy is growing. The researchers were able to gauge the ages of the clusters and their star formation histories. They found that they experienced a burst of star formation at around the same time. “The cluster ages suggest that they are gravitationally bound with star formation histories showing a recent starburst possibly triggered by the interaction with a companion galaxy at the same redshift at a projected distance of ~2 kpc away from the Firefly Sparkle.”

There are two candidates for the interacting galaxy: Firefly Best Friend (BF) and Firefly New Best Friend (NBF). But NBF is about 13 kpcs away, while BF is about two kpcs away, making BF the likely interactor. “Faint low-surface brightness features are visible at the corners of the arc close to the neighbour, hinting at a possible interaction between the two galaxies <FS and BF> which may have triggered a burst of star formation in both of them,” explain the researchers.

This figure from the study illustrates the star formation histories of each cluster, as well as each galaxy. In the top right, “The Firefly Sparkle and FF-BF both show a recent burst of star formation in the last ~ 50 Myr indicative of recent interactions,” the authors explain. Image Credit: Mowla et al. 2024.

The researchers paid special attention to the central cluster. They found that the temperature is extremely high at about 40,000 Kelvin (40,000 C; 72,000 F.) It also has a top-heavy initial mass function, a signal that it formed in a very metal-poor environment. These observations and other evidence show that Firefly Sparkle is very likely a progenitor of galaxies like ours. For these reasons, “… the Firefly Sparkle provides an unprecedented case study of a Milky Way-like galaxy in the earliest stages of its assembly in
only a 600 million-year-old Universe,” the authors write.

Fortunately, the researchers behind these results have a powerful supercomputer simulation to compare observations with. It’s called Illustris TNG. It’s a massive cosmological magnetohydrodynamical simulation based on a comprehensive physical model of the Universe. Illustris TNG has made three runs, called TNG50, TNG 100, and TNG 300. The researchers compared their results with TNG 50.

This figure compares Firefly Sparkle’s current mass with the TNG 50 simulations of galaxy growth and with the growth rate of the Milky Way, according to an upcoming paper. Image Credit: Mowla et al. 2024.

Finding these ancient star clusters is intriguing, but we can’t assume they’ll survive intact. There are tidal and evaporative forces at work. The authors examined the stability of the individual star clusters and how they’ll fare over time.

“Most of these star clusters are expected to survive to the present-day universe and will expand and then get ripped apart to form the stellar disk and the halo of the galaxy,” the authors explain. “The only way they survive is to get kicked out to large distances, away from the dense tidal field of the galaxy.” The ones that get kicked out may persist as globular clusters.

One of the JWST’s primary science goals is to study how galaxies formed and evolved in the early Universe. By finding one in which clusters are still forming, the space telescope is reaching its goal.

“The Firefly Sparkle represents one of JWST’s first spectrophotometric observations of an extremely lensed galaxy assembling at high redshifts, with clusters that are in the process of formation instead of seen at later epochs,” the authors conclude.

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It’s an exciting time in astronomy today, where records are being broken and reset regularly. We are barely two months into 2023, and already new records have been set for the farthest black hole yet observed, the brightest supernova, and the highest-energy gamma rays from our Sun. Most recently, an international team of astronomers using the ESO’s Very Large Telescope in Chile reportedly saw the brightest object ever observed in the Universe: a quasar (J0529-4351) located about 12 billion light years away that has the fastest-growing supermassive black hole (SMBH) at its center.

The international team responsible for the discovery consisted of astrophysicists from the Research School of Astronomy and Astrophysics (RSAA) and the Center for Gravitational Astrophysics (CGA) at the Australian National University (ANU). They were joined by researchers from the University of Melbourne, the Paris Institute of Astrophysics (IAP), and the European Southern Observatory (ESO). The paper that describes their findings, titled “The accretion of a solar mass per day by a 17-billion solar mass black hole,” recently appeared online and will published in the journal Nature Astronomy.

First observed in 1963 by Dutch-American astronomer Maarten Schmidt, quasars (short for “quasi-stellar objects”) are the bright cores of galaxies powered by SMBHs. These black holes collect matter from their surroundings and accelerate it to near the speed of light, which releases tremendous amounts of energy across the electromagnetic spectrum. Quasars become so bright that their cores will outshine all the stars in their disk, making them the brightest objects in the sky and visible from billions of light-years away.

