The output from the study reveals the most polluted areas of the Mediterranean and the main entry points from the mainland. It will help us to improve our understanding of the processes and mechanisms that transport debris across the ocean and even help us to perhaps predict movement. The results also show that the amount of debris in the Mediterranean covers around 95 square kilometres.

Unfortunately the research does not help resolve the issue of pollution but it does help us understand the scale. The team propose future satellites should be equipped with detectors to monitor the debris. It would increase the ability to detect plastic in the open ocean by a factor of 20 and help to model the impact of marine pollution on first, tourism and the marine ecosystem. 

One element of the studies conclusion is that population density, geography and rainfall patterns play an important part in the accumulation of marine litter. Dry arid lands like deserts that play host to cities seem to contribute much less to marine litter while those that are much more temperate with higher rainfall seem to contribute more. 

It is also interesting to note that the majority of litter that originates from land masses seems to be confined to 15 kilometres form the coast and subsequently returns after a few days of months. The team conclude that satellite based monitoring is an essential element in our battle against litter in the ocean. The technology can also be used for the detection of other floating objects such as the loss of ships, oil spills and even search and rescue elements. 

Source : 

• Satellites to monitor marine debris from space

 { https://www.universetoday.com/ }

24-06-2024 om 23:37 geschreven door peter  

The output from the study reveals the most polluted areas of the Mediterranean and the main entry points from the mainland. It will help us to improve our understanding of the processes and mechanisms that transport debris across the ocean and even help us to perhaps predict movement. The results also show that the amount of debris in the Mediterranean covers around 95 square kilometres.

Unfortunately the research does not help resolve the issue of pollution but it does help us understand the scale. The team propose future satellites should be equipped with detectors to monitor the debris. It would increase the ability to detect plastic in the open ocean by a factor of 20 and help to model the impact of marine pollution on first, tourism and the marine ecosystem. 

One element of the studies conclusion is that population density, geography and rainfall patterns play an important part in the accumulation of marine litter. Dry arid lands like deserts that play host to cities seem to contribute much less to marine litter while those that are much more temperate with higher rainfall seem to contribute more. 

It is also interesting to note that the majority of litter that originates from land masses seems to be confined to 15 kilometres form the coast and subsequently returns after a few days of months. The team conclude that satellite based monitoring is an essential element in our battle against litter in the ocean. The technology can also be used for the detection of other floating objects such as the loss of ships, oil spills and even search and rescue elements. 

Source : 

• Satellites to monitor marine debris from space

 { https://www.universetoday.com/ }

24-06-2024 om 23:37 geschreven door peter  

Microgravity causes a redistribution of fluids around the body and can cause conditions like ‘puffy face bird leg syndrome.’ The name aptly describes the effect, the face swells up and the legs thin. It results in an increase in venous pressure in the upper body, this is fine for healthy people but heart failure sufferers are at a much higher risk. Given that there are over 100 million people around the world that suffer heart failure it is essential this is explored. 

Looking at the wide spectrum of heard failure, conditions can be grouped into two categories; a weak hart that cannot pump effectively and a heart that cannot relax and fill properly. All possible conditions need to be studied with specific ways to treat and mitigate the risk during space travel. 

This is a study that is difficult to collect real data in space so we have to turn to computer modelling to simulate the effects. The team led by Dr Loon showed that a microgravity environment leads to an increase in cardiac output (the quantity of blood pumped by the heart in a given period of time.) This is not a problem for most people but with heart failure patients it is accompanied by a rise in pressure in the left atrial region of the heart, to dangerous levels. If left unchecked, it can lead to a condition where fluid accumulates in the lungs known as a pulmonary edema, making it difficult to breathe!

With the increase in corporate interest in space travel, space tourism is slowly becoming a reality. People can already pay for trips into space but as costs come down, the number of people heading out into space will increase. Eventually, trips into space will be as common as trips to other countries. It is imperative we understand the impact on our health and what we can do to make space as widely accessible as possible without putting our health at risk. 

Source : 

• Heart failure in space: scientists calculate potential health threats facing future space tourists in microgravity

 { https://www.universetoday.com/ }

24-06-2024 om 23:28 geschreven door peter  

A New Study Debunks A Long-Standing Myth About the Inhabitants of Easter Island

Without satellites, archaeologists would have spent years or decades searching for these clues.

BY DORIS ELÍN URRUTIA

 

Xinhua News Agency/Xinhua News Agency/Getty Images

“That gives credit to the Rapa Nui people, their ancestors, and the ingenuity they had for surviving on this island,” Carl Lipo, archaeologist and professor at Binghamton University in New York, told reporters on Monday. He is the lead author of the new study, published Friday in the journal Science Advances.

“You know, 14 by seven miles doesn’t give you a lot of different things you could do with it, but they made the most of what they had. And certainly there’s a linkage of this ingenuity of carving and manipulating rocks [into moai statues] and understanding of the rock’s properties. It’s something really clearly embedded in their culture,” Lipo said. “Europeans when they arrived to this island were bewildered by the fact that there were spectacular statues and very few numbers of people. They assumed that in order to move these gigantic statues, there must have been much larger populations. Really that’s a European perspective,” he added.

Satellite imagery allowed the researchers to do this debunking work faster than otherwise possible. “Satellite imagery enabled us to produce an island-wide estimate of rock mulch, where a field study would have taken years, if not decades, of walking around to map these things,” Lipo said.

Their work shows that the Rapa Nui people were likely able to sustain their population size centuries ago. But their work also looks forward.

“What inspired us to do this particular study is the fact that ecologists often continue to use Rapa Nui as a case study for collapse and ecological failure,” Lipo said. “They use it for modeling and for policy setting over and over again, which we think is really misguided. Easter Island is a great case of how populations adapt to limited resources on a very finite place and how they did so sustainably.”

{ https://www.inverse.com/ }

23-06-2024 om 23:31 geschreven door peter  

“The underlying problem we want to solve is the measurement of the flux of solid particles in space,” Dr. Christou tells Universe Today. “The smallest particles (what we normally refer to as ‘dust’) can be efficiently counted with small-area impact detectors mounted on spacecraft, while objects larger than a meter or two (asteroids) we can find at the telescope. However, anything between a couple of hundred microns and a meter fall into a kind of gap; they are too rarefied to count with impact detectors and also too small to see with a telescope. The best way to look for those particles is to see them burning up as meteors in the atmosphere, essentially by treating entire planets as area detectors.”

For the study, the researchers used a survey simulation toolkit known as SWARMS (Simulator for Wide Area Recording of Meteors from Space) to ascertain the feasibility if a camera onboard a future Venus orbiter could observe meteors within Venus’ atmosphere. Parameters for SWARMS included using the same meteoroid populations observed on Earth for Venus, along with atmospheric modeling and the type of instrument, with the researchers putting a hypothetical meteor camera onboard the upcoming European Space Agency’s EnVision orbiter.  

In the end, the researchers found the number of meteors their orbiter camera could observe in the Venusian atmosphere would be 1.5 to 2.5 times greater than on Earth. The team notes this indicates the feasibility of observing meteors within the Venusian atmosphere, assuming the data would be successfully sent back to Earth. So, what were the most significant results from this study?

Dr. Christou tells Universe Today, “I’d say the two principal results are (a) that meteors at Venus occur well above the cloud layers, and (b) that they should be consistently brighter than their Earth counterparts. Point (a) removes one potential obstacle in detecting those particles in the orbital camera while point (b) tells us that any camera design flight-proven in Earth orbit should perform at least as well and probably better at Venus.”

Regarding follow-up studies, Dr. Christou tells Universe Today, “There were a number of assumptions made in the study that we want to explore in later work. One of the assumptions is that the camera is at a fixed altitude above the surface. We want to better understand the implications of observing from an elliptical orbit where the altitude and therefore the range to the target changes with time and location. In addition, Venus’s orbit is close to Earth’s, and it may just be possible to detect the brightest meteors (we call these fireballs) with telescopes from the ground as we have done with Jupiter. A future study will better quantify this possibility.”

