A 2-Mile Wide ‘Planet Killer’ Asteroid Is Headed Towards Earth At 58,000 MPH

BY DOUGLAS CHARLES

ISTOCKPHOTO

Mountain-sized “planet-killer” Asteroid 2011 UL21 is headed towards Earth this week and during its trip it will be making a very close approach to our planet.

The asteroid, classified as a Potentially Hazardous Asteroid (PHA) by NASA, is supposed to go zooming by Earth at 58,000 mph on June 27th.

Asteroid 2011 UL21 is also classified as a near-Earth object (NEO), which means that its orbit can move the space rock within 1.3 astronomical units (AU) of the sun. An AU is the average distance between Earth and the Sun, or about 93 million miles.

VIA NASA-JPL

This asteroid is no tiny space rock either. According to SpaceReference.org, it is comparable in size to Mount Everest – Earth’s highest mountain above sea level – and is between 1.1 and 2.4-miles wide.

Needless to say, a 2-mile wide rock traveling at 58,000 mph would definitely “kill” our planet.

Thankfully, the asteroid will only pass Earth at a distance of around 4.1 million miles. Still, that is the closest it will have come to Earth in the past 110 years, at least.

And while 4.1 million miles may sound like a great distance, in terms of space it isn’t so much. By comparison, Mars is 245.22 million miles from Earth.

According to Gianluca Masi, astrophysicist and director of the Virtual Telescope Project, “There is absolutely no risk for our planet.”

“The term ‘Potentially Hazardous Asteroid’ (PHA) is a precise formal definition, referring to minor planets larger than approximately 140 meters that can come within 7.5 million km from the Earth,” said Masi. “In other words, only the largest asteroids capable of approaching close enough to our planet are flagged as PHAs, which does not mean they are going to hit the Earth, but they nonetheless warrant a better monitoring.”

That being said, there is always the possibility that the gravitational tug of Earth could alter the “planet killer” asteroid’s orbit (called the Yarkovsky Effect). And if that were to ever occur there isn’t much we could do to stop it.

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26-06-2024 om 23:26 geschreven door peter  

Study: Active, Seafloor Hydrothermal Systems on Small Ocean Worlds Could Support Life

Ocean worlds are planetary bodies that have a liquid ocean, often under an icy shell or within the rocky interior. In our own Solar System, several moons of Jupiter and Saturn are ocean worlds. Some ocean worlds are thought to have hydrothermal circulation, where water, rocks, and heat combine to drive fluids in and out of the seafloor. Hydrothermal circulation would impact the chemistry of the water and rock of ocean worlds, and could help life to develop deep below the icy surface. In a new study, planetary researchers used computer simulations of hydrothermal circulation, based on a well-understood system on Earth, to measure the influence of lower gravity at values appropriate for ocean worlds smaller than our home planet. The simulations with ocean world (lower) gravity result in fluid circulation much like that occurring on and below Earth’s seafloor, but with several important differences. Lower gravity reduces buoyancy, so fluids don’t become as light when heated, and this reduces flow rates. This can raise temperatures in the circulating fluid, which could allow more extensive chemical reactions, perhaps including those that sustain life.

This graphic illustrates how Cassini scientists think water interacts with rock at the bottom of Enceladus’ ocean, producing hydrogen gas.

Image credit: NASA / JPL-Caltech / Southwest Research Institute.

Rock-heat-fluid systems were discovered on Earth’s seafloor in the 1970s, when scientists observed discharging fluids that carried heat, particles, and chemicals.

Many vent sites were surrounded by novel ecosystems, including specialized bacterial mats, red-and-white tubeworms, and heat-sensing shrimp.

In the new study, University of California, Santa Cruz’s Professor Andrew Fisher and colleagues used a complex computer model based on hydrothermal circulation as it occurs on Earth.

After changing variables like gravity, heat, rock properties and fluid-circulation depth, they found that hydrothermal vents could be sustained under a wide range of conditions.

If these kinds of flows occur on an ocean world, like Jupiter’s moon Europa, they could raise the odds that life exists there as well.

“This study suggests that low temperature — not too hot for life — hydrothermal systems could have been sustained on ocean worlds beyond Earth over timescales comparable to that required for life to take hold on Earth,” Professor Fisher said.

The seawater-circulation system that the researchers based their computer models on was found on a 3.5 million-year-old seafloor in the northwestern Pacific Ocean, east of the Juan de Fuca Ridge.