As a general rule, astronomers gauge the growth rate of SMBHs based on the luminosity of their galaxy’s core region – the brighter the quasar, the faster the black hole is accreting matter. In this case, the SMBH at the core of J0529-4351 is growing by the equivalent of one Solar mass a day, making it the fastest-growing black hole yet observed. In the process, the accretion disk alone releases a radiative energy of 2 × 1041 Watts, more than 500 trillion times the luminous energy emitted by the Sun. Christian Wolf, an ANU astronomer and lead author of the study, characterized the discovery in a recent ESO press release:

“We have discovered the fastest-growing black hole known to date. It has a mass of 17 billion Suns, and eats just over a Sun per day. This makes it the most luminous object in the known Universe. Personally, I simply like the chase. For a few minutes a day, I get to feel like a child again, playing treasure hunt, and now I bring everything to the table that I have learned since.”

But what was most surprising was that this quasar was hiding in plain sight. “All this light comes from a hot accretion disc that measures seven light-years in diameter — this must be the largest accretion disc in the Universe,” said ANU Ph.D. student and co-author Samuel Lai. “It is a surprise that it has remained unknown until today, when we already know about a million less impressive quasars. It has literally been staring us in the face until now,” added co-author Christopher Onken, who is also an astronomer at ANU.

As Onken explained, J0529-4351 showed up in images taken by the ESO Schmidt Southern Sky Survey dating back to 1980. It was only in recent years that it was recognized as a quasar, thanks to improved instruments and measurements. Finding quasars requires precise observations from large areas of the sky, resulting in massive datasets that often require machine learning algorithms to analyze them. However, these models are somewhat limited because they are trained on existing data, meaning candidates are selected based on previously observed objects.

This image shows the region of the sky in which the record-breaking quasar J0529-4351 is situated. Credit: ESO/Digitized Sky Survey 2/Dark Energy Survey

Since J0529-4351 is so luminous, it was dismissed by the ESA’s Gaia Observatory as being too bright to be a quasar and was ruled to be a bright star. Last year, the ANU-led team identified it as a distant quasar based on observations using the 2.3-meter telescope at the Siding Spring Observatory in Australia. They then conducted follow-up observations using the X-shooter spectrograph on the ESO’s VLT telescope to confirm their results. The quasar is also an ideal target for the GRAVITY+ upgrade on ESO’s Very Large Telescope Interferometer (VLTI), designed to accurately measure the mass of black holes.

In addition, astronomers look forward to making observations with next-generation telescopes like the ESO’s Extremely Large Telescope (ELT). This 39-meter telescope, currently under construction in the Atacama Desert in Chile, will make identifying and characterizing distant quasars easier. Studying these objects and their central black holes could reveal vital details about how SMBHs and galaxies co-evolved during the early Universe.

Further Reading: ESO, ESO Science Papers

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Japan successfully tested its new flagship H3 rocket after an earlier version failed last year. The rocket lifted off from the Tanegashima Space Center on Saturday, February 17, reaching an orbital altitude of about 670 kilometers (420 miles). It deployed a set of micro-satellites and a dummy satellite designed to simulate a realistic payload.

With the successful launch of the H3, Japan will begin transitioning away from the previous H-2A rocket which has been in service since 2001 and is set to be retired after two more launches. Several upcoming missions depend on the H3, so this successful test was vital.

The launch came after two days of delays because of bad weather. The H3 rocket, built by Mitsubishi Heavy Industries, is now set to become the main launch vehicle of Japan’s space program. The rocket’s first flight in March 2023 failed to reach orbit, which resulted in the loss of an Earth imaging satellite.

The successful launch and deployment of the satellites was a relief for JAXA and members of the project. A livestream of the launch and subsequent successful orbit insertion showed those in the JAXA command cheering and hugging each other.

“I now feel a heavy load taken off my shoulders,” said JAXA H3 project manager Masashi Okada, speaking at a press briefing after the launch. “But now is the real start for H3, and we will work to steadily improve it.”