This study comes as NASA plans to launch the VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) orbiter sometime between 2029 and 2031, whose goal is to obtain high-resolution maps of Venus’ surface using synthetic aperture radar and near-infrared spectroscopy to penetrate Venus’ thick atmosphere. The images obtained will provide updated data from NASA’s Magellan probe in the 1990s, as this is the most recent surface data available regarding Venus’ surface activity. Additionally, the European Space Agency is slated to launch EnVision in 2032 with the goal of mapping Venus’ surface using synthetic aperture radar, as well. Therefore, since this study involves putting a hypothetical meteor camera onboard the EnVision orbiter, what plans are in the works for putting such a camera on a future spacecraft?

Dr. Christou tells Universe Today, “There are no specific plans to my knowledge, however with the current level of international interest in exploring Venus, I believe this is the right time to advocate for it. Actually, there is an instrument called Mini-EUSO recording meteors from the ISS with a detection rate of ~16,000 meteors for every month of observing time. In comparison, a meteor survey of the kind we explore in the paper requires to detect ~200 meteors every month. This indicates that the concept is technically mature and could be implemented over the next 5-10 years say.”

Venus was the sole focus of this study due to its thick atmosphere, while also having the thickest atmosphere of the terrestrial planets additionally comprised of Mercury, Earth, and Mars. Given the results of this study, a future Venus orbiter designed to observe and detect meteors within Venus’ atmosphere could be feasible while providing valuable scientific knowledge pertaining to the properties and populations of meteoroids throughout the solar system.

However, Venus is not the only planet comprised of a thick atmosphere, as the gas giants of the outer solar system (Jupiter, Saturn, Uranus, and Neptune) boast even thicker atmospheres mostly comprised of hydrogen and helium with no visible surfaces underneath. Therefore, could this meteor survey method potentially be used to identify meteors on those planets?

Dr. Christou tells Universe Today, “In some sense, we already have! In 1994, the world observed the fragments of comet Shoemaker-Levy 9 enter the atmosphere of Jupiter. More recently, amateur astronomers have observed the meteors caused by smaller, decameter-class objects against the disk of the planet. To observe fainter meteors, one would have to bring the detector and the planet closer together but, given that the gas giants have 1-2 orders of magnitude (with an order of magnitude being a factor of 10) more surface area than Earth, the potential is definitely there. Actually, such fainter meteors were detected by Voyager 1 during the brief encounter in 1979 and again more recently by the Juno orbiter. These incidents bode well for future orbital surveys.”

Studying meteoroids and meteors enables scientists to better understand the composition and properties of other planetary bodies throughout the solar system which also teaches us about the formation and evolution of the solar system, as well. As the exploration of Venus expands in the coming years, studying meteors within its thick atmosphere could provide even more clues to how we came to be, overall.

Dr. Christou concludes by telling Universe Today, “Meteors should be ubiquitous to planets and moons with appreciable atmospheres. For instance, one should expect to see meteors on Titan and even on Triton, the largest moon of Neptune where the atmospheric pressure at the surface is 100,000x lower than Earth.”

Will scientists send a Venus orbiter to study meteors within the Venusian atmosphere in the coming years and decades? Only time will tell, and this is why we science!

• As always, keep doing science & keep looking up!

{ https://www.universetoday.com/ }

23-06-2024 om 22:01 geschreven door peter  

The observations of the Crab Nebula, particularly the high rotational speed of the pulsar, seemed to conflict with current supernova theory. In the model for lower mass stars like that which was the progenitor star of the Crab Nebula, the oxygen in the core ignites as the core collapses. This process does not have sufficient energy to generate such a fast rotating pulsar. 

A team of astronomers have addressed this curiosity using MIRI (Mid-Infrared Instrument) and NIRCam (Near-Infrared Camera) onboard the James Webb Space Telescope to collect data from the Crab Nebula. The team was led by Tea Temim from the Princeton University in New Jersey. They report that the gas composition of the cloud suggests the star may have been more evolved with some iron in the core which could have led to a higher energy supernova than previously thought.

With Webb’s sensitive infrared instruments, the iron and nickel emission lines can be seen with more clarity than ever before. Studying the bright lines in the spectrum of the nebula has allowed a much more reliable estimate of the iron and nickel ratio to be deduced. They found it was a higher percentage compared to the Sun which was expected for a more energetic supernova. 

The results are promising but the readings were taken from two small regions of the nebula so to rule out variations across the entire 11 light years further readings are needed. If the data from Webb is representative from the entire nebula then it’s possible one of the mysteries of the nebula may finally be solved.

Source  : 

• Investigating the Origins of the Crab Nebula With NASA’s Webb

{ https://www.universetoday.com/ }

22-06-2024 om 18:32 geschreven door peter  

Distant Titan is an oddball in the Solar System. Saturn’s largest moon—and the second largest in the entire Solar System—has an atmosphere denser than Earth’s. It also has stable lakes and seas of liquid hydrocarbons on its surface.

New research shows that waves on these seas are eroding Titan’s coastlines.

The research is “Signatures of Wave Erosion in Titan’s Coasts,” and it’s published in Science Advances. The lead author is Rose Palermo, an MIT graduate and research geologist at the U.S. Geological Survey.

In 2007, the Cassini spacecraft spotted lakes and seas of liquid hydrocarbons, mostly methane and ethane, on Saturn’s moon Titan. Titan and Earth are the only two bodies in the Solar System known to have surface liquids. Scientists have only Cassini data from Titan to work with, and they’ve been poring over the data in an effort to understand this strange world.

The moon’s seas are one of the most intriguing features throughout the entire Solar System. But they’re difficult to observe because of the thick atmosphere. Researchers have wondered if waves shape the coastlines, but there are conflicting signs about the nature of the seas. They could be rough, or they could be smooth. A paper from 2014 suggested that transient features in Titan’s northern sea, Ligeia Mare, could be waves.

But there’s no certainty.

“We found that if the coastlines have eroded, their shapes are more consistent with erosion by waves than by uniform erosion or no erosion at all.”

Rose Palermo, lead author, U.S. Geological Survey

“Some people who tried to see evidence for waves didn’t see any, and said, ‘These seas are mirror-smooth,'” lead author Palermo said in a press release accompanying the research. “Others said they did see some roughness on the liquid surface but weren’t sure if waves caused it.”

It seems likely that there would be waves on Titan. To investigate this question, researchers at MIT compared Titan’s shorelines to shorelines on Earth to see if they match.

The seas and lakes on Titan look much like some on Earth. They appear to be flooded valleys and depressions. But scientists are uncertain if these bodies of water are eroding their coastlines like those on Earth. “Spacecraft observations and theoretical models suggest that wind may cause waves to form on Titan’s seas, potentially driving coastal erosion, but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titan remain unknown,” the authors write in their paper.

The problem is that there’s no reliable way to connect shoreline morphology directly to the mechanisms that shape it, even on Earth. To try to understand how erosion affects Titan’s coastlines, the researchers started with Earth. They examined how different coastal erosion mechanisms shape Earth’s coastlines, then applied the framework to Titan.

There are basically two types of coastal erosion: wave-driven erosion and uniform erosion. Each type produces different coastlines.

Wave erosion is driven by wind and produces a change proportional to the strength of the waves. Waves are usually stronger the farther they travel before they hit a coast. Wave erosion creates long, smooth stretches of coast where the coast is fully exposed and bays in protected areas where less erosion occurs. The distance the wind can blow to generate waves on a particular water body before striking a coast is called ‘fetch.’

“Wave erosion is driven by the height and angle of the wave,” Palermo explained. “We used fetch to approximate wave height because the bigger the fetch, the longer the distance over which wind can blow and waves can grow.”

Uniform erosion is different. It doesn’t rely on mechanical wave action. The compositional differences between Earth and Titan are apparent when it comes to uniform erosion. “Titan’s crust consists mainly of water ice, but its surface solids may also include heavy hydrocarbon molecules, such as benzene, that are soluble in liquid methane and ethane, such that the liquid lakes and seas may slowly dissolve the solid coasts of the north polar terrain,” the authors explain in their research.

