'God of Destruction' asteroid Apophis will come to Earth in 2029 — and it could meet some tiny spacecraft

As to why Apophis is an apt target for a planetary defense study? Well, discovered in 2004, the asteroid quickly rose to the top of tables that measure the risk of so-called potentially hazardous asteroids (PHAs), or asteroids with widths of 460 feet (140 meters) or more that come within 20 lunar distances of Earth.

Both the size of Apophis and how close to Earth its trajectory brings it saw the asteroid remain at the top of both the European Space Agency's (ESA's) "impact risk list" of PHAs and NASA's Sentry Risk Table for 17 years. That was until a close flyby of the asteroid — a space rock that is almost as wide as the Empire State Building is tall — in March 2021 allowed NASA scientists to determine Apophis actually won't hit the Earth for at least 100 years. 

Though we now know Apophis won't collide with Earth in the next century, its scientific impact in 2029 will still be tremendous, and space agencies from countries across the globe will be closely tracking its trajectory.

Plus, as an asteroid that formed around the same time as the planets from leftover material around the infant sun, Apophis also offers researchers a unique opportunity to determine what the solar system's chemical composition was around 4.6 billion years ago

Meet the rendezvous candidates

Despite the fact that we are aware of around 1.3 million asteroids in the solar system, of which 2,500 are considered potentially hazardous (though none are expected to hit Earth for at least a century), spacecraft missions to study asteroids are relatively rare.

Thus far, only 20 missions have been deployed to study asteroids in situ, including the aforementioned OSIRIS-REx, Japan's Hayabusa1 and Hayabusa2 crafts, the ESA's Rosetta space probe, and the asteroid-hopping NASA mission Lucy, currently journeying to the Trojan asteroids that share their orbit with Jupiter.  Thus, the JMU team must carefully consider its options when considering a future asteroid-investigating spacecraft. 

The team's first concept is a small satellite that will join Apophis for a period of two months as it makes its close approach to Earth in April 2029. The craft will stick with the "God of Destruction" space rock for weeks after, even as it moves away. Over the course of the mission, this German national spacecraft will photograph Apophis and make measurements documenting any changes the NEA undergoes during its flyby.

This particular mission would be a challenging one because of its duration, the distance it will be required to travel, and the fact that the craft will have to function autonomously for long periods. It would also have to launch at least a year before Apophis arrives in Earth's vicinity.

The team's second concept involves integration with a larger spacecraft that's being planned by the ESA called RAMSES. This mission will be outfitted with smaller satellites, measuring equipment and telescopes. RAMSES, named after Egyptian pharaoh Ramesses the Great, would journey to Apophis and stay with the asteroid as it passes Earth.

If the second concept reaches fruition, one of the small satellites carried by RAMSES will be designed by the JMU team, with this project requiring less technical effort than the first concept while promising to reap greater scientific knowledge. 

One of the primary issues the second concept faces, however, has to do with getting REMESES off the ground — not literally, but figuratively. It's success will depend on the willingness of ESA partner countries to fund the mission. Again, a lead time of at least 365 days would be needed to ensure the success of this concept.

The third concept involves a small satellite that will only briefly fly past Apophis when the asteroid is at its absolute closest to Earth, snapping images of the asteroid in the process. This concept would require much less effort, and the craft would be relatively inexpensive.

The downside of concept 3, however, is that its observation time would be limited, which would also limit the volume of knowledge this mission would add to our understanding of asteroids.

On the plus side, the small-scale mission could launch just two days before Apophis arrives. Also, if concept 3 were to successfully observe Apophis, it would demonstrate the capability of small and inexpensive satellites in studying asteroids, perhaps leading to an increased interest for in situ asteroid-studying missions going forward.

The NEAlight project kicked off at the beginning of May 2024; between now and April 30, 2025, the JMU scientists will work out the requirements and specificities of the respective missions.

Beyond the visit of Apophis, the three concepts considered could remain options for future missions to other solar system planets, the moon — or maybe other intriguing NEAs.

Orbit of asteroid Apophis (pink) in contrast to the orbit of Earth (blue), from the years 2028 to 2030. The yellow dot represents the sun. Apophis takes 323.6 days to orbit the sun. Earth takes 365.3 days. Thus this asteroid is a fairly frequent visitor to our region of space.

Image via Phoenix7777/ Wikimedia Commons.

This animation shows the distance between the Apophis asteroid and Earth at the time of the asteroid’s closest approach in 2029. The blue dots are manmade satellites orbiting our planet, and the pink represents the International Space Station.

Image via NASA/ JPL-Caltech.

LINKS VIDEOS

• https://youtu.be/eOTH5SBVU00

• https://youtu.be/8MFh27Y9DTw

{ https://www.space.com/ }

15-05-2024 om 01:40 geschreven door peter  

Computersimulaties tonen nieuw bewijs

{ https://www.nu.nl/ }

14-05-2024 om 20:30 geschreven door peter  

History Of Ceres’s Young Cold Traps

Ceres, the largest asteroid in our Solar System, harbors a dark secret: Extremely young ice deposits in permanently shadowed craters near its poles. If that sounds vaguely familiar, it’s because our Moon and planet Mercury also have such polar ice deposits, which have been studied for decades.

“For Ceres, the story started in 2016, when the Dawn spacecraft, which orbited around Ceres at the time, glimpsed into these permanently dark craters and saw bright ice deposits in some of them,” said Norbert Schorghofer, lead author of “History of Ceres’s Cold Traps Based on Refined Shape Models”that appears in The Planetary Science Journal. PSI scientists Robert Gaskell and John Weirich, and NASA Goddard Space Flight Center Scientist Erwan Mazarico, are coauthors on the paper.

“The discovery back in 2016 posed a riddle: Many craters in the polar regions of Ceres remain shadowed all year – which on Ceres lasts 4.6 Earth years – and therefore remain frigidly cold, but only a few of them harbor ice deposits,” Schorghofer said. “Soon, another discovery provided a clue why: The rotation axis of Ceres oscillates back and forth every 24,000 years due to tides from the Sun and Jupiter. When the axis tilt is high and the seasons strong, only a few craters remain shadowed all year, and these are the craters that contain bright ice deposits.”

To determine how large shadows were inside of craters thousands of years ago, scientists construct digital elevation maps and then perform ray-tracing calculations with them to theoretically reconstruct the shadows cast on the crater floors. The results are only as reliable as the digital shape models on which they are based. Keep in mind that the floors of these craters are always in shadow, so it is not easy to measure how deep they are.

The Dawn spacecraft had a very sensitive camera, which could discern features on the shadowed crater floors. Stereo images of sunlit regions are often used to construct digital elevation maps of sunlit regions, but making an elevation map of shadowed terrain is a challenge that had rarely been taken on. As part of the new study, PSI scientist Robert Gaskell developed a new technique to reconstruct heights even in the shadowed portions of a stereo pair of images. These improved elevation maps can then be used for ray-tracing to predict the extent of cold, permanently shadowed regions.

These more accurate maps yielded a surprising result: When Ceres reaches its maximum axis tilt, which last occurred about 14,000 years ago, no crater on Ceres remains perennially shadowed and any ice in them must have quickly sublimated into space. “That leaves only one plausible explanation: The ice deposits must have formed more recently than that. The results suggest all of these ice deposits must have accumulated within the last 6,000 years or less. Considering that Ceres is well over 4 billion years old, that is a remarkably young age,” Schorghofer said.

Map of the north polar region of Ceres. The color areas are areas that are continuously shadowed over a Ceres year, and therefore very cold. The axis tilt (obliquity) of Ceres slowly changes over time and is currently 4 degrees, but ranged between 2 and 20 degrees over time. The color indicates the maximum obliquity at which a location is in shadow through an entire orbit.

Credit: Erwan Mazarico/GSFC.

“Ceres is an ice-rich object, but almost none of this ice is exposed on the surface. The aforementioned polar craters and a few small patches outside the polar regions are the only ice exposures. However, ice is ubiquitous at shallow depths – as discovered by PSI scientist Tom Prettyman and his team back in 2017 – so even a small dry impactor could vaporize some of that ice.” Schorghofer said. “A fragment of an asteroid may have collided with Ceres about 6,000 years ago, which created a temporary water atmosphere. Once a water atmosphere is generated, ice would condense in the cold polar craters, forming the bright deposits that we still see today. Alternatively, the ice deposits could have formed by avalanches of ice-rich material. This ice would then survive in only the cold shadowed craters. Either way, these events were very recent on an astronomical time scale.”