H3 stands about 57-meter (187-feet) tall and is designed to carry larger payloads. The two microsatellites were deployed approximately 16 minutes and 43 seconds after liftoff. They included an Earth observation satellite named CE-SAT-IE, developed by Canon Electronics, and TIRSAT, an infrared Earth observation instrument that will observe the temperature of the Earth’s surface and seawater.

“We feel so relieved to be able to announce the good results,” JAXA President Hiroshi Yamakawa said at the briefing. Yamakawa added that the main goals of H3 are to secure independent access to space and allow Japan to be competitive as international demand for satellite launches continues to grow. “We made a big first step today toward achieving that goal,” he said.

An image sent back by a mini-probe shows Japan’s SLIM lander on its side on the lunar surface. (JAXA / Takara Tomy / Sony Group / Doshisha Univ.)

The successful launch comes after two other recent successes for JAXA last month where the H-2A rocket successfully placed a spy satellite into orbit, and just days later JAXA’s robotic SLIM (Smart Lander for Investigating Moon) made the first-ever precise “pinpoint” Moon landing – although unfortunately the lander came down on its side. However, during the final stages of the descent two autonomous rovers were successfully deployed: a tiny hopping robot and the other designed to roll about the surface. Both have sent back pictures and can continue exploring and sending back information even if SLIM cannot be operated.

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One of the central predictions of general relativity is that in the end, gravity wins. Stars will fuse hydrogen into new elements to fight gravity and can oppose it for a time. Electrons and neutrons exert pressure to counter gravity, but their stability against that constant pull limits the amount of mass a white dwarf or neutron star can have. All of this can be countered by gathering more mass together. Beyond about 3 solar masses, give or take, gravity will overpower all other forces and collapse the mass into a black hole.

While black holes have a great deal of theoretical and observational evidence to prove their existence, the theory of black holes is not without issue. For one, general relativity predicts that the mass compresses to an infinitely dense singularity where the laws of physics break down. This singularity is shrouded by an event horizon, which serves as a point of no return for anything devoured by the black hole. Both of these are problematic, so there has been a long history of trying to find some alternative. Some mechanism that prevents singularities and event horizons from forming.

One alternative is a gravitational vacuum star or gravitational condensate star, commonly called a gravastar. It was first proposed in 2001, and takes advantage of the fact that most of the energy in the universe is not regular matter or even dark matter, but dark energy. Dark energy drives cosmic expansion, so perhaps it could oppose gravitational collapse in high densities.

Illustration of a hypothetical gravastar. Credit: Daniel Jampolski and Luciano Rezzolla, Goethe University Frankfurt

The original gravastar model proposed a kind of Bose-Einstein condensate of dark energy surrounded by a thin shell of regular matter. The internal condensate ensures that the gravastar has no singularity, while the dense shell of matter ensures that the gravastar appears similar to a black hole from the outside. Interesting idea, but there are two central problems. One is that the shell is unstable, particularly if the gravastar is rotating. There are ways to tweak things just so to make it stable, but such ideal conditions aren’t likely to occur in nature. The second problem is that gravitational wave observations of large body mergers confirm the standard black hole model. But a new gravastar model might solve some of those problems.

The new model essentially nests multiple gravastars together, somewhat like those nested Matryoshka dolls. Rather than a single shell enclosing exotic dark energy, the model has a layers of nested shells with dark energy between the layers. The authors refer to this model as a nestar, or nested gravastar. This alternative model makes the gravastar more stable, since the tension of dark energy is better balanced by the weight of the shells. The interior structure of the nestar also means that the gravitational waves of a nestar and black hole are more similar, meaning that technically their existence can’t be ruled out.

That said, even the authors note that there is no likely scenario that could produce nestars. They likely don’t exist, and it’s almost certain that what we observe as black holes are true black holes. But studies such as this one are great for testing the limits of general relativity. They help us understand what is possible within the framework of the theory, which in turn helps us better understand gravitational physics.

Reference: Jampolski, Daniel and Rezzolla, Luciano. “Nested solutions of gravitational condensate stars.” Classical and Quantum Gravity 41 (2024): 065014.

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One of the largest reentries in recent years, ESA’s ERS-2 satellite is coming down this week.

After almost three decades in orbit, an early Earth-observation satellite is finally coming down this week. The European Space Agency’s (ESA) European Remote Sensing satellite ERS-2 is set to reenter the Earth’s atmosphere on or around Wednesday, February 21st.