Over a long enough period of time, uniform erosion occurs at the same rate in all locations, producing distinct morphological features: shorelines that are generally smooth even inside bays with sharp headlands that punctuate them.

“Here, we test the hypothesis that coastal erosion has shaped Titan’s seas by investigating whether coastline shapes are most consistent with wave-driven erosion, uniform erosion, or no coastal erosion,” the authors write.

The different morphological features produced by wave-driven erosion and uniform erosion are obvious. Wave-driven erosion tends to smooth exposed sections of the coastline where fetch is large and preserve the coastline where fetch is small inside embayments.

Uniform erosion is different. It widens embayments and smooths out small-scale roughness on the coastline regardless of fetch. Headlands are the exception, which sharpen into thick-necked points that stick out into the main basin.

“We had the same starting shorelines, and we saw that you get a really different final shape under uniform erosion versus wave erosion,” said co-author Taylor Perron, Professor of Earth, Atmospheric and Planetary Sciences at MIT. “They all kind of look like the Flying Spaghetti Monster because of the flooded river valleys, but the two types of erosion produce very different endpoints.”

“We found that if the coastlines have eroded, their shapes are more consistent with erosion by waves than by uniform erosion or no erosion at all,” Perron said.

But these are just simulations, and they have to be tested rigorously. The team’s next step was to quantify these differences in the real world. The researchers explain that they “developed a technique focusing on local relationships between shoreline roughness and fetch area” to understand and quantify the differences. Specifically, they quantified what they call “roughness” to differentiate wave-driven erosion from uniform erosion. “Simply put, a lower roughness means a smoother stretch of shoreline compared to the rest of the lake, and a higher roughness means a comparatively rough stretch of shoreline,” they write.

The researchers say that “… shoreline roughness and normalized fetch area can be used to fingerprint wave-driven and uniform erosion and distinguish them from a coastline consisting only of flooded river valleys,” as shown in the first image.

So, what does this all boil down to?

“Our results suggest that the coastlines of Titan’s largest liquid bodies are most consistent with shorelines that have been modified by wave erosion and river incision,” the researchers write in their paper. They analyzed four coastlines and found a less than 5% probability of uniform erosion in a saturation-limited scenario and a less than 20% probability of uniform erosion in a fetch-limited scenario. That leaves wind-driven erosion as the most likely cause of erosion, which seems to confirm that Titan’s lakes and seas experience waves. “Therefore, our results suggest that the largest seas and lakes are not consistent with erosion by uniform processes (i.e., dissolution), as previously hypothesized for some of Titan’s landscapes,” they conclude.

That’s the scientific way of presenting their results, and their paper is like part of a long conversation with other scientists. In the press release, they state their conclusion more plainly for the rest of us.

“We can say, based on our results, that if the coastlines of Titan’s seas have eroded, waves are the most likely culprit,” said Perron, Professor of Earth, Atmospheric and Planetary Sciences at MIT. “If we could stand at the edge of one of Titan’s seas, we might see waves of liquid methane and ethane lapping on the shore and crashing on the coasts during storms. And they would be capable of eroding the material that the coast is made of.”

“Waves are ubiquitous on Earth’s oceans. If Titan has waves, they would likely dominate the surface of lakes,” says Juan Felipe Paniagua-Arroyave, associate professor in the School of Applied Sciences and Engineering at EAFIT University in Colombia, who was not involved in the study.” It would be fascinating to see how Titan’s winds create waves, not of water, but of exotic liquid hydrocarbons.”

The next step is to determine how strong Titan’s winds have to be to create coastal erosion. The researchers also hope to decipher which directions the wind is predominantly blowing from.

“Titan presents this case of a completely untouched system,” Palermo said. “It could help us learn more fundamental things about how coasts erode without the influence of people, and maybe that can help us better manage our coastlines on Earth in the future.”

{ https://www.universetoday.com/ }

22-06-2024 om 18:21 geschreven door peter  

Mars holds a very special place in our hearts. Chiefly because of all the other planets in the Solar System Mars is probably the place we are going to find some tantalising clues or maybe even evidence of prehistoric life. NASA Perseverance Rover has been trundling around the Jezero Crater looking for evidence that it was once hospitable to life. To that end it has not only been collecting rock samples but air samples too and scientists can’t wait to get their hands on them. 

The Mars Perseverance Rover is part of NASA’s Mars 2020 mission. It launched on 30 July 2020 and landed in the Jezero Crater successfully on 18 February 2021. The site was picked because it’s a dried up river bed and if there is any evidence of ancient primitive life on Mars, it is a likely location. Perseverance is equipped with a host of instruments including a drone named Ingenuity to survey the planet. 

One exciting element of the mission is the collection of rock samples as part of the Mars Sample Return Campaign. Twenty four core samples have been collected to date and deposited on the surface ready for collection by a future mission. It’s not just rock samples that have been collected though. Known as ‘headspace’ there is air in the space around the rock samples and it is this that has got scientists excited. 

Not only do the rocks hold secrets about Mars but the atmosphere does too. It’s an atmosphere rich in Carbon Dioxide but is expected to have trace amounts of other gasses  too. Information about the current climate can be gained from the trapped gasses but it’s also possible to learn about the evolution of the atmosphere through analysis of the rocks. There is one particularly important tube that has been filled entirely with gas from the atmosphere. 

With the sample sat on the surface of Mars potentially for many years, the gas trapped will interact with the rock in the sample tube. It will only be when the tubes are opened up when they arrive back here on the Earth that the interaction will cease. It’s hoped to understand more about the levels of water vapour near the Martian surface. 

It isn’t just the water vapour that is of interest but the levels of trace gas too are of interest. Through analysing the gas samples we can tell if there are gasses like neon, argon and xenon which are non reactive gasses. Because these gasses do not react then there presence in the tube samples may suggest that Mars stated with an atmosphere. We know that it had a much thicker atmosphere in the past but we don’t know whether it has always been there or whether it developed later.  

There are many benefits that will come from analysing the samples even, the prevalence of dust that will help future human exploration. As Justin Simon from NASA’s Johnson Space Center in Houston said “The gas samples have a lot to offer Mars scientists, even those who don’t study Mars would be interested because it will shed light on how the planet forms and evolves.”

Source : 

• Why Scientists Are Intrigued by Air in NASA’s Mars Sample Tubes

{ https://www.universetoday.com/ }

22-06-2024 om 18:04 geschreven door peter  

“Imagine you’ve been observing a distant galaxy for years, and it always seemed calm and inactive,” explained Paula Sánchez Sáez, an astronomer at ESO in Germany and lead author of the study accepted for publication in Astronomy & Astrophysics. “Suddenly, its [core] starts showing dramatic changes in brightness, unlike any typical events we’ve seen before.”

Follow-up analysis by a host of the most advanced space observatories confirmed the incredible event while pointing to a likely culprit: a massive black hole lying at the heart of galaxy SDSS1335+0728, which is located 300 million light-years away in the constellation Virgo, had seemingly awakened from a long slumber and was devouring the gas in its immediate surrounding. This activity resulted in the massive and growing glow witnessed by astronomers.

Of course, people in this field regularly observe unexpected changes in the cosmos. However, events like supernova explosions or other tidal disruption events which generate large amounts of light typically last for a very short time, ranging from a few days to a few hundred days, before their brightness runs out. In this case, the researchers behind the discovery say they knew something was different when the increase in brightness first spotted in 2019 not only persisted but began to increase over time.

Since then, they have spent half a decade pouring through archived data collected by other space observatories, including the European Southern Observatory’s Very Large Telescope (ESO’s VLT), to search for an explanation. That analysis found that SDSS1335+0728 was emitting more light in the visible spectrum and ultraviolet, optical, and infrared wavelengths. Then, in February 2024, the galaxy started emitting X-rays. According to Sánchez Sáez, who is also affiliated with the Millennium Institute of Astrophysics (MAS) in Chile, such behaviour is “unprecedented.”

