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Engineer Says Where You Sit in a Room Can Influence Your Risk of Catching COVID-19 - ScienceAlert
It doesn't take long for airborne coronavirus particles to make their way through a room. At first, only people sitting near an infected speaker are at high risk, but as the meeting or class goes on, the tiny aerosols can spread.
It doesn't take long for airborne coronavirus particles to make their way through a room. At first, only people sitting near an infected speaker are at high risk, but as the meeting or class goes on, the tiny aerosols can spread. That doesn't mean everyone faces the same level of risk, however. As an engineer, I have been conducting experiments tracking how aerosols move, including those in the size range that can carry viruses. What I've found is important to understand as more people return to universities, offices and restaurants and more meetings move indoors as temperatures fall. It points to the highest-risk areas in rooms and why proper ventilation is crucial. As we saw this past few weeks with President Donald Trump and others in Washington, the coronavirus can spread quickly in close quarters if precautions aren't taken. University campuses have also been struggling with COVID-19. Cases among 18- to 22-year-olds more than doubled in the Midwest and Northeast after schools reopened in August. As the case numbers rise, the risk to anyone who spends time in those rooms rises as well. An experiment shows who's at greatest risk Most current models describing the role of ventilation on the fate of airborne microbes in a room assume the air is well mixed, with the particle concentration uniform throughout. In a poorly ventilated room or small space, that is likely true. In those scenarios, the entire room is a high-risk region. However, in larger spaces, such as classrooms, good ventilation reduces risk, but likely not uniformly. My research shows that how high the level of risk gets depends a lot on ventilation. To understand how the coronavirus can spread, we injected aerosol particles similar in size to those from humans into a room and then monitored them with sensors. We used a 30-foot by 26-foot university classroom designed to accommodate 30 students that had a ventilation system that met the recommended standards. When we released particles at the front of the classroom, they reached all the way to the back of the room within 10 to 15 minutes. However, because of active ventilation in the room, the concentrations at the back, about 20 feet (6.1 metres) from the source, were about one-tenth of the concentrations close to the source. That suggests that with appropriate ventilation, the highest risk for getting COVID-19 could be limited to a small number of people near the infected speaker. As the time spent indoors with an infected speaker increases, however, risk extends to the entire room, even if ventilation is good. CDC finally acknowledges the aerosol risk In the past, the transmission of respiratory diseases has focused on the role of larger particles that are generated when we sneeze and cough. These droplets fall quickly to the ground, and social distancing and mask wearing can largely prevent infection from them. The bigger concern now is the role of tiny particles known as aerosols that are generated when we talk, sing or even just breathe. These particles, often smaller than 5 micrometers, can escape from cloth face masks and linger in air for up to about 12 hours. The Centers for Disease Control and Prevention finally acknowledged that risk on October 5 after Trump was hospitalized and several other people in or close to the administration tested positive for COVID-19. While these smaller particles, on average, carry less virus than larger particles that people emit when they cough or sneeze, the high infectivity of SARS-CoV-2 combined with the high viral load before symptoms appear makes these particles important for airborne disease transmission. How much ventilation is enough? To minimize COVID-19 transmission indoors, the CDC's top recommendation is to eliminate the source of infection. Remote learning has effectively done this on many campuses. For face-to-face teaching, engineering measures such as ventilation, partition shields and filtration units can directly remove particles from the air. Of all the engineering controls, ventilation is probably the most effective tool to minimize infection spread. Understanding how ventilation lowers your risks of getting COVID-19 starts with air exchange rates. An air exchange of one per hour means that the air supplied to the room over one hour equals the volume of air in the room. Air exchange rate ranges from less than one for homes to around 15-25 for hospital operating rooms. For classrooms, the current regulations of primary air flow correspond to an air exchange of about six per hour. That means that every 10 minutes, the amount of air brought into the room equals that of the volume of the room. How high the concentration gets depends in part on the number of people in the room, how much they emit and the air exchange rate. With social distancing reducing classroom populations by half and everyone wearing masks, the air in many indoor spaces is actually cleaner now than it was before the pandemic. Parts of the room to avoid It's important to remember that not all parts of a room are at equal risk. The corners of the room will likely have a lower air exchange so particles can linger there longer. Being close to an air exit vent could mean that airborne particles from the rest of the room could wash over you. A study of ventilation airflow in a restaurant in China traced its role in several COVID-19 illnesses among the patrons there. About 95 percent of particles in the room will be removed by a properly functioning ventilation system in 30 minutes, but an infected person in the room means those particles are also continuously emitted. The pace of particle removal can be accelerated by increasing the air exchange rate or adding other engineering controls such as filtration units. Opening windows will also often increase the effective air exchange rate. As schools, restaurants, malls and other communal spaces start accommodating more people indoors, understanding the risks and following the CDC's recommendations can help minimize infection spread. This story has been updated with the CDC's newly released guidance on aerosols. Suresh Dhaniyala, Bayard D. Clarkson Distinguished Professor of Mechanical and Aeronautical Engineering, Clarkson University. This article is republished from The Conversation under a Creative Commons license. Read the original article.