A Trail Blazing Mission

Launched atop an Ariane-4 rocket from the Kourou Space Center in French Guiana on April 21st, 1995, ERS-2 was one of ESA’s first Earth observation satellites. ERS-2 monitored land masses, oceans, rivers, vegetation and the polar regions of the Earth using visible light and ultraviolet sensors. The mission was on hand for several natural disasters, including the flood of the Elbe River across Germany in 2006. ERS-2 ceased operations in September 2011.

Anatomy of the reentry of ERS-2. ESA

ERS-2 was placed in a retrograde, Sun-synchronous low Earth orbit, inclined 98.5 degrees relative to the equator. This orbit is typical for Earth-observing and clandestine spy satellites, as it allows the mission to image key target sites at the same relative Sun angle, an attribute handy for image interpretation.

ERS-2 tracks and ice floe. ESA The Last Days of ERS-2

Reentry predictions for the satellite are centered on February 21st at 00:19 Universal Time (UT)+/- 25 hours. As we get closer, expect that time to get refined. The mass of ERS-2 at launch (including fuel) was 2,516 kilograms. Expect most of the satellite to burn up on reentry.

The orbital path of ERS-2. Orbitron

For context, recent high profile reentries include the UARS satellite (6.5 tons, in 2011), and the massive Long March-5B booster that launched the core module for China’s Tiangong Space Station in late 2022 (weighing in at 23 tons).

ERS-2 in the clean room on Earth prior to launch. ESA

ESA passed its first space debris mitigation policy in 2008, 13 years after ERS-2 was launched. In 2011, ESA decided to passively reenter the satellite, and began a series of 66 deorbiting maneuvers to bring its orbit down from 785 kilometers to 573 kilometers. Its fuel drained and batteries exhausted, ERS-2 is now succumbing to the increased drag of the Earth’s atmosphere as we near the peak of the current solar cycle.

Flooding in Prague, seen by ERS-2. ESA Tracking the Reentry

Tracking the satellite is as simple as knowing where and when to look. The ID number for ERS-2 is 1995-021A/23560. ESA has a site set up dedicated to tracking the decay of ERS-2. Aerospace.Org, Space-Track and Heavens-Above are other good sites to follow the end of ERS-2.

Expect the satellite to be a real ‘fast mover’ on its final passes. We saw UARS on its final orbit, flashing as it tumbled swiftly across the sky.

Taking out ERS-2 highlights the growing dilemma posed by space junk. There are currently over 25,800 objects in Earth orbit. That amount is growing exponentially as the annual launch cadence increases. 2023 saw a record 212 launches reach orbit, and 2024 is on track to break that number. The rise of mega-constellations such as SpaceX’s Starlink is adding to this burden.

The Age of Space Debris

Space junk adds to the number of artificial ‘stars’ seen whizzing across the night sky, impacts astronomical sky surveys, and poses a hazard to crewed missions and the International Space Station and the Tiangong Space Station. Reentries also contaminate the atmosphere, and a recent study suggests that mega-constellations may even impact the Earth’s magnet field. And while it’s mainly wealthier countries in the northern hemisphere that are launching satellites, the global south disproportionately bears the brunt of uncontrolled reentries.

Finally, all of these are consequences we don’t fully understand and are worthy of further study. For now, you can still track the demise of ERS-2, as it comes to a fiery end this week.

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The solar cycle has been reasonably well understood since 1843 when Samuel Schwabe spent 17 years observing the variation of sunspots. Since then, we have regularly observed the ebb and flow of the sunspots cycle every 11 years. More recently ESA’s Solar Orbiter has taken regular images of the Sun to track the progress as we head towards the peak of the current solar cycle. Two recently released images from February 2021 and October 2023 show how things are really picking up as we head toward solar maximum.

The Sun is a great big ball of plasma, electrically charged gas, which has the amazing property that it can move a magnetic field that may be embedded within.  As the Sun rotates, the magnetic field gets dragged around with it but, because the Sun rotates faster at the equator than at the poles, the field lines get wound up tighter and tighter.