The study also looked into the possibility that other types of ices, other than water ice, might be trapped in these unusual craters on Ceres. On our Moon, portions of polar craters are so cold that even CO2 ice and a few other chemical species could last in them for billions of years. Ceres is farther from the Sun, so its polar craters could be expected to be even colder than the Moon’s.

Schorghofer calculated temperatures inside Ceres’s polar craters, something that had never been done before. The answer was surprising: although these craters are cold enough to retain water ice, they are too warm to retain other common types of ice. Two circumstances contribute to this. First, the axis tilt of Ceres, currently 4 degrees, is higher than the Moon’s 1.5 degree tilt, so more of the crater rims are sunlit and more light is scattered onto the crater floor. Second, Ceres simply has no perennially shadowed craters very near the north pole, unlike the Moon, where one crater sits almost exactly on the south pole. For these reasons, temperatures are not as low on Ceres than they are on parts of the lunar surface.

The study describes the new method used to reconstruct topography using stereo images of shadowed craters, provides a new map of perennially shadowed regions for the entire north polar region of Ceres, determines the extent of perennially shadowed regions inside polar craters with bright ice deposits, and estimates the temperatures for the interior of these craters. “Whatever the history of these ice deposits, it resulted from events not much older than human civilization,” Schorghofer said.

This work was funded by a grant from NASA’s Discover Data Analysis Program to PSI (80NSSC21K1033).

Images of two craters in the north polar region of Ceres captured by the Dawn spacecraft. The shadowed regions contain bright ice deposits, whereas sunlit regions appear saturated (white) in these contrast-stretched images. The superimposed color contours represent the extent of the area that is in shadow over the entire Cerean year for different values of the axis tilt. The current axis tilt is 4 degrees (yellow contour). The bright ice deposits must have accumulated at an axis tilt of 10 degrees or less (orange contour), which last occurred 6,000 years ago.

Credit: Norbert Schorghofer/PSI.

THE PLANETARY SCIENCE INSTITUTE:

The Planetary Science Institute is a private, nonprofit 501(c)(3) corporation dedicated to Solar System exploration. It is headquartered in Tucson, Arizona, where it was founded in 1972.

PSI scientists are involved in numerous NASA and international missions, the study of Mars and other planets, the Moon, asteroids, comets, interplanetary dust, impact physics, the origin of the Solar System, extra-solar planet formation, dynamics, the rise of life, and other areas of research. They conduct fieldwork on all continents around the world. They also are actively involved in science education and public outreach through school programs, children’s books, popular science books and art.

PSI scientists are based in 35 states and the District of Columbia.

{ https://astrobiology.com/ }

14-05-2024 om 20:21 geschreven door peter  

Planetary Scientists Create Map of Ceres’ Cold Traps

The dwarf planet Ceres hosts permanently shadowed areas in its polar regions, and these regions are an interesting analog to Mercury and the Moon. Ceres’ permanently shadowed regions were mapped by NASA’s Dawn spacecraft, and, thanks to scattered sunlight, bright deposits were discovered in a fraction of the permanently shadowed regions. To arrive at a clearer understanding of the nature of cold-trapped ice deposits on Ceres, researchers from the Planetary Science Institute and NASA’s Goddard Space Flight Center constructed improved shape models of permanently shadowed region-hosting craters.

Permanently shadowed regions in the north polar region of Ceres; the color indicates the maximum obliquity at which a location is in shadow through an entire orbit.

Image credit: Schorghofer et al., doi: 10.3847/PSJ/ad3639.

“For Ceres, the story started in 2016, when the Dawn spacecraft, which orbited around Ceres at the time, glimpsed into these permanently dark craters and saw bright ice deposits in some of them,” said lead author Dr. Norbert Schorghofer, a researcher at the Planetary Science Institute.

“The discovery back in 2016 posed a riddle: many craters in the polar regions of Ceres remain shadowed all year — which on Ceres lasts 4.6 Earth years — and therefore remain frigidly cold, but only a few of them harbor ice deposits.”

“Soon, another discovery provided a clue why: the rotation axis of Ceres oscillates back and forth every 24,000 years due to tides from the Sun and Jupiter.”

“When the axis tilt is high and the seasons strong, only a few craters remain shadowed all year, and these are the craters that contain bright ice deposits.”

To determine how large shadows were inside of craters thousands of years ago, scientists construct digital elevation maps and then perform ray-tracing calculations with them to theoretically reconstruct the shadows cast on the crater floors.

The results are only as reliable as the digital shape models on which they are based. Keep in mind that the floors of these craters are always in shadow, so it is not easy to measure how deep they are.

NASA’s Dawn spacecraft had a very sensitive camera, which could discern features on the shadowed crater floors.

Stereo images of sunlit regions are often used to construct digital elevation maps of sunlit regions, but making an elevation map of shadowed terrain is a challenge that had rarely been taken on.

As part of their study, the authors developed a new technique to reconstruct heights even in the shadowed portions of a stereo pair of images.

These improved elevation maps can then be used for ray-tracing to predict the extent of cold, permanently shadowed regions.

These more accurate maps yielded a surprising result: when Ceres reaches its maximum axis tilt, which last occurred about 14,000 years ago, no crater on Ceres remains perennially shadowed and any ice in them must have quickly sublimated into space.

“That leaves only one plausible explanation: the ice deposits must have formed more recently than that,” Dr. Schorghofer said.

“The results suggest all of these ice deposits must have accumulated within the last 6,000 years or less.”

“Considering that Ceres is well over 4 billion years old, that is a remarkably young age.”

“Ceres is an ice-rich object, but almost none of this ice is exposed on the surface. The aforementioned polar craters and a few small patches outside the polar regions are the only ice exposures. However, ice is ubiquitous at shallow depths, so even a small dry impactor could vaporize some of that ice.”

“A fragment of an asteroid may have collided with Ceres about 6,000 years ago, which created a temporary water atmosphere.”

“Once a water atmosphere is generated, ice would condense in the cold polar craters, forming the bright deposits that we still see today.”

“Alternatively, the ice deposits could have formed by avalanches of ice-rich material. This ice would then survive in only the cold shadowed craters.”

“Either way, these events were very recent on an astronomical time scale.”

The researchers also looked into the possibility that other types of ices, other than water ice, might be trapped in these unusual craters on Ceres.

On our Moon, portions of polar craters are so cold that even carbon dioxide ice and a few other chemical species could last in them for billions of years.

Ceres is farther from the Sun, so its polar craters could be expected to be even colder than the Moon’s.

The scientists calculated temperatures inside Ceres’ polar craters, something that had never been done before.

The answer was surprising: although these craters are cold enough to retain water ice, they are too warm to retain other common types of ice. Two circumstances contribute to this.

First, the axis tilt of Ceres, currently 4 degrees, is higher than the Moon’s 1.5 degree tilt, so more of the crater rims are sunlit and more light is scattered onto the crater floor.

Second, Ceres simply has no perennially shadowed craters very near the north pole, unlike the Moon, where one crater sits almost exactly on the south pole.

For these reasons, temperatures are not as low on Ceres than they are on parts of the lunar surface.

“Whatever the history of the ice deposits, it resulted from events not much older than human civilization,” Dr. Schorghofer said.

• The findings appear in the Planetary Science Journal.
• Norbert Schorghofer et al. 2024. History of Ceres’s Cold Traps Based on Refined Shape Models. Planet. Sci. J 5 (99); doi: 10.3847/PSJ/ad3639

{ https://www.sci.news/ }

14-05-2024 om 18:42 geschreven door peter  

Ancient Lake On Mars Was Hospitable Enough To Support Life

The Gale Crater site once flowed with rivers ending in a lake

WRITTEN BY Amanda Doyle

SOURC Eastrobio.net

An up-close view of Mars’ rocky deposits by NASA’s Curiosity rover shows a changing climate in the planet’s ancient past that would have left the surface warm and humid enough to support liquid water — and possibly life. Evidence of an ancient lake points to the prospect of two unique habitats within its shores; the lower part of the lake was devoid of oxygen compared to an oxygen-rich upper half.

In a recent paper published in the journal Science, “Redox stratification of an ancient lake in Gale crater,” Stony Brook University geoscientist Joel Hurowitz and his colleagues used more than three years of data retrieved from the rover to paint a picture of ancient conditions at Gale Crater, the lowest point in a thousand kilometers. The site, a 150-mile kilometer crater formed during an impact around 3.8 billion years ago, once flowed with rivers ending in a lake. The sedimentary rocks laid down by these rivers and onto the lakebed tell the story of how the environment changed over time.