There, cool bottom water flows in through an extinct volcano (seamount), travels underground for about 30 miles (48.3 km), then flows back out into the ocean through another seamount.

“The water gathers heat as it flows and comes out warmer than when it flowed in, and with very different chemistry,” Kristin Dickerson, a Ph.D. candidate at the University of California, Santa Cruz.

“The flow from one seamount to another is driven by buoyancy, because water gets less dense as it warms, and more dense as it cools,” Professor Fisher added.

“Differences in density create differences in fluid pressure in the rock, and the system is sustained by the flows themselves — running as long as enough heat is supplied, and rock properties allow enough fluid circulation. We call it a hydrothermal siphon.”

“While high-temperature vent systems are driven mainly by sub-seafloor volcanic activity, a much larger volume of fluid flows in and out of Earth’s seafloor at lower temperatures, driven mainly by background cooling of the planet.”

“The flow of water through low-temperature venting is equivalent, in terms of the amount of water being discharged, to all of the rivers and streams on Earth, and is responsible for about a quarter of Earth’s heat loss.”

“The entire volume of the ocean is pumped in and out of the seafloor about every half-million years.”

Many previous studies of hydrothermal circulation on Europa and Enceladus have considered higher temperature fluids.

“Cartoons and other drawings often depict systems on their seafloors that look like black smokers on Earth. Lower-temperature flows are at least as likely to occur, if not more likely,” said Dr. Donna Blackman, also from the University of California, Santa Cruz.

The findings show that, under very low gravity — like that found on the seafloor of Enceladus — circulation can continue with low to moderate temperatures for millions or billions of years.

This could help to explain how small ocean worlds can have long-lived fluid-circulation systems below their seafloors, even though heating is limited: the low efficiency of heat extraction could lead to considerable longevity — essentially, throughout the life of the Solar System.

The scientists acknowledge the uncertainty of when the seafloors of ocean worlds will be directly observed for the presence of active hydrothermal systems.

Their distance from Earth and physical characteristics present major technical challenges for spacecraft missions.

“Thus, it is essential to make the most of available data, much of it collected remotely, and leverage understanding from decades of detailed studies of analog Earth systems,” the authors concluded.

• Their paper was published in the Journal of Geophysical Research: Planets.

• A.T. Fisher et al. 2024. Sustaining Hydrothermal Circulation with Gravity Relevant to Ocean Worlds. Journal of Geophysical Research: Planets 129 (6): e2023JE008202; doi: 10.1029/2023JE008202

{ https://www.sci.news/ }

26-06-2024 om 22:11 geschreven door peter  

After helium leaks and thruster problems with Boeing’s Starliner capsule, NASA has been pushing back the return date from the International Space Station. On Friday, the agency announced they no longer had a planned return date. Instead, they will keep testing the capsule, trying to understand its issues, and seeing if they can make any fixes. Plenty of supplies are on the station, so there’s no urgent need to bring the two astronauts back to Earth.

Another reason NASA decided to cancel the planned departure of Wednesday, June 26 is because of conflicting timelines with a series of planned spacewalks on the ISS, set for today (Monday, June 24), and Tuesday, July 2. The delay also allows mission teams time to review propulsion and system data.

After years of delays and two recent scrubbed launch attempts, Starliner finally launched on June 5, 2024 with NASA astronauts Butch Wilmore and Suni Williams on board. Although two of the spacecraft’s thrusters failed during the flight, the spacecraft managed to reach the ISS and delivered 227 kg (500 lbs) of cargo. Additionally, five small leaks on the service module were also detected, and the crew and ground teams have been working through safety checks.

“We are taking our time and following our standard mission management team process,” said Steve Stich, manager of NASA’s Commercial Crew Program in a NASA blog post. “We are letting the data drive our decision making relative to managing the small helium system leaks and thruster performance we observed during rendezvous and docking. Additionally, given the duration of the mission, it is appropriate for us to complete an agency-level review, similar to what was done ahead of the NASA’s SpaceX Demo-2 return after two months on orbit, to document the agency’s formal acceptance on proceeding as planned.”

Safety and gaining a better understanding of the issues with Starliner are NASA and Boeing’s motivations for the delay in returning the spacecraft and crew back to Earth.