Under this immense stressing, the field lines occasionally break, snap or burst through the surface of the Sun and when they do, we see a sunspot. These dark patches on the visible surface of the Sun are regions where denser concentrations of solar material prohibit heat flow to the visible surface giving rise to slightly cooler, and therefore darker patches on the Sun. 

A collage of new solar images captured by the Inouye Solar Telescope, which is a small amount of solar data obtained during the Inouye’s first year of operations throughout its commissioning phase. Images include sunspots and quiet regions of the Sun, known as convection cells. (Credit: NSF/AURA/NSO)

The slow rotation of the Sun and the slow but continuous winding up of the field lines means that sun spots become more and more numerous as the field gets more distorted. Observed over a period of years the spots seem to slowly migrate from the polar regions to the equatorial regions as the solar cycle progresses. 

To try and help understand this complex cycle and unlock other mysteries of the Sun, the European Space Agency launched its Solar Orbiter on 10 February 2020. Its mission to explore the Sun’s polar regions, understand what drives the 11 year solar cycle and what drives the heating of the corona, the outer layers of the Sun’s atmosphere. 

Solar Orbiter

Images from Solar Orbiter have been released that show closeups of the Sun’s visible surface, the photosphere as it nears peak of solar activity. At the beginning of the cycle, at solar minimum in 2019, there was relatively little activity and only a few sunspots. Since then, things have been slowly increasing. The image from February 2021 showed a reasonably quiet Sun but an image taken in October last year shows that things are, dare I say, hotting up! The maximum of this cycle is expected to occur in 2025 which supports theories that the period of maximum activity could arrive a year earlier. 

Understanding the cycle is not just of whimsical scientific interest, it is vital to ensure we minimise damage to ground based and orbiting systems but crucially understand impact on life on Earth. 

Source : Sun’s surprising activity surge in Solar Orbiter snapshot

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Quasars are fascinating objects; supermassive black holes that are actively feasting on material from their accretion disks. The result is a jet that can outshine the combined light from the entire galaxy! There are smaller blackholes too that are the result of the death of stars and these also sometimes seem to host accretion disks and jets just like their larger cousins. We call these microquasars and, whilst there are similarities between them, there are differences too.

The term quasar gives a clue to their nature, the term is an abbreviated version of ‘qausi-stellar radio source’ which is exactly what they are.  A source of radio energy which seems to present as the pinpoint nature of stars.  The first quasar to be discovered was given the rather unimaginative name ‘3C 273’ and it was found in the constellation Virgo.  Most objects of this nature tend to have catalogue numbers rather than more common names and in the case of 3C 273 it tells us it is the 273rd object in the 3rd Cambridge Catalogue of Radio Sources.

It was in 1964 that we started to understand the nature of quasars and their incredible luminosity which is the result of the accretion of material onto a supermassive black hole. The accretion process seems to drive twin radio lobes that appear as opposing jets out of their rotational axis. The microquasars seem to be scaled-down versions. 

In a paper recently published by J I Katz from the Washington University the differences between the two are explored and, despite the common nature of quasars across the Universe, to date only 19 microquasars have been discovered and there is one key difference emerging.

It seems that the radio lobes are the key.  In quasars, a significant propotion of the power appears to come from particle acceleration along their polar jets, driving the energy release from the radio lobes. In microquasars, this seems to be the opposite with thermal emissions from their accretion disk more prominent. In quasars, for some as yet unknown reason, the accretion of material onto the supermassive black holes seems to drive the particle acceleration along the jet rather than thermal radiation yet this is not the case for the smaller microquasars. 

Supermassive blackholes that are the powerhouses for quasars seem to offer a more favourable environment for the accretion and acceleration of energetic particles. Katz proposes that a lower electron density in the accretion disk of supermassive black holes allows quasars to accelerate much larger quantities of relativistic particles than their stellar mass equivalents.

Source : Quasars vs. Microquasars

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Intuitive Machines’ Odysseus lander has beamed back a series of snapshots that were captured as it headed out from the Earth toward the moon, and one of the pictures features Australia front and center. The shots also show the second stage of the SpaceX Falcon 9 rocket that launched the spacecraft, floating away as Odysseus pushed onward.