Curiosity landed on rocks known as the Bradbury group. The Murray formation consist of younger rocks at the base of Mount Sharp. The height is exaggerated in the diagram.

IMAGE CREDIT: NASA/JPL-CALTECH.

Curiosity landed on a group of sedimentary rocks known as the Bradbury group. The rover sampled a part of this group called the Sheepbed mudstones, as well as rocks from the Murray formation at the base of the 5-kilometer high peak at the center of the crater known as Mount Sharp. Both types of rocks were deposited in the ancient lake, but the Sheepbed rocks are older and occur lower in the stratigraphic layers of rocks. Comparing the two types of rocks can lead to interesting revelations about the paleoenvironment.

Rocks that form at the same time in the same area can nevertheless display differences in composition and other characteristics. These different groupings are known as “facies” and the Murray formation is split into two facies. One is comprised mainly of hematite and phyllosilicate, and given the name HP, while the other is the magnetite-silicate facies, known as MS.

“The two Murray facies were probably laid down at about the same time within different parts of the lake,” explained Hurowitz. “The former laid down in shallow water, and the latter in deeper water.”

The near-shore HP facies have thicker layers in the rocks compared to the thin layers of the deeper water MS facies. This difference in layer thickness is because the river flowing into the lake would have slowed down and dumped some of its sedimentary material at the lake shore. The flow would then have spread into the lake and dropped finer material into the deeper parts of the lake. .

The different mineralogy of the two facies was caused by the lake becoming separated into two layers. Ultraviolet (UV) radiation along with low levels of atmospheric oxygen penetrated the upper part of the lake and acted as oxidants on molecules in the water. These ions of iron (Fe²⁺) and manganese (Mn²⁺) were brought to the lake via seepage of groundwater through the lake floor.

An illustration showing how the lake in the crater might have looked.

IMAGE CREDIT: NASA/JPL-CALTECH/ESA/DLR/FU BERLIN/MSSS.

When the UV and oxygen interacted with these, they lost electrons, meaning that they had become “oxidized.” The oxidized iron and manganese precipitated into minerals — hematite and manganese oxide — that eventually made up the rocks sampled by Curiosity in the HP facies. However, the UV and oxygen didn’t reach all the way to the lake floor, so the iron and manganese wasn’t oxidized in the deeper part of the lake, and instead became the mineral known as magnetite, making up the MS facies.

The difference in oxidation of the two facies in the Murray formation due to differences in layers of the lake is known as redox stratification. Identifying redox stratification in the ancient lake shows that there were two completely different types of potential habitat available to any microbial life that might have been present.

The researchers also discovered that the Murray formation has a high concentration of salts, which provide clues relating to evaporation of the lake, and thus the end of the potential habitat. High salinity is a result of water evaporating and leaving salts behind. However, evaporation leaves other tell-tale signs such as desiccation cracks — similar to what you see when mud dries and cracks — and none of these signs appear in the Murray formation. This indicates that the evaporation occurred at a later period of time and that the salts seeped through layers overlying the Murray formation before becoming deposited in the Mursaid Hurowitz. “In fact, that’s exactly what the rover is doing as we speak at the area known as Vera Rubin Ridge.”

Once Curiosity examines these rocks, it will be able to confirm that the salts found in the Murray formation came from a later period of evaporation, and therefore no significant evaporation occurred during the time that the Murray formation was deposited, meaning the environment would have been stable enough to support possible life forms.

Another result of the research is evidence of climate change. The older Sheepbed formation shows very little evidence of chemical weathering coray rocks.

“Curiosity will definitely be able to examine the rocks higher up in the stratigraphy to determine if lake evaporation influenced the rocks deposited in it,” mpared to the Murray formation. The change to substantial chemical weathering in the younger rocks indicates that the climate likely changed from cold, arid conditions to a warm, wet one.

Thicker material (clastics) are close to the shore. Finer material is towards the deeper part of the lake. UV and O₂ oxidize iron and manganese, creating what is known as redox stratification. This is reflected in the mineralogy.

IMAGE CREDIT: HUROWITZ ET AL. (2017). SCIENCE..

“The timing of this climate shift is not something we can tell for sure because we haven’t seen the Sheepbed member and the Murray formation in contact with each other,” said Hurowitz. “If we had, then we might be able to tell if the change in their chemical and mineralogical properties were abrupt (indicating rapid climate change) or gradual. At best, what we can say is that the rocks that we examined were likely deposited over a timespan of tens of thousands of years to as much as around 10 million years.”

The cause of the climate change on Mars is still a matter of debate. If the climate changed in a short period of time, it could have been due to short-term variations or an asteroid impact. A slower change in climate could have been the result of changes in the obliquity cycle of the planet.

The climate change indicated in the rocks shows that the ancient Martian environment would have been warm and humid enough to sustain liquid water on the surface. The redox stratification of the lake as revealed by the different mineralogy in the Murray formation shows that there would have been two different environments within the lake itself. If microbial life was present on Mars at this time, the different potentially habitable niches could have encouraged diversity with anaerobic forms possibly living in the lower depths of the lake.

“I’m not sure that this was something we would have predicted if we hadn’t had the opportunity to examine

Curiosity Rover's Self Portrait at 'John Klein' Drilling Site.

IMAGE CREDIT: NASA/JPL-CALTECH/MSSS.

The Astrobiology Program was involved in all stages of the MSL mission. This included the development of instruments onboard the Curiosity rover, including Sample Analysis at Mars (SAM) and Chemistry & Mineralogy (CheMin).

The Astrobiology Program currently supports researchers involved in Curiosity mission operations and analysis of data from the rover.

{ https://astrobiology.nasa.gov/ }

14-05-2024 om 15:08 geschreven door peter  

I can remember when Perseverance was launched, travelled out into the Solar System and landed on Mars in February 2021.  In all the time since it arrived, having clocked up 1000 days of exploration, it has collected 23 samples from different geological areas within the Jezero Crater. The area was once home to an ancient lake and if there is anywhere on Mars to find evidence of ancient (fossilised) life, it is here. 

The date was 30 July 2020 when a gigantic Atlas V-541 rocket roared off the launchpad from Cape Canaveral in Florida. On board was the Perseverance rover, on its way to Mars. It arrived around 7 months later, entered the Martian atmosphere and successfully landed using a complex sequence of parachutes, retrorockets and for the first time, a sky crane to lower it from a hovering platform. Its chief purpose on Mars was to explore the geology, climate and atmospheric conditions as a precursor to human exploration. 

The landing site, the Jezero Crater, was chosen because previous orbital studies revealed clear evidence of an ancient lake that once filled the crater. It is thought that water is a key ingredient to the evolution of life so if there had been a body of water, then there is a greater chance of life evolving. Studying the rocks here is like taking a flick through the history books as it preserves signs of ancient life and also ancient environmental conditions. 

The crater had been formed, like the majority of other craters in the Solar System from some form of impact event. In the case of Jezero it was an asteroid impact around 4 billion years ago. On its arrival at the crater the floor was soon discovered to be made of igneous rock, formed from a huge underground chamber of magma and bought to the surface through volcanic activity. Since then, other types of rock from sand and mud were found providing evidence of the presence of water in Mars’ distant past. 

By the time Perseverance had hit the 1000 day anniversary of its exploration of the red planet it had collected the rock samples, safely packaged them up ready for collection and by and large, completed its exploration of the ancient lake bed. One sample in particular which has been called ‘Lefroy Bay’ has been found to contain fine grained silica. This material is commonly found on Earth and known to preserve fossils. Another of the samples contains phosphate which, on Earth is most definitely associated with biological processes. Both of these contain carbon which can be used to study the environmental conditions from when the rock formed. 

Jezero crater is a big place, 45 kilometres across so deciding on where to collect the samples was challenging. When a target site had been identified, Perseverance would first use its abrasion tool to wear away the surface and then use the onboard instruments such as PIXL, the Planetary Instrument for X-ray Lithochemistry. The instruments on board have the ability to detect both microscopic, fossil-like structures and also to identify chemical changes left behind by ancient microbes. Alas to date, whilst Perseverance has achieved an amazing amount, the detection of signs of life have alluded the rover. 