The team followed up on their findings by studying archival data from NASA’s Wide-field Infrared Survey Explorer (WISE) and Galaxy Evolution Explorer (GALEX), the Two Micron All Sky Survey (2MASS), the Sloan Digital Sky Survey (SDSS), and the eROSITA instrument on IKI and DLR’s Spektr-RG space observatory. That work, along with supporting data collected by the Southern Astrophysical Research Telescope (SOAR), the W. M. Keck Observatory, NASA’s Neil Gehrels Swift Observatory and the Chandra X-ray Observatory, confirmed the original findings: astronomers had indeed witnessed a black hole appear out of nowhere.

“The most tangible option to explain this phenomenon is that we are seeing how the [core] of the galaxy is beginning to show (…) activity,” says co-author Lorena Hernández García from MAS and the University of Valparaíso in Chile. “If so, this would be the first time that we see the activation of a massive black hole in real-time.”

This artist’s impression shows two stages in the formation of a disc of gas and dust around the massive black hole at the centre of the galaxy SDSS1335+0728. The core of this galaxy lit up in 2019 and keeps brightening today — the first time we observed a massive black hole become active in real-time.

Image Credit: ESO/M. Kornmesser

“These giant monsters usually are sleeping and not directly visible,” added study co-author Claudio Ricci, from the Diego Portales University, also in Chile. “In the case of SDSS1335+0728, we were able to observe the awakening of the massive black hole, [which] suddenly started to feast on gas available in its surroundings, becoming very bright.”

Hernández García says this process was so rare that it had “never been observed before.” Some previous studies had reported galaxies that were thought to be inactive suddenly becoming active, but this was the first time astronomers had seen it unfolding in real-time.

While the team of astronomers admits they don’t exactly know what makes a black hole appear out of nowhere, they believe it is unlikely to be a one-time event. They even believe it could happen much closer to home, at the center of our own Milky Way galaxy.

“This is something that could happen also to our own Sgr A*, the massive black hole (…) located at the centre of our galaxy,” said Ricci.

Moving forward, the team says that additional observations and data analysis should shed even more light on their discovery. They also believe that collecting more data on SDSS1335+0728, which the Chilean-led Automatic Learning for the Rapid Classification of Events (ALeRCE) broker has classified as having an ‘active galactic nucleus’ (AGN), could benefit other researchers trying to understand the life cycle of black holes.

“Regardless of the nature of the variations, [this galaxy] provides valuable information on how black holes grow and evolve,” Sánchez Sáez said. “We expect that instruments like [MUSE on the VLT or those on the upcoming Extremely Large Telescope (ELT)] will be key in understanding [why the galaxy is brightening].”

• Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.

{ https://thedebrief.org/category/space/ }

21-06-2024 om 22:28 geschreven door peter  

Eind 2019 begon het tot dan toe onopvallende sterrenstelsel SDSS1335+0728 plotseling helderder te stralen dan ooit tevoren. Om te begrijpen waarom, hebben astronomen gegevens van diverse instrumenten in de ruimte en op de grond, waaronder de Very Large Telescope (VLT) van de Europese Zuidelijke Sterrenwacht (ESO), gebruikt om bij te houden hoe de helderheid van het stelsel is veranderd. In een vandaag gepubliceerd onderzoeksartikel komen ze tot de conclusie dat ze getuige zijn van veranderingen die nog nooit eerder in een sterrenstelsel zijn waargenomen – waarschijnlijk als gevolg van het plotselinge ontwaken van het enorme zwarte gat in diens kern.

Nog nooit zijn astronomen er getuige van geweest dat een zwart gat ontwaakt. Tot nu, zo lijkt.

Want onlangs hebben onderzoekers mogelijk gezien hoe het zwarte gat in het hart van het verder heel onopvallende sterrenstelsel SDSS1335+0728 opeens actief werd. Dat is te lezen in het blad Astronomy & Astrophysics.

Helderheidsverandering
“Stel je voor dat je een ver sterrenstelsel al jaren waarneemt en dat het altijd rustig en inactief leek te zijn,” vertelt onderzoeker Paula Sánchez Sáez. “En dan begint zijn kern plotseling dramatische helderheidsveranderingen te vertonen – op een manier die je nog nooit eerder hebt gezien.” Het klinkt misschien als het begin van een spannende sciencefictionfilm, maar voor Sánchez Sáez en collega’s was het het begin van een opwindend onderzoek. Want de helderheidsveranderingen die de onderzoeker beschrijft, zagen zij in werkelijkheid plaatsvinden.

Lastig te duiden
En die helderheidsveranderingen waren in beginsel niet zo gemakkelijk te duiden. Want hoewel onderzoekers sterrenstelsels wel vaker zien oplichten – bijvoorbeeld door toedoen van een supernova-explosie of een tidal disruption event (waarbij een ster zich te dicht bij een zwart gat in de buurt waagt en uit elkaar wordt getrokken) – was de helderheidsverandering die SDSS1335+0728 onderging, duidelijk anders. Want waar een supernova of tidal disruption event de helderheid doorgaans enkele tientallen of hooguit honderden dagen beïnvloedt, duurde de helderheidsverandering in SDSS1335+0728 maar voort. Zelfs zo’n vier jaar nadat de onderzoekers de helderheid van het sterrenstelsel voor het eerst zagen toenemen, nam de helderheid nog steeds toe!

Ongekend
Ook spotten de onderzoekers nog niet eerder waargenomen helderheidsvariaties. Zo blijkt SDSS1335+0728 nu veel meer licht op ultraviolette, optische en infrarode golflengten af te geven dan een paar jaar geleden. En in februari van dit jaar begon het sterrenstelsel ook röntgenstraling uit te zenden. “Dit gedrag is ongekend,” stelt Sánchez Sáez.

Primeur
En eigenlijk is er maar één verklaring voor. Namelijk dat het zwarte gat in het hart van dit sterrenstelsel actief begint te worden. “Als dat inderdaad zo is, zou het voor het eerst zijn dat we een enorm zwart gat zien ontwaken,” stelt onderzoeker Lorena Hernández García.

Zwarte gaten: hoe zit het ook alweer?
Een zwart gat is een gebied in de ruimte waar de zwaartekracht zo immens sterk is dat niets – zelfs licht niet – eraan kan ontsnappen. Hierdoor zijn zwarte gaten volslagen donker en in feite dus onzichtbaar. Dat verandert echter als zo’n zwart gat ‘actief’ wordt, oftewel gas naar zich toe gaat trekken. En dat is wat onderzoekers in SDSS1335+0728 – een sterrenstelsel op zo’n 300 miljoen lichtjaar afstand – gezien denken te hebben. “In het geval van SDSS1335+0728 waren we er getuige van hoe het centrale zwarte gat zich plotseling tegoed begon te doen aan gas dat in zijn omgeving voorhanden was, waar het heel helder van werd,” legt onderzoeker Claudio Ricci uit. Dat gat verdwijnt namelijk niet direct in het zwarte gat, maar begeeft zich eerst in een baan rond het zwarte gat en vormt daar een zogenoemde accretieschijf. Het gas in zo’n accretieschijf wordt heel heet en begint te gloeien. Hierdoor neemt de helderheid van het sterrenstelsel waarin het zwarte gat zich bevindt, toe. Eerder hebben onderzoekers wel vastgesteld dat zwarte gaten die eerder inactief waren, actief zijn geworden. Maar tot voor kort waren ze nog nooit daadwerkelijk getuige geweest van het actief worden – of ontwaken – van een zwart gat.