Intuitive Machines successfully transmitted its first IM-1 mission images to Earth on February 16, 2024. The images were captured shortly after separation from @SpaceX's second stage on Intuitive Machines’ first journey to the Moon under @NASA's CLPS initiative. pic.twitter.com/9LccL6q5tF

— Intuitive Machines (@Int_Machines) February 17, 2024

The pictures were taken on Feb. 16, the day of the launch.

“Payload integration managers programmed the lander’s wide and narrow field-of-view cameras to take five quick images every five minutes for two hours, starting 100 seconds after separating from SpaceX’s second stage,” Houston-based Intuitive Machines explained in a posting to X / Twitter. “Out of all the images collected, Intuitive Machines chose to show humanity’s place in the universe with four wonderful images we hope to inspire the next generation of risk-takers.”

If Intuitive Machines’ IM-1 mission is successful, Odysseus is due to become the first commercial spacecraft to make a soft landing on the moon, and the first U.S. spacecraft to do so since NASA’s Apollo 17 crewed mission in 1972.

The lander, which is about the size of an old-fashioned telephone booth, is carrying six science payloads for NASA, plus six commercial payloads — including a miniaturized camera system that would be dropped off just before landing to record the touchdown.

Odysseus is scheduled to reach lunar orbit on Feb. 21 and descend to Malapert A crater, near the moon’s south pole, on the 22nd. The mission’s objective is to test out spacecraft systems and assess the environment in the south polar region, in advance of a crewed landing that could take place as early as 2026.

Assuming all goes well, Intuitive Machines is in line to receive $118 million from NASA through the Commercial Lunar Payload Services program, which was created to take advantage of private-sector innovation and reduce NASA’s costs.

In a Feb. 18 mission update, Intuitive Machines reported that Odysseus “continues to be in excellent health, and flight controllers are preparing planned trajectory correction maneuvers to prepare the lander for lunar orbit insertion.”

Odysseus continues to be in excellent health, and flight controllers are preparing planned trajectory correction maneuvers to prepare the lander for lunar orbit insertion.
?(18FEB2024 1745 CST) 1/5 pic.twitter.com/vp6PV5hqGU

— Intuitive Machines (@Int_Machines) February 18, 2024

Success isn’t guaranteed: Just last month, a NASA-supported commercial lander built by Astrobotic fell back to Earth after missing its chance to make a moon landing due to a propellant leak. Over the past few years, other robotic moon landing missions planned by Israel’s SpaceIL team, Japan’s iSpace and the Russian Space Agency have also ended in failure.

That being said, failure isn’t inevitable: In the past year, India and the Japan Aerospace Exploration Agency have successfully put landers on the lunar surface to send back science data.

If Odysseus survives its landing attempt, Intuitive Machines expects the solar-powered robot to be in operation for seven days. The mission is expected to end when the sun sinks below the lunar horizon.

The post Odysseus Moon Lander Sends Back Selfies With Earth in the Picture appeared first on Universe Today.

April 8’s North American solar eclipse is just around the corner, and it has astronomy fans and weather aficionados alike preparing for an incredible show. But it’s not just fun and games. Eclipses are rare opportunities for scientists to study phenomena that only come around once in a while.

Last week, a team of meteorological experts from the Netherlands released a paper describing how eclipses can disrupt the formation of certain types of clouds. Their findings have implications for futuristic geoengineering schemes that propose to artificially block sunlight to combat climate change.

Published in Nature Communications Earth & Environment, the paper examines satellite imagery of cloud cover during three solar eclipses between 2005 and 2016.

They found that in the wake of an eclipse, shallow cumulus clouds tend to disappear – and it doesn’t even need to be a total eclipse for this to occur – it happens when just 15% of the Sun is obscured.

The effect isn’t immediate. There’s a delay of about 20 minutes. That’s because the eclipse isn’t destroying the clouds directly. Instead, it’s cooling the land beneath, interrupting packets of warm air that race upwards in updrafts to condense into clouds. By suppressing the updrafts, the eclipse puts a pause on cumulus cloud formation.

Proposals to reduce climate change by artificially blocking the Sun work on a similar principle to an eclipse. A swarm of sun-shade spacecraft, or an injection of light-absorbing aerosols into the atmosphere, could reduce the amount of solar energy reaching the surface of the Earth, cooling the temperature back to historical norms. For a project like this to work, about 3.5% to 5% of sunlight would have to be blocked.