This first crewed flight of Starliner was supposed to validate the spacecraft as part of NASA’s Commercial Crew Program (CCP), with the hope of it working alongside SpaceX’s Crew Dragon to make regular deliveries of cargo and crew to the ISS. This mission is the second time the Starliner has flown to the ISS and the third flight test overall. During the first uncrewed test flight (OFT-1), which took place back in December 2019, the Starliner launched successfully but failed to make it to the ISS. After making 61 corrective actions recommended by NASA, another attempt was made (OFT-2) on May 22nd, 2022. That flight successfully docked to the ISS, staying there for four days before undocking and landing in the White Sands Missile Range in New Mexico.

Wilmore and Williams are now  working with the Expedition 71 crew, assisting with station operations as needed and completing add-on in-flight objectives for NASA’s certification of Starliner.

Stich said that despite all the issues, Starliner is performing well in orbit while docked to the space station.

“We are strategically using the extra time to clear a path for some critical station activities while completing readiness for Butch and Suni’s return on Starliner,” he said, “and gaining valuable insight into the system upgrades we will want to make for post-certification missions.”

Mission managers will evaluate future return opportunities for Starliner and NASA said they will host a media telecon with mission leadership following a readiness review. NASA added that Starliner is actually cleared for return in case of an emergency on the space station that would require the crew to leave orbit and come back to Earth.

{ https://www.universetoday.com/ }

25-06-2024 om 23:50 geschreven door peter  

“The Chang’e-6 lunar exploration mission achieved complete success,” Zhang Kejian, director of the China National Space Administration, said from mission control. Chinese President Xi Jinping extended congratulations to the mission team, the state-run Xinhua news service reported.

Chang’e-6 followed a flight plan similar to the one used for Chang’e-5, a mission that brought back samples from the moon’s Earth-facing side in 2020. After entering lunar orbit, the spacecraft sent a lander down to the moon’s South Pole-Aitken Basin region.

The lander used an onboard drill and robotic arm to collect and store samples on its ascent stage. It also gathered data about its surroundings with a radon detector, a negative-ion detector and a mini-rover. Data and telemetry were relayed between Chang’e-6 and Earth via China’s Queqiao-2 satellite.

On June 4, Chang’e-6’s ascent stage lifted off for a rendezvous with the orbiting spacecraft. The samples were transferred to a re-entry capsule, and the spacecraft left lunar orbit several days ago for the trip back to Earth. The re-entry capsule was released as the spacecraft sped about 5,000 kilometers (3,100 miles) over the South Atlantic Ocean, CNSA said in a mission update.

After an initial round of processing at the landing site in China’s Inner Mongolia region, the capsule is due to be airlifted to Beijing, where the mission’s precious cargo will be removed for distribution to researchers.

The samples are expected to include volcanic rock and other materials that could shed fresh light on the moon’s origins and compositional differences between the near side and the far side. Scientists may also learn more about resources in the moon’s south polar region. That region is of high interest because it’s thought to harbor deposits of water ice that could be used to support future lunar settlements.

NASA is targeting the south polar region for a series of robotic missions — leading up to a crewed landing during the Artemis 3 mission, which is currently scheduled for 2026. China has its own lunar ambitions, including plans for sending astronauts to the lunar surface by 2030.

{ https://www.universetoday.com/ }

25-06-2024 om 23:37 geschreven door peter  

If all stars shone as brightly as main sequence stars like our Sun do, it would be easy to catalogue the stars in our neighbourhood. But they don’t. Some are so small and dim that they’re considered failed stars. We call them brown dwarfs or substellar objects.

When we look up at the night sky with the unaided eye, our view is dominated by main sequence stars and giant stars, many of which are far beyond our stellar neighbourhood. Many stars are too dim to see, like red dwarfs and brown dwarfs. In fact, Proxima Centauri, a red dwarf and our nearest neighbour, wasn’t discovered until the early 20th century.

In the early days of astronomy, measurements of proper motions showed that some stars that appear fixed in place are closer than other stars. All stars move and have proper motion; it’s just not always noticeable in the span of a single lifetime. High proper motion surveys of stars led to the selection of certain stars for measurements of their parallax, which helped locate more stars correctly in space. Then, in the early 20th century, as astronomy and photography were used in conjunction, photographic astrometry triggered a wave of discoveries of our solar neighbours. Those efforts showed that our nearest neighbours are red dwarfs (M dwarfs).