Hoewel de waargenomen helderheidsverandering van SDSS1335+0728 het beste te verklaren is door het feit dat het zwarte gat in het hart van dit sterrenstelsel is ontwaakt, houden de onderzoekers nog een kleine slag om de arm. En dat komt doordat er ook nog andere – maar wellicht minder plausibele – verklaringen denkbaar zijn voor de helderheidsverandering die SDSS1335+0728 ondergaat. Zo zou er bijvoorbeeld ook een ongekend traag verlopend tidal disruption event aan ten grondslag kunnen liggen. Of misschien wel een ander proces dat we op dit moment helemaal niet kennen. Vervolgwaarnemingen zijn dan ook nodig om met zekerheid te kunnen stellen dat onderzoekers zojuist – voor het eerst – getuige zijn geweest van het ontwaken van een zwart gat. “We verwachten dat instrumenten zoals MUSE van de VLT (Very Large Telescope, red.) of die van de komende Extremely Large Telescope (ELT) van cruciaal belang zullen zijn om te begrijpen waarom de helderheid van dit sterrenstelsel toeneemt,” zo stelt Sánchez Sáez.

Alsof het nooit anders is geweest: wetenschappers geven mensen een extra duim - en die wennen daar vervolgens bizar snel aan.

Bronmateriaal

• "Astronomen zien een enorm zwart gat ontwaken" - ESO
  
• Afbeelding bovenaan dit artikel: ESO / M. Kornmesser

{ https://scientias.nl/ }

21-06-2024 om 22:04 geschreven door peter  

Infrared astronomy is necessary when studying particularly dusty nebulae since the clouds of dust and gas obscure most of the visible light of the stars within them. Thanks to its advanced infrared optics, Webb was able to detect slightly longer wavelengths using its MIRI instrument. Mary Barsony, an astronomer with the Carl Sagan Center for the Study of Life in the Universe (part of the SETI Institute), was the lead author of a new paper that describes the results. As she related in a recent NASA press statement.

“Our jaws dropped. After studying this source for decades, we thought we knew it pretty well. But we would not have known this was two stars or that these jets existed without MIRI. That’s really astonishing. It’s like having brand new eyes.”

Radio telescopes are another way to study nebulae, though they are not guaranteed to reveal the same features as infrared instruments. In the case of WL 20S, the absorbed light was visible in the submillimeter range, making ALMA the ideal choice for follow-up observations. However, the high-resolution mid-infrared data was needed to discern WL 20S as a pair of stars with individual accretion disks. This allowed the team to resolve stellar jets composed of ionized gas that is not visible at submillimeter wavelengths.

“The power of these two telescopes together is really incredible. If we hadn’t seen that these were two stars, the ALMA results might have just looked like a single disk with a gap in the middle. Instead, we have new data about two stars that are clearly at a critical point in their lives, when the processes that formed them are petering out.”

The combined MIRI and ALMA results revealed that the twin stars are nearing the end of their formation period and may already have a system of planets. Future observations of these stars with Webb and other telescopes will enable astronomers to learn more about how young stars transition from formation to their main sequence phase. “It’s amazing that this region still has so much to teach us about the life cycle of stars,” said Ressler. “I’m thrilled to see what else Webb will reveal.”

Further Reading: 

• NASA

{ https://www.universetoday.com/ }

21-06-2024 om 20:40 geschreven door peter  

There have been numerous, almost fanciful ideas proposed from great big balloons covered in sticky stuff like giant fly paper in orbit to pickup bits and bobs floating around. Nets have also been proposed even lasers to piece by piece destroy the offending objects. If I were a betting man I would go for something along the lines of a net travelling through space at similar velocity, scooping up the debris and controlling its gentle deorbit until either landed safely for collection or burnt up in the atmosphere. 

The ideas are there, what we are lacking, is data to assess their feasibility. Enter Astroscale, a company that was founded in 2013 and develops in-orbit solutions. They have been selected by the Japan Aerospace Exploration Agency – JAXA – for the first phase of Commercial Removal of Debris Demonstration. The purpose to demonstrate how the technology for removing large pieces of debris. This has led to the development of ADRAS-J (Active Debris Removal by Astroscale-Japan.)

ADRAS-J was launched on 18 February and started its rendezvous phase four days later. On 9 April it began its approach from a few hundred kilometres and from 16 April it began its automated relative navigation approach taking it to within a few hundred metres using the onboard infrared camera. On 23 May it approached to 50 metres, a first for any spacecraft to arrive in such proximity to a large piece of debris. 

The item is the upper stage of a Japanese rocket that measures 11 metres long and 4 metres in diameter. Now the two are so close, ADRAS-J will demonstrate proximity operations and collect images of the rocket to assess its movements. This is a particularly interesting object for ADRAS-J to study becausey it has no technology or infrastructure to enable docking or servicing so is a challenging piece of debris to remove.

Source : 

• Historic Approach to Space Debris: Astroscale’s ADRAS-J Closes in by 50 Meters

{ https://www.universetoday.com/ }

21-06-2024 om 20:32 geschreven door peter  

A tardigrade, or water bear.

DR. DIANE R. NELSON Getty Images

{ https://scientias.nl/ }

21-06-2024 om 18:35 geschreven door peter  

Webb Spots Enigmatic Group of Aligned Protostellar Outflows in Serpens Nebula

These protostellar outflows are formed when jets of gas spewing from newborn stars collide with nearby gas and dust at high speeds. Typically these objects have a variety of orientations within one region. Within the Serpens Nebula, however, they are all slanted in the same direction, to the same degree, like sleet pouring down during a storm.

This Webb image shows a grouping of aligned protostellar outflows within one small region (the top left corner) of the Serpens Nebula.

Image credit: NASA / ESA / CSA / STScI / K. Pontoppidan, NASA’s Jet Propulsion Laboratory / J. Green, Space Telescope Science Institute.

“So just how does the alignment of the stellar jets relate to the rotation of the star?” the Webb astronomers said.

“As an interstellar gas cloud collapses in on itself to form a star, it spins more rapidly.”

“The only way for the gas to continue moving inward is for some of the spin (known as angular momentum) to be removed.”

“A disk of material forms around the young star to transport material down, like a whirlpool around a drain.”

“The swirling magnetic fields in the inner disk launch some of the material into twin jets that shoot outward in opposite directions, perpendicular to the disk of material.”

“In the Webb image, these jets are identified by bright red clumpy streaks, which are shockwaves caused when the jet hits the surrounding gas and dust.”

“Here, the red color indicates the presence of molecular hydrogen and carbon monoxide.”

Credit: NASA, ESA, CSA, STScI, K. Pontoppidan (NASA's Jet Propulsion Laboratory), J. Green (Space Telescope Science Institute)

© Provided by Phys.org

“Webb can image these extremely young stars and their outflows, which were previously obstructed at optical wavelengths.”

“There are a few forces that potentially can shift the direction of the outflows during this period of a young star’s life.”

“One way is when binary stars spin around each other and wobble in orientation, twisting the direction of the outflows over time.”

The Serpens Nebula is a so-called reflection nebula located approximately 1,300 light-years away in the constellation of Serpens.

Credit: NASA, ESA, CSA, STScI, K. Pontoppidan (NASA’s Jet Propulsion Laboratory), J. Green (Space Telescope Science Institute)

© Provided by Phys.org

The object is between 1 and 2 million years old, which is very young in cosmic terms.

“The Serpens Nebula is also home to a particularly dense cluster of protostars (around 100,000 years old) at the center of this image, some of which will eventually grow to the mass of our Sun,” the astronomers said.

“It is a reflection nebula, which means it’s a cloud of gas and dust that does not create its own light but instead shines by reflecting the light from stars close to or within the nebula.”

“So, throughout the region in this image, filaments and wisps of different hues represent reflected starlight from still-forming protostars within the cloud.”

“In some areas there is dust in front of that reflection, which appears here in an orange, diffuse shade.”

Credit: NASA, ESA, CSA, STScI, K. Pontoppidan (NASA’s Jet Propulsion Laboratory), J. Green (Space Telescope Science Institute)

© Provided by Phys.org

“This region has been home to other coincidental discoveries, including the flapping Bat Shadow, which earned its name when 2020 data from the NASA/ESA Hubble Space Telescope revealed it to flap, or shift. This feature is visible at the centre of the Webb image.”

