Watch 4 solar flares erupt from the sun at nearly the same time in extremely rare event 

25-04-2024 om 00:30 geschreven door peter  

Earth's weird 'quasi-moon' Kamo'oalewa is a fragment blasted out of big moon crater

Kamo'oalewa, which means "an oscillating celestial object" in Hawaiian, was later found to orbit the sun in synchronization with Earth and is spinning extremely fast for an asteroid. These puzzling characteristics led scientists to investigate the quasi-moon's origins. In 2021, research revealed that Kamo'oalewa's composition is similar to rocks recovered from the moon, hinting at its lunar origin. The question was, Where exactly on the moon did it come from?

Related: 

• A 'quasi-moon' asteroid companion of Earth may actually be a moon relic

"Our major findings are that Kamo’oaelewa originated from the moon, and not from the asteroid belt, contrary to the majority of asteroids belonging to the NEO population," Patrick Michel, team member and senior researcher at Centre National de la Recherche Scientifique (CNRS), France's state research agency, told Space.com. 

"Like detectives, we used all known information regarding this Kamo‘oalewa and the lunar surface to derive a scenario for the origin of this object, starting from the impact that produced the Giordano Bruno crater," Michel said.

Robert Lea

Senior Writer

Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.

{ https://www.space.com/ }

24-04-2024 om 17:04 geschreven door peter  

But one possible savior could be the private aerospace sector, whose biggest player is SpaceX.

WHAT’S GOING ON WITH MARS SAMPLE RETURN?

On our planet, the samples would reveal untold secrets about the big “if” in space science: Are we alone in the universe? Over the last several decades, robotic explorers have gleaned from the reddish landscape that life may have had the right conditions to flourish on the fourth rock from the Sun. Scientists might be able to prove this tantalizing possibility if they can get ahold of these rocks. The Voyager golden records, the myriad of international missions that have orbited Mars, and the host of upcoming missions to the possibly aquatic moons in the outer Solar System, would win an incredible endorsement.

Extending the mission timeline is what makes the most sense to preserve the MSR plan as it currently exists, Casey Dreier, chief of space policy at the non-profit The Planetary Society, told The New York Times on Monday.

But NASA leadership does not want to wait until 2040. “That is unacceptable to wait that long. It’s the decade of the 2040s that we are going to be landing astronauts on Mars. It’s also unacceptable at $11 billion,” NASA Administrator Bill Nelson told reporters at a news conference on Monday.

NASA will ask for proposals from the private sector to find solutions that would offset costs and maintain the project’s integrity. In addition to that, NASA will develop “a revised plan that leverages innovation and proven technology,” according to their published announcement.

WHAT COULD PUT MARS SAMPLE RETURN BACK ON TRACK?

NASA has historically leveraged its partnerships with the private sector to save on costs. For its Artemis program, which marks NASA’s first major crewed return to the Moon since Apollo, the agency has already issued contracts for companies to launch instruments for studying the lunar environment in preparation for crews and has selected proposals for crewed Moon rovers.

MSR’s architecture shares some similarities with that of Artemis III, of which SpaceX will play a key role.

NASA is now building upon the success, and resolving issues, from 2022’s Artemis I mission. For Artemis II, four astronauts are currently in training to fly around the Moon and back as early as September 2025. Then on Artemis III, the program scales up in a whole new way.

SpaceX holds the contract to build the Starship human landing system for NASA, which would ferry astronauts from lunar orbit to the Moon’s surface, and then carry them back up there.

The vehicle will reach the Moon before the four Artemis III astronauts set sail there, according to NASA. Soon after the Orion capsule arrives with the crew, it will rendezvous with the SpaceX lander, and two brave explorers will get onboard to become the first people to descend to and walk on the Moon’s surface since 1972. When the week of the surface expedition ends, Starship would ferry the duo up to meet the orbital Orion capsule, which would then exit the Moon’s environment and fly the crew back to Earth

Artemis III’s sequence resembles, in part, what must happen on Mars Sample Return. Titanium tubes containing the Red Planet samples would be placed on a spacecraft that could launch them into Martian orbit. Here, another spacecraft would jet off to Earth, carrying the samples to their new home.

“The challenges of getting off the surface of the Moon have been demonstrated already through the Apollo missions,” Dianne DeTurris, an aerospace engineer at California Polytechnic State University, tells Inverse in an email. “A vehicle got off the surface with people onboard successfully 6 times. The issues for getting on and off of Mars are similar, but the distance to travel to get there is much greater, and with that, there is a greater signal lag due to the time difference. Can it be done? Yes. Will it be done? Very likely. The technology exists already, it is just about finding a cost-effective way to execute the task.”

In February, Dreier wrote a column for The Planetary Society arguing that Starship likely wouldn’t come to MSR’s rescue. Among several reasons he cited, a November 2023 report from the U.S. Government Accountability Office says the Starship human landing system for Artemis III is running into delays.

“NASA remains responsible for its own destiny,” Dreier wrote. For now, MSR and the first modern human landing seem so close — but just out of reach.

{ https://www.inverse.com/ }

24-04-2024 om 16:46 geschreven door peter  

Voyager 1 Just Sent Its First Coherent Message Back to NASA In Months

A clever programming fix has cured the spacecraft's electronic aphasia.

BY KIONA SMITH

 

NASA/JPL

“In the last decade, I have learned from Voyager that there is (almost) always a way around a problem, no matter how dire it is,” Voyager mission assurance manager Bruce Waggoner told Inverse in March. “You just have to think ‘outside the box’ when people tell you not to do so.”

FLIPPED BITS AND ELECTRONIC GIBBERISH

Back in November, a passing cosmic ray hit one of Voyager 1’s three onboard computers, and it “flipped a bit” (or altered a tiny unit of data) in the spacecraft’s Flight Data Subsystem. This unit of data happened to be a key piece of the code that tells Voyager 1 how to package up science and engineering data, including information about its own condition, before sending the message to Earth.

Like the robot version of a person recovering from a stroke, Voyager 1 could receive and understand messages from home, and it could gather data to send back. But when it tried to “speak,” its data came out as a gibberish of random 0s and 1s.

Engineers at NASA realized that to fix the problem, they needed to reprogram Voyager 1 with the correct code. However, there wasn’t enough data storage space on the Flight Data Subsystem computer to hold it all. The programmers had to split the code into sections, which could be tucked into Voyager 1’s computer wherever there was room. Then include instructions about where to find each one.

On April 18, Voyager 1’s team transmitted the new code to the distant spacecraft. Then they waited. It took 22.5 hours for the data, moving at the speed of light, to cross more than 15 billion miles of space to reach Voyager 1, and then it took another 22.5 hours for Voyager 1’s response to cross the vastness of space and reach NASA’s Jet Propulsion Laboratory. But after a tense 45 hours, on April 20, the team downloaded Voyager 1’s message: a clear, understandable status update declaring that all was well with the intrepid space robot.

The Voyager 1 team will spend the next few weeks reworking the code that packages science data, and they expect Voyager 1 to return to sending back reports from the edge of the Solar System — ones its human operators can actually read.

Meanwhile, Voyager 2, a well-behaved space robot that hasn’t been in the news lately, is still cruising out of the Solar System on its own trajectory. NASA says it hopes to keep both missions gathering data and calling home until around 2035.

{ https://www.inverse.com/ }

24-04-2024 om 16:34 geschreven door peter  

Na reis van 8 miljard jaar bereikte het zonet onze aarde

Een enorme flits van radiogolven werd in 2022 aan de hemel van onze planeet gedetecteerd, en dit na een reis die maar liefst acht miljard jaar duurde. Dat blijkt uit een onlangs gepubliceerd wetenschappelijk onderzoek. Dit fenomeen, door wetenschappers een ‘snelle radio-uitbarsting’ genoemd, werd voor het eerst waargenomen in 2007 en blijft nog steeds grotendeels een mysterie.

Volgens een studie die op 19 oktober in het tijdschrift Science werd gepubliceerd, had geen van de eerder waargenomen ‘snelle radio-uitbarstingen’ (of FRB’s) een zo verre oorsprong of een kracht die vergelijkbaar is met deze die in 2022 werd bestudeerd door het ASKAP-radiotelescoopnetwerk, gevestigd in West Australië.

Ondanks de beperkte duur van slechts minder dan een milliseconde, zou deze explosie van elektromagnetische golven die acht miljard jaar geleden plaatsvond, volgens CNN een hoeveelheid energie hebben vrijgemaakt die equivalent is aan de energie die onze zon over een periode van dertig jaar heeft uitgestraald.

Sinds hun eerste detectie in 2007 zijn er ongeveer duizend FRB’s gesignaleerd, maar de precieze oorsprong van deze signalen blijft vaak onbekend. Voor de FRB die in 2022 werd gedetecteerd, gebruikten wetenschappers de European Very Large Telescope (VLT) vanuit de Atacama-woestijn in Chili. Ze slaagden erin de bron van de emissies te lokaliseren in een groep van twee of drie sterrenstelsels midden in het proces van fusie, interacties en vorming van nieuwe sterren.

Deze ontdekking lijkt de huidige theorieën te bevestigen dat snelle radio-uitbarstingen afkomstig zouden kunnen zijn van magnetars (een zeldzaam type neutronenster) of andere extreem energetische astronomische objecten die het gevolg zijn van exploderende sterren.

FRB's zijn van groot belang voor astronomen omdat hun onderzoek zou kunnen helpen bij het oplossen van andere mysteries van het universum, waaronder die van 'ontbrekende materie'.

• (FVDV and LpR for Tagtik/Source: Courrier International/Illustration picture: Pixabay via Pexels)

 { https://www.msn.com/nl-be/ }

24-04-2024 om 15:59 geschreven door peter  

Asteroids have also been known to “photobomb” images acquired by Hubble of distant cosmic objects like UGC 12158 (see image above). By knowing Hubble’s position when it took exposures of asteroids and measuring the curvature of the streaks they leave, scientists can determine the asteroids’ distances and estimate the shapes of their orbits. The ability to do this with large samples allows astronomers to test theories about Main Asteroid Belt formation and evolution. As Martin said in a recent ESA Hubble press release:

“We are getting deeper into seeing the smaller population of main-belt asteroids. We were surprised to see such a large number of candidate objects. There was some hint that this population existed, but now we are confirming it with a random asteroid population sample obtained using the whole Hubble archive. This is important for providing insights into the evolutionary models of our Solar System.”

According to one widely accepted model, small asteroids are fragments of larger asteroids that have been colliding and grinding each other down over billions of years. A competing theory states that small bodies formed as they appear today billions of years ago and have not changed much since. However, astronomers can offer no plausible mechanism for why these smaller asteroids would not accumulate more dust from the circumstellar disk surrounding our Sun billions of years ago (from which the planets formed).

In addition, astronomers have known for some time that collisions would have left a certain signature that could be used to test the current Main Belt population. In 2019, astronomers from the European Science and Technology Centre (ESTEC) and the European Space Astronomy Center’s Science Data Center (ESDC) came together with the world’s largest and most popular citizen-science platform (Zooniverse) and Google to launch the citizen-science project Hubble Asteroid Hunter (HAH) to identify asteroids in archival Hubble data.

The HAH team comprised 11,482 citizen-science volunteers who perused 37,000 Hubble images spanning 19 years. After providing nearly two million identifications, the team was given a training set for an automated algorithm to identify asteroids based on machine learning. This yielded 1,701 asteroid trails, with 1,031 corresponding to previously uncatalogued asteroids – about 400 of which were below 1 km (~1090 ft) in size. Said Martin:

“Asteroid positions change with time, and therefore you cannot find them just by entering coordinates, because they might not be there at different times. As astronomers we don’t have time to go looking through all the asteroid images. So we got the idea to collaborate with more than 10,000 citizen-science volunteers to peruse the huge Hubble archives.”

This pioneering approach may be effectively applied to datasets accumulated by other asteroid-hunting observatories, such as NASA’s Spitzer Space Telescope and Stratospheric Observatory for Infrared Astronomy (SOFIA). Once the James Webb Space Telescope (JWST) has accumulated a large enough dataset, the same method could also be applied to its archival data. As a next step, the HAH project will examine the streaks of previously unknown asteroids to characterize their orbits, rotation periods, and other properties.

Further Reading:

• ESA Hubble, 
• Astronomy & Astrophysics

{ https://www.universetoday.com/ }

23-04-2024 om 23:42 geschreven door peter  

The TRAPPIST-1 system has been the focal point of attention ever since astronomers confirmed the presence of three exoplanets in 2016, which grew to seven by the following year. As one of many systems with a low-mass, cooler M-type (red dwarf) parent star, there are unresolved questions about whether any of its planets could be habitable. Much of this concerns the variable and unstable nature of red dwarfs, which are prone to flare activity and may not produce enough of the necessary photons to power photosynthesis.

With so many rocky planets found orbiting red dwarf suns, including the nearest exoplanet to our Solar System (Proxima b), many astronomers feel these systems would be the ideal place to look for extraterrestrial life. At the same time, they’ve also emphasized that these planets would need to have thick atmospheres, intrinsic magnetic fields, sufficient heat transfer mechanisms, or all of the above. Determining if exoplanets have these prerequisites for life is something that the JWST and other next-generation telescopes – like the ESO’s proposed Extremely Large Telescope (ELT) – are expected to enable.

But even with these and other next-generation instruments, there is still the question of what biosignatures we should look for. As noted, our planet, its atmosphere, and all life as we know it have evolved considerably over the past four billion years. During the Archean Eon (ca. 4 to 2.5 billion years ago), Earth’s atmosphere was predominantly composed of carbon dioxide, methane, and volcanic gases, and little more than anaerobic microorganisms existed. Only within the last 1.62 billion years did the first multi-celled life appear and evolve to its present complexity.

Moreover, the number of evolutionary steps (and their potential difficulty) required to get to higher levels of complexity means that many planets may never develop complex life. This is consistent with the Great Filter Hypothesis, which states that while life may be common in the Universe, advanced life may not. As a result, simple microbial biospheres similar to those that existed during the Archean could be the most common. The key, then, is to conduct searches that would isolate biosignatures consistent with primitive life and the conditions that were common to Earth billions of years ago.

As Dr. Jake Eager-Nash, a postdoctoral research fellow at the University of Victoria and the lead author of the study, explained to Universe Today via email:

“I think the Earth’s history provides many examples of what inhabited exoplanets may look like, and it’s important to understand biosignatures in the context of Earth’s history as we have no other examples of what life on other planets would look like. During the Archean, when life is believed to have first emerged, there was a period of up to around a billion years before oxygen-producing photosynthesis evolved and became the dominant primary producer, oxygen concentrations were really low. So if inhabited planets follow a similar trajectory to Earth, they could spend a long time in a period like this without biosignatures of oxygen and ozone, so it’s important to understand what Archean-like biosignatures look like.”

For their study, the team crafted a model that considered Archean-like conditions and how the presence of early life forms would consume some elements while adding others. This yielded a model in which simple bacteria living in oceans consume molecules like hydrogen (H) or carbon monoxide (CO), creating carbohydrates as an energy source and methane (CH₄) as waste. They then considered how gases would be exchanged between the ocean and atmosphere, leading to lower concentrations of H and CO and greater concentrations of CH₄. Said Eager-Nash:

“Archean-like biosignatures are thought to require the presence of methane, carbon dioxide, and water vapor would be required as well as the absence of carbon monoxide. This is because water vapor gives you an indication there is water, while an atmosphere with both methane and carbon monoxide indicates the atmosphere is in disequilibrium, which means that both of these species shouldn’t exist together in the atmosphere as atmospheric chemistry would convert all of the one into the other, unless there is something, like life that maintains this disequilibrium. The absence of carbon monoxide is important as it is thought that life would quickly evolve a way to consume this energy source.”

When the concentration of gases is higher in the atmosphere, the gas will dissolve into the ocean, replenishing the hydrogen and carbon monoxide consumed by the simple life forms. As biologically produced methane levels increase in the ocean, it will be released into the atmosphere, where additional chemistry occurs, and different gases are transported around the planet. From this, the team obtained an overall composition of the atmosphere to predict which biosignatures could be detected.

“What we find is that carbon monoxide is likely to be present in the atmosphere of an Archean-like planet orbiting an M-Dwarf,” said Eager-Nash. “This is because the host star drives chemistry that leads to higher concentrations of carbon monoxide compared to a planet orbiting the Sun, even when you have life-consuming this [compound].”

For years, scientists have considered how a circumsolar habitable zone (CHZ) could be extended to include Earth-like conditions from previous geological periods. Similarly, astrobiologists have been working to cast a wider net on the types of biosignatures associated with more ancient life forms (such as retinal-photosynthetic organisms). In this latest study, Eager-Nash and his colleagues have established a series of biosignatures (water, carbon monoxide, and methane) that could lead to the discovery of life on Archean-era rocky planets orbiting Sun-like and red dwarf suns.

Further Reading: 

• arXiv

{ https://www.universetoday.com/ }

23-04-2024 om 23:31 geschreven door peter  

It was 1903 that the Wright brothers made the first successful self-propelled flight. Launching themselves to history, they set the foundations for transatlantic flights, supersonic flight and perhaps even the exploration of the Solar System. Now we are on the precipice of travel among the stars but among the many ideas and theories, what is the ultimate and most effective way to explore our nearest stellar neighbours? After all, there are 10,000 stars within a region of 110 light years from Earth so there are plenty to choose from. 

It’s not just the stars that entice us to explore beyond our Solar System. Ever since the first exoplanet discovery in 1992 we have been discovering more and more alien worlds around distant stars. The tally has now reached over 5,500 confirmed exoplanets and they too demand our attention as we reach out among the stars. There have been many ideas and technologies proposed over the past few years but to date, even Proxima Centauri (the nearest star system to our own) remains out of reach. 

In his thesis recently published, lead author Johannes Lebert from the Technische Universität München (TUM) attempts to develop a strategy, based on existing interstellar probe concepts and knowledge of nearby star systems. Lebert was driven by the exoplanet discoveries that continue at pace and the development and interest, both commercially and technically in interstellar probes. Not only does he explore the technologies but he also looks at the returns too. 

In the strategy developed in the thesis he looks at the two main objectives which are duration of the mission and the returns. By returns he refers to the sum of all rewards provided by the stars explored during the mission and of course be largely scientific.  He considers a multi vehicle approach using several probes which do not return to Earth and are capable of exploring different stars thereby maximising the mission returns. Finally he explores the routing of such a mission to ensure maximum mission returns. Succinctly he calls this his ‘Bi-objective multi- vehicle open routing problem with profits.’

The thesis concludes with several recommendation. First that the use of efficient routing around the stars, a more limited number of probes can be used, limiting reducing fuel costs. This should be balanced by the mission returns which increase faster should more probes be used to explore the same number of stars simultaneously. This does however increase mission costs due to increase fuel costs. Whichever strategy is used, small-scale remotely operated or autonomous craft are far more suited to the need. 

Lebert goes on to explain that higher probe numbers also brings the benefit that probes can be tailored to suit the star systems they are destined to explore. Unlike a smaller number of probes that will have to cater for a greater range of systems.  There is a concept known as the ‘derived scaling law’ which articulates that higher probe numbers do inherit a risk of less efficient deployment.

It’s an interesting read that reminds us that, whilst we are developing the probes, and there are quite a number on the drawing board; Breakthrough Starshot, Interstellar Express, Interstellar Probe, Innovative Interstellar Explorer, Tau Mission to name a few, we do need to consider just how we plan, manage and deploy to maximise the scientific gain. 

Source : 

• Optimal Strategies for the Exploration of Near-by Star

{ https://www.universetoday.com/ }

21-04-2024 om 01:16 geschreven door peter  

Juno made the two close flybys of Io in December 2023 and February 2024. Images from Juno’s JunoCam included the first close-up images of the moon’s northern latitudes. Undoubtedly, Io looks like a pizza – which has been the conclusion since our first views of this moon, when Voyager 1 flew through the Jupiter system in March 1979. The mottled and colorful surface comes from the volcanic activity, with hundreds of vents and calderas on the surface that create a variety of features. Volcanic plumes and lava flows across the surface show up in all sorts of colors, from red and yellow to orange and black. Some of the lava “rivers” stretch for hundreds of kilometers.

Juno scientists were also able to re-create a spectacular feature on Io, a spired mountain that has been nicknamed “The Steeple.” This feature is between 5 and 7 kilometers (3-4.3 miles) in height. It’s hard to comprehend the type of volcanic activity that could have created such a stunning landform.

Speaking of volcanic activity, two recent papers have come to a jaw-dropping conclusion about Io: this moon has been erupting since the dawn of the Solar System.

All the volcanic on Io is activity is driven by tidal heating. Io is in an orbital resonance with two other large moons of Jupiter, Europa and Ganymede.

“Every time Ganymede orbits Jupiter once, Europa orbits twice, and Io orbits four times,” explained the authors of a paper published in the Journal of Geophysical Research: Planets, led by Ery Hughes of GNS Science in New Zealand. “This situation causes tidal heating in Io (like how the Moon causes ocean tides on Earth), which causes the volcanism.”

However, scientists haven’t known how long this resonance has been occurring and whether what we observe today is what has always been happening in the Jupiter system. This is because volcanism renews Io’s surface almost constantly, leaving little trace of the past.

The team of scientists, led by Katherine de Kleer at Caltech and Hughes at GNS Science used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile observe the sulphur gases in Io’s atmosphere. The isotopes of sulfur were used as a tracer of tidal heating on Io because sulfur is released through volcanism, processed in the atmosphere, and recycled into the mantle. Additionally, some of the sulfur is lost to space, and because of Jupiter’s magnetosphere, a bunch of charged particles whirling around Jupiter that hit Io’s atmosphere continuously.

It turns out that the sulfur that is lost to space on Io is a little bit isotopically lighter than the sulfur that is recycled back into Io’s interior. Because of this, over time, the sulfur remaining on Io gets isotopically heavier and heavier. How much heavier depends on how long volcanism has been taking place.

What the teams found is that tidal heating on Io has been occurring for billions of years.

“The isotopic composition of Io’s inventory of volatile chemical elements, including sulfur and chlorine, reflects its outgassing and mass loss history, and thus records information about its evolution,” the team wrote in the paper published in Science. “These results indicate that Io has been volcanically active for most (or all) of its history, with potentially higher outgassing and mass-loss rates at earlier times.”

Juno continues to makes its way through the Jupiter system. And during Juno’s most recent flyby of Io, on April 9, the spacecraft came within about 16,500 kilometers (10,250 miles) of the moon’s surface. It will perform its 61st flyby of Jupiter on May 12.

JunoCam is a public camera, where members of the public can choose targets for imaging, as well as process all the data.  JunoCam’s raw images are available here for the public to peruse and process into image products. Here you can see the most recent images that have been processed.

Papers: 

1. Isotopic Evidence of Long-Lived Volcanism on Io
2. Using Io’s Sulfur Isotope Cycle to Understand the History of Tidal Heating
   

Further Reading: 

• NASA, 
• GNS Science

{ https://www.universetoday.com/ }

21-04-2024 om 01:07 geschreven door peter  

NASA’s Juno Mission Provides Close-Ups of Intriguing Features on Io

In December 2023 and February 2024, NASA’s Juno spacecraft made extremely close flybys of Jupiter’s volcanic moon Io, getting within about 1,500 km (930 miles) of the surface and obtaining the first close-up images of the moon’s northern latitudes. Planetary scientists have now transformed the images collected during the flybys into animations that highlight two of Io’s most dramatic features: a mountain and an almost glass-smooth lake of cooling lava called Loki Patera.

The JunoCam instrument aboard NASA’s Juno spacecraft imaged Io, the most geologically active body in our Solar System, on February 3, 2024, from a distance of about 7,904 km (4,911 miles).

Image credit: NASA / SwRI / MSSS.

“Io is simply littered with volcanoes, and we caught a few of them in action,” said Juno’s principal investigator Scott Bolton, director of the Space Science and Engineering Division at the Southwest Research Institute.

“We also got some great close-ups and other data on a 200-km- (127-mile-) long lava lake called Loki Patera.”

“There is amazing detail showing these crazy islands embedded in the middle of a potentially magma lake rimmed with hot lava.”

“The specular reflection our instruments recorded of the lake suggests parts of Io’s surface are as smooth as glass, reminiscent of volcanically created obsidian glass on Earth.”

Maps generated with data collected by Juno’s Microwave Radiometer (MWR) instrument reveal Io not only has a surface that is relatively smooth compared to Jupiter’s other Galilean moons, but also has poles that are colder than middle latitudes.

During Juno’s extended mission, the spacecraft flies closer to the north pole of Jupiter with each pass.

This changing orientation allows the MWR instrument to improve its resolution of Jupiter’s northern polar cyclones.

The data allow multiwavelength comparisons of the poles, revealing that not all polar cyclones are created equal.

“Perhaps most striking example of this disparity can be found with the central cyclone at Jupiter’s north pole,” said Juno’s project scientist Dr. Steve Levin, a researcher at NASA’s Jet Propulsion Laboratory.

“It is clearly visible in both infrared and visible light images, but its microwave signature is nowhere near as strong as other nearby storms.”

“This tells us that its subsurface structure must be very different from these other cyclones.”

“The MWR team continues to collect more and better microwave data with every orbit, so we anticipate developing a more detailed 3D map of these intriguing polar storms.”

{ https://www.sci.news/ }

20-04-2024 om 21:07 geschreven door peter  

Astronomers Discover 454 New Asteroids in Main Belt

A set of 632 main-belt asteroids (178 previously known and 454 unknown objects) has been identified in the archival images from the NASA/ESA Hubble Space Telescope. Citizen scientists from around the world contributed to the identification of this asteroid bounty. Professional astronomers combined the volunteers’ efforts with machine learning algorithm to identify the asteroids.

This Hubble image of the barred spiral galaxy UGC 12158 looks like someone took a white marking pen to it. In reality it is a combination of time exposures of a foreground asteroid moving through Hubble’s field-of-view, photobombing the observation of the galaxy. Several exposures of the galaxy were taken, what is evidence in the dashed pattern. The asteroid appears as a curved trail due to parallax: because Hubble is not stationary, but orbiting Earth, and this gives the illusion that the faint asteroid is swimming along a curved trajectory. The uncharted asteroid is in inside the asteroid belt in our Solar System, and hence is 10 trillion times closer to Hubble than the background galaxy.

Image credit: NASA / ESA / Hubble / Pablo García Martín, UAM / Joseph DePasquale, STScI / Alex Filippenko, UC Berkeley.

Over 4 billion years ago, the eight major planets around our Sun formed by sweeping up debris from a vast disk of dust and gas surrounding the Sun.

This is common to the planet birthing process, and the NASA/ESA Hubble Space Telescope was the first to optically see similar disks surrounding newborn stars, providing a peek into the Solar System’s formative years.

Now, 4 billon years later, the planet construction yard is still cluttered with leftover debris.

Most of this ancient space rubble — asteroids — can be found between the orbits of Mars and Jupiter within the main asteroid belt.

“We are getting deeper into seeing the smaller population of main belt asteroids,” said Dr. Pablo García Martín, an astronomer at the Autonomous University of Madrid.

“We were surprised with seeing such a large number of candidate objects.”

“There was some hint of this population existing, but now we are confirming it with a random asteroid population sample obtained using the whole Hubble archive.”

“This is important for providing insights into the evolutionary models of our Solar System.”

Because of Hubble’s fast orbit around the Earth, it can capture wandering asteroids through their telltale trails in the Hubble exposures.

As viewed from an Earth-based telescope, an asteroid leaves a streak across the picture.

Asteroids ‘photobomb’ Hubble exposures by appearing as unmistakable, curved trails in the photographs.

As Hubble moves around the Earth, it changes its point of view while observing an asteroid, which also moves along its own orbit.

By knowing the position of Hubble during the observation and measuring the curvature of the streaks, scientists can determine the distances to the asteroids and estimate the shapes of their orbits.

The asteroids snagged mostly dwell in the main belt, which lies between the orbits of Mars and Jupiter.

Their brightness is measured by Hubble’s sensitive cameras. And comparing their brightness to their distance allows for a size estimate.

The faintest asteroids in the survey are roughly one forty-millionth the brightness of the faintest star that can be seen by the human eye.

“Asteroid positions change with time, and therefore you cannot find them just by entering coordinates, because at different times, they might not be there,” Dr. Merín said.

“As astronomers we don’t have time to go looking through all the asteroid images.”

“So we got the idea to collaborate with over 10,000 citizen-science volunteers to peruse the huge Hubble archives.”

• The results appear in the journal Astronomy & Astrophysics.
• Pablo García-Martín et al. 2024. Hubble Asteroid Hunter III. Physical properties of newly found asteroids. A&A 683, A122; doi: 10.1051/0004-6361/202346771

{ https://www.sci.news/ }

20-04-2024 om 00:13 geschreven door peter  

New research in the journal Science establishes dates for giant planet migration in our Solar System. Its title is “Dating the Solar System’s giant planet orbital instability using enstatite meteorites.” The lead author is Dr. Chrysa Avdellidou from the University of Leicester’s School of Physics and Astronomy.

“The question is, when did it happen?” Dr. Avdellidou asked. “The orbits of these planets destabilised due to some dynamical processes and then took their final positions that we see today. Each timing has a different implication, and it has been a great matter of debate in the community.”

“What we have tried to do with this work is to not only do a pure dynamical study, but combine different types of studies, linking observations, dynamical simulations, and studies of meteorites.”

The meteorites in this study are enstatites or E-type asteroids. E-type asteroids have enstatite (MgSiO3) achondrite surfaces. Achondrite means they lack chondrules, grains of rock that were once molten before being accreted to their parent body. Specifically, this group of meteorites are the low-iron chondrites called ELs.

When giant planets move, everything else responds. Tiny asteroids are insignificant compared to Jupiter’s mass. Scientists think E-type asteroids were dispersed during the gas giants’ outward migration. They may even have been the impactors in the hypothetical Late Heavy Bombardment.

Enstatite achondrites that have struck Earth have similar compositions and isotope ratios as Earth. This signals that they formed in the same part of the protoplanetary disk around the young Sun. Previous research by Dr. Avdellidou and others has linked the meteorites to a population of fragments in the asteroid belt named Athor.

This work hinges on linking meteorites to parent asteroids and measuring the isotopic ratios.

“If a meteorite type can be linked to a specific parent asteroid, it provides insight into the asteroid’s composition, time of formation, temperature evolution, and original size,” the authors explain. When it comes to composition, isotopic abundances are particularly important. Different isotopes decay at different rates, so analyzing their ratio tells researchers when each meteorite closed, meaning when it became cool enough that there was no more significant diffusion of isotopes. “Therefore, thermochronometers in meteorites can constrain the epoch at which major collisional events disturbed the cooling curves of the parent asteroid,” the authors explain.

The team’s research shows that Athor is a part of a once much larger parent body that formed closer to the Sun. It also suffered from a collision that reduced its size out of the asteroid belt.

Athor found its way back when the giant planets migrated. Athor was at the mercy of all that shifting mass and underwent its own migration back into the asteroid belt. Analysis of the meteorites showed that this couldn’t have happened earlier than 60 million years ago. Other research into asteroids in Jupiter’s orbit showed it couldn’t have happened later than 100 million years ago. Since the Solar System formed about 4.56 billion years ago, the giant planet migration happened between 4.5 and 4.46 billion years ago.

Another important event happened right around the same time. About 4.5 billion years ago, a protoplanet named Theia smashed into Earth, creating the Moon. Could it all be related?

“The formation of the Moon also occurred within the range that we determined for the giant planet instability,” the authors write in their research. “This might be a coincidence, or there might be a causal relationship between the two events.”

“It’s like you have a puzzle, you understand that something should have happened, and you try to put events in the correct order to make the picture that you see today,” Dr. Avdellidou said. “The novelty with the study is that we are not only doing pure dynamical simulations, or only experiments, or only telescopic observations.”

“There were once five inner planets in our Solar System and not four, so that could have implications for other things, like how we form habitable planets. Questions like, when exactly objects came delivering volatile and organics to our planet to Earth and Mars?”

The Solar System’s history is a convoluted, beautiful puzzle that somehow led to us. Everything had to work out for life to arise on Earth, sustain itself, and evolve for so long. The epic migration of the gas giants must have played a role, and this research brings its role into focus.

Never mind habitability, complex life, and civilization, the migration may have allowed Earth to form in the first place.

“The timing is very important because our Solar System at the beginning was populated by a lot of planetesimals,” said study co-author Marco Delbo, Director of Research at France’s Nice Observatory. “And the instability clears them, so if that happens 10 million years after the beginning of the Solar System, you clear the planetesimals immediately, whereas if you do it after 60 million years you have more time to bring materials to Earth and Mars.

{ https://www.universetoday.com/ }

19-04-2024 om 22:18 geschreven door peter  

But there are ways to indirectly track down their origin. One of the more promising methods is by observing gamma rays (which do travel in straight lines, thankfully).

When cosmic rays bump into other bits of matter, they produce gamma rays. So when a supernova goes off and sends cosmic rays out into the Universe, it should also send a gamma-ray signal letting us know it’s happening.

That’s the theory, anyway.

But the evidence hasn’t matched expectations. Studies of old, distant supernovas show some gamma ray production occurring, but not as much as predicted. Astronomers explained away the missing radiation as a result of the supernovas’ age and distance. But in 2023, the Fermi telescope captured a bright new supernova occurring nearby. Named SN 2023ixf, the supernova went off just 22 million light-years away in a galaxy called Messier 101 (better known as the ‘Pinwheel Galaxy’). And yet again, gamma rays were conspicuously absent.

“Astrophysicists previously estimated that supernovae convert about 10% of their total energy into cosmic ray acceleration,” said Guillem Martí-Devesa, University of Trieste. “But we have never observed this process directly. With the new observations of SN 2023ixf, our calculations result in an energy conversion as low as 1% within a few days after the explosion. This doesn’t rule out supernovae as cosmic ray factories, but it does mean we have more to learn about their production.”

So where is all the missing gamma radiation?

It’s possible that interstellar material around the exploding star could have blocked gamma rays from reaching the Fermi telescope. But it might also mean that astronomers need to look for alternative explanations for the production of cosmic rays.

Nobody likes a good mystery better than astronomers, and digging into the missing gamma radiation could eventually tell us a whole lot more about cosmic rays and where they come from.

Astronomers plan to study SN 2023ixf in other wavelengths to improve their models of the event, and will of course keep an eye out for the next big supernova, in an effort to understand what is going on.

• The most recent gamma-ray data from SN 2023ixf will be published in Astronomy and Astrophysics in a paper led by Martí-Devesa.

 { https://www.universetoday.com/ }

19-04-2024 om 22:05 geschreven door peter  

You had to be in the right part of North America to get a great view of the recent solar eclipse. But a particular telescope may have had the most unique view of all. Even though that telescope is in Hawaii and only experienced a partial eclipse, its images are interesting.

The Daniel K. Inouye Solar Telescope (DKIST) is at the Haleakala Observatory in Hawaii. With its four-meter mirror, it’s the largest solar telescope in the world. It observes in visible to near-infrared light, and its sole target is the Sun. It can see features on the Sun’s surface as small as 20 km (12 miles.) It began science operations in February 2022, and its primary objective is to study the Sun’s magnetic fields.

Though seeing conditions weren’t perfect during the eclipse and the eclipse was only partial when viewed from Hawaii, the telescope still gathered enough data to create a movie of the Moon passing in front of the Sun. The bumps on the Moon’s dark edge are lunar mountains.

via GIPHY

“The team’s primary mission during Maui’s partial eclipse was to acquire data that allows the characterization of the Inouye’s optical system and instrumentation,” shares National Solar Observatory scientist Dr. Friedrich Woeger.

The Moon plays a critical role in measuring the telescope’s performance. Its edge is well-known and as a dark object in front of the Sun, it acts as a unique tool to measure the Inouye telescope’s performance and to understand the data it collects. Since the telescope has to correct for Earth’s turbulent atmosphere with adaptive optics, the Moon’s known qualities help researchers work with the telescope’s optical elements.

“With the Inouye’s high order adaptive optics system operating, the blurring due to the Earth’s atmosphere was greatly reduced, allowing for extremely high spatial resolution images of the moving lunar edge,” said Woeger. “The appearance of the edge is not straight but serrated because of mountain ranges on the Moon!” This serrated dark edge covers the granular convection pattern that governs the “surface of the Sun.”

The Inouye Solar Telescope studies the Sun’s magnetic fields, which drive space weather. What we see in the video is visually interesting, but there’s a lot of data behind it.

It’ll take several months to analyze all of the data it gathered during the eclipse.

{ https://www.universetoday.com/ )

19-04-2024 om 21:54 geschreven door peter  

Tales of a Total Solar Eclipse

We were also treated to some amazing images of the eclipse from Earth and space. NASA also had several efforts underway to chase the eclipse. Even now, we’re still processing the experience. It takes time (and patience!) for astro-photos to make their way through the workflow. Here are some of the best images we’ve seen from the path of totality:

Tony Dunn had an amazing experience, watching the eclipse from Mazatlan, Mexico. “When totality hit, it didn’t look real,” Dunn told Universe Today. “It looked staged, like a movie studio. the lighting is something that can’t be experienced outside a total solar eclipse.”

Dunn also caught an amazing sight, as the shadow of the Moon moved across the low cloud cover:

Black Hole Sun

Peter Forister caught the eclipse from central Indiana. “It was my second totality (after 2017 in South Carolina), so I knew what was coming,” Forister told Universe Today. “But it was still as incredible and beautiful as anything I’ve ever seen in nature. The Sun and Moon seemed huge in my view—a massive black hole (like someone took a hole punch to the sky) surrounded by white and blue flames streaking out. Plus, there was great visibility of the planets and a few stars. The memory has been playing over and over in my head since it happened—and it’s combined with feelings of awe and wonder at how beautiful our Universe and planet really are. The best kind of memory!”

Like many observers, Eliot Herman battled to see the eclipse through clouds. “As you know, we had really frustrating clouds,” Herman told Universe Today. “I shot a few photos (in) which you can see the eclipse embedded in the clouds and then uncovered to show the best part. For me it almost seemed like a cosmic mocking, showing me what a great eclipse it was, and lifting the veil only at the end of the eclipse to show me what I missed…”

Totality Crosses Into Canada

Astrophotographer Andrew Symes also had a memorable view from Cornwall, Ontario. “While I’ve seen many beautiful photos and videos from many sources, they don’t match what those us there in person saw with our eyes,” Symes told Universe Today. “The sky around the Sun was not black but a deep, steely blue. The horizon was lighter–similar to what you’d see during a sunset or sunrise–but still very alien.”

“The eclipsed Sun looked, to me, like an incredibly advanced computer animation from the future! The Sun and corona were very crisp, and the Sun looked much larger in the sky than I’d expected. The eclipsed Sun had almost a three-dimensional quality… almost as if it were a dark, round button-like disk surrounded by a bright halo affixed to a deep blue/grey background. It was as if a ‘worm hole’ or black hole had somehow appeared in front of us. I’m sure my jaw dropped as it was truly a moment of utter amazement. I’m smiling as I type it now… and still awestruck as I recall it in my mind!”

Success for the Total Solar Eclipse in Aroostook County Maine

We were met with success (and clear skies) watching the total solar eclipse with family from our hometown of Mapleton, Maine. We were mostly just visually watching this one, though we did manage to nab a brief video of the experience.

What I was unprepared for was the switch from partial phases to totality. It was abrupt as expected, but there almost seemed to be brief but perceptible pause from day to twilight, as the corona seemed to ‘switch on.’ We all agreed later on that the steely blue sky was not quite night… but not quite twilight, either.

When’s the next one? I often wonder how many watchers during a given eclipse were ‘bitten by the bug,’ and looking to chase the next one. Spain is set to see an eclipse a year for the next three years, starting in 2026:

Spain in August… be sure to stay cool and bring sunblock. Don’t miss the next total solar eclipse, and be thankful for our privileged vantage point in time and space.

{ https://www.universetoday.com/ )

19-04-2024 om 21:40 geschreven door peter  

Purple is the New Green: Purple Bacteria Could Dominate Wide Range of Exoplanetary Environments

With more than 5,500 detected exoplanets, the search for life is entering a new era. Using life on Earth as a guide, astrobiologists from Cornell University and the University of Minnesota looked beyond green landscapes to expand their ability to detect signs of surface life on other worlds. In new research, they characterized the reflectance spectra of a collection of purple sulfur and purple non-sulfur bacteria from a variety of environments.

To expand our baseline for finding life in the cosmos, Coelho et al. have measured the reflectance of purple bacteria that thrive across a range of anoxic and oxic environments.

Image credit: Sci.News.

From house plants and gardens to fields and forests, green is the color we most associate with surface life on Earth, where conditions favored the evolution of organisms that perform oxygen-producing photosynthesis using the green pigment chlorophyll a.

But an Earth-like planet orbiting another star might look very different, potentially covered by bacteria that receive little or no visible light or oxygen, as in some environments on Earth, and instead use invisible infrared radiation to power photosynthesis.

Instead of green, many such bacteria on Earth contain purple pigments, and purple worlds on which they are dominant would produce a distinctive ‘light fingerprint’ detectable by next-generation ground- and space-based telescopes.

“Purple bacteria can thrive under a wide range of conditions, making it one of the primary contenders for life that could dominate a variety of worlds,” said Dr. Lígia Fonseca Coelho, a postdoctoral researcher with the Carl Sagan Institute at Cornell University.

“We need to create a database for signs of life to make sure our telescopes don’t miss life if it happens not to look exactly like what we encounter around us every day,” added Dr. Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University.

For the study, the authors collected and grew samples of more than 20 purple sulfur and purple non-sulfur bacteria that may be found in a variety of environments, from shallow waters, coasts and marshes to deep-sea hydrothermal vents.

What are collectively referred to as purple bacteria actually have a range of colors including yellow, orange, brown and red due to pigments related to those that make tomatoes red and carrots orange.

They thrive on low-energy red or infrared light using simpler photosynthesis systems utilizing forms of chlorophyll that absorb infrared and don’t make oxygen.

They are likely to have been prevalent on early Earth before the advent of plant-type photosynthesis and could be particularly well-suited to planets that circle cooler red dwarf stars — the most common type in our Galaxy.

“They already thrive here in certain niches,” Dr. Coelho said.

“Just imagine if they were not competing with green plants, algae and bacteria: a red sun could give them the most favorable conditions for photosynthesis.”

After measuring the purple bacteria’s biopigments and light fingerprints, the researchers created models of Earth-like planets with varying conditions and cloud cover.

“Across a range of simulated environments, both wet and dry purple bacteria produced intensely colored biosignatures,” Dr. Coelho said.

“If purple bacteria are thriving on the surface of a frozen Earth, an ocean world, a snowball Earth or a modern Earth orbiting a cooler star, we now have the tools to search for them.”

• The team’s work appears in the Monthly Notices of the Royal Astronomical Society.
• Lígia Fonseca Coelho et al. 2024. Purple is the new green: biopigments and spectra of Earth-like purple worlds. MNRAS 530 (2): 1363-1368; doi: 10.1093/mnras/stae601

{ https://www.sci.news/ }

17-04-2024 om 22:53 geschreven door peter  

University of Arizona astronomer Adeene Denton, one of the study’s co-authors, said the formation of the heart “provides a critical window into the earliest periods of Pluto’s history.”

“By expanding our investigation to include more unusual formation scenarios, we’ve learned some totally new possibilities for Pluto’s evolution,” Denton said in a news release. Similar scenarios could apply to other objects in the Kuiper Belt, the ring of icy worlds on the edge of our solar system.

The study focuses on the western half of the heart, a roughly 1,000-mile-wide, teardrop-shaped region called Sputnik Planitia. That region contains an assortment of ices and is roughly 2.5 miles lower in elevation than the rest of Pluto. It’s clearly the result of a massive impact.

“While the vast majority of Pluto’s surface consists of methane ice and its derivatives, covering a water-ice crust, the Planitia is predominantly filled with nitrogen ice which most likely accumulated quickly after the impact due to the lower altitude,” said study lead author Harry Ballantyne, a research associate at the University of Bern.

The eastern half of the heart is covered by a similar but much thinner layer of nitrogen ice. The origins of that part of Tombaugh Regio are still unclear, but it’s probably related to the processes that shaped Sputnik Planitia.

Ballantyne and his colleagues ran a wide assortment of computer simulations for the ancient impact. Those simulations reflected a range of sizes and compositions for the impacting body, at different velocities and angles of approach. The best fit for Sputnik Planitia’s shape involved a 400-mile-wide object, composed of 15% rock, coming in at an angle of 30 degrees and hitting Pluto at a relatively low velocity.

Based on those parameters, the object would have plowed through Pluto’s surface with a splat. The resulting shape wouldn’t look like your typical impact crater. Instead, it would look like a bright, icy teardrop, with the rocky core of the impacting body ending up at the tail of the teardrop.

“Pluto’s core is so cold that the rocks remained very hard and did not melt despite the heat of the impact, and thanks to the angle of impact and the low velocity, the core of the impactor did not sink into Pluto’s core, but remained intact as a splat on it,” Ballantyne explained.

Previous scenarios for Sputnik Planitia’s origin relied on the presence of a deep ocean beneath Pluto’s surface to explain why the impact region hasn’t drifted toward Pluto’s nearest pole over time. But the researchers behind the newly published study found that the best matches in their simulations called for an ocean measuring no more than 30 miles in depth. “If the influence of ammonia proves negligible, Pluto might not possess a subsurface ocean at all, in accordance with our nominal case,” they wrote.

The researchers say they’ll continue their work to model Pluto’s geological history — and how those models could apply to other Kuiper Belt objects as well.

Meanwhile, the New Horizons spacecraft is continuing its journey through the solar system’s far reaches, nearly nine years after its Pluto flyby. Mission scientists recently reported detecting higher than expected levels of interplanetary dust, which suggests there may be more to the Kuiper Belt than they thought. They’re hoping to identify yet another icy world that the spacecraft can observe up close in the late 2020s or the 2030s.

• In addition to Ballantyne and Denton, the authors of the Nature Astronomy study, titled “Sputnik Planitia as an Impactor Remnant Indicative of an Ancient Rocky Mascon in an Oceanless Pluto,” include Erik Asphaug, Alexandre Emsenhuber and Martin Jutzi.

{ https://www.universetoday.com/ }

17-04-2024 om 18:26 geschreven door peter  

Is Dark Matter Real? Inside the Theories That Leave This Mysterious Phenomenon Out

Is there more to the universe than meets the eye, or are the rules different than we thought? (Spoiler alert: it's probably the first one.)

BY KIONA SMITH

 

William Attard McCarthy/Moment/Getty Images

The universe is hiding something.

Stars at the outer edges of galaxies whirl around the galactic center far more swiftly than the laws of physics say they should. At even larger scales, galaxy clusters clump together in ways that should only be possible if the galaxies were more massive than they appear. And most of our models of how the Big Bang happened suggest that much more matter should have been created than we see.

Either there’s more to the universe than meets the eye, or the rules of physics work very differently than we think they do. Most astrophysicists and cosmologists (scientists who study the origins and evolution of the universe) today lean toward the first option: dark matter. But a few have devoted their efforts to finding a set of rules that could produce the universe we see, without dark matter.

Inverse spoke with experts in both fields about dark matter, the laws that make our universe work, and the quest to understand everything.

HIDDEN MASS OR NEW RULES OF PHYSICS?

The things we can see in the universe — planets, stars, vast clouds of gas, and galaxies — make up only about 5 percent of what’s out there, according to physicists. Another 70 percent is dark energy, a little-understood force that’s driving the expansion of our universe (we know it’s expanding because astronomers have measured the way light waves from distant stars get stretched out as their sources accelerate away from us), and the remaining 25 percent is stuff called dark matter.

Dark matter doesn’t absorb, emit, or reflect light, and it doesn’t seem to interact with normal matter in most ways; theoretically, you could walk through a wall made of dark matter and never see it or feel it. The only rule of physics that dark matter seems to follow is gravity: It has mass, apparently, and that mass has gravity and forms a vital part of the scaffolding of galaxies, galaxy clusters, and the universe itself at a large scale.

As explanations go, dark matter sounds weird, but it works well. The amount of “extra” matter created in the Big Bang seems to match the amount of unseen mass in the universe. It balances physicists’ equations nicely and explains what we see in the universe around us.

But because dark matter doesn’t interact with light or matter, scientists haven’t yet actually detected it directly; they can only see how its gravity affects the universe around it. That leaves a little sliver of doubt and inspires some physicists and cosmologists to look for other ways to explain those effects.

One of the most popular alternatives to dark matter is called Modified Newtonian Dynamics, or MOND, and it proposes that gravity works a little differently than Isaac Newton first described it. The farther away an object is, the weaker its gravitational pull feels. According to MOND, gravity’s effect weakens slightly less over distance than it does in Newton’s original equations. That, allegedly, explains why galaxies seem to spin fast, as if they have a lot more mass on their outer edges than it appears.

MOND, and other modified ways of describing gravity, “are quite good at describing the properties of galaxies, but usually fail at describing the large-scale structure of the Universe,” astrophysicist Sébastien Comerón tells Inverse. And to replace dark matter, any new model of how the universe works has to explain everything we see, at large scales and small ones.

A recent study, led by cosmologist Rajendra Gupta, tackled that problem. Gupta suggested earlier this year that the universe might be 26.7 billion years old — nearly twice as old as all our evidence so far suggests — and that the laws of physics are much less consistent than we thought.

“I was trying to understand the so-called 'impossible early galaxy' problem,” Gupta tells Inverse. When astronomers peer into the distant, early universe with the James Webb Space Telescope (JWST), they see galaxies that look more massive and more neatly structured than they should; just 1 billion years after the Big Bang, galaxies shouldn’t have had time to pull so much mass together. (The same is true of some of the earliest supermassive black holes in the universe.)

Those precocious early galaxies challenge what we think we know about how supermassive black holes and galaxies form and evolve.

But Gupta tackled the “impossible early galaxies” problem by developing a new model of the universe, which would explain the precocious early galaxies. His model hinges on a century-old theory called tired light, which suggests that light actually loses energy as it travels across space. It also leans on another old theory that suggests the laws that govern how our universe works (like gravity) aren’t so constant after all — they weaken over distance. According to Gupta’s model, those changes add up to differences in how light appears by the time it reaches JWST, making the universe look younger than it is.

The model suggested another conclusion as well: Dark matter and dark energy don’t exist.

“The model yields matter content just enough for the Universe's ordinary matter; there is no room for dark matter. In fact, there is no dark energy in this model either,” says Gupta. “Accelerated expansion of the Universe, attributed to the dark energy, is due to the weakening of the forces of nature in the new model.”

But there are some problems with the idea, starting with the fact that both “tired light” and the idea of varying physical constants (like gravity) fell out of fashion among scientists a long time ago because they didn’t fit with observations about how the universe behaved.

“I think it is an interesting idea to explain the origin of recently discovered compact bright galaxies at high redshift with just varying two new parameters that determine the property of photons. However, it remains to be seen whether the model can explain the other phenomena,” cosmologist Kaiki Inoue tells Inverse. Those other phenomena include some inconsistences in how the cosmic microwave background looks in different directions, as well as how galaxy clusters and even larger-scale structures form. “So, in my opinion, it is an interesting idea but not a fully developed model,” says Inoue.

DON’T BET AGAINST DARK MATTER

“It is worth doing exploratory work outside the box,” says Comerón. “But the likelihood of this particular avenue being the one that solves the problems in cosmology is rather low in my opinion.”

It’s not clear yet whether modified gravity theories, like MOND, actually fit well with Gupta’s proposed model of the universe, either.

One of the best arguments in favor of dark matter may be its inconsistency. Comerón and his colleagues recently discovered a galaxy that apparently contains no dark matter — which is weird but not unheard of. And if we’re seeing not invisible, undetectable matter, but different laws of physics, those laws should apply to all galaxies in the same way.

“I have sometimes been attracted by the idea of alternative gravities myself, but the discovery of the odd properties of NGC 1277 leaves me little doubt that dark matter exists,” says Comerón. “If dark matter could be explained by a modification of gravities, it would be odd to have gravity modified in all galaxies except in a few. On the other hand, one could conceive mechanisms to remove dark matter from galaxies that have got a peculiar formation or interaction history.”

And that seems to be the consensus among most astrophysicists and cosmologists. So far, no one has figured out how to directly measure dark matter — and until they do, there will always be at least a little room for debate about its existence. But Inoue and his colleagues recently used gravitational lensing to map how dark matter is distributed along one narrow swath of the universe, and others are busily trying to work out exactly what it’s made of and how it behaves.

“I would not bet any money against dark matter,” says Comerón.

{ https://www.inverse.com/ }

16-04-2024 om 21:26 geschreven door peter  

BepiColombo Detects Oxygen and Carbon Ions in Magnetosphere of Venus

by Natali Anderson

In August 2021, the ESA/JAXA Mercury-bound BepiColombo spacecraft performed its second flyby of Venus and provided a short-lived observation of its induced magnetosphere. The spacecraft detected cold oxygen and carbon ions at a distance of about six planetary radii in a region of the magnetosphere that has never been explored before.

Schematic view of planetary material escaping through Venus magnetosheath flank; the red line and arrow show the region and direction of observations by BepiColombo when the escaping ions (C⁺, O⁺, H⁺) were observed.

Image credit: Thibaut Roger / Europlanet 2024 RI / Hadid et al.

During its formation, Venus was similar to Earth in many ways, including the existence of substantial amounts of liquid water.

However, Venus eventually evolved in a divergent way, leading to substantial differences between the two planets.

Unlike Earth, Venus is now an extremely dry planet that lacks an intrinsic magnetic field.

The continuous impact of the solar wind on the atmospheres of both planets results in important atmospheric losses.

The atmosphere of Venus, predominantly composed of carbon dioxide with smaller amounts of nitrogen and other minor species, is affected by interactions with the solar wind, leading to important ion outflows.

“This is the first time that positively charged carbon ions have been observed escaping from Venus’ atmosphere,” said Dr. Lina Hadid, a researcher at the Plasma Physics Laboratory and CNRS.

“These are heavy ions that are usually slow moving, so we are still trying to understand the mechanisms that are at play.”

“It may be that an electrostatic ‘wind’ is lifting them away from the planet, or they could be accelerated through centrifugal processes.”

“Unlike Earth, Venus does not generate an intrinsic magnetic field in its core.”

“Nonetheless, a weak, comet-shaped ‘induced magnetosphere’ is created around the planet by the interaction of charged particles emitted by Sun (solar wind) with electrically charged particles in Venus’ upper atmosphere.”

“Draped around the magnetosphere is a region called the ‘magnetosheath’ where the solar wind is slowed and heated.”

On August 10, 2021, BepiColombo passed by Venus to slow down and adjust course towards its final destination of Mercury.

The spacecraft swooped up the long tail of the planet’s magnetosheath and emerged through the nose of the magnetic regions closest to the Sun.

Over a 90-minute period of observations, BepiColombo’s Mass Spectrum Analyzer (MSA) and the Mercury Ion Analyzer (MIA) measured the number and mass of charged particles it encountered, capturing information about the chemical and physical processes driving atmospheric escape in the flank of the magnetosheath.

“Characterizing the loss of heavy ions and understanding the escape mechanisms at Venus is crucial to understand how the planet’s atmosphere has evolved and how it has lost all its water,” said MSA’s principal investigator Dr. Dominique Delcourt, a researcher at the Plasma Physics Laboratory.

“This result shows the unique results that can come out of measurements made during planetary flybys, where the spacecraft may move through regions generally unreachable by orbiting spacecraft,” said Dr. Nicolas André, a researcher at the Institut de Recherche en Astrophysique et Planétologie.

• The study was published in the journal Nature Astronomy.
• L.Z. Hadid et al. BepiColombo observations of cold oxygen and carbon ions in the flank of the induced magnetosphere of Venus. Nat Astron, published online April 12, 2024; doi: 10.1038/s41550-024-02247-2

{ https://www.sci.news/ }

15-04-2024 om 22:20 geschreven door peter  

SpaceX Starship will be 500 feet tall to prepare for Mars missions, Elon Musk says (video)

SpaceX's Starship, the largest rocket in the world, will get even bigger as the company continues to target Mars missions in the future.

Elon Musk, the billionaire founder of SpaceX, told employees on April 4 that Starship will eventually be as tall as 500 feet (150 meters), roughly 20 percent higher than the massive system aboard the Super Heavy rocket right now. 

What's more, advances in reusability will have each launch cost roughly $3 million each, Musk predicted; that's less than a third of what a (much smaller) Falcon 1 rocket launch cost in 2004 when inflation is taken into account. (The figure two decades ago was $5.9 million, according to NBC, which is roughly $9.5 million in 2024 dollars.) 

"These are sort of unthinkable numbers," Musk said in the Starship update, released publicly April 6, roughly one month after the third and last test flight to date. "Nobody ever thought that this was possible, but we're not breaking any physics to achieve this. So this is within the bounds, without breaking physics. We can do this."

Related:

•  SpaceX fires up huge Super Heavy booster ahead of 4th Starship test flight (photos, video)

Musk tends to deliver Starship updates at least once ayear to highlight progress the company is making toward its long-term plans of settling Mars. Indeed, the last year has seen three Starship launches, so there has been progress made recently. Musk didn't, however, address delays in launching Starship that have contributed to pushing back the launch date for the first moon landing under the NASA-led Artemis program.

SpaceX was named the vendor for the Artemis 3 landing mission that, until recently, was set for 2025. In January, NASA elected to hold the launch date another year, to 2026, due to a range of technical issues. Aside from Starship not being ready — the agency wants many successful launches before approving it for astronaut flights — Artemis 3 was also delayed due to slow progress on spacesuits and problems with the mission's Orion spacecraft, among other factors.

However, Musk's words about Artemis, to employees, focused on Starship's future capabilities: orbiting the Earth and refilling its tanks, both of which have yet to be proven on its three test flights.

"This will ... be very important for the Artemis program for the NASA to get back to the moon," Musk said of those capabilities. He also envisions a "Moon Base Alpha" that would include ships "specialized for going to and from the moon", meaning there would be no heat shield or flaps due to the lack of atmosphere.

Related: 

• NASA celebrates SpaceX Starship's 3rd test flight, but more work needed ahead of Artemis moon missions

Musk's 45-minute speech touched on the usual themes for his Red Planet updates, focusing on how to send a lot of cargo out there for eventual settlers. He noted that would take thousands of launches to do; for perspective, Musk said the company has completed 327 successful Falcon series launches and about 80 percent of those had reused boosters (a key factor in reducing cost.)

SpaceX is by far the most active launching entity on Earth, and Musk forecasts the company will send roughly 90 percent of orbital mass aloft this year compared to China's 6 percent (the second-largest entity.) 

Starship's next and fourth spaceflight attempt, expected to take place in May, aims to have the first stage of Super Heavy land "on essentially a virtual tower" in the Gulf of Mexico, Musk said. Once the company safely gets that done, they will consider using the launching area at Starbase, in south Texas, for future landings as soon as Flight 5. (Musk pegged the chances of success on Flight 4 at 80% or 90%.)

Musk also wants to perform two splashdowns of the upper stage of Starship in a row, in a controlled fashion, before sending it to Starbase on a future flight. "We do not want to rain debris over Mexico or the U.S.," he said. "My guess is probably next year when we will be able to reuse Starship."

Overall, Musk plans for multiple Starship launches to take place this year, and suggests SpaceX will build an additional six spacecraft by the end of 2024. A new rocket factory for the company should be available in 2025, which would make production even faster. 

Future versions of Starship will include a "Starship 2" to send 100 tons of payload to low-Earth orbit and the 500-foot "Starship 3" for 200 or more tons. Bigger vehicles, Musk stressed, will mean fewer (four or five) refueling missions in low Earth orbit to get a Starship ready for the journey to Mars someday. 

Of these milestones, Musk said it would be "very much a success-oriented schedule." His speech did not mention the Federal Aviation Administration, which must approve each one of the launches, nor ongoing criticism of the environmental impact of Starship on the ecologically sensitive area near Starbase.

That impact may continue to grow, as Musk said it would take roughly 10 launches a day to send hundreds of vehicles to Mars every two years (when the planet is closest) to make a long-term settlement feasible. As for the number of Mars-bound people, that would be roughly a million folks, he said — that matches predictions he made at least as far back as 2017. Musk also says he wants to get the settlement going "in 20 years." He said the same thing in 2011.

{ https://www.space.com/space-exploration }

14-04-2024 om 23:09 geschreven door peter