Source : 

• NASA’s Perseverance Rover Deciphers Ancient History of Martian Lake

{ https://www.universetoday.com/ }

14-05-2024 om 14:56 geschreven door peter  

The suit also has redundancy features, such as additional seals and pressure valves to help ensure the suit remains pressurized during EVAs. The new 3D-printed helmet incorporates a new visor that reduces glare and features a camera and a new Heads-Up Display (HUD) that monitors conditions inside the suit. These suits will make their debut during the first of three Polaris missions – Polaris Dawn – scheduled to take place this summer (at the earliest). This mission will be commanded by Isaacman and will see a Crew Dragon launched from Launch Complex 39A atop a Falcon 9 rocket. The crew will spend five days in orbit and attempt to reach the highest Earth orbit ever flown.

During their time in space, the Polaris Dawn crew will conduct the first commercial spacewalk (and the first EVA where four astronauts were in space simultaneously) and be the first to test the Starlink laser-based communication system in space. The crew will also conduct scientific research in collaboration with the Translational Research Institute for Space Health (TRISH), BioServe Space Technologies, Space Technologies Lab, Weill Cornell Medicine, the Johns Hopkins University Applied Physics Laboratory (JHUAPL), the Pacific Northwest National Laboratory, and the U.S. Air Force Academy.

These efforts are designed to advance our understanding of human health during long-duration spaceflights, with applications for health here on Earth. According to the company website, these research activities will include:

• Using ultrasound to monitor, detect, and quantify venous gas emboli (VGE), contributing to studies on human prevalence to decompression sickness;
• Gathering data on the radiation environment to better understand how space radiation affects human biological systems;
• Providing biological samples towards multi-omics analyses for a long-term Biobank; and
• Research related to Spaceflight Associated Neuro-Ocular Syndrome (SANS), which is a key risk to human health in long-duration spaceflight.

Polaris Dawn will be followed up by a second mission (Polaris II, the date of which is TBD) that will attempt to build upon these objectives. The third mission (Polaris III) will be the first human spaceflight involving the Starship and Super Heavy launch vehicle. But as is made clear in the company’s statement, the suits are intended to fulfill SpaceX’s long-term goals:

“While Polaris Dawn will be the first time the SpaceX EVA suit is used in low-Earth orbit, the suit’s ultimate destiny lies much farther from our home planet. Building a base on the Moon and a city on Mars will require the development of a scalable design for the millions of spacesuits required to help make life multiplanetary.”

Further Reading: 

• SpaceX, 
• Polaris Program

{ https://www.universetoday.com/ }

14-05-2024 om 14:43 geschreven door peter  

“Watches at this level are very rare,” the SWPC said in an advisory on Saturday.

Let’s take a look at the incredible views of our readers and friends, many shared on Universe Today’s Flickr page. Our lead image comes from Julien Looten, who took this photo at the cliffs of Étretat in northern France. Looten said, “These auroras began to be visible around 10:30 PM, even before nightfall… From then on, they were visible to the naked eye until dawn… Without interruption…”

{ https://www.universetoday.com/ }

14-05-2024 om 14:18 geschreven door peter  

Hundreds of alleged UFOs were spotted in the skies of southern Norway by a man trying to observe the Northern Lights phenomenon, but instead witnessed what he believes were 'dancing orbs'

By Ewan Gleadow - News Reporter

Possible UFO sightings were made in south Norway (file) 

(Image: Getty Images)

Regardless of what the lights represented, viewers were left stunned by one of "the coolest videos" they had ever seen. One user wrote the video was "super neat" and another said it was "beautiful".

Others questioned whether user CrayRazy had captured evidence of life from other planets. He wrote: "Saw this tonight in the south of Norway. At first I thought it was light beams from a festival but I live in a tiny city and that cloud is either over mountains, a lake or just a residential area.

"Really confused to what this could be. Any ideas?" Other users were left wondering if the lights in the sky were the recent sightings of aurora borealis, but one pointed out: "Aurora borealis is way higher up."

Another wrote: "UFOs are popping up for this storm. I saw one here". A third added: "I don't know, looks like a lot of shiny orbs. There seems to be a lot of UFO activity around this solar event!"

One said: "We are having a solar storm. The whole northern hemisphere is capable of seeing the aurora borealis." The original poster replied: "That's why I went outside but that doesn't look like the northern lights at all."

While a definitive answer was unavailable on what had caused the hundreds of tiny orbs to appear, some were adamant it was not UFOs and just a collection of northern lights sightings. But that's what they want you to think.

{ https://www.dailystar.co.uk/ }

12-05-2024 om 22:20 geschreven door peter  

There’s something poetic about humanity’s attempt to detect other civilizations somewhere in the Milky Way’s expanse. There’s also something futile about it. But we’re not going to stop. There’s little doubt about that.

One group of scientists thinks that we may already have detected technosignatures from a technological civilization’s Dyson Spheres, but the detection is hidden in our vast troves of astronomical data.

A Dyson Sphere is a hypothetical engineering project that only highly advanced civilizations could build. In this sense, ‘advance’ means the kind of almost unimaginable technological prowess that would allow a civilization to build a structure around an entire star. These Dyson Spheres would allow a civilization to harness all of a star’s energy.

A Civilization could only build something so massive and complex if they had reached Level II in the Kardashev Scale. Dyson Spheres could be a technosignature, and a team of researchers from Sweden, India, the UK, and the USA developed a way to search for Dyson Sphere technosignatures they’re calling Project Hephaistos. (Hephaistos was the Greek god of fire and metallurgy.)

They’re publishing their results in the Monthly Notices of the Royal Academy of Sciences. The research is titled “Project Hephaistos – II. Dyson sphere candidates from Gaia DR3, 2MASS, and WISE.” The lead author is Matías Suazo, a PhD student in the Department of Physics and Astronomy at Uppsala University in Sweden. This is the second paper presenting Project Hephaistos. The first one is here.

“In this study, we present a comprehensive search for partial Dyson spheres by analyzing optical and
infrared observations from Gaia, 2MASS, and WISE,” the authors write. These are large-scale astronomical surveys designed for different purposes. Each one of them generated an enormous amount of data from individual stars. “This second paper examines the Gaia DR3, 2MASS, and WISE photometry of ~5 million sources to build a catalogue of potential Dyson spheres,” they explain.

Combing through all of that data is an arduous task. In this work, the team of researchers developed a special data pipeline to work its way through the combined data of all three surveys. They point out that they’re searching for partially-completed spheres, which would emit excess infrared radiation. “This structure would emit waste heat in the form of mid-infrared radiation that, in addition to the level of completion of the structure, would depend on its effective temperature,” Suazo and his colleagues write.

The problem is, they’re not the only objects to do so. Many natural objects do, too, like circumstellar dust rings and nebulae. Background galaxies can also emit excess infrared radiation and create false positives. It’s the pipeline’s job to filter them out. “A specialized pipeline has been developed to identify potential Dyson sphere candidates focusing on detecting sources that display anomalous infrared excesses that cannot be attributed to any known natural source of such radiation,” the researchers explain.

This flowchart shows what the pipeline looks like.

The pipeline is just the first step. The team subjects the list of candidates to further scrutiny based on factors like H-alpha emissions, optical variability, and astrometry.

368 sources survived the last cut. Of those, 328 were rejected as blends, 29 were rejected as irregulars, and 4 were rejected as nebulars. That left only 7 potential Dyson Spheres out of about 5 million initial objects, and the researchers are confident that those 7 are legitimate. “All sources are clear mid-infrared emitters with no clear contaminators or signatures that indicate an obvious mid-infrared origin,” they explain.

These are the seven strongest candidates, but the researchers know they’re still just candidates. There could be other reasons why the seven are emitting excess infrared. “The presence of warm debris disks surrounding our candidates remains a plausible explanation for the infrared excess of our sources,” they explain.

But their candidates seem to be M-type (red dwarf) stars, and debris disks around M-dwarfs are very rare. However, it gets complicated because some research suggests that debris disks around M-dwarfs form differently and present differently. One type of debris disk called Extreme Debris Disks (EDD) can explain some of the luminosity the team sees around their candidates. “But these sources have never been observed in connection with M dwarfs,” Suazo and his co-authors write.

That leaves the team with three questions: “Are our candidates strange young stars whose flux does not vary with time? Are these stars’ M-dwarf debris disks with an extreme fractional luminosity? Or something completely different?”