The cloud modeling data from this paper indicates reasons to be cautious, however. First and foremost, it suggests that blocking sunlight isn’t as effective as you might think, because while it does cool the ground initially, it also reduces cloud cover, which once again increases the amount of solar energy reaching the Earth.

The decrease in cloud cover would also have an effect on precipitation – fewer clouds means less rain – which might result in regional increases in drought and desertification.

It’s unclear whether the reduction in cumulus clouds would persist with a more permanent, artificially constructed eclipse – true solar eclipses only last a few minutes locally, after all. But the authors say the data ought to influence the design of any serious geoengineering proposals going forward. A solar shade stationed between the Sun and Earth, at Lagrange point 1, for example, might not block the Sun uniformly. If it caused either partial or intermittent local eclipses, it would be more likely to feature these cloud-destroying effects.

Atmospheric aerosol injection might seem like a more uniform method of blocking sunlight, but large-scale weather patterns actually make these methods potentially even more variable, blocking up to 45% of sunlight locally on occasion (well beyond the 15% needed to see a reduction in cloud formation).

These geoengineering projects, in other words, might solve climate change only to introduce new, unexpected challenges, and the costs might not be borne equitably across the globe.

So what’s the lesson? Well, if you’re going out to see the eclipse on April 8, and you feel a little chill in the air, you’re not imagining it. The Earth around you is cooling – and it might also get a little sunnier after it’s over, as cumulus cloud formation gets interrupted. These effects are tangible reminders that the relationship between Earth’s climate and the Sun is complex – and tinkering with it comes with a high chance of unintended consequences.

Read the Paper:

Victor Trees et al. “Clouds dissipate quickly during solar eclipses as the land surface cools.” Communications Earth and Environment. February 12, 2024.

The post Solar Eclipses Provide a Rare Way to Study Cloud Formation appeared first on Universe Today.

Whether or not you agree that Pluto isn’t a planet, in many ways, Pluto is quite different from the classical planets. It’s smaller than the Moon, has an elliptical orbit that brings it closer to the Sun than Neptune at times, and is part of a collection of icy bodies on the edge of our solar system. It was also thought to be a cold dead world until the flyby of New Horizons proved otherwise. The plucky little spacecraft showed us that Pluto was geologically active, with a thin atmosphere and mountains that rise above icy plains. Geologically, Pluto is more similar to Earth than the Moon, a fact that has led some to reconsider Pluto’s designation as a dwarf planet.

Astronomers still aren’t sure how Pluto has remained geologically active. Perhaps the gravitational interactions with its moon Charon, or perhaps interior radioactive decay. But regardless of the cause, the general thought has been that Pluto is an exception, not a rule. Other outer worlds of similar size and composition are likely dead worlds. But a new study shows that isn’t the case for at least two dwarf planets, Eris and Makemake.

This new study doesn’t rely on high-resolution images like we have for Pluto. Our current observations of Eris and Makemake show them only as small, blurry dots. But we do have spectral observations of these worlds, which is where this study comes in.

The team looked at the spectral lines of molecules on the surface of these worlds, most specifically that of methane. Methane, or CH4 has two important variants. One is composed of standard hydrogen atoms, while the other contains one or more atoms of a type of hydrogen known as deuterium. Deuterium has a nucleus containing a proton and neutron rather than just a proton, and this skews the spectrum of methane a bit. From the spectral observations, the team could measure the D/H ratio for methane on both worlds.

How D/H ratios compare to possible origins. Credit: Glein, et al

This ratio is determined by the source of the methane. If Eris and Makemake are dead worlds, then the methane they have stems from their origin more than 4 billion years ago, and the D/H level should be on the higher end. On the other hand, if the surface methane was generated through an interior process and vented through active geological processes, then the D/H ratio should be lower. The team found that the ratio is most consistent with thermogenic and abiotic mechanisms, suggesting that both Eris and Makemake are active worlds, or at least were active in geologically recent times.

Eris is about the same size as Pluto, so it isn’t too surprising that it’s a geologically active world given what we now know about Pluto. But Makemake is much smaller, about 60% the size of Pluto. If Makemake is an active world, then it is likely that other dwarf planets such as Haumea are as well. If that’s the case, then most if not all dwarf planets are geologically active. As the authors suggest, it might be worth sending a probe or two to the outer worlds for more study.