• The findings were published in the Astrophysical Journal.
• Joel D. Green et al. 2024. Why are (almost) all the protostellar outflows aligned in Serpens Main? ApJ, in press;

{ https://www.sci.news/ }

21-06-2024 om 00:14 geschreven door peter  

Coastlines of Titan’s Largest Lakes and Seas Were Eroded by Wave Activity: Study

Titan, Saturn’s largest moon, is the only known planetary body besides Earth on which standing liquids persist. Liquid hydrocarbons, supplied by rainfall from the moon’s thick atmosphere, form rivers, lakes, and seas, most of which are found in the polar regions. In new research, a team of geologists at MIT studied Titan’s shorelines and found that the moon’s large lakes and seas have likely been shaped by waves.

An artist’s rendering of the surface of Saturn’s largest moon, Titan.

Image credit: Benjamin de Bivort, debivort.org / CC BY-SA 3.0.

The presence of waves on Titan has been a somewhat controversial topic ever since NASA’s Cassini spacecraft spotted bodies of liquid on the moon’s surface.

“Some people who tried to see evidence for waves didn’t see any, and said, ‘These seas are mirror-smooth.’ Others said they did see some roughness on the liquid surface but weren’t sure if waves caused it,” said Dr. Rose Palermo, a geologist at the U.S. Geological Survey.

“Knowing whether Titan’s seas host wave activity could give scientists information about the moon’s climate, such as the strength of the winds that could whip up such waves.”

“Wave information could also help scientists predict how the shape of Titan’s seas might evolve over time.”

“Rather than look for direct signs of wave-like features in images of Titan, we had to take a different tack, and see, just by looking at the shape of the shoreline, if we could tell what’s been eroding the coasts.”

Titan’s seas are thought to have formed as rising levels of liquid flooded a landscape crisscrossed by river valleys.

The researchers zeroed in on three scenarios for what could have happened next: no coastal erosion; erosion driven by waves; and uniform erosion, driven either by dissolution, in which liquid passively dissolves a coast’s material, or a mechanism in which the coast gradually sloughs off under its own weight.

They simulated how various shoreline shapes would evolve under each of the three scenarios.

To simulate wave-driven erosion, they took into account a variable known as fetch, which describes the physical distance from one point on a shoreline to the opposite side of a lake or sea.

“Wave erosion is driven by the height and angle of the wave,” Dr. Palermo said

“We used fetch to approximate wave height because the bigger the fetch, the longer the distance over which wind can blow and waves can grow.”

Cassini pinged the surface of Titan with microwaves, finding that some channels are deep canyons filled with liquid hydrocarbons. One such feature is Vid Flumina, the branching network of narrow lines in the upper-left quadrant of the image.

Image credit: NASA / JPL-Caltech / ASI.

To test how shoreline shapes would differ between the three scenarios, the scientists started with a simulated sea with flooded river valleys around its edges.

For wave-driven erosion, they calculated the fetch distance from every single point along the shoreline to every other point, and converted these distances to wave heights.

Then, they ran their simulation to see how waves would erode the starting shoreline over time.

They compared this to how the same shoreline would evolve under erosion driven by uniform erosion.

The authors repeated this comparative modeling for hundreds of different starting shoreline shapes.

They found that the end shapes were very different depending on the underlying mechanism.

Most notably, uniform erosion produced inflated shorelines that widened evenly all around, even in the flooded river valleys, whereas wave erosion mainly smoothed the parts of the shorelines exposed to long fetch distances, leaving the flooded valleys narrow and rough.

“We had the same starting shorelines, and we saw that you get a really different final shape under uniform erosion versus wave erosion,” Dr. Perron said.

“They all kind of look like the flying spaghetti monster because of the flooded river valleys, but the two types of erosion produce very different endpoints.”

This image is a composite of several images taken during two separate Titan flybys in 2006. The large circular feature near the center of Titan’s disk may be the remnant of a very old impact basin. The mountain ranges to the southeast of the circular feature, and the long dark, linear feature to the northwest of the old impact scar may have resulted from tectonic activity on Titan caused by the energy released when the impact occurred.

Image credit: NASA/JPL/University of Arizona.

Dr. Perron and colleagues checked their results by comparing their simulations to actual lakes on Earth.

They found the same difference in shape between Earth lakes known to have been eroded by waves and lakes affected by uniform erosion, such as dissolving limestone.

Their modeling revealed clear, characteristic shoreline shapes, depending on the mechanism by which they evolved.

They then wondered: Where would Titan’s shorelines fit, within these characteristic shapes?

In particular, they focused on four of Titan’s largest, most well-mapped seas: Kraken Mare, which is comparable in size to the Caspian Sea; Ligeia Mare, which is larger than Lake Superior; Punga Mare, which is longer than Lake Victoria; and Ontario Lacus, which is about 20% the size of its terrestrial namesake.

The researchers mapped the shorelines of each Titan sea using Cassini’s radar images, and then applied their modeling to each of the sea’s shorelines to see which erosion mechanism best explained their shape.

They found that all four seas fit solidly in the wave-driven erosion model, meaning that waves produced shorelines that most closely resembled Titan’s four seas.

“We found that if the coastlines have eroded, their shapes are more consistent with erosion by waves than by uniform erosion or no erosion at all,” Dr. Perron said.

The scientists are working to determine how strong Titan’s winds must be in order to stir up waves that could repeatedly chip away at the coasts.

They also hope to decipher, from the shape of Titan’s shorelines, from which directions the wind is predominantly blowing.

“Titan presents this case of a completely untouched system,” Dr. Palermo said

“It could help us learn more fundamental things about how coasts erode without the influence of people, and maybe that can help us better manage our coastlines on Earth in the future.”

• The findings appear today in the journal Science Advances.
• Rose V. Palermo et al. 2024. Signatures of wave erosion in Titan’s coasts. Science Advances 10 (25); doi: 10.1126/sciadv.adn4192

{ https://www.sci.news/ }

20-06-2024 om 01:00 geschreven door peter  

It wasn’t the only observer that captured an interesting image of China’s sixth mission in a series named after Chang’e, the Chinese Moon goddess. NASA’s Lunar Reconnaissance Orbiter captured the orbiter from overhead space and showed a dramatic change in its surroundings. 

In the image, the lander itself appears as a bright white dot. However, the surrounding area also appears significantly lighter. This had to do with the blast radius of the lander’s retrograde rockets for its soft landing. Those powerful rockets blew away the dark lunar regolith that had remained untouched for millions of years. The picture was snapped on June 7th, after the Chang’e-6 ascent vehicle had launched back off the surface and rendezvoused with the orbiter that will take the samples it collected back to Earth. In so doing, it likely blew away plenty of material with its own ascent rockets.

During its time on the Moon, Chang’e-6 collected 2 kg of samples, which it will return to a laboratory on Earth. This is the second time CNSA has planned such a mission and the first time one has taken place on the far side that humans cannot see from Earth. 

The next in the sequence of Chinese moon missions is Chang’e-7, which will focus its research efforts on the lunar south pole. Scientists predict water ice might be abundant there and that it might be the potential future site of a crewed Chinese moon base. Chang’e-7 will also include a hopping rover to explore the local environs surrounding its lander, but it isn’t scheduled for launch until 2026.

Currently, the Chang’e-6 mission orbiter, which has already successfully docked with the ascent vehicle containing the collected samples, is waiting for the opportune time to return to Earth. It will also serve as the return vehicle, which is planned to land back on Earth on June 25th. If all goes according to plan, there will soon be more lunar samples for scientists to explore and another successful mission for the CSNA that will have been documented in some pretty astounding pictures.