“After analyzing the optical/NIR/MIR photometry of ~5 x 10⁶ sources, we found 7 apparent M dwarfs exhibiting an infrared excess of unclear nature that is compatible with our Dyson sphere models,” the researchers write in their conclusion. There are natural explanations for the excess infrared coming from these 7, “But none of them clearly explains such a phenomenon in the candidates, especially given that all are M dwarfs.”

The researchers say that follow-up optical spectroscopy would help understand these 7 sources better. A better understanding of the H-alpha emissions is especially valuable since they can also come from young disks. “In particular, analyzing the spectral region around H-alpha can help us ultimately discard or verify the presence of young disks,” the researchers write.

“Additional analyses are definitely necessary to unveil the true nature of these sources,” they conclude.

{ https://www.universetoday.com/ }

12-05-2024 om 18:37 geschreven door peter  

Near-Collapse of Geomagnetic Field May Have Contributed to Diversification of Life on Earth

An ultra-weak geomagnetic field between 591 and 565 million years ago (Ediacaran period) coincided with a significant increase in the oxygen levels in the atmosphere and oceans, says a research team led by University of Rochester geoscientists.

Earth’s magnetic field was in a highly unusual state when macroscopic animals of the Ediacara Fauna diversified and thrived.

Image credit: NASA.

Between 600 and 540 million years ago, life on Earth consisted of soft-bodied organisms known as the Ediacaran Fauna, the earliest known complex multicellular animals.

The fossil record shows that these organisms significantly diversified in complexity and type between 575 and 565 million years ago

Previous research has suggested that this diversification is linked to a significant increase in atmospheric and oceanic oxygen levels that occurred over the same period.

However, it is not yet clear why this increase in oxygen occurred.

In the new study, University of Rochester’s Professor John Tarduno and colleagues analyzed the magnetic properties of 21 plagioclase crystals, a common mineral in Earth’s crust, which were extracted from a 591-million-year-old rock formation in Brazil.

Plagioclase crystals contain tiny magnetic minerals which preserve the intensity of the Earth’s magnetic field at the time they are formed.

An analysis of the crystals showed that, at their point of formation, the Earth’s magnetic field was the weakest ever recorded — some 30 times weaker than both the current magnetic field intensity, and that measured from similar crystals formed approximately two billion years ago.

The scientists combined their results with previous measurements to establish that the Earth’s magnetic field was at this weak level for at least 26 million years, from 591 to 565 million years ago.

This overlaps with the rise in oxygen, which occurred between 575 and 565 million years ago.

“The weakened magnetic field may have allowed more hydrogen to escape to space, resulting in a greater percentage of oxygen in Earth’s atmosphere and oceans, which may in turn have supported the diversification in the types and complexity of organisms,” the authors concluded.

• The findings were published in the journal Communications Earth & Environment.
• W. Huang et al. 2024. Near-collapse of the geomagnetic field may have contributed to atmospheric oxygenation and animal radiation in the Ediacaran period. Commun Earth Environ 5, 207; doi: 10.1038/s43247-024-01360-4

{ https://www.sci.news/ }

12-05-2024 om 00:49 geschreven door peter  

Krachtige zonne-explosies hebben een sterke impact op de aarde: wat zou er kunnen gebeuren?

 Door Janine

De krachtige uitbarstingen die op onze moederster exploderen, hebben een sterke impact op de aarde en lijken niet te stoppen. Dit is wat er gebeurt.

Wat zijn zonnevlammen?

SPACE WEATHER PREDICTION CENTER

Een zonnevlam, zo meldt NASA, is "een intense uitbarsting van straling door het vrijkomen van magnetische energie die gepaard gaat met zonnevlekken". Dit zijn, legt de Amerikaanse ruimtevaartorganisatie uit, de grootste explosieve gebeurtenissen in ons zonnestelsel. Ze manifesteren zich als heldere gebieden op de zon die enkele minuten tot enkele uren zichtbaar zijn.

Wat ons in staat stelt om ze te detecteren is het licht, dus de fotonen, die vrijkomen en die worden gecontroleerd door optisch licht en röntgenstraling. In zonnevlammen worden de zwaarste deeltjes versneld. De afgelopen dagen zijn zonnevlammen in volle actie: X1.6 vond plaats op 3 mei, gevolgd door andere krachtige fenomenen volgens het Space Weather Prediction Center van NOAA. Elk van deze fenomenen heeft een grote impact gehad op onze planeet.

De gevolgen van krachtige zonnevlammen op aarde

Een X1.3 en een X1.2 zonnevlam barstten op 5 mei los uit de actieve groep zonnevlekken AR 3663. In beide gevallen traden radio blackouts op op onze planeet, in Japan, Australië en grote delen van China, en de effecten zouden langer kunnen duren als coronale massa uitstoot, enorme wolken van zonneplasma doordrenkt met magnetische veldlijnen, geladen deeltjes naar de aarde zouden leiden.

Hierover zijn echter geen zekere gegevens bekend. Er zijn momenteel negen clusters zonnevlekken aanwezig aan de kant van de zon die naar onze planeet is gericht, die ongeveer 150 zonnevlekken omvatten. AR 3663 is op dit moment in ieder geval het meest actief en heeft sinds 30 april meerdere M-klasse en vier X-klasse vlammen uitgezonden, waarmee hij op de tweede plaats staat van de sterkste vlammen die onze ster kan produceren.

Maar wat zijn de voorspellingen van de wetenschappers en wat kunnen we verwachten? Volgens de voorspellers zullen er meer M-klasse vlammen zijn en mogelijk nog een of meer X-klasse vlammen voordat ze buiten de baan van de aarde draaien.

Keith Strong, een zonnefysicus, schreef in een bericht op X, voorheen Twitter: “Het gebied van zonnevlekken AR3663 produceerde een X4.5 vlam, de op twee na grootste sinds het begin van zonnecyclus 25 (4,3 jaar geleden)." Hij voegde eraan toe dat de vlam een sterke black-out veroorzaakte in een groot deel van Azië, Oost-Afrika en Oost-Europa. "Als het een coronale massa uitstoot produceerde, zal deze waarschijnlijk binnen een dag of twee de aarde raken."

Geomagnetische storm op komst? Er is iets positiefs aan

SDO | Solar Dynamics Observatory NASA

Zonnevlammen gaan soms gepaard met uitbarstingen die de aarde met een paar dagen vertraging kunnen bereiken, omdat plasma zich minder snel verplaatst dan licht. Op het moment dat de coronale massa uitstoot ons bereikt, ontstaat er echter een geomagnetische storm met aanzienlijke gevolgen voor de communicatie. Op het moment dat het de magnetosfeer van de planeet raakt, ontstaan er elektrische stromen die door elektriciteitsnetwerken kunnen reizen, stroomuitval kunnen veroorzaken en satellieten, radio- en navigatiesignalen kunnen beïnvloeden.

Maar er is ook een positief aspect: de wisselwerking tussen zonnedeeltjes, de magnetosfeer en de atmosfeer van de aarde leidt tot een opvallend poollicht boven de polen van de aarde, dat alleen 's nachts zichtbaar is, wanneer er geen zonlicht is. In elk geval zullen de volgende uitbarstingen kleine gevolgen hebben, omdat AR 3663 van de baan van de aarde af draait, maar de zon zit midden in haar activiteitscyclus, haar piek vindt om de elf jaar plaats en kan ons nog meer “verrassingen” bezorgen.

{ https://www.curioctopus.nl/ }

12-05-2024 om 00:31 geschreven door peter  

The sun appears to be angry; a massive coronal mass ejection unveils a striking image resembling a grimacing demonic face. Striking are the letters DV (DeVil?) standing out on the forehead of the figure. 

Obviously, the strange phenomenon captured by NASA's solar satellite SOLO EUI HRI 174 on 2024/05/11 is an ordinary natural occurrence triggered by the eruption of solar material but a fact is that a huge CME hit Earth's magnetic field on May 10th, leading up to the biggest geomagnetic storm in almost 20 year. 

And it is not yet over as forecasts predict additional coronal mass ejections to follow closely behind, prolonging the storm well into the weekend. Anticipation mounts for widespread auroras, promising captivating displays over regions like Europa and the United States. 

The storm has now reached level G5 which is the strongest level of geomagnetic storm, on a scale from G1 to G5. The solar storm could lead to disruption of satellite communication systems, low-frequency radio navigation systems such as GPS or even widespread power grid failures. 