The Atmosphere of One of The Hottest Exoplanets in The Galaxy Is Full of Metal - ScienceAlert
Using the light of the star it orbits, astronomers have peered into the atmosphere of an exoplanet 850 light-years away. Not just any exoplanet, but one of the hottest we've ever found - and at least seven metals have now been identified floating aro
Using the light of the star it orbits, astronomers have peered into the atmosphere of an exoplanet 850 light-years away. Not just any exoplanet, but one of the hottest we've ever found - and at least seven metals have now been identified floating around its atmosphere as gas. The exoplanet is WASP-121b, a type of planet we call a hot Jupiter. That's because it's a gas giant so close to its star that its temperature rivals that of stars itself; cool stars, to be sure, but stars nevertheless. WASP-121b is pretty famous, as far as exoplanets go. It was first discovered in 2015, an exoplanet about 1.18 times the mass and 1.81 times the size of Jupiter, on a close orbit of just 1.27 days. Two years later, it became the first exoplanet in whose stratosphere water had been found - although, given the planet's extreme heat, it's highly unlikely to be habitable. Now astronomers have taken a closer look at the exoplanet's atmosphere, and what they found has surprised them. At temperatures between 2,500 and 3,000 degrees Celsius (roughly 4,500 and 5,500 degrees Fahrenheit), it isn't the hottest of these exoplanets that we've seen. But it is so hot that its atmosphere should be a lot simpler than what astronomers have observed in earlier studies - complex molecules should not be able to form in such high temperatures. These earlier studies suggested that molecules containing the rare metal vanadium and a lack of titanium could explain the spectrum in earlier observations of WASP-121b's atmosphere. "Previous studies tried to explain these complex observations with theories that did not seem plausible to me," said astronomer Jens Hoeijmakers of the Universities of Bern and Geneva in Switzerland. "But it turned out that they were right. To my surprise, we actually found strong signatures of vanadium in the observations." Peering into exoplanet atmospheres is not an easy thing to do. First, you need the exoplanet to pass between us and the star. This is actually a good way to find exoplanets in the first place - you look for really faint, regular dips in starlight to tell you something large is orbiting the star. To study the atmosphere, you need even fainter signals. As the exoplanet passes in front of the star, some of the star's light passes through the atmosphere. Depending on the elements present in the atmosphere, some wavelengths of light will be absorbed and enhanced. If you can take a full spectrum of wavelengths, these will appear as absorption and emission lines. As you can imagine, the signal isn't very strong, and there's a lot of noise. So, for a start, you need good noise reduction tools that aren't going to destroy the data you need. The signal can also be magnified and clarified by taking multiple transit spectra and stacking them - so exoplanets with short orbital periods that allow us to take more transit spectra will be easier to analyse. An exoplanet on a 12-year orbit like Jupiter's would not be an ideal candidate, for example. But WASP-121b's tight orbit works well. To obtain a strong spectrum for WASP-121b, Hoeijmakers and his team used three transits previously observed using the HARPS spectrograph instrument on the European Southern Observatory's La Silla 3.6m telescope, and reprocessed the data. And they found an interesting metallic cocktail in the exoplanet's atmosphere. There was the aforementioned vanadium, of course. In addition, the team identified the spectral signatures of iron, chromium, calcium, sodium, magnesium, and nickel. Notably, there's no titanium - consistent with the earlier findings. "All metals evaporated as a result of the high temperatures prevailing on WASP-121b, thus ensuring that the air on the exoplanet consists of evaporated metals, among other things," Hoeijmakers explained. Hot Jupiters are very mysterious planets, and such analyses of their atmospheres can help us understand them. We don't know why or how they are so close to their stars, and learning about what's in their atmospheres can help us figure out if they formed there, or if they migrated inwards from a farther orbit. But these studies are also helping develop the toolkit for probing planets in search of alien life. What we use to identify iron and sodium today could, with more sensitive equipment, one day help find the molecules produced and used by living organisms, such as oxygen and methane. "After years of cataloguing what is out there, we are now no longer just taking measurements," Hoeijmakers said. "We are really beginning to understand what the data from the instruments show us. How planets resemble and differ from each other. In the same way, perhaps, that Charles Darwin began to develop the theory of evolution after characterising countless species of animals, we are beginning to understand more about how these exoplanets were formed and how they work." The research has been published in Astronomy & Astrophysics.