Learn More:

• CGTN – Unraveling Chang’e-6: Discover the mini rover that snapped a photo of Chang’e-6 probe
• NASA – NASA’s LRO Spots China’s Chang’e 6 Spacecraft on Lunar Far Sid
• UT – Chinese Probe Collects Moon Samples and Heads for Earth
• UT – Chinese Probe Lands on Moon’s Far Side to Collect Samples for Return

Lead Image:

This image from NASA’s Lunar Reconnaissance Orbiter shows China’s Chang’e 6 lander in the Apollo basin on the far side of the Moon on June 7, 2024. The lander is the bright dot in the center of the image. The image is about 0.4 miles wide (650 meters); lunar north is up.
Credit: NASA/Goddard/Arizona State University

{ https://www.universetoday.com/ }

19-06-2024 om 01:41 geschreven door peter  

It is very difficult to design complex machinery to work reliably under such conditions. The long nights mean that the energy harvested from solar panels needs to be stored in very large batteries, but batteries do not cope well with low temperatures. They can be electrically warmed, but heaters need a constant flow of electricity, draining the batteries. Alternatively, a machine can be heavily insulated to keep it functional when idle, but this leads to overheating when it is active, and when the Sun rises.

Overheating can damage batteries, but it’s equally bad for electronic components. Active cooling systems are the traditional answer. They work similarly to the radiator in a car by pumping coolant through a large radiator, but these require power to run. This is a problem when you need your batteries to last 14 days before the next recharge. Passive systems, such as LHPs, are effective and don’t require power, but they run continuously, even when you would prefer heating.

“Heat-switch technology that can switch between daytime heat dissipation and nighttime insulation is essential for long-term lunar exploration,” said lead researcher Masahito Nishikawara. “During the day, the lunar rover is active, and the electronic equipment generates heat. Since there is no air in space, the heat generated by the electronics must be actively cooled and dissipated. On the other hand, during extremely cold nights, electronics must be insulated from the outside environment so that they don’t get too cold.”

LHPs can be thought of as a cross between the machinery of a refrigerator or air conditioner, and the heat pipes in modern laptop computers. Like a refrigerator, a liquid refrigerant is allowed to absorb heat which causes it to vaporise. The vapour then passes through a radiator, which cools it back to ambient temperatures. This turns it back into a liquid, and the cycle repeats. The phase changes, from liquid to gas and back, allow the refrigerant to transfer heat very efficiently. Heat pipes, by contrast, use capillary action to move a liquid between a heat source (such as your computer’s CPU or graphics accelerator) and a radiator. LHPs combine the capillary transport action of a heat pipe with the phase changes of a refrigeration unit.

LHPs have been used in space before, where they have been equipped with valves to block the flow of refrigerant when cooling is not needed. However, these valves significantly reduce the system’s cooling efficiency. Nishikawara’s innovation is to replace the valves with an Electrohydrodynamic pump. EHPs are low-powered pumps which work by inducing electric currents in a fluid, and then using the resulting magnetic field to apply force to the fluid. This has the advantage of not intruding into the plumbing of the system, which means there is no interference with flow when it isn’t active.

Nishikawara’s team have added low-powered EHPs to an LHP to act as a very efficient valve: When they need to turn cooling off, the EHP is activated to create a small opposing force that stops the flow of refrigerant, while sipping only a tiny amount of power.

“This groundbreaking approach not only ensures the rover’s survival in extreme temperatures but also minimizes energy expenditure, a critical consideration in the resource-constrained lunar environment,” Nishikawara said. “It lays the foundation for potential integration into future lunar missions, contributing to the realization of sustained lunar exploration efforts.”

• https://www.eurekalert.org/news-releases/1047341

{ https://www.universetoday.com/ }

19-06-2024 om 01:30 geschreven door peter  

Supernovae are dangerous, and the closer a planet is to one, the more deadly its effects. Scientists have speculated on the effects that supernova explosions have had on Earth, wondering if it triggered mass extinctions or at least partial extinctions. A supernova’s gamma-ray burst and cosmic rays can deplete Earth’s ozone and allow ionizing UV radiation to reach the planet’s surface. The effects can also create more aerosol particles in the atmosphere, increasing cloud coverage and causing global cooling.

A new research article in Nature Communications Earth and Environment examines supernova explosions and their effect on Earth. It is titled “Earth’s Atmosphere Protects the Biosphere from Nearby Supernovae.” The lead author is Theodoros Christoudias from the Climate and Atmosphere Research Center, Cyprus Institute, Nicosia, Cyprus.

The Local Bubble isn’t the only evidence of nearby core-collapse supernovae (SNe) in the last few million years. Ocean sediments also contain ⁶⁰Fe, a radioactive isotope of iron with a half-life of 2.6 million years. SNe expel ⁶⁰Fe into space when they explode, indicating that a nearby supernova exploded about 2 million years ago. There’s also ⁶⁰Fe in sediments that indicate another SN explosion about 8 million years ago.

Researchers have correlated an SN explosion with the Late Devonian extinction about 370 million years ago. In one paper, researchers found plant spores burned by UV light, an indication that something powerful depleted Earth’s ozone layer. In fact, Earth’s biodiversity declined for about 300,000 years prior to the Late Devonian extinction, suggesting that multiple SNe could’ve played a role.

Earth’s ozone layer is in constant flux. As UV energy reaches it, it breaks ozone molecules (O3) apart. That dissipates the UV energy, and the oxygen atoms combine into O3 again. The cycle repeats. That’s a simplified version of the atmospheric chemistry involved, but it serves to illustrate the cycle. A nearby supernova could overwhelm the cycle, depleting the ozone column density and allowing more deadly UV to reach Earth’s surface.

But in the new paper, Christoudias and his fellow authors suggest that Earth’s ozone layer is much more resilient than thought and provides ample protection against SNe within 100 parsecs. While previous researchers have modelled Earth’s atmosphere and its response to a nearby SN, the authors say that they’ve improved on that work.

They modelled Earth’s atmosphere with an Earth Systems Model with Atmospheric Chemistry (EMAC) model to study the impact of nearby SNe explosions on Earth’s atmosphere. Using EMAC, the authors say they’ve modelled “the complex atmospheric circulation dynamics, chemistry, and process feedbacks” of Earth’s atmosphere. These are needed to “simulate stratospheric ozone loss in response to elevated ionization, leading to ion-induced nucleation and particle growth to CCN” (cloud condensation nuclei.)

“We assume a representative nearby SN with GCR (galactic cosmic ray) ionization rates in the atmosphere that are 100 times present levels,” they write. That correlates with a supernova explosion about 100 parsecs or 326 light-years away.

“The maximum ozone depletion over the poles is less than the present-day anthropogenic ozone hole over Antarctica, which amounts to an ozone column loss of 60–70%,” the authors explain. “On the other hand, there is an increase of ozone in the troposphere, but it is well within the levels resulting from recent anthropogenic pollution.”

But let’s cut to the chase. We want to know if Earth’s biosphere is safe or not.

The maximum mean stratospheric ozone depletion from 100 times more ionizing radiation than normal, representative of a nearby SN, is about 10% globally. That’s about the same decrease as our anthropogenic pollution causes. It wouldn’t affect the biosphere very much.

“Although significant, it is unlikely that such ozone changes would have a major impact on the biosphere, especially because most of the ozone loss is found to occur at high latitudes,” the authors explain.

But that’s for modern Earth. During the pre-Cambrian, before life exploded in a multiplication of forms, the atmosphere had only about 2% oxygen. How would an SN affect that? “We simulated a 2% oxygen atmosphere since this would likely represent conditions where the emerging biosphere on land would still be particularly sensitive to ozone depletion,” the authors write.

“Ozone loss is about 10–25% at mid-latitudes and an order of magnitude lower in the tropics,” the authors write. At minimum ozone levels at the poles, ionizing radiation from an SN could actually end up increasing the ozone column. “We conclude that these changes of atmospheric ozone are unlikely to have had a major impact on the emerging biosphere on land during the Cambrian,” they conclude.

What about global cooling?

Global cooling would increase, but not to a dangerous extent. Over the Pacific and Southern oceans, CCN could increase by up to 100%, which sounds like a lot. “These changes, while climatically relevant, are comparable to the contrast between the pristine pre-industrial atmosphere and the polluted present-day atmosphere.” They’re saying that it would cool the atmosphere by about the same amount as we’re heating it now.

The researchers point out that their study concerns the entire biosphere, not individuals. “Our study does not consider the direct health risks to humans and animals resulting from exposure to elevated ionizing radiation,” they write. Depending on individual circumstances, individuals could be exposed to dangerous levels of radiation over time. But overall, the biosphere would hum along despite a 100-fold increase in UV radiation. Our atmosphere and magnetosphere can handle it.

“Overall, we find that nearby SNe are unlikely to have caused mass extinctions on Earth,” the authors write. “We conclude that our planet’s atmosphere and geomagnetic field effectively shield the biosphere from the effects of nearby SNe, which has allowed life to evolve on land over the last hundreds of million years.”

• This study shows that Earth’s biosphere will not suffer greatly as long as supernova explosions keep their distance.

{ https://www.universetoday.com/ }

19-06-2024 om 01:20 geschreven door peter  

Story by Emily Mae Czachor

While exploring a crater on Mars that may give scientists insights into life that potentially once existed there, NASA said its Perseverance rover made an unprecedented discovery. The rover, which landed on the Red Planet in 2021 specifically to probe the ancient Jezero crater, found a mysterious light-toned boulder earlier this month that was the first of its kind seen on Martian land.

• https://youtu.be/go-b6wcVwYM

Perseverance encountered the boulder while traversing the Neretva Vallis, a dried river delta that flowed into the crater billions of years ago, on its way to an area inside the rim where rocky outcrops are being examined for sediment that could shed light on Mars' history, said NASA. The rover had changed course along its route to avoid rough terrain when, traveling a short cut through a dune field, it reached a hill that scientists have dubbed Mount Washburn.

The hill was covered with boulders, some of which NASA described as belonging to "a type never observed before on Mars."

One small boulder particularly intrigued the scientists working with Perseverance from Earth. Measuring roughly 18 inches across and 14 inches tall, the speckled and conspicuously light-toned rock was spotted among a field of darker boulders on the hill.

Stitched together from 18 images taken by NASA’s Perseverance rover, this mosaic shows a boulder field on “Mount Washburn” on May 27. Intrigued by the diversity of textures and chemical composition in the light-toned boulder at center, the rover’s science team nicknamed the rock “Atoko Point.”

Credit: NASA/JPL-Caltech/ASU/MSSS 

Full Image Details

"The diversity of textures and compositions at Mount Washburn was an exciting discovery for the team, as these rocks represent a grab bag of geologic gifts brought down from the crater rim and potentially beyond," said Brad Garczynski of Western Washington University, who co-leads the current Perseverance mission, in a statement. "But among all these different rocks, there was one that really caught our attention." 

Garczynski and his team nicknamed the mysterious boulder Atoko Point, and a deeper examination of the rock using the rover's instruments suggested that it was composed of the minerals pyroxene and feldspar. NASA said the size, shape and overall arrangement of minerals in Atoko Point, as well as the potential composition of the boulder on a chemical level, put the rock "in a league of its own" in terms of Martian sediment, at least among those already known to scientists.

Pyroxene and feldspar are minerals also found in the Earth's crust and on the moon, according to the U.S. Geological Survey and NASA. The space agency said that some scientists on the Perseverance team speculated that the minerals detected on Atoko Point may have come from magma that originated below the surface of Mars and became exposed on the rim of the Jezero crater over time because of erosion. 

Other members of the team suggested that the boulder may have appeared out of place on Washburn Hill if it was really produced on a different part of the planet and moved with the ancient river channel to its present location on the rim. But NASA said all of the Perseverance scientists believe that more rocks with a similar composition must exist elsewhere on Mars.

NASA's Perseverance rover was traveling in the channel of an ancient river, Neretva Vallis, when it captured this view of an area of scientific interest nicknamed

© Provided by CBS News

The rover discovered Atoko Point in the midst of its fourth "campaign" on Mars, which focuses on finding evidence of carbonate and olivine deposits in the interior of the Jezero crater. Both groups of minerals exist on Earth, with carbonate typically found in deposits near the shores of lakes and olivine typically associated with volcanic activity. 

They are of interest to scientists studying Mars —and they've both been observed already by Perseverance— because of their abilities to encapsulate remnants of the past for long periods of time. Identifying carbonate in the Martian crater could theoretically give scientists access to traces of ancient life on the planet preserved within the mineral itself, and olivine helps them understand when in history the Martian climate may have been conducive to organic compounds, like flowing water, and, potentially, life. 

Scientists say that learning about the makeup of Mars, and what it may have been like long ago, could help them figure out whether the planet's current landscape could ever be habitable for humans. It could also offer important clues about the origins and evolution of life on Earth.

Credit: NASA / JPL-Caltech / ASU / MSSS

The Perseverance rover found an exceptional boulder on Mars, thought to be an anorthosite.

Credit: NASA / JPL-Caltech / ASU

The NASA team hopes to discover many more rocks like Atoco Point in a couple of months when Perseverance reaches the crater rim.

Credit: NASA / JPL-Caltech / University of Arizona

NASA's Perseverance rover was traveling in the channel of an ancient river, Neretva Vallis, when it captured this view of an area of scientific interest nicknamed "Bright Angel" – the light-toned area in the distance at right.

NASA/JPL-CALTECH

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18-06-2024 om 22:47 geschreven door peter  

Scientists have discovered a mysterious object at the center of our Milky Way that does not fit the criteria of anything else in the galaxy.

The team found the object emits microwaves, which suggests it contains dust and fast-moving gas that is traveling nearly 112,000 miles per hour from a very small area in the heart of our galaxy.

Astronomers have considered a range of options for what the object could be, from a black hole to a collapsing cloud and evolved star, but found 'its features do not match well with those of any known type of astronomical body.'

The team found the object emits microwaves, which has suggested it contains dust and fast-moving gas. The gas was detected moving nearly 112,000 miles per hour from a very small area in the heart of our galaxy© Provided by Daily Mail

‘The center of our Galaxy contains billions of stars, tens of millions of solar masses of gas, a supermassive black hole, a tenth of our Galaxy's ongoing star formation, and an extensive graveyard of stellar remnants,’ researchers shared in the study published in the Astrophysical Journal Letters.

‘It is therefore the likeliest place to find new classes of objects. We present one such object in this work.

The object, labeled G0.02467–0.0727, was discovered using the Atacama Large Millimeter/submillimeter Array (ALMA) observatory in Chile.

'We consider several explanations for the Millimeter Ultra-Broad Line Object (MUBLO), including protostellar outflow, explosive outflow, collapsing cloud, evolved star, stellar merger, high-velocity compact cloud, intermediate mass black hole, and background galaxy,' the team wrote.

'Most of these conceptual models are either inconsistent with the data or do not fully explain it.'

The object was observed while the team was ALMA to study a special area in the center of our galaxy, known as the central molecular zone (CMZ).

The CMZ, measuring about 700 light-years across, contains nearly 80 percent of all the dense gas in the galaxy and is home to giant molecular clouds and massive star forming clusters that are poorly understood.

Astronomers detected millimeter waves coming from the object, with the surrounding dust showing broad, spread-out signals.

The object also gave off continuous radiation, which appeared to come from the dust and emitted specific signals from certain molecules like carbon monosulfide and sulfur monoxide. 

Carbon monosulfide has been detected in molecular clouds and sulfur monoxide has been observed around Io, one of Jupiter's moons.

Scientists have discovered a mysterious object at the center of our Milky Way that does not fit the criteria of anything else in our universe

© Provided by Daily Mail

The gas's temperature was around -436 degrees Fahrenheit, much colder than what has been typically seen in this part of the galaxy.

Researches also found that the gas molecules were not traveling in a simple ring, which suggested they could be flowing away from an exploding star, reported Nature.

However, shock waves create specific chemicals that MUBLO lacks.

Researchers said that the most plausible explanations would be an intermediate-mass black hole or a pair of merging stars obscured by dust.

But they also noted that the object does not fit either definition.

'The MUBLO is, at present, an observationally unique object,' the team concluded in the study.

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18-06-2024 om 21:15 geschreven door peter