Reference: Glein, Christopher R., et al. “Moderate D/H ratios in methane ice on Eris and Makemake as evidence of hydrothermal or metamorphic processes in their interiors: Geochemical analysis.” Icarus (2024): 115999.

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 A recently submitted study to The Astronomical Journal continues to search for the elusive Planet Nine (also called Planet X), which is a hypothetical planet that potentially orbits in the outer reaches of the solar system and well beyond the orbit of the dwarf planet, Pluto. The goal of this study was to narrow down the possible locations of Planet Nine and holds the potential to help researchers better understand the makeup of our solar system, along with its formation and evolutionary processes. So, what was the motivation behind this study regarding narrowing down the location of a potential Planet Nine?

Dr. Mike Brown, who is a Richard and Barbara Rosenberg Professor of Astronomy at Caltech and lead author of the study, tells Universe Today, “We are continuing to try to systematically cover all of the regions of the sky where we predict Planet Nine to be. Using data from Pan-STARRS allowed us to cover the largest region to date.”

Pan-STARRS, which stands for Panoramic Survey Telescope and Rapid Response System, is a collaborative astronomical observation system located at Haleakala Observatory and operated by the University of Hawai’I Institute of Astronomy with telescope construction being funded by the U.S. Air Force. For the study, the researchers used data from Data Release 2 (DR2) with the goal of narrowing down the possible location of Planet Nine based on findings from past studies.

In the end, the team narrowed down possible locations of Planet Nine by eliminating approximately 78 percent of possible locations that were calculated from previous studies. Additionally, the researchers also provided new estimates for the approximate semimajor axis (measured in astronomical units (AU)) and Earth-mass size of Planet Nine at 500 and 6.6, respectively. So, what are the most significant results from this study, and what follow-up studies are currently being conducted or planned?

“While I would love to say that the most significant result was finding Planet Nine, we didn’t,” Dr. Brown tells Universe Today. “So instead, it means that we have significantly narrowed the search area. We’ve now surveyed approximately 80% of the regions where we think Planet Nine might be.”

In terms of follow-up studies, Dr. Brown tells Universe Today, “I think that the LSST is the most likely survey to find Planet Nine. When it comes online in a year or two it will quickly cover much of the search space and, if Planet Nine is there, find it.”

LSST stands for Legacy Survey of Space and Time, and is an astronomical survey currently scheduled as a 10-year program to study the southern sky and take place at the Vera C. Rubin Observatory in Chile, which is presently under construction. Objectives for LSST include studying identifying near-Earth asteroids (NEAs) and small planetary bodies within our solar system, but also include deep space studies, as well. These include investigating the properties of dark matter and dark energy and the evolution of the Milky Way Galaxy. But what is the importance of finding Planet Nine?

Dr. Brown tells Universe Today, “This would be the 5th largest planet of our solar system and the only one with a mass between Earth and Uranus. Such planets are common around other stars, and we would suddenly have a chance to study one in our own solar system.”

Scientists began hypothesizing the existence of Planet Nine shortly after the discovery of Neptune in 1846, including an 1880 memoir authored by D. Kirkwood and later a 1946 paper authored by American astronomer, Clyde Tombaugh, who was responsible for discovering Pluto in 1930. More recent studies include studies from 2016 and 2017 presenting evidence for the existence of Planet Nine, the former of which was co-authored by Dr. Brown. This most recent study marks the most complete investigation of narrowing down the location of Planet Nine, which Dr. Brown has long-believed exists, telling Universe Today, “There are too many separate signs that Planet Nine is there. The solar system is very difficult to understand without Planet Nine.”

He continues by telling Universe Today that “…Planet Nine explains many things about orbits of objects in the outer solar system that would be otherwise unexplainable and would each need some sort of separate explanation. The cluster of the directions of the orbits is the best know, but there is also the large perihelion distances of many objects, existence of highly inclined and even retrograde objects, and the high abundance of very eccentric orbits which cross inside the orbit of Neptune. None of these should happen in the solar system, but all are easily explainable as an effect of Planet Nine.”

Does Planet Nine exist and where will we find it in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

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