This unique solar phenomenon emphasizes once more the importance of constant monitoring and readiness in response to solar disruptions in order to prevent another Carrington event which was the most intense geomagnetic storm in recorded history, peaking from 1–2 September 1859.

  

{ https://ufosightingshotspot.blogspot.com/ }

12-05-2024 om 00:18 geschreven door peter  

Cassini Observations Suggest Underground Ocean on Titan

Titan, the largest moon of Saturn, harbors an internal low-density ocean of water or ammonia, according to an analysis of archival data from NASA’s Cassini mission.

Representation of Cassini’s orbits used to calculate Titan’s gravity; the colored part of the orbits shows the distance from Cassini to Titan with the smallest distance in red; the cross-section of Titan shows the moon’s different layers with the ocean in blue; Saturn with rings and ring shadows can be seen in the background.

Image credit: Britt Griswold, NASA’s Goddard Space Flight Center.

“Liquid water is one of the prerequisites for the emergence of life,” said Dr. Sander Goossens from NASA’s Goddard Space Flight Center and colleagues.

“Water is rarely liquid on the surface of a planet, but a number of moons in our Solar System, such as Titan, contain underground oceans.”

“These probably formed long ago, which raises the question of why they are not yet frozen in the cold environment far from the Sun.”

“Our study supports the explanation that ammonia extended the life of the liquid ocean in Titan. In addition, it provides insight into Titan’s deeper layers.”

NASA’s Cassini mission explored Saturn and its icy moons for more than a decade.

Among its many instruments, Cassini carried a radio science subsystem that enabled Earth-based radiometric tracking of the spacecraft by the Deep Space Network.

These data were used to determine the gravity field and interior structure of several of Saturn’s moons as well as those of Saturn itself. Cassini data were also used to determine Titan’s tidal response.

“The Cassini space mission flew around Saturn between 2005 and 2017,” the researchers said.

“To precisely measure Titan’s gravity, the spacecraft was sent close to the moon several times.”

“Cassini had to skim past Titan at exactly the right time to properly map the change in gravity.”

“This is because Titan’s deformation is due to Saturn’s tidal force, which depends on the distance between Titan and Saturn.”

“By measuring at times when Titan is close and far away from Saturn, the difference in Titan’s deformation and thus its effect on gravity was maximum.”

From precise radar measurements, the scientists calculated Cassini’s velocity and then the change in gravity and Titan’s deformation associated with it.

They carefully examined the effect of tides on Titan at each location in the spacecraft’s orbit and concluded that the deformation is smaller than previously calculated.

Numerical simulations of the moon’s deformation for different internal structures show that the most likely scenario is that the ocean has a density similar to that of water with a small proportion of ammonia.

“An underground ocean can help transport organic material from a moon’s rock core to the surface,” the authors said.

“For Titan, it was assumed that a thick ice layer between the ocean and the core made this difficult.”

“Our analysis suggests that the ice layer is possibly thinner than previously thought, making exchange of material between rock and the ocean more plausible.”

“The organic molecules that this can produce are seen as important ingredients for the emergence of life.”

• The study was published in the journal Nature Astronomy.
• S. Goossens et al. A low-density ocean inside Titan inferred from Cassini data. Nat Astron, published online March 21, 2024; doi: 10.1038/s41550-024-02253-4

{ https://www.sci.news/ }

10-05-2024 om 23:20 geschreven door peter  

Look! This Strange Cosmic Cloud Looks Like a Dinosaur

This striking image of CG4 was captured by a telescope instrument originally built to study dark energy.

BY KIONA SMITH

 

NOIRLab

This strange cosmic cloud is called “the hand of God,” but it looks more like a Tyrannosaurus rex to us.

The reddish aura surrounding the cloud of gas and dust called CG4 comes from hydrogen gas, heated and ionized (electrically charged) by the radiation from massive nearby stars. That powerful bombardment of radiation is probably what eroded and stretched CG4 into its distinctive shape.

Astronomers call clouds like CG4 cometary globules, because their long, dust-shrouded tails look a bit like comets, even though they form completely different ways and on drastically different scales (one cometary globule probably contains a few star systems’ worth of actual comets). This one, CG4, is an especially dense patch of gas and dust within the larger Gum Nebula, which is home to the Vela Supernova Remnant and the Vela Pulsar.

Cometary globules like CG4 are just one form of a type of cosmic cloud called a Bok Globule. These clouds of gas and dust are so dense that visible and ultraviolet light can’t pass through them, making them appear as dark shadows in telescope images (when we can see them at all). The best way to see a Bok Globule is with an infrared telescope, like the Dark Energy Camera: an instrument mounted on the Victor Blanco Telescope on a mountaintop in Chile.

Weirdly, all of the 32 cometary globules in the Gum Nebula have their heads pointed toward the center of the nebula, where the fast-spinning Vela Pulsar lurks at the heart of the Vela Supernova Remnant; the pulsar and the expanding cloud of stellar debris around it are all that’s left of a massive star that exploded in a supernova about 1 million years ago. That explosion, along with radiation and charged particles from nearby massive stars in the Gum Nebula, may have shaped CG4 and other cometary globules into their streamlined shapes.

If you’d like a sense of scale, CG4 is about 1300 light years away. Its head is about 1.5 light-years wide, and its faint tail stretches across 8 light years.

{ https://www.inverse.com/ }

10-05-2024 om 21:57 geschreven door peter  

New NASA Visualization Shows Supermassive Black Hole’s Event Horizon

Thanks to a new visualization produced on a NASA supercomputer, you can plunge into the event horizon, a black hole’s point of no return.

“People often ask about this, and simulating these difficult-to-imagine processes helps me connect the mathematics of relativity to actual consequences in the real Universe,” said Dr. Jeremy Schnittman, an astrophysicist at NASA’s Goddard Space Flight Center.

“So I simulated two different scenarios, one where a camera — a stand-in for a daring astronaut — just misses the event horizon and slingshots back out, and one where it crosses the boundary, sealing its fate.”

To create the visualizations, Dr. Schnittman teamed up with Goddard Space Flight Center scientist Brian Powell and used the Discover supercomputer at the NASA Center for Climate Simulation.

They generated about 10 terabytes of data and took about 5 days running on just 0.3% of Discover’s 129,000 processors. The same feat would take more than a decade on a typical laptop.

The destination is a supermassive black hole with 4.3 million times the mass of our Sun, equivalent to the monster located at the center of our Milky Way Galaxy.

“If you have the choice, you want to fall into a supermassive black hole,” Dr. Schnittman said.

“Stellar-mass black holes, which contain up to about 30 solar masses, possess much smaller event horizons and stronger tidal forces, which can rip apart approaching objects before they get to the horizon.”

This occurs because the gravitational pull on the end of an object nearer the black hole is much stronger than that on the other end. Infalling objects stretch out like noodles, a process astrophysicists call spaghettification.

The simulated black hole’s event horizon spans about 16 million miles (25 million km), or about 17% of the distance from Earth to the Sun.

A flat, swirling cloud of hot, glowing gas called an accretion disk surrounds it and serves as a visual reference during the fall.

So do glowing structures called photon rings, which form closer to the black hole from light that has orbited it one or more times.

A backdrop of the starry sky as seen from Earth completes the scene.

As the camera approaches the black hole, reaching speeds ever closer to that of light itself, the glow from the accretion disk and background stars becomes amplified in much the same way as the sound of an oncoming racecar rises in pitch.

Their light appears brighter and whiter when looking into the direction of travel.

The movies begin with the camera located nearly 640 million km (400 million miles) away, with the black hole quickly filling the view.

Along the way, the black hole’s disk, photon rings, and the night sky become increasingly distorted — and even form multiple images as their light traverses the increasingly warped space-time.

In real time, the camera takes about 3 hours to fall to the event horizon, executing almost two complete 30-min orbits along the way. But to anyone observing from afar, it would never quite get there.

As space-time becomes ever more distorted closer to the horizon, the image of the camera would slow and then seem to freeze just shy of it. This is why astronomers originally referred to black holes as “frozen stars.”

At the event horizon, even space-time itself flows inward at the speed of light, the cosmic speed limit.

Once inside it, both the camera and the space-time in which it’s moving rush toward the black hole’s center — a one-dimensional point called a singularity, where the laws of physics as we know them cease to operate.

The NASA visualization tracks a camera as it approaches, briefly orbits, and then crosses the event horizon — the point of no return — of a supersized black hole similar in mass to the one at the center of our Galaxy.

