China launches mysterious reusable 'test spacecraft' to Earth orbit

08-08-2022 om 21:53 geschreven door peter  

US Space Force tests robot dogs to patrol Cape Canaveral

08-08-2022 om 21:33 geschreven door peter  

Curious Kids: Is it possible to see what is happening in distant solar systems now?

08-08-2022 om 20:46 geschreven door peter  

The physics of accretion: How the universe pulled itself together

Material from an accretion disk swirls around the young star FU Orionis in this artist’s concept.

NASA/JPL-Caltech

Accretion is one of the most fundamental processes in the cosmos. It is a universal phenomenon triggered by gravity, and the process by which bits of matter accumulate and coalesce with more bits of matter. It works inexorably on all scales to attract and affix smaller things to bigger things, from the tiniest dust grains to supermassive black holes. 

Accretion creates everything there is: galaxies, stars, planets, and eventually, us. It is the reason the universe is filled with a whole bunch of somethings instead of a whole lot of nothing.

The fact that matter tends to glom together may seem intuitive. But to scientists, accretion remains a mysterious topic, filled with unanswered questions.

For instance: Why do some stellar nurseries form a few massive stars instead of lots of smaller ones? What causes so much accreting material to ultimately fall inward onto its central object, instead of just circling it forever? And how do space rocks ultimately stick together to form planets instead of just bouncing off each other? No one knows the definitive answers to any of these questions yet, but there are some theories gaining traction — and evidence.

The Taurus Molecular Cloud is a vast star-forming region threaded by a network of filaments. It was captured here by the European Space Agency’s Herschel Space Observatory, which operated from 2009 to 2013.

ESA/Herschel/NASA/JPL-Caltech, CC BY-SA 3.0 IGO; Acknowledgement: R. Hurt (JPL-Caltech)

All objects great and small

Accretion is the inevitable result of gravitational forces operating on all scales, and on all types of material — gas, dust, plasma, even dark matter. Gravity makes matter accrete. And when matter accretes, it forms objects. Thus, accretion and formation are very closely related in astronomy: The former can be considered an aspect of the latter. 

The Soviet scientist Otto Schmidt devised the first accretion model of planetary formation in 1944, and his countryman Viktor Safronov fleshed out the mathematics of accretion in 1969. The underlying principles of gravitational attraction have since been applied to the formation of stars and even galaxies. The discovery of quasars and compact X-ray sources in the 1960s, using optical, radio, and X-ray observations, set the field in motion.

But the true renaissance began a decade ago, when the Atacama Large Millimeter/submillimeter Array (ALMA), an array of 66 radio telescopes in Chile, came online. With the ability to study distant, cool objects in detail came the data necessary to understand the process of accretion in a variety of circumstances. Seeing accretion in action promised to be a game-changer.

Today, ALMA and other advanced telescopes are observing numerous objects of different sizes and stages of evolution: galaxy groups, molecular clouds, stellar nurseries, protostars, planetary disks, black holes, and many more. We now know that whether on scales of kilometers or light-years, accretion operates on the same broad principles. The particular mechanisms remain mysterious, but the veil is beginning to lift.

The reason that the gas in a molecular cloud can accrete into a star may be due to magnetohydrodynamics (MHD), the physics of how magnetic fields interact with hot ionized gas.

Interstellar space and everything in it is permeated by a weak magnetic field. Normally, this background magnetic field has no effect on a cold, dense cloud of gas and dust.

But this changes when a collapsing cloud heats up and begins to generate plasma. Because plasma is electrically charged, it is linked to the magnetic field: As it moves, it drags the magnetic field lines with it. As the cloud collapses further and begins to form an accretion disk, the magnetic field becomes wound up by the disk’s rotation. The magnetic field also becomes stronger as the field lines bunch together.

All of these magnetic field lines then act as highways for plasma to escape the strong magnetic field: Following the field lines, the charged particles zip away from the accretion disk into space. This MHD wind carries angular momentum away from the disk — and this, astronomers suspect, helps the cloud collapse into a star.

---

The Giant GRB Ring is a suspected superstructure — a collection of nine gamma-ray bursts (immensely powerful stellar explosions) arranged in a loose ring that spans 5.6 billion light-years, as shown in this artist’s concept.

Pablo Carlos Budassi/Wikimedia Commons/CC BY-SA 4.0

Stellar nurseries at the crossroads

The largest structures in the universe are groups of galaxies that are gravitationally bound to each other. We are not yet able to see them, but peculiar arrangements of objects have been interpreted as evidence of such superstructures. They are given various names according to their observed shapes, such as arcs, rings, or walls.