NASA Finds Billion-Year-Old Sand Dunes Preserved on Mars, And They Look Familiar - ScienceAlert
Tucked away in a canyon on Mars, scientists have discovered a windswept field of solid sand, which turned to rock roughly a billion years ago.
Tucked away in a canyon on Mars, scientists have discovered a windswept field of solid sand, which turned to rock roughly a billion years ago. Despite being heavily eroded, this frozen plain of palaeo-dunes has withstood time remarkably well, much more so than fossilised waves of sand on Earth, which are subject to the whims of wind, water, and the shifting landscapes of deep time. Understanding how these duneforms stood the test of time could give us insight into the sedimentary processes on Mars and reveal something about the planet's geologic history at the same time. "This level of preservation is rare for terrestrial sand dunes due to ongoing erosion and tectonics," explains planetary scientist Matthew Chojnacki from the Planetary Science Institute. "Based on the dune deposit's relationships to other geologic units and modern erosion rates we estimate these to be roughly a billion years old." (NASA/JPL/University of Arizona) Today on Mars, sand dunes, whipped up by wind, are a common feature, and the size and arrangement of those fixed in place in the widest part of the Valles Marineris canyon - the Melas Chasma - look remarkably similar to ones formed more recently. This suggests the climate and atmosphere on Mars has changed little in a very, very long time. Astronomers say the orientation, length, height, shape and slope of the Melas Chasma palaeo-dunes all resemble recently-made waves of sand seen elsewhere on the Red Planet. "This indicates the major wind directions that are responsible for the dunes' shape have not changed substantially over time," Chojnacki told EarthSky. "We also see very similarly sized and spaced sand dunes from the two time periods. This may indicate the atmospheric pressure wasn't significantly different." Using images from the High Resolution Imaging Science Experiment (HiRISE) and Martian topography data, researchers have documented and dated the bedform properties of Melas Chasma. Although the topography of this canyon is still incomplete, as some of the dunes have eroded away or been buried, the paleo-dunes we can decipher "do not paint a dramatically different picture than what can be gained from their modern counterparts," the researchers explain. The authors found some dunes were buried under tens of metres of material, which appeared to come from a catastrophic volcanic event. (Chojnacki et al., JGR Planets 2020) Sometime afterwards, the authors predict, a volatile compound came into contact with the compacted sand dunes and helped harden them, freezing the waves in time as they migrated across the Melas Chasma. This same sort of process can be seen on Earth when groundwater invades a partially buried sand dune - formed layers of lithified sand like those famous striped structures seen in Zion National Park. Unlike our planet, however, lithified sand dunes on Mars have far fewer elements to contend with. In the absence of water, vegetation or plate tectonics, exposure to trade winds is the main eroder on Mars, and over deep time, this has helped chisel back the volcanic shell that once covered these dunes. Close up of sand dunes taken by HiRISE Camera. ( NASA/ JPL-Caltech/University of Arizona) The mere existence and degree of preservation seen in these dunes indicates an important difference in the landscape evolution of Earth and Mars. While ancient lithified sand dunes on Earth are rare to find and much more eroded, the Melas Chasma appears to possess "extensive paleo-dune fields scattered across the basin floor, where many duneforms and their morphology appear largely intact." "Water and tectonics that constantly reshape the surface of Earth are not currently a factor on Mars, thus there is an opportunity to learn from the geologic record of the red planet," says Chojnacki. "These results inform us that wind-driven sand transport, deposition, and lithification have occurred throughout much of Mars' recent history and illustrate how landscape evolution there greatly differs compared to that of Earth." The study has been published in JGR Planets.
This Week, Mars Is The Closest to Earth It'll Be For Another 15 Years - ScienceAlert
Mars, our second closest cosmic cousin, has been in our collective imagination for decades. Between fantasies of martian visits and the promise of water under its icy surface, Mars doesn't need to do much to be in our collective good books.