Image credit: J. Schnittman & B. Powell, NASA’s Goddard Space Flight Center.

“Once the camera crosses the horizon, its destruction by spaghettification is just 12.8 seconds away,” Dr. Schnittman said.

From there, it’s only 128,000 km (79,500 miles) to the singularity. This final leg of the voyage is over in the blink of an eye.

In the alternative scenario, the camera orbits close to the event horizon but it never crosses over and escapes to safety.

If an astronaut flew a spacecraft on this 6-hour round trip while her colleagues on a mothership remained far from the black hole, she’d return 36 min younger than her colleagues.

That’s because time passes more slowly near a strong gravitational source and when moving near the speed of light.

“This situation can be even more extreme,” Dr. Schnittman said.

“If the black hole were rapidly rotating, like the one shown in the 2014 movie Interstellar, she would return many years younger than her shipmates.”

{ https://www.sci.news/ }

09-05-2024 om 23:48 geschreven door peter  

Krachtige zonne-explosies hebben een sterke impact op de aarde: wat zou er kunnen gebeuren?

Door Janine

De krachtige uitbarstingen die op onze moederster exploderen, hebben een sterke impact op de aarde en lijken niet te stoppen. Dit is wat er gebeurt.

Wat zijn zonnevlammen?

SPACE WEATHER PREDICTION CENTER

Een zonnevlam, zo meldt NASA, is "een intense uitbarsting van straling door het vrijkomen van magnetische energie die gepaard gaat met zonnevlekken". Dit zijn, legt de Amerikaanse ruimtevaartorganisatie uit, de grootste explosieve gebeurtenissen in ons zonnestelsel. Ze manifesteren zich als heldere gebieden op de zon die enkele minuten tot enkele uren zichtbaar zijn.

Wat ons in staat stelt om ze te detecteren is het licht, dus de fotonen, die vrijkomen en die worden gecontroleerd door optisch licht en röntgenstraling. In zonnevlammen worden de zwaarste deeltjes versneld. De afgelopen dagen zijn zonnevlammen in volle actie: X1.6 vond plaats op 3 mei, gevolgd door andere krachtige fenomenen volgens het Space Weather Prediction Center van NOAA. Elk van deze fenomenen heeft een grote impact gehad op onze planeet.

De gevolgen van krachtige zonnevlammen op aarde

Een X1.3 en een X1.2 zonnevlam barstten op 5 mei los uit de actieve groep zonnevlekken AR 3663. In beide gevallen traden radio blackouts op op onze planeet, in Japan, Australië en grote delen van China, en de effecten zouden langer kunnen duren als coronale massa uitstoot, enorme wolken van zonneplasma doordrenkt met magnetische veldlijnen, geladen deeltjes naar de aarde zouden leiden.

Hierover zijn echter geen zekere gegevens bekend. Er zijn momenteel negen clusters zonnevlekken aanwezig aan de kant van de zon die naar onze planeet is gericht, die ongeveer 150 zonnevlekken omvatten. AR 3663 is op dit moment in ieder geval het meest actief en heeft sinds 30 april meerdere M-klasse en vier X-klasse vlammen uitgezonden, waarmee hij op de tweede plaats staat van de sterkste vlammen die onze ster kan produceren.

Maar wat zijn de voorspellingen van de wetenschappers en wat kunnen we verwachten? Volgens de voorspellers zullen er meer M-klasse vlammen zijn en mogelijk nog een of meer X-klasse vlammen voordat ze buiten de baan van de aarde draaien.

Keith Strong, een zonnefysicus, schreef in een bericht op X, voorheen Twitter: “Het gebied van zonnevlekken AR3663 produceerde een X4.5 vlam, de op twee na grootste sinds het begin van zonnecyclus 25 (4,3 jaar geleden)." Hij voegde eraan toe dat de vlam een sterke black-out veroorzaakte in een groot deel van Azië, Oost-Afrika en Oost-Europa. "Als het een coronale massa uitstoot produceerde, zal deze waarschijnlijk binnen een dag of twee de aarde raken."

Geomagnetische storm op komst? Er is iets positiefs aan

SDO | Solar Dynamics Observatory NASA

Zonnevlammen gaan soms gepaard met uitbarstingen die de aarde met een paar dagen vertraging kunnen bereiken, omdat plasma zich minder snel verplaatst dan licht. Op het moment dat de coronale massa uitstoot ons bereikt, ontstaat er echter een geomagnetische storm met aanzienlijke gevolgen voor de communicatie. Op het moment dat het de magnetosfeer van de planeet raakt, ontstaan er elektrische stromen die door elektriciteitsnetwerken kunnen reizen, stroomuitval kunnen veroorzaken en satellieten, radio- en navigatiesignalen kunnen beïnvloeden.

Maar er is ook een positief aspect: de wisselwerking tussen zonnedeeltjes, de magnetosfeer en de atmosfeer van de aarde leidt tot een opvallend poollicht boven de polen van de aarde, dat alleen 's nachts zichtbaar is, wanneer er geen zonlicht is. In elk geval zullen de volgende uitbarstingen kleine gevolgen hebben, omdat AR 3663 van de baan van de aarde af draait, maar de zon zit midden in haar activiteitscyclus, haar piek vindt om de elf jaar plaats en kan ons nog meer “verrassingen” bezorgen.

Source:

{ https://www.curioctopus.nl/ }

09-05-2024 om 23:38 geschreven door peter  

The search for life on Mars can be traced to the late 19th and early 20th centuries when Percival Lowell made extensive observations from his observatory in Flagstaff, Arizona. Inspired by Schiaparelli’s illustrations of the Martian surface (which featured linear features he called “canali”), Lowell recorded what he also believed were canals and spent many years searching for other indications of infrastructure and an advanced civilization. During the ensuing decades, observatories worldwide observed Mars closely, looking for indications of life and similarities with Earth.

However, it was not until the Space Age that the first robotic probes flew past Mars, gathering data directly from its atmosphere and taking close-up images of the surface. These revealed a planet with a thin atmosphere composed predominantly of carbon dioxide and a frigid surface that did not appear hospitable to life. However, it was the Viking 1 and 2 missions, which landed on Mars in 1976, that forever dispelled the myth of a Martian civilization. But as Fletcher told Universe Today via email, the possibility of extant life has not been completely abandoned:

“It’s my personal belief that it is unlikely we will find evidence of extant (current) life on Mars, as opposed to evidence of past life on Mars. If we were to find extant life on Mars that could be proven to be endemic to Mars and not contamination from Earth, some think it might be found underground in lava tubes, for example, and some think the ice caps or any possible source of liquid water might be suitable places.”

Ironically, it was the same missions that discredited the notion of there being life on Mars that revealed evidence that water once flowed on its surface. Thanks to the many orbiter, lander, and rover missions sent to Mars since the turn of the century, scientists theorize that this period coincided with the Noachian Era (ca. 4.1 – 3.7 billion years ago). According to the most recent fossilized evidence, it was also during this period that life first appeared on Earth (in the form of single-celled bacteria).

Our current astrobiology efforts on behalf of NASA and other space agencies are focused on Mars precisely for this reason: to determine if life emerged on Mars billions of years ago and whether or not it co-evolved with life on Earth. This includes the proposed Mars Sample Return (MSR) mission that will retrieve the drill samples obtained by the Perseverance rover in the Jezero Crater and return them to Earth for analysis. In addition, NASA and China plan to send crewed missions to Mars by 2040 and 2033 (respectively), including astrobiology studies.

These activities could threaten the very abodes where evidence of past life could be found or (worse) still exists. “Human activities might threaten sites like this in part due to possible microbial contamination,” said Fletcher. “Evidence of life (past and extant) also has greater scientific value when in its palaeoenvironmental context, so any human activities that might damage the evidence of life and/or its surrounding environmental context pose a risk. This could be something innocuous, like debris falling in the wrong spot, or something more serious, like driving over possibly significant outcrops with a rover.”

Conservation measures must be developed and implemented before additional missions are sent to Mars. Given humanity’s impact on Earth’s natural environment and our attempts to mitigate this through conservation efforts. In particular, there have been numerous cases where scientific studies were conducted without regard for the heritage value of the site and where damage was done because of a lack of proper measures. These lessons, says Fletcher, could inform future scientific efforts on Mars:

“It’s important that we learn from what has been considered “damaging” on Earth and take this into consideration when exploring Mars. If a site is damaged beyond being able to be studied in the future, then we limit what can actually be learned from a site. When considering Mars missions cost billions of dollars and are to meet specific scientific goals, limiting the information being learned from a site is incredibly detrimental. My recommendations are that of my paper: interdisciplinary cooperation, drawing on experience and knowledge from Earth, creating norms and a code of practice (part of my PhD work), and working towards creating legislation for these issues.”

The need for exogeoconservation is paramount at this juncture. In addition to Mars, multiple astrobiology missions will travel to the outer Solar System this decade to search for evidence of life on icy moons like Europa, Ganymede, Titan, and Enceladus. This includes the ESA’s JUpiter ICy moons Explorer (JUICE) mission, currently en route to Ganymede, and NASA’s Europa Clipper and Dragonfly missions that will launch for Europa and Titan in October 2024 and 2028 (respectively). Therefore, the ability to search for extant or past life without damaging its natural environment is an ethical and scientific necessity.

“I hope this paper is very much a starting point for anyone working in Mars science and exploration, as well as anyone thinking about space policy and exogeoconservation,” said Fletcher. “My goal was to start drawing attention to these issues, and that way start a generation of researchers and practitioners focused on exogeoconservation of Mars.”

Further Reading: 

• Space Policy

{ https://www.universetoday.com/ }

09-05-2024 om 22:53 geschreven door peter  

Earth is naked without its protective barrier. The planet’s magnetic shield surrounds Earth and shelters it from the natural onslaught of cosmic rays. But sometimes, the shield weakens and wavers, allowing cosmic rays to strike the atmosphere, creating a shower of particles that scientists think could wreak havoc on the biosphere.

This has happened many times in our planet’s history, including 41,000 years ago in an event called the Laschamps excursion.

Cosmic rays are high-energy particles, usually protons or atomic nuclei, that travel through space at relativistic speeds. Normally, they’re deflected into space and away from Earth by the planet’s magnetic shield. But the shield is a natural phenomenon and its strength fluctuates, as does its orientation. When that happens, cosmic rays strike the Earth’s atmosphere.

That creates a shower of secondary particles called cosmogenic radionuclides. These isotopes become embedded in sediments and ice cores and even in the structure of living things like trees. There are different types of these isotopes, including ones like Calcium 41 and Carbon 14.

Some of the isotopes are stable, and some are radioactive. The radioactive ones have half-lives ranging from only 20 minutes (Carbon 11) up to 15.7 million years (Xenon 129.)

When Earth’s shield weakens, more of these isotopes reach the planet’s surface and collect in sediments and ice. By studying these cores and sediments, scientists can determine the magnetic shield’s history. Their observations show that Earth experienced a geomagnetic excursion or reversal 41,000 years ago. It’s called the Laschamps excursion after the Laschamps lava flows in France, where geomagnetic anomalies revealed its occurrence.

Every few hundred thousand years, the Earth’s magnetic poles flip. North becomes South and vice versa. In between those major events are more minor events called excursions. During excursions, the poles shift around for a while without swapping places. The excursions weaken the Earth’s shield and can last from a few thousand to tens of thousands of years. When that happens, more cosmic rays strike the atmosphere, creating more radionuclides that shower down onto Earth.

Scientists often focus on one particular radioactive isotope in paleomagnetic studies. Beryllium 10 has a relatively long half-life of 1.36 million years and tends to accumulate on the soil surface.

Sanja Panovska is a researcher at GFZ Potsdam, Germany, who studies geomagnetism. At the recent European Geosciences Union (EGU) General Assembly 2024, Panovska presented new research on the Laschamps excursion. She found that during the Laschamps excursion, production of Be 10 was twice as high as normal.

To understand the Laschamps excursion more thoroughly, Panovska combined cosmogenic radionuclide and paleomagnetic data to reconstruct the Earth’s magnetic field at the time. She found that when the field decreased in strength, it also shrank. The transition from normal field to reversed field took about 250 years, and it stayed flipped for about 440 years. During the transition, the Earth’s shield weekend to as little as 5% of its normal strength. When it was fully reversed, it was at about 25% of its regular strength. This weakening allowed more Be 10 and other cosmogenic radionuclides to reach Earth’s surface.

These radionuclides do more than collect in sediments and ice. Some of them are radioactive. The weakening of the shield also weakened the ozone layer, letting more UV radiation reach Earth’s surface. The high-altitude atmosphere also cooled, which changed the wind flows. This could’ve caused drastic changes on the Earth’s surface.

For these reasons, the Laschamps event has been linked to the extinction of the Neanderthals, the extinction of Australian megafauna, and even to the appearance of cave art. Those links haven’t withstood scientific scrutiny, but that doesn’t mean that events like the Laschamps event aren’t hazardous. If it occurred now, it would knock out our power grids. The Earth’s equatorial region would light up with aurorae.

“Understanding these extreme events is important for their occurrence in the future, space climate predictions, and assessing the effects on the environment and on the Earth system,” Panovska said.

Scientists are learning that the magnetic shield isn’t static. There are anomalies. One of them is the South Atlantic Anomaly, a region where the magnetic field is weakest near Earth. When satellites pass over this region, they’re exposed to higher levels of ionizing radiation. The anomaly is likely caused by a reservoir of dense rock inside Earth, illustrating how complex the magnetic shield is.

Scientists are uncertain about what effect the cosmic rays have on life when the magnetic shield is weak. It’s tempting to correlate extinctions with events like the Laschamps excursion when they line up temporally. But the poles have shifted, weakened, and reversed many times and life is still here and still thriving.

If humanity lasts long enough, we’ll go through one of these reversals. Then we’ll know.

{ https://www.universetoday.com/ }

09-05-2024 om 22:40 geschreven door peter  

In one, the viewpoint plunges directly into the black hole like a free-falling astronaut, with explanatory text to guide us through what we’re seeing. The other is a 360-degree view of the black hole.

Schnittman created them with a NASA supercomputer called Discover in only five days, generating about 10 terabytes of data. The computer used only about 0.3% of its power. The same visualization would’ve taken more than a decade to create on an average laptop computer.

The black hole in the visualization is the same size as Sagittarius A star, the supermassive black hole (SMBH) at the heart of the Milky Way. It has 4.3 million solar masses and dominates the galaxy’s inner regions. Its event horizon reaches about 25 million km (16 million miles). That’s about 17% of the distance from Earth to the Sun. The event horizon is surrounded by an accretion disk, a swirling disk of superheated material drawn in by the black hole’s overpowering gravity.

Another type of black hole, the stellar-mass black hole, is much less massive. Schnittman says that if you’re going to fall into a black hole, you’d rather fall into the supermassive one.

“If you have the choice, you want to fall into a supermassive black hole,” Schnittman explained. “Stellar-mass black holes, which contain up to about 30 solar masses, possess much smaller event horizons and stronger tidal forces, which can rip apart approaching objects before they get to the horizon.”

Powerful gravity is the reason. The SMBH’s gravity is so strong that it pulls harder on the end of the object nearest it. That stretches the object and elongates it. Stephen Hawking was the first to call this ‘spaghettification,’ and the name has stuck. Presumably, you’d get a better look if you fall into an SMBH.

In the movies, the camera begins at a distance of 640 million km (400 million miles.) Since space-time is warped around a black hole, so are the images of the sky, the black hole’s disk, and the photon ring. It takes the camera three hours of real-time to fall into the event horizon, and it completes almost two 30-minute orbits as it falls. A distant observer would never see an object ever reach the black hole. From a distance, the object would freeze at the event horizon.

When a falling object reaches the event horizon, it and space-time itself reach the speed of light. After crossing the horizon, the object and the space-time around it surge toward the singularity, a point of infinite density and gravity. “Once the camera crosses the horizon, its destruction by spaghettification is just 12.8 seconds away,” Schnittman said.

In the second video, the camera never crosses the event horizon and instead escapes. But the powerful black hole still has an effect. Imagine if the camera were an astronaut, and they flew this six-hour roundtrip while a separate astronaut stayed far away from the SMBH. The astronaut would return and be 36 minutes younger than the astronaut who never approached the black hole.

“This situation can be even more extreme,” Schnittman noted. “If the black hole were rapidly rotating, like the one shown in the 2014 movie ‘Interstellar,’ she would return many years younger than her shipmates.”

The bottom line is, don’t fall into a black hole. In fact, resist your fascination and don’t even approach one.

Leave them for the physicists.

{ https://www.universetoday.com/ }

09-05-2024 om 22:23 geschreven door peter