In the 1990s, as technology advanced, infrared sky surveys found more dim stars. “A second wave of discoveries started in the late 1990s with the advance of infrared sky surveys,” the authors write. Missions like the Two Micron All-Sky Survey (2MASS) gave us a new, unprecedented look at the sky. It found M dwarfs, brown dwarfs, and substellar objects like L, T, and Y types, and even minor planets in the Solar System. (Definitions of brown dwarfs and other substellar objects overlap.) By the year 2,000, the Sloan Digital Sky Survey came online, strengthening our catalogue of the sky.

In 1997, Henry et al. published an important paper on the solar neighbourhood titled “The solar neighborhood IV: discovery of the twentieth nearest star.” It showed that the discovery of LHS 1565, about 3.7 pc from Earth, spelled trouble for our census of the neighbourhood. “It ranks as the twentieth closest stellar system and underscores the incompleteness of the nearby star sample, particularly for objects near the end of the main sequence,” Henry et al. wrote. “Ironically, this unassuming red dwarf provides a shocking reminder of how much we have yet to learn about even our nearest stellar neighbours.”

Since about 1997, there’s been a burst of discoveries of stars within the Sun’s neighbourhood. The authors say that these seem to have filled in the gaps in our 10 pc neighbourhood. But some of the knowledge was still based on two assumptions. The first was that the survey out to 5 parsecs was complete, and the second was that the density was uniform out to 10 parsecs. “The first of these is not true, and the second is in question,” the authors write.

Where does that leave us? Up to 90 star systems could still be missing.

“Using all neighbours the luminosity and mass functions and the star-to-brown dwarf (BD) number ratio can be studied,” the authors state. Astronomers don’t fully understand the ratio of brown dwarfs to other stars, but two recent papers (1,2), in particular, have continued the work to better understand and catalogue our stellar neighbourhood’s dim members.

Earlier this year, Kirkpatrick et al. published a study claiming that a complete survey of nearby stars is possible, largely thanks to Gaia data. They found 462 objects (including the Sun) in 339 systems within 10?pc. of the Sun.

In previous work, the authors of this new paper added 16 more stars to the list. These were late M-dwarfs, some of the coolest and dimmest main sequence stars, and brown dwarfs. They also discovered a new white dwarf companion to an existing M dwarf.

But how complete is this newest survey?

The problem lies in the difficulty of detecting dim stars like brown dwarfs and late M-dwarfs. The further we look, the more difficult they are to detect. They’re also more difficult to detect in the direction of the galactic plane.

The authors say that our neighbourhood stellar catalogue is still likely missing 93 stellar systems, “… corresponding to a deficit of ?21.5%,” they write. In terms of individual stars, it’s not much better: “…138 missing objects corresponding to a deficit of ?23.0%,” they write.

They broke it down even further to individual star types. We’re probably missing 28.1% of AFGK stars, -31% of white dwarfs, and ?27.8% of M-dwarfs. There’s also a higher deficit for late M-dwarfs. These deficits are higher than expected. What does it mean?

“The estimated deficits of systems and individual objects within 10?pc exceed expectations, in particular for the well-known AFGK stars,” the authors write. They conclude that the general assumption of a constant stellar density in the solar neighbourhood is incorrect. They say that small-scale density fluctuations can at least partly explain the deficits.

“Our statistical estimates show that the probability of these discrepancies being caused by random fluctuations is around 40%,” the authors conclude.

We clearly have more work to do.

{ https://www.universetoday.com/ }

25-06-2024 om 23:31 geschreven door peter  

Webb Observes Intricate Structures in Ionosphere of Jupiter

Jupiter’s upper atmosphere is composed of a neutral thermosphere and charged ionosphere. Astronomers using the NASA/ESA/CSA James Webb Space Telescope have spotted unexpected small-scale intensity features such as arcs, bands and spots in Jupiter’s low-latitude ionosphere in the region above the Great Red Spot.

This graphic shows the region observed by Webb: first its location on a NIRCam image of the whole planet (left), and the region itself (right), imaged by Webb’s Near-InfraRed Spectrograph (NIRSpec).

Image credit: NASA / ESA / CSA / Webb / Jupiter ERS Team / J. Schmidt / H. Melin / M. Zamani, ESA & Webb.