Mars, our second closest cosmic cousin, has been in our collective imagination for decades. Between fantasies of martian visits and the promise of water under its icy surface, Mars doesn't need to do much to be in our collective good books. But very soon, Mars is not just going to be close to our hearts, but also nearest to our actual planet - a mere 62.1 million kilometres (38.6 million miles) away from Earth. This is the closest it'll be for the next 15 years. And it means that stargazing is highly recommended as Mars will be bright, big and easy to see with or without a telescope. We'd recommend checking out a sky chart to work out where Mars will be in the night sky in your location so you can plan for the best viewing. But the good news is, it'll be in a region of the night sky with very few stars, and if you're lucky, you should also be able to catch Jupiter and Saturn shining brightly closer to the horizon. The day we'll be the absolute closest to Mars is the 6 October, so get a move on. As you can see in this video below, Mars and Earth are both on slightly elliptical orbits, which means they can occasionally get very close to each other. The closest possible encounter is when Earth is the furthest away from the Sun (aphelion) and Mars is the closest to the Sun (perihelion). At this point the two would be at the minimum 54.6 million kilometres (33.9 million miles) apart. This configuration is called an opposition, and it happens every two years or so. But we've never actually recorded us hitting that perfect 'closest' point. The closest approach we've ever recorded happened back in 2003, with just 55.7 million kilometres separating us with Mars. Two years ago, 2018 was pretty close too, with just 57.6 million kilometres (35.8 million miles) between us. Unfortunately though, we're getting further and further out of alignment with our closest neighbour and won't start getting closer again until 2029, culminating in a very close approach in 2035 only 56.9 million kilometres (35.4 million miles) apart so start planning your 2035 Mars watching schedule well in advance! At the other end of the scale from an opposition is a conjunction, when the two planets are furthest from each other. They can end up a 401 million kilometres (250 miles) away from each other. This occurs when Earth and Mars are on opposite sides of the Sun and both in their aphelion. It's for this reason that space organisations take advantage of the short distance between our planets when these windows arise. This year was a peak opportunity for many missions to the Red Planet. If you remember, Mars One planned to launch a Mars lander in 2020 before it um, never did that. But three missions did successfully take off. NASA's Perseverance rover is close to half way through its journey to the red planet after blasting off back in July, while two other missions left for Mars in the same two-week window. The next lot of Mars missions like the Mars Sample Return - will be travelling in 2022, but they'll have to travel an extra 20 million kilometres, as we'll be at a distance of 81.5 million kilometres (50.6 million miles) at our closest approach during this time. So this week is a pretty special opportunity that we won't have again until 2035. Make sure you wave to Mars as it goes past!
We May Finally Know What Life on Earth Breathed Before There Was Oxygen - ScienceAlert
Billions of years ago, long before oxygen was readily available, the notorious poison arsenic could have been the compound that breathed new life into our planet.
Billions of years ago, long before oxygen was readily available, the notorious poison arsenic could have been the compound that breathed new life into our planet. In Chile's Atacama Desert, in a place called Laguna La Brava, scientists have been studying a purple ribbon of photosynthetic microbes living in a hypersaline lake that's permanently free of oxygen. "I have been working with microbial mats for about 35 years or so," says geoscientist Pieter Visscher from the University of Connecticut. "This is the only system on Earth where I could find a microbial mat that worked absolutely in the absence of oxygen." Microbial mats, which fossilise into stromatolites, have been abundant on Earth for at least 3.5 billion years, and yet for the first billion years of their existence, there was no oxygen for photosynthesis. How these life forms survived in such extreme conditions is still unknown, but examining stromatolites and extremophiles living today, researchers have figured out a handful of possibilities. While iron, sulphur, and hydrogen have long been proposed as possible replacements for oxygen, it wasn't until the discovery of 'arsenotrophy' in California's hypersaline Searles Lake and Mono Lake that arsenic also became a contender. Since then, stromatolites from the Tumbiana Formation in Western Australia have revealed that trapping light and arsenic was once a valid mode of photosynthesis in the Precambrian. The same couldn't be said of iron or sulphur. Just last year, researchers discovered an abundant life form in the Pacific Ocean that also breathes arsenic. Even the La Brava life forms closely resemble a purple sulphur bacterium called Ectothiorhodospira sp., which was recently found in an arsenic-rich lake in Nevada and which appears to photosynthesise by oxidising the compound arsenite into a different form -arsenate. While more research needs to verify whether the La Brava microbes also metabolise arsenite, initial research found the rushing water surrounding these mats is heavily laden with hydrogen sulphide and arsenic. If the authors are right and the La Brava microbes are indeed 'breathing' arsenic, these life forms would be the first to do so in a permanently and completely oxygen-free microbial mat, similar to what we would expect in Precambrian environments. As such, its mats are a great model for understanding some of the possible earliest life forms on our planet. While genomic research suggests the La Brava mats have the tools to metabolise arsenic and sulphur, the authors say its arsenate reduction appears to be more effective than its sulfate reduction. Regardless, they say there's strong evidence that both pathways exist, and these would have been enough to support extensive microbial mats in the early days of life on Earth. If the team is right, then we might need to expand our search for life forms elsewhere. "In looking for evidence of life on Mars, [scientists] will be looking at iron and probably they should be looking at arsenic also," says Visscher. It really is so much more than just a poison. The study was published in Communications Earth and Environment.
A Physicist Has Come Up With Math That Makes 'Paradox-Free' Time Travel Plausible - ScienceAlert
No one has yet managed to travel through time – at least to our knowledge – but the question of whether or not such a feat would be theoretically possible continues to fascinate scientists.
No one has yet managed to travel through time at least to our knowledge but the question of whether or not such a feat would be theoretically possible continues to fascinate scientists. As movies such as The Terminator, Donnie Darko, Back to the Future and many others show, moving around in time creates a lot of problems for the fundamental rules of the Universe: if you go back in time and stop your parents from meeting, for instance, how can you possibly exist in order to go back in time in the first place? It's a monumental head-scratcher known as the 'grandfather paradox', but now a physics student Germain Tobar, from the University of Queensland in Australia, says he has worked out how to "square the numbers" to make time travel viable without the paradoxes. "Classical dynamics says if you know the state of a system at a particular time, this can tell us the entire history of the system," says Tobar. "However, Einstein's theory of general relativity predicts the existence of time loops or time travel where an event can be both in the past and future of itself theoretically turning the study of dynamics on its head." What the calculations show is that space-time can potentially adapt itself to avoid paradoxes. To use a topical example, imagine a time traveller journeying into the past to stop a disease from spreading if the mission was successful, the time traveller would have no disease to go back in time to defeat. Tobar's work suggests that the disease would still escape some other way, through a different route or by a different method, removing the paradox. Whatever the time traveller did, the disease wouldn't be stopped. Tobar's work isn't easy for non-mathematicians to dig into, but it looks at the influence of deterministic processes (without any randomness) on an arbitrary number of regions in the space-time continuum, and demonstrates how both closed timelike curves (as predicted by Einstein) can fit in with the rules of free will and classical physics. "The maths checks out and the results are the stuff of science fiction," says physicist Fabio Costa from the University of Queensland, who supervised the research. Fabio Costa (left) and Germain Tobar (right). (Ho Vu) The new research smooths out the problem with another hypothesis, that time travel is possible but that time travellers would be restricted in what they did, to stop them creating a paradox. In this model, time travellers have the freedom to do whatever they want, but paradoxes are not possible. While the numbers might work out, actually bending space and time to get into the past remains elusive the time machines that scientists have devised so far are so high-concept that for they currently only exist as calculations on a page. We might get there one day Stephen Hawking certainly thought it was possible and if we do then this new research suggests we would be free to do whatever we wanted to the world in the past: it would readjust itself accordingly. "Try as you might to create a paradox, the events will always adjust themselves, to avoid any inconsistency," says Costa. "The range of mathematical processes we discovered show that time travel with free will is logically possible in our universe without any paradox." The research has been published in Classical and Quantum Gravity.
The Latest Flyby of Jupiter Has Offered Some of The Most Marvellous Views Yet - ScienceAlert
Jupiter. Most massive planet in the solar system twice that of all the other planets combined. This giant world formed from the same cloud of dust and gas that became our Sun and the rest of the planets. But Jupiter was the first-born of our planetary family. As the first planet, Jupiter's massive gravitational field likely shaped the rest of the entire solar system. Jupiter could've played a role in where all the planets aligned in their orbits around the Sunor didn't, as the asteroid belt is a vast region which could've been occupied by another planet were it not for Jupiter's gravity. Gas giants like Jupiter can also hurl entire planets out of their solar systems, or themselves spiral into their stars. Saturn's formation several million years later probably spared Jupiter this fate. Jupiter may also act as a "comet catcher." Comets and asteroids which could otherwise fall toward the inner solar system and strike the rocky worlds like Earth are captured by Jupiter's gravitational field instead and ultimately plunge into Jupiter's clouds. But at other times in Earth's history, Jupiter may have had the opposite effect, hurling asteroids in our direction typically a bad thing but may have also resulted in water-rich rocks coming to Earth that led to the blue planet we know of today. Jupiter is a window into our own solar system's past a past literally enshrouded beneath Jupiter's clouds which is why Juno, the probe currently orbiting Jupiter, is so named. Juno, Jupiter's wife in mythology, was able to peer through a cloak of clouds Jupiter used to hide himself and his wrongful deeds. In this case, however, we are looking through Jupiter's clouds into our own history. Juno entered orbit of Jupiter 5 July 2016 after travelling for nearly five years to reach the gas giant. Falling into Jupiter's gravity well, Juno arrived at a speed of 210,000 km/h, one of the fastest speed records set by any human-made object. Juno is in a highly eccentric 53 day orbit. During Perijove, or the closest orbital approach, Juno skims Jupiter at an altitude of 4,200 km and then sweeps outward to 8.1 million km. Juno's orbit is designed to navigate through weaker areas of Jupiter's incredibly powerful magnetic field. Second in power only to the Sun itself, Jupiter's magnetic field accelerates high energy particles from the Sun creating powerful bands of radiation that encircle the planet electronics-frying radiation. In addition to its nimble navigation, Juno's electronics are hardened against radiation with its "radiation vault" a 1 cm thick titanium shell that houses its sensitive scientific equipment. One piece of equipment which dazzles all of us back on Earth is JunoCam an RGB colour camera taking visual images of Jupiter's clouds as the probe buzzes the planet in just two hours each orbit spending as little time as possible in Jupiter's radiation. Most recently, Juno completed Perijove 29 and some of the photos were posted by "Software Engineer, planetary and climate data wrangler, and science data visualization artist" Kevin Gill. Kevin has an absolutely astonishing Flickr page where he posts images he's processed from Juno as well as other missions like Saturn's Cassini and the HiRISE camera orbiting Mars on the Mars Reconnaissance Orbiter. Okay. And finally, why you came here: Behold Juno's Perijove 29 processed by Kevin Gill (You can click each image to see their full size). Jupiter from Juno PJ29 - c. (NASA/JPL/Kevin Gill) Jupiter from Juno PJ29 c. (NASA/JPL/Kevin Gill) Jupiter from Juno PJ29 c. (NASA/JPL/Kevin Gill) Jupiter from Juno PJ29 c. (NASA/JPL/Kevin Gill) Jupiter from Juno PJ29 c. (NASA/JPL/Kevin Gill) Jupiter from Juno PJ29 c. (NASA/JPL/Kevin Gill) Jupiter from Juno PJ29 c. (NASA/JPL/Kevin Gill) You can also follow Kevin's work on Twitter (@kevinmgill) and Instagram (@apoapsys). JunoCam isn't really part of Juno's primary scientific mission. But the camera does provide a key function allowing Juno to bring us along for the journey. Which I think is truly spectacular. Sometimes astrophotography is thought more of as art than science. But as an astrophotographer myself, I believe these images inspire future scientists, general awareness of ongoing scientific missions, and hopefully public support for the funding of science. Speaking of which, what has our science discovered about our giantest of giant worlds? One of the greatest mysteries of Jupiter is what lies at its heart. Juno helped settle an ongoing debate in the planetary science community about how Jupiter formed. There were two possibilities: The first is that Jupiter began as a rocky world a core about 10 times the mass of Earth. The gravity of this core drew in surrounding hydrogen and helium until the Jupiter we know of was formed that original rocky world buried beneath the churning maelstrom. The second possibility is that eddies in the rotating protoplanetary disk of our early solar system collapsed on themselves and Jupiter formed from them directly with no rocky core. Both theories describe different conditions at the start of our solar system. Juno revealed something stranger, not a solid core, but a "fuzzy" or "diluted" core. It appears that Jupiter did form from a rocky body, but rather than that core being situated at the centre of the planet, its is spread throughout the interior of Jupiter. The core's dilution is likely the result of a massive planet-sized impact with Jupiter that shattered the initial core and spread it through half of Jupiter's diameter. Imagine being present for an event like that Jupiter swallowing a would-be planet in our solar system we've never known. History of our place in space revealed. We've also learned that Jupiter's winds dive deep below the outer clouds, that the Great Red Spot is hundreds of kilometers deep, and we've seen giant cyclones at Jupiter's North and South Poles that could swallow a country. Jupiter South Polar Cyclones in Infrared with Size Comparison to US and Texas. (JPL/NASA/Caltech) Jupiter is presently the brightest object in the night sky after sunset. If you have clear skies and can see it, look South! Remember, that bright point is a giant world hundreds the times the size of Earth, millions of kilometers away, and yet potentially one of the key factors in your existence. By Jove, that's amazing. This article was originally published by Universe Today. Read the original article.
Myriad Exoplanets in Our Galaxy Could Be Made of Diamond And Rock - ScienceAlert
Here in the Solar System, we have quite an interesting variety of planets, but they are limited by the composition of our Sun. Since the planets, moons, asteroids and other bodies are made out of what was left over after the Sun was finished forming,
Here in the Solar System, we have quite an interesting variety of planets, but they are limited by the composition of our Sun. Since the planets, moons, asteroids and other bodies are made out of what was left over after the Sun was finished forming, their chemistry is thought to be related to our host. But not all stars are made out of the same stuff as our Sun, which means that out there in the wide expanses of our galaxy, we can expect to find exoplanets wildly different from the offering in our little Solar System. For example, stars that are rich in carbon compared to our Sun - with more carbon than oxygen - could have exoplanets that are made primarily of diamond, with a little bit of silica, if the conditions are just right. And now, in a lab, scientists have squished and heated silicon carbide to find out what those conditions could be. "These exoplanets are unlike anything in our Solar System," said geophysicist Harrison Allen-Sutter of Arizona State University's School of Earth and Space Exploration. The idea that stars with a higher carbon-to-oxygen ratio than the Sun might produce diamond planets first emerged with the discovery of 55 Cancri e, a super-Earth exoplanet orbiting a star thought to be rich in carbon 41 light-years away. It was later discovered that this star wasn't as carbon-rich as previously thought, which put paid to that idea - at least as far as 55 Cancri e is concerned. But between 12 and 17 percent of planetary systems could be located around carbon-rich stars - and with thousands of exoplanet-hosting stars identified to date, the diamond planet seems a distinct possibility. Scientists have already explored and confirmed the idea that such planets are likely to be composed primarily of carbides, compounds of carbon and other elements. If such a planet was rich in silicon carbide, the researchers hypothesised, and if water was present to oxidise the silicon carbide and convert it into silicon and carbon, then with sufficient heat and pressure, the carbon could become diamond. In order to confirm their hypothesis, they turned to a diamond anvil cell, a device used to squeeze small samples of material to very high pressures. They took minute samples of silicon carbide and immersed them in water. Then, the samples were placed in the diamond anvil cell, which squeezed them to pressures up to 50 gigapascals - about half a million times Earth's atmospheric pressure at sea level. After the samples had been squeezed, the team heated them with lasers. In all, they conducted 18 runs of the experiment - and they found that, just as they had predicted, at high heat and high pressure, their silicon carbide samples reacted with water to convert into silica and diamond. Thus, the researchers concluded that at temperatures of up to 2,500 Kelvin, and pressures up to 50 gigapascals, in the presence of water, silicon carbide planets could become oxidised, and have their interior compositions dominated by silica and diamond. If we could identify these planets - perhaps by their density profiles, and the composition of their stars - we could therefore rule them out as planets that could host life. Their interiors, the researchers said, would be too hard for geological activity, and their composition would make their atmospheres inhospitable to life as we know it. "This is one additional step in helping us understand and characterise our ever-increasing and improving observations of exoplanets," Allen-Sutter said. "The more we learn, the better we'll be able to interpret new data from upcoming future missions like the James Webb Space Telescope and the Nancy Grace Roman Space Telescope to understand the worlds beyond on our own Solar System." The research has been published in The Planetary Science Journal.
NASA Rover Glimpses a Ghostly Martian Dust Devil Whirling Across The Red Planet - ScienceAlert
Mars may have only a thin atmosphere compared to other Solar System planets, but boy does it make the most of it. Water ice can rise high in the sky to form thin clouds. Wild winds can whip up into uncontrolled dust storms that shroud the entire plan
Mars may have only a thin atmosphere compared to other Solar System planets, but boy does it make the most of it. Water ice can rise high in the sky to form thin clouds. Wild winds can whip up into uncontrolled dust storms that shroud the entire planet, or create dust towers that extend almost into space. So it should come as no surprise that NASA's Mars Curiosity rover, beavering away in the Gale Crater, sometimes lays its electronic eyes on Martian weather phenomena and now, it's spotted a dust devil spinning across the rocky crater floor. Seeing weather phenomena on Mars that we also see on Earth isn't just interesting, though - it can also tell us a lot about seasonal atmospheric changes on the Red Planet. It's coming into Martian summer in the planet's southern hemisphere, where the Gale Crater can be found, and the atmosphere in the region is heating up. Just as uneven heating of the atmosphere on Earth generates atmospheric movement, so too is the Martian atmosphere affected. "Stronger surface heating tends to produce stronger convection and convective vortices, which consist of fast winds whipping around low pressure cores," writes atmospheric scientist Claire Newman of Aeolis Researchon the Mars Exploration blog. "If those vortices are strong enough, they can raise dust from the surface and become visible as 'dust devils' that we can image with our cameras." Dust devils are pretty well understood, and they come about the same way on both Earth and Mars. They form best in relatively flat, dry terrain, when the air at the surface level is warmer than the air above it. This hot surface air rises through the cooler, denser air, creating an updraft. This causes the cooler air to sink. If a horizontal wind then blows through this vertical circulation, a dust devil whips into action. They're extremely common on Mars, but we only know this because, as they move across the ground, they sweep up the dust in their path, leaving tracks behind them. Actually seeing them in action on the Red Planet is quite rare, since our observational capabilities are limited, and dust devils themselves are relatively short-lived. The dust devil above, seen in the top centre of the image, was captured by Curiosity's Navcam on Sol 2847, and covers a span of about 5 minutes, Newman says. Even though it seems ghostly, the fact that we can see it means it was pretty powerful. "We often have to process these images, by enhancing what's changed between them, before dust devils clearly show up," she writes. "But this dust devil was so impressive that - if you look closely! - you can just see it moving to the right, at the border between the darker and lighter slopes, even in the raw images." Studying these movies can reveal a lot about dust devils on Mars - where they form, for instance, how they evolve, how long they last, the type of dust they pick up, and how they vary from location to location. They can also reveal wind speed and duration, which, in combination with meteorological readings, can help scientists learn more about Martian weather, and how dust devils fit into it. Curiosity is the only operational rover on Mars at the moment (InSight is a stationary lander), so whatever surface information can be gleaned on Martial dust devils is very limited. Mars also has operational orbiters, though, which cover a lot more ground. These have caught the occasional dust devil in action from space, as well as the many, many tracks they have left behind after they fade away.
So, The International Space Station Is Leaking Air Again - ScienceAlert
The International Space Station (ISS), in Earth orbit at hundreds of kilometres altitude, is not perfectly airtight. Every day, the cabin loses a minute amount of air, monitored carefully so that a liveable atmospheric pressure can be maintained, and
The International Space Station (ISS), in Earth orbit at hundreds of kilometres altitude, is not perfectly airtight. Every day, the cabin loses a minute amount of air, monitored carefully so that a liveable atmospheric pressure can be maintained, and to identify leaks. Now the latter has come to pass, just two years after the last leak. The rate of air loss on the station has risen above a level that can be explained by the normal ISS day-to-day, according to a NASA blog post. Mission control first noticed something awry in September of 2019, but the increase in air leakage was slight - not enough to cause serious concern. Now that rate has increased, so they're buckling in to find out where the extra air is escaping. The current ISS crew are not in any danger, but NASA astronaut Commander Chris Cassidy and Roscosmos cosmonauts Ivan Vagner and Anatoly Ivanishin will have to hole up in the Zvezda Service Module for the weekend while mission control searches for the source of the leak. "All the space station hatches will be closed this weekend so mission controllers can carefully monitor the air pressure in each module," NASA's Mark Garcia wrote. "The test presents no safety concern for the crew. The test should determine which module is experiencing a higher-than-normal leak rate." The last leak on the ISS took place two years ago, identified by ground control at 23:00 UTC (19:00 EDT) on 29 August 2018. At that time, the same measures were taken - the crew moved to the Russian segment, and the space station modules were sealed off and their atmospheric pressure examined. This procedure narrowed down the leak to the Soyuz MS-09 spacecraft, which was temporarily attached to the Rassvet module of the ISS at the time. It was traced to a small, two-millimetre hole with drill tracks next to it, leading to speculation that it was caused by a manufacturing mistake. But, although Roscosmos has concluded its investigation, the source of the hole has not been revealed. An earlier leak was identified and patched in 2004, in a vacuum jumper cable used to equalise air pressure across a window in the Destiny laboratory module. Tracking down such leaks can be challenging because of the normal air pressure fluctuations inside the space station. In addition to the normal leak rate, the pressure also changes due to temperature fluctuations, as well as routine station operations, such as spacewalks and the arrival and departure of resupply spacecraft. During their weekend in the Zvezda module, the ISS crew will continue their normal duties as much as they are able. Once the leak has been traced to a specific module, the crew will be able to perform a more granular search to find the precise source. "The US and Russian specialists expect preliminary results should be available for review by the end of next week," Garcia wrote.