The observable portions of superstructures consist mostly of molecular clouds of gas millions of light-years across. Over the eons, these diffuse regions are perturbed by a variety of effects: the chaotic motions of the galaxies within them, the winds thrown by quasar jets, the passing wakes of rotating black holes, and blasts from supernovae. Here and there, a confluence of gas and dust will become dense enough that gravity takes over and a domino effect begins, as more and more mass is drawn into a conglomeration, where a star-forming region is born.

The mechanics of these stellar nurseries, from which hundreds or thousands of stars are created, are not completely understood. Sometimes a region containing a few hundred solar masses of dense gas and dust will form 100 Sun-like stars. Other times a few massive stars will also appear. This difference is of particular interest to astronomers because massive stars can alter the evolution of a galaxy. What guides the seemingly random accretion process on these vast scales?

One theory posits that there are “filaments of flowing gas, which thread through these clusters,” says Todd Hunter, an astronomer at the National Radio Astronomy Observatory. Astronomers are starting to see evidence of these filaments. “They fragment and intersect at certain places, especially in the center of clusters,” says Hunter. “And where they meet is where protostars have access to a lot of gas on a short timescale” — which feeds the formation of massive stars.

The accretion disk that surrounds the elliptical galaxy M87 feeds its central supermassive black hole (SMBH) and relativistic jet in this artist’s concept.

ESO/M. Kornmesser

These objects are called infrared dark clouds, and they are very large, very cold objects that were difficult to detect and resolve until recently. The first observations were made with the Infrared Space Observatory in 1996. It was a serendipitous find, made during the first detailed survey of stellar populations in the galactic plane. Nowadays these regions are studied in detail with ALMA and the Submillimeter Array in Hawaii, which are more sensitive and have higher resolution at submillimeter wavelengths where cold molecular gas is easiest to detect.

These facilities have allowed astronomers to map the gas flows they believe provide the necessary supply for the growth of massive stars. One survey, published in The Astrophysical Journal in 2019, identified hundreds of protostellar and prestellar core candidates in a particular region and studied how they affect each other. The researchers suggest a kind of “competitive accretion” process takes place, alongside what they call “global hierarchical collapse” — where chaotic gravitational forces cause a series of collapses within collapses, with small-scale events happening later and faster than large-scale events. This process works over a couple of million years, eventually transforming a diffuse cloud of starless cores into a flattened disk of protostars.

A widening gyre

Where there is gravity and matter, there will also be accretion. Infalling matter forms a swirling accretion disk. This gravitational gyre forms because the infalling material — like everything else in the universe — had some motion and angular momentum before becoming caught up by an object’s gravity. The laws of physics state that angular momentum must be conserved — so, to fall into a star, black hole, or other object, material must lose its angular momentum first. It cannot be simply sucked toward the core along a straight line. Instead, it forms a flattened structure called an accretion disk.

At just 450 light-years away, the Taurus Molecular Cloud is an ideal place to search for accretion disks. Two examples are the young stars HL Tauri (bright blue, at upper center left) and V1213 Tauri (lower right). The latter is hidden by an accretion disk, though the star partly illuminates the disk above and below it. The visible disk and the jets comprise the object HH 30.

ESA/Hubble and NASA; Acknowledgement: Judy Schmidt

The closer the material is carried to the center, the faster it spins. (Physicists often use the metaphor of a figure skater to demonstrate this effect; when the skater pulls their arms in, they spin faster.) There’s just a small problem: For material to actually fall onto the core, it must slow down and eventually come to a stop. But how can this happen when the closer it gets, the faster it moves? Why doesn’t it just swirl around forever? What dissipates the angular momentum, allowing gravity to win the tug-of-war?

There are two prevailing theories. “The old idea is that disks are turbulent, and this turbulence generates a kind of viscosity,” or friction within a fluid, says Ilaria Pascucci, an astrophysicist and planetary scientist at the University of Arizona in Tucson. In this scenario, the disk is full of eddies, which means the gas particles don’t orbit smoothly. As inner material accelerates, it drags the material outside of it along for the ride, like a jar of molasses being stirred. “The viscosity redistributes angular momentum outward, enabling disk gas close in to accrete,” says Pascucci.

This turbulence-viscosity model of disk accretion was first suggested around 40 years ago. But astronomers have never really been able to make the numbers add up. The models required disks to be stickier and more viscous than turbulence could probably account for.

Then, in the last decade, an overlooked characteristic of accretion disks — magnetic fields — started to show promise. “What if the angular momentum is not redistributed in the disk, but extracted through winds?” Pascucci says.

The ghostly halo we see in the groundbreaking image of an SMBH from the Event Horizon Telescope is the hot, glowing plasma in the accretion disk surrounding it.

Event Horizon Telescope Collaboration

Star-forming regions have magnetic fields running through them. While they do not affect neutral gas, particles that have been heated and ionized have an electric charge and will tend to follow these magnetic field lines. As the large-scale clouds collapse under their own gravity, these magnetic field lines also become twisted and tangled. And if magnetic field lines are somehow bent outward, anchored to plasma that remains outside the collapsing cloud, plasma that is zipping along the magnetic field might be able to overcome gravity and accelerate away from the disk. Astronomers call these outflows magnetohydrodynamic (MHD) winds, and they could carry away angular momentum. This would enable the leftover disk material to fall onto the forming protostar.

Both observations and simulations seem to point toward the MHD wind hypothesis. The best evidence so far for an MHD wind is a 2021 study in The Astrophysical Journal of an active young star, where astronomers have measured how high the wind appears to sustain itself as it flows away from the disk. Measuring how powerful these winds are — and therefore how much angular momentum they carry away — will be the next major task in testing the theory.

Disk worlds

At the same time a star is forming, so are the planets that will orbit it. Both star formation and planet formation happen within disks via accretion. As gas and dust swirls around the star, delineations begin to appear in the disk. Astronomers saw this for the first time in 2014 in a young star called HL Tauri. This observation, made using ALMA, was a major advancement in our understanding of how planets form.

In a nascent planetary system, the congregation of matter depends on lots of different factors. Turbulence, magnetic fields, and the play of viscosity between gas and dust may cause a kind of traffic jam that eventually congeals to form protoplanets. Closer in, most of the gas gets consumed by the star, leaving rocky material and heavy metals, which form terrestrial planets.

In 2014, the ALMA radio telescope revealed distinctive gaps in HL Tauri’s accretion disk. They mark regions where planets are accreting and sweeping up material.

ALMA (ESO/NAOJ/NRAO)

But there is a long-standing question about how rocky bodies accrete, involving a concept called the bouncing barrier. Electrostatic forces cause small grains to stick together and larger planetesimals are attracted to each other by gravity. But how does a particle become a planet? Models show that objects in that middle range between tiny and massive just tend to bounce off each other. So how do amassing objects overcome this barrier to growth?

One theory is that the particles experience a drag force as they move through gas in the disk. “There’s a strong interaction between solid particles and the gas in the disk,” says James Stone, an astrophysicist at Princeton University. “This causes clumps to form, which over time can produce larger and larger objects.”

So far, this protoplanetary evolution mechanism, called streaming instability, seems to be a promising way to grow things from centimeter to kilometer sizes. The most intriguing part of the theory is that the gas is the crucial component: Without it, dust in the disk couldn’t coalesce to form planetesimals. But there is not yet direct evidence.

The hope is that within a decade or two, we will have seen lots of planets at different stages of formation. This will stand in as a kind of time-lapse and we can judge how well predictions of prevailing hypotheses, like streaming instability, match up to actual exoplanets. This ambitious venture received a kickstart in 2021 with the discovery of the youngest planet ever observed: 2M0437b. The discovery image, taken by the Subaru Telescope on Mauna Kea in Hawaii, shows a world still glowing hot from energy released during its formation, meaning it just recently (astronomically speaking) finished accreting. The study, led by Eric Gaidos of the University of Hawai’i, also fills in our picture of how quickly planetary systems form, because the star is only about 2.5 million years old.

Supercomputer simulations reveal the turbulent and hierarchical dynamics of collapsing infrared dark clouds (IRDCs), forming filaments within filaments. In the densest regions of this simulation, shown in red, molecular clouds are forming cores that will become massive stars.

Richard Klein, Lawrence Livermore National Laboratory; Pak Shing Li, University of California, Berkeley; Tim Sandstrom, NASA Ames Research Center

Gathering dust

Every star grows up on its own schedule. The protostar stage is like a star’s volatile teen years. When its accretion disk stabilizes and material stops falling into the core, it becomes a main sequence star. There may still be a debris disk and the planets around might still be figuring out where they orbit, but accretion has largely stopped. That doesn’t mean there won’t be any more accretion in the star’s future, though. Depending on its mass, when fusion ceases, it will then transition into either a white dwarf, a neutron star, or a black hole, all of which can form accretion disks of their own.

The supply for this new disk can come from a variety of sources. Compact objects, like white dwarfs and black holes, may siphon gas from a companion star. A white dwarf may also pull in material that it puffed off in the earlier red giant phase. And when black holes grow and merge to become the supermassive black holes (SMBHs) at the centers of galaxies, they draw material from the vast roaming stars, clouds, and nebulae within the galaxy itself.

As material from the disk falls into the central object — whether a star, planet, or singularity — it releases energy in the form of radiation. The disk itself also radiates as it swirls around the gravity well and heats up, with different factors like viscosity, friction, and speed making some parts hotter than others. The stronger the draw of the central object, the more powerful the radiation emitted, as gas can be transformed into plasma. The groundbreaking 2019 image of the supermassive black hole at the center of the galaxy M87 is not of the hole itself, but of the black hole’s shadow on the charged plasma swirling around it.

A black hole gains mass from everything it accretes over time. But while we understand how Sun-sized black holes form, we don’t know how SMBHs got as big as they are. For example, the SMBH at the center of the Whirlpool Galaxy (M51) in Canes Venatici has a mass equivalent to 1 million Suns. There is no way for a single small, stellar-mass black hole to accrete enough material to grow this large at the universe’s current age.

“It’s one of the biggest mysteries of black hole research,” says Joanna Piotrowska, a graduate student at Cambridge University. The laws of physics limit how quickly an object can accrete matter, called the Eddington limit. Above that limit, the radiation from the accretion disk is so intense, it blows material away — preventing more accretion from happening. “The mass of [SMBHs] exceeds what is expected from continuous accretion at the Eddington limit over the lifetime of our universe,” says Piotrowska.

One proposed solution is that SMBHs were big to start with. Perhaps in the early universe, even before the first stars, there were molecular clouds with just the right conditions to collapse straight away into singularities. The James Webb Space Telescope might be able to shed some light on this dark topic when it comes online this year. It was designed especially to see the first galaxies and stars, and those primordial formations could help us to understand the initial distribution of potential collapsible matter.

IRDCs appear as shadows splayed across the bright mid-infrared background of the Milky Way, as seen in this false-color image from NASA’s Spitzer Space Telescope. Though they are some of the darkest objects in the sky, these ultracold and dense clouds give birth to the brightest, most massive stars in the galaxy.

NASA/JPL-Caltech

And that’s not all ...

It’s tempting to picture accretion as a peaceful, gradual, and constructive process, like erosion in reverse. It can certainly take time to get going. But the methods by which an accretor gains mass can be quite quick and chaotic. Recently, observers have seen what they call accretion bursts around protostars — instances of extreme instability in a disk, where large amounts of material suddenly plunge into the star. Hunter recently observed this on NGC 6334 I, a protostar cluster in the Cat’s Paw Nebula (NGC 6334) in the constellation Scorpius, using the Stratospheric Observatory for Infrared Astronomy (or SOFIA). He theorizes that a high proportion of the total accretion of some stars — up to 50 percent — may actually happen in this way.

08-08-2022 om 18:07 geschreven door peter  

© AP

{ https://www.hln.be/ }

08-08-2022 om 17:21 geschreven door peter  

Dwarf Galaxies Found Without Influence From Dark Matter

Ask astronomers about dark matter and one of the things they talk about is that this invisible, mysterious “stuff” permeates the universe. In particular, it exists in halos surrounding most galaxies. The mass of the halo exerts a strong gravitational influence on the galaxy itself, as well as on others in the neighborhood. That’s pretty much the standard view of dark matter and its influence on galaxies. However, there are problems with the idea of those halos. Apparently, some oddly shaped dwarf galaxies exist that look like they have no halos. How could this be? Do they represent an observationally induced challenge to the prevailing ideas about dark matter halos?

Finding Perturbed Dwarf Galaxies

In the so-called “Standard Model” of cosmology, shells or halos of dark matter protect galaxies from the gravitational influence of nearby galactic neighbors. However, when astronomers at the University of Bonn and Saint Andrews in Scotland looked in the nearby Fornax Cluster, which lies some 62 million light-years away from us, they saw something strange. It contains a number of dwarf galaxies with distorted, perturbed shapes. This is odd, especially if they should be surrounded by dark matter halos.

Let’s take a quick look at dwarf galaxies. They’re small and faint and usually found riding along in galaxy clusters or near much larger companions. The Milky Way Galaxy has a coterie of dwarf galaxies around it,. It is, in fact, cannibalizing ones such as the Sagittarius Dwarf Spheroidal. Interestingly, recent studies show that at least one of the dwarf galaxies near ours, an ancient one called Tucana II, has an astoundingly massive dark matter halo.

So, what’s happening in Fornax that’s different? There, dwarf galaxies could be “disturbed” by gravitational tides from nearby larger ones in the cluster. Tides happen when gravity from one body pulls differently on different parts of another body. These are similar to tides on Earth when the Moon pulls more strongly on the side of Earth that faces it.

The distorted shapes of the dwarf galaxies seen by the team indicate a problem with our understanding of dark matter. “Such perturbations in the Fornax dwarfs are not expected according to the Standard Model,” said Pavel Kroupa, Professor at the University of Bonn and Charles University in Prague. “This is because, according to that model, the dark matter halos of these dwarfs should partly shield them from tides raised by the cluster.”

Dwarf galaxy NGC1427A, part of the Fornax galaxy cluster.

(ESO)

Explaining Distorted Dwarf Galaxies

Kroupa and Ph.D. student Elena Ascencio analyzed observations of the perturbed dwarfs in Fornax. They wanted to understand the extent of gravitational distortions these galaxies show and what causes them. The expected levels of distortion depend on a couple of factors. One is the internal characteristics of the dwarf galaxy. In addition, their distance to the center of the cluster is important. That’s where gravitational influences are much stronger. As a rule, galaxies with large sizes but not many stars could be easily disturbed by strong gravitational tides. The same is true for galaxies closer to the core of the cluster.

The team members compared what they saw in the cluster with observations made by the VLT Survey Telescope at the European Southern Observatory. Asencio pointed out that what they found seems to point to problems with the Standard Model. “The comparison showed that, if one wants to explain the observations in the standard model,” she said, “the Fornax dwarfs should already be destroyed by gravity from the cluster center even when the tides it raises on a dwarf are sixty-four times weaker than the dwarf’s own self-gravity.”

Not only is this counter-intuitive, she said, it also contradicts previous studies. The team also found that the force needed to disturb a dwarf galaxy is about the same as its self-gravity.

What Does This Mean for the Standard Model?

The research team points out that it’s difficult to explain these perturbed, disturbed shapes of the dwarf galaxies in Fornax if they’re surrounded by dark matter. In other words, they shouldn’t be misshapen if they do have halos. Yet, there they are with disturbed-looking shapes. That means that there are no dark matter halos around those galaxies.

Obviously, if what the astronomers found is confirmed, then the Standard Model needs some tweaking. And, there is at least one alternative explanation for the strange galaxy shapes. It’s called the MOND model (short for Modified Newtonian Dynamics). It suggests that Newton’s law of universal gravitation should be modified to account for the observed properties of galaxies. It could be applied to explain why misshapen galaxies look the way they do.

According to Hongsheng Zhao, a member of the research team from the University of Saint Andrews, finding disturbed dwarfs without dark matter halos is a major challenge to the current view. It states that galaxies have halos. It appears not all of them do, he points out. “Our results have major implications for fundamental physics,” he said. “We expect to find more disturbed dwarfs in other clusters, a prediction which other teams should verify”.

For More Information

• No trace of dark matter halos
• The distribution and morphologies of Fornax Cluster dwarf galaxies suggest they lack dark matter
• Modified Newtonian Dynamics

The post Dwarf Galaxies Found Without Influence From Dark Matter appeared first on Universe Today.

Source: 

• https://www.universetoday.com/157056/dwarf-galaxies-found-without-influence-from-dark-matter/

RELATED VIDEOS, selected and posted by peter2011

{ https://beforeitsnews.com/ }

08-08-2022 om 17:02 geschreven door peter  

Ancient records and religious texts describe multiple "Gods" (aka extraterrestrials) creating humanity in a series of genetic experiments and warring among themselves over who would be dominant in influencing Earth's future. 

The world's oldest known creation story, Sumer's Enuma Elish, and other ancient texts introduce the different creator Gods and how they formed grand assemblies to resolve their differences over the destiny of humanity. 

This new video is the official trailer/short film for the "World Religions and Extraterrestrial Contact" webinar to be held on August 13. In addition to the above issues, the trailer discusses the rise and fall of Atlantis in relation to creator Gods/extraterrestrials alarmed over humanity's rapid technological development. 

Finally, this short film covers the return of the creator Gods (Elohim/Anunnaki) to our solar system and what this means for us today.

  

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

08-08-2022 om 16:29 geschreven door peter  

Stationary blinking UFO over Boynton, Florida 31-May-2022

This blinking unidentified flying object was filmed above the sea near Boynton in Florida. This happened on 31st May 2022.

Witness report: 

Here’s the 12 minutes video of various times during the 45 + minute sighting. However, please study this at 10 minutes and 35 seconds into the video above when a very large Ufo streaks across the screen from top right to bottom left quadrant!

So, let’s use logic. This craft flew at least 2 1/2 miles over the sea (which is a VERY conservative estimate because it really appears to have gone over the horizon which is 35 miles away). Theirs 3,600 seconds in one hour. IF this craft only went 2 1/2 miles in 1/10 th of a second – that would put the speed of the Ufo at 90,000 per hour!

However, if it’s gone out of sight over the horizon (35 miles) in 1/10 th of a second , using the same equation…(3,600 seconds in one hour) that would put the speed of the Ufo at an Astounding 1,260,000 mph!!

RECENT UFO-VIDEOS FLORIDA, selected and posted by peter2011

{ https://www.latest-ufo-sightings.net/ }

08-08-2022 om 16:00 geschreven door peter  

Kosmisch overgewicht: waarom sterren, planeten en manen rond zijn

08-08-2022 om 01:42 geschreven door peter  

{ https://www.eoswetenschap.eu/ }

08-08-2022 om 01:25 geschreven door peter  

Future Space Travelers May Follow Cosmic Lighthouses

For centuries, lighthouses helped sailors navigate safely into harbor. Their lights swept across the water, cutting through fog and darkness, guiding mariners around dangerous obstacles and keeping them on the right path. In the future, space explorers may receive similar guidance from the steady signals created by pulsars.

Scientists and engineers are using the International Space Station to develop pulsar-based navigation using these cosmic lighthouses to assist with wayfinding on trips to the Moon under NASA’s Artemis program and on future human missions to Mars.

Pulsars, or rapidly spinning neutron stars, are the extremely dense remains of stars that exploded as supernovas. They emit X-ray photons in bright, narrow beams that sweep the sky like a lighthouse as the stars spin. From a great distance they appear to pulse, hence the name pulsars.

An X-ray telescope on the exterior of the space station, the Neutron star Interior Composition Explorer or NICER, collects and timestamps the arrival of X-ray light from neutron stars across the sky. Software embedded in NICER, called the Station Explorer for X-ray Timing and Navigation Technology or SEXTANT, is using the beacons from pulsars to create a GPS-like system. This concept, often referred to as XNAV, could provide autonomous navigation throughout the solar system and beyond.

“GPS uses precisely synchronized signals. Pulsations from some neutron stars are very stable, some even as stable as terrestrial atomic clocks in the long term, which makes them potentially useful in a similar way,” says Luke Winternitz, a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The stability of the pulses allows highly accurate predictions of their time of arrival to any reference point in the solar system. Scientists have developed detailed models that predict precisely when a pulse would arrive at, for example, the center of Earth. Timing the arrival of the pulse to a detector on a spacecraft, and comparing that to when it is predicted to arrive at a reference point, provides information for navigating far beyond our planet.

“Navigation information provided by pulsars does not degrade by moving away from Earth since pulsars are distributed throughout our Milky Way galaxy,” says SEXTANT team member Munther Hassouneh, navigation technologist.  

“It effectively turns the ‘G’ in GPS from Global to Galactic,” adds team member Jason Mitchell, director of the Advanced Communications and Navigation Technology Division in NASA’s Space Communication and Navigation Program. “It could work anywhere in the solar system and even carry robotic or crewed systems beyond the solar system.”

Pulsars also can be observed in the radio band but, unlike radio waves, X-rays are not delayed by matter in space. Additionally, detectors for X-rays can be more compact and smaller than radio dishes.

But because X-ray pulses are very weak, a system must be robust enough to collect a signal sufficient for navigating. NICER’s large collection area makes it nearly ideal for XNAV research. A future XNAV system could be made smaller, trading size for longer collection time.

“NICER is roughly the size of a washing machine, but you could dramatically reduce its size and volume,” Mitchell says. “For example, it would be interesting to fit an XNAV telescope into a small satellite that could independently navigate the asteroid belt and characterize primitive solar system bodies.”

As published in a 2018 paper, SEXTANT already has successfully demonstrated real-time pulsar-based navigation aboard the space station. It also studied the use of pulsars for time-keeping and clock synchronization and is helping expand the catalog of pulsars to use as reference points for XNAV.

The SEXTANT team also includes Samuel Price, Sean Semper and Wayne Yu at Goddard; Naval Research Lab partners Paul Ray and Kent Wood; and NICER principal investigator Keith Gendreau and science lead Zaven Arzoumanian.

The team now is studying the possibility of using XNAV autonomous navigation as a technique on NASA’s Gateway platform, to study support for crewed missions to Mars.

These kinds of experiments could bring cosmic lighthouses to guide spacecraft to their destinations another step closer to reality.

• For daily updates, follow @ISS_Research, Space Station Research and Technology News or our Facebook. Follow the ISS National Lab or information on its sponsored investigations. For opportunities to see the space station pass over your town, check out Spot the Station.

Melissa Gaskill

International Space Station Program Research Office

Johnson Space Center

{ https://www.nasa.gov/ }

08-08-2022 om 01:04 geschreven door peter  

Water in Ganymede’s atmosphere

Hubble Space Telescope finds evidence for water around Jupiter’s largest moon.

Depiction of Ganymede centered over 45° W. longitude.

Credit: National Oceanic and Atmospheric Administration

An international team of astronomers has used Hubble to peer into the atmosphere of Jupiter’s biggest moon, Ganymede – and find evidence for water vapour there.

More on  Ganymede

• Jupiter’s aurorae put the Earth’s to shame
• Summer on Saturn and an icy pole
• The biggest moon in the solar system

Ganymede is the biggest of our Solar System’s moons, with a diameter of 5,200km – 1.5 times bigger than our own satellite. It’s a cold world, made up of equal amounts of rock and water, with an ocean below the surface that may contain more water than all of Earth’s oceans combined.

But it’s also the largest body in the Solar System without any kind of substantial atmosphere. When the Voyager 1 spacecraft soared by in 1979, it didn’t detect any atmosphere, although a couple of decades later the Hubble Space Telescope managed to spot a very thin and tenuous one comprised primarily of oxygen molecules (O₂).

These molecules are thought to be created when charged particles and solar radiation hit the icy surface of Ganymede. This splits up the water molecules into various groups of molecules and atoms, including atomic hydrogen (H) and molecular oxygen. The lighter hydrogen is quickly lost, while the moon’s gravity holds onto the heavier oxygen molecules.

Astronomers have long suspected that there must be some water in Ganymede’s atmosphere, too, created from the same process on the surface. In particular, the icy surface “sublimates”, with ice turned directly into water vapour (H₂O) and skipping the liquid stage.

Modelling has suggested that H₂O should dominate the atmosphere at Ganymede’s subsolar point – that is, the warmest part of the atmosphere where the Sun’s radiation directly hits – while molecular oxygen dominates the rest.

Now, this new research has turned Hubble’s eyes back to the Jovian moon to settle this. The team, led by Lorenz Roth from the KTH Royal Institute of Technology in Sweden, used Hubble’s Cosmic Origins Spectrograph to study the chemical composition of Ganymede’s atmosphere.

Their findings were consistent with the modelling: spectral signatures indicated that H₂O was more abundant around the subsolar point, but O₂ was more abundant elsewhere.

• The result is published in Nature Astronomy.

The team notes that finding water in Ganymede’s atmosphere will inform future space missions, including the European Space Agency’s Jupiter Icy Moons Explorer (JUICE). Expected to reach the gas giant in 2031, JUICE will make several fly-bys of the moons before settling into orbit around Ganymede in 2034 for at least 280 days.

“Several science instruments are equipped to measure Ganymede’s neutral gas environment and particularly the H₂O abundance by remote sensing of UV, optical, infrared and submillimetre emissions, as well as in situ sensing with the neutral particle detector,” the authors explain in their paper.

“Our results place observational constraints on the contribution of sublimation to the atmosphere, and provide the JUICE instrument teams with valuable information that may be used to refine their observation plans.”

Read more:

• Jupiter’s moon Europa may glow in the dark
• Mystery solved: Jupiter’s X-ray aurora explained
• Hydrothermal vents on Saturn’s moon Enceladus may harbour life

{ https://cosmosmagazine.com/ }

08-08-2022 om 00:00 geschreven door peter  

60 Unsolved Mysteries That Cannot Be Explained

60 UNSOLVED MYSTERIES THAT CANNOT BE EXPLAINED – PREMIERED 2022

60 unsolved mysteries that cannot be explained | compilation.Today, we take a look at 60 unsolved mysteries that cannot be explained.

There is nothing more tantalising to the human species than a good mystery. Thrillers in the forms of novels, movies, and even campfire tales are often consumed by the thousands by those who love the adrenaline rush of solving a mystery. However, some of the most pervasive mysteries are those that occur in real life, and these are the ones that are often most difficult to solve. So today, here at unexplained mysteries, we take a look at these 60 unsolved mysteries that cannot be explained.

Thank you for watching!

Thank you to CO.AG for the background music!

RELATED VIDEOS, selected and posted by peter2011

{  https://beforeitsnews.com/ }

07-08-2022 om 23:16 geschreven door peter  

Elon Musk says Tesla would continue to do very well even if he was kidnapped by aliens or 'went back to my home planet' UFO Sighting News.

Date of announcement: Aug 6, 2022

 

During a live Tesla interview with Elon Musk, he stated that he is an alien from another planet. Now he says it with a smile and there is laughter, but I have long said he is an alien and not of this world. Here, he admits it 100%. 

Scott C. Waring - Taiwan 

"We have a very talented team here. So I think Tesla, you know, would continue to do very well even if I was kidnapped by aliens, or went back to my home planet," the Tesla CEO said at the firm's 2022 Cyber roundup meeting of stock owners. He was responding to a question from stockholder Gary Black, a managing partner of the Future Fund, concerning how Tesla's board would potentially handle his succession.

 

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

07-08-2022 om 21:47 geschreven door peter  

Plane Buzzes UFO Over Airport, El Paso, Texas, Aug 4, 2022, Video, UFO Sighting News.

Date of sighting: Aug 4, 2022
Location of sighting: El Paso, Texas, USA

 

Here is an interesting video from Texas, one of the top 3 UFO hotspots of America. Someone caught a UFO over the airport during sunset, then the UFO flew closer and began to pass over the neighborhood. He even said when he went to start his truck...it just would not start and had to leave it till morning. This has all the signs of a real UFO. 

Scott C. Waring - Taiwan 

 

Eyewitness states:

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

07-08-2022 om 21:44 geschreven door peter  

Farmers find large and rare pieces of China space junk in the Snowy Mountains, UFO Sighting News.

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

07-08-2022 om 21:39 geschreven door peter  

Out of the Blue - UFO Phenomenon ( VIDEOS )

Producer James Fox and his team travel the globe, interviewing eyewitnesses and high-ranking military & government personnel about their UFO knowledge and experiences. As narrator, actor Peter Coyote guides the viewer through these interviews and through new and historic film footage & information related to the UFO Phenomenon.

{  https://www.youtube.com/ }

07-08-2022 om 21:15 geschreven door peter  

Blue UFO filmed over Denver, Colorado 21-Jul-2022

This blue UAP or Orb was filmed in the night sky above Denver, Colorado on 21st July 2022.

Witness report: 

I was driving westbound on Evans near Zuni and I seen this blue orb looking object flying fast!

RELATED VIDEOS, selected and posted by peter2011

{ https://www.latest-ufo-sightings.net/ }

07-08-2022 om 21:01 geschreven door peter  

The Egyptian myth of intelligent giant snakes killed by a flying Death Star

A condensed version of an ancient Egyptian legend goes as follows: the wise servant tells his master how he survived the shipwreck and came ashore on a mysterious island where he met a great talking serpent who called himself the Lord of Punt. All good things were on the island and the sailor and the snake converse until a ship is hailed and he can return to Egypt.

A number of the myth’s fragments lead to some interesting reflections. The size of the enigmatic reptile is the first thing that strikes you as astonishing. The surviving sailor recounts his misadventures in this manner:

“The trees were cracking, the ground was shaking. When I opened my face, I saw that the serpent was approaching me. Its length is thirty cubits. His beard is more than two cubits long. His scales are of gold, his eyebrows are of lapis lazuli, his body is curved upwards.”

This myth’s serpent is quite fascinating. Signs point to him having a beard and eyebrows thick enough to resemble the legendary golden Chinese dragons of Chinese mythology. However, a little beard was occasionally depicted on sacred snakes in Egypt. Ancient Egyptian and East Asian traditions about enormous reptiles appear to be derived from the same source.

The second unusual thing you notice is that, there is a reference made in the legend to a particular star that was responsible for the death of the entire serpent family. This is what the last serpent told the man:

“Now since you have survived this accident, let me tell you of a tale of calamity that befell me. I once lived on this island with my family – 75 serpents in all without counting an orphan girl who was brought to me by chance and who was dear to my heart. One night a star came crashing down from heaven and they all went up in flames. It happened when I wasn’t there – I wasn’t among them. Only I was spared, and behold, here I am, utterly alone.”

What kind of star was it that burnt down seventy-five enormous creatures all at once? – let’s remember the size of the serpent. What an accurate and effective hit and what a powerful striking factor!

Let us recall another myth from ancient Egypt, in which Sekhmet, the dreadful eye of the deity Ra, is said to have severed the head of a giant snake or serpent Apep (also known as Apophis). Apep was viewed as the greatest enemy of Ra, and thus was given the title Enemy of Ra, and also “the Lord of Chaos”.

In this particular instance — the tale of Serpent Island — this destruction of serpents by a star resembles a real celestial punishment, in the literal sense of the word!

Let’s take a step back from the myth for a moment and concentrate on the specifics. The last surviving sailor describes waves of eight cubits, and he estimates the length of the snake to be thirty cubits. These are key comparative measurements that can be used to estimate the scale:

“And now the wind is getting stronger, and the waves are eight cubits high. And then the mast fell into the wave, and the ship was lost, and no one survived except me.”

In other words, based on the narrative, there can be no doubt regarding the size; the waves are big, and the snakes are at least three times larger than the waves. And with one swift strike from a certain “star,” all of this enormous “snake pit” of the seventy-five giant serpents is eradicated. It is clear that the explosion had a significant amount of power.

What struck the intelligent serpents? Somehow, it is difficult to accept a “crazy” asteroid hitting at random.

There is no doubt that ancient sources that tell about the history of peoples often include fictional tales in their folklore. We believe that this story parallels the ancient mythology of peoples that lived a long way from Egypt, where gods or heroes fought with reptiles or dragons in ancient stories. Why were such myths popular among ancient cultures?

 

07-08-2022 om 18:26 geschreven door peter  

Humans have been in the Arctic for over 40,000 years, new discoveries reveal

BY NEIL EN

The discovery was made by scientists from the Siberian Section of the Russian Academy of Sciences (СО РАН) conducted radiocarbon analyses of