Jupiter is one of the brightest objects in the night sky, and it is easily seen on a clear night.

Aside from the bright northern and southern lights at the planet’s polar regions, the glow from Jupiter’s upper atmosphere is weak and is therefore challenging for ground-based telescopes to discern details in this region.

However, Webb’s infrared sensitivity allows scientists to study Jupiter’s upper atmosphere above the infamous Great Red Spot with unprecedented detail.

The gas giant’s upper atmosphere is the interface between the planet’s magnetic field and the underlying atmosphere.

Here, the bright and vibrant displays of northern and southern lights can be seen, which are fuelled by the volcanic material ejected from Jupiter’s moon Io.

However, closer to the equator, the structure of the planet’s upper atmosphere is influenced by incoming sunlight.

Because Jupiter receives only 4% of the sunlight that is received on Earth, astronomers predicted this region to be homogeneous in nature.

University of Leicester astronomer Henrik Melin and his colleagues observed the Great Red Spot in July 2022 using the Integral Field Unit of Webb’s Near-InfraRed Spectrograph (NIRSpec).

Their Early Release Science observations sought to investigate if this region was in fact dull, and the region above the iconic Great Red Spot was targeted for Webb’s observations.

They were surprised to discover that the upper atmosphere hosts a variety of intricate structures, including dark arcs and bright spots, across the entire field of view.

“We thought this region, perhaps naively, would be really boring. It is in fact just as interesting as the northern lights, if not more so. Jupiter never ceases to surprise,” Dr. Melin said.

Although the light emitted from this region is driven by sunlight, the team suggests there must be another mechanism altering the shape and structure of the upper atmosphere.

“One way in which you can change this structure is by gravity waves — similar to waves crashing on a beach, creating ripples in the sand,” Dr. Melin said.

“These waves are generated deep in the turbulent lower atmosphere, all around the Great Red Spot, and they can travel up in altitude, changing the structure and emissions of the upper atmosphere.”

“These atmospheric waves can be observed on Earth on occasion, however they are much weaker than those observed on Jupiter by Webb.”

“We hope to conduct follow-up Webb observations of these intricate wave patterns in the future to investigate how the patterns move within the planet’s upper atmosphere and to develop our understanding of the energy budget of this region and how the features change over time.”

• The findings appear in the journal Nature Astronomy.
• H. Melin et al. Ionospheric irregularities at Jupiter observed by JWST. Nat Astron, published online June 21, 2024; doi: 10.1038/s41550-024-02305-9

{ https://www.sci.news/feedb }

25-06-2024 om 21:35 geschreven door peter  

Hey @NASA @NASAjpl @NASA_Johnson could you please answer this question? UFO Sighting News.

Hey everyone, I decided to tweet to three NASA accounts and see if they respond or not. So I made this video and sent it off to them. They will see it for sure, but the real question is...are they prepared to answer it?

Also I'm currently keeping the NASA like to this photo a secret for now, otherwise NASA would delete it immediately. 

Scott C. Waring - Utah

{ https://www.ufosightingsdaily.com/ }

25-06-2024 om 21:25 geschreven door peter  

De binnenkern van onze planeet heeft zijn rotatie vertraagd, dat is bevestigd

 Door Janine

NASA/JPL-Université Paris Diderot - Institut de Physique du Globe de Paris / Pexels

De binnenkern vertraagt ​​al meer dan tien jaar, bevestigt een nieuwe studie. Wat veroorzaakt dit fenomeen en wat kan er in de toekomst gebeuren?

De binnenkern draait nu langzamer dan het aardoppervlak

In het centrum van onze aarde bevindt zich een vaste, dichte, hete binnenkern, bestaande uit ijzer en kleine hoeveelheden nikkel. De straal bedraagt ​​1.221 kilometer en de temperaturen bereiken die van het zonneoppervlak, rond de 5.200°. Dergelijke hitte is voldoende om ijzer te smelten, maar de enorme druk van de planeet zorgt ervoor dat de binnenkern vast blijft. De druk bedraagt ​​bijna 3,6 miljoen atmosfeer.

De kern roteert in dezelfde richting als het aardoppervlak, maar iets sneller, waardoor elk millennium een ​​volledige rotatie meer wordt bereikt. Tenminste, dat dachten wij, of dat was tot enkele jaren geleden zo. Nu heeft een nieuw onderzoek, uitgevoerd door het team van wetenschappers van de Universiteit van Zuid-Californië, aangetoond dat het hart van onze planeet zijn rotatie heeft vertraagd en dat het proces al in 2010 begon. Het onderzoek bevestigde dat nu dus de binnenkern langzamer roteert dan het aardoppervlak.

Waarom de binnenkern van de aarde langzamer beweegt

NASA (ADAPTED FROM GODDARD MEDIA STUDIOS)

De kwestie van de beweging van de kern is al twintig jaar omstreden: verschillende onderzoeken beweerden dat de rotatie van de kern groter was dan die van het aardoppervlak. De nieuwe studie bewijst echter onomstotelijk dat dit niet langer het geval is.

John Vidale, hoogleraar aardwetenschappen aan het USC Dornsife College of Letters, Arts and Sciences, zei: "Toen ik voor het eerst de seismogrammen zag die deze verandering suggereerden, was ik verbaasd, maar toen we nog twee dozijn waarnemingen vonden die op hetzelfde patroon wezen, was het resultaat onvermijdelijk. De binnenkern was voor het eerst in vele decennia vertraagd. Andere wetenschappers hebben onlangs soortgelijke en andere modellen beargumenteerd, maar onze laatste studie biedt de meest overtuigende resolutie.”

Maar waarom is de rotatie van de binnenkern van de aarde vertraagd? Wetenschappers denken dat dit fenomeen te wijten is aan de beweging van de aardmantel, die de afgelopen veertig jaar iets langzamer is geworden in plaats van andersom.

Seismische golven onthullen de beweging van de binnenkern

Deze vaste bol, omringd door zijn vloeibare buitenkern die ook uit ijzer en nikkel bestaat, ligt meer dan 4.800 km onder de grond en het is een echte uitdaging om hem te bereiken. Om de beweging ervan te begrijpen, zijn wetenschappers afhankelijk van seismische golven. Voor het nieuwe onderzoek maakten Vidale en Wei Wang van de Chinese Academie van Wetenschappen gebruik van de golven van herhaalde seismische gebeurtenissen, dat wil zeggen gebeurtenissen die in hetzelfde gebied plaatsvonden en identieke seismogrammen opleverden.

De onderzoekers kozen als locatie de Britse Zuidelijke Sandwicheilanden, waar zich tussen 1991 en 2023 121 seismische episodes voordeden. Met behulp van gegevens van kernproeven kwamen ze tot de conclusie dat de vertraging van de binnenkern werd veroorzaakt door de vermenging van de vloeibare buitenkern, die een groot deel van het magnetische veld van de aarde genereert, maar ook door de zwaartekracht van de rotsachtige mantel.

Voorlopig blijven de gevolgen voor het aardoppervlak pure theorie: Vidale schat dat deze verandering de duur van een dag met slechts een paar fracties van een seconde kan veranderen, dus onmerkbaar, maar toekomstig onderzoek zal meer duidelijkheid verschaffen over de kwestie en over waarom de kern zijn rotatie precies vertraagt.

{ https://www.curioctopus.nl/ }

25-06-2024 om 21:07 geschreven door peter  

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

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

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

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

Source : 

• Satellites to monitor marine debris from space

 { https://www.universetoday.com/ }

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

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

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

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

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

Source : 

• Satellites to monitor marine debris from space

 { https://www.universetoday.com/ }

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

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

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

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

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

Source : 

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

 { https://www.universetoday.com/ }

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

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

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

BY DORIS ELÍN URRUTIA

 

Xinhua News Agency/Xinhua News Agency/Getty Images

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

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

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

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

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

{ https://www.inverse.com/ }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

{ https://www.universetoday.com/ }

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

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

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

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

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

Source  : 

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

{ https://www.universetoday.com/ }

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

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

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

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

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

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

But there’s no certainty.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

So, what does this all boil down to?

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

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

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

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

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

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

{ https://www.universetoday.com/ }

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

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

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

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

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

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

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

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

Source : 

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

{ https://www.universetoday.com/ }

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

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

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

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

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

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

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

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

Image Credit: ESO/M. Kornmesser

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Bronmateriaal

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

{ https://scientias.nl/ }

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

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

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

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

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

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

Further Reading: 

• NASA

{ https://www.universetoday.com/ }

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

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

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

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

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

Source : 

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

{ https://www.universetoday.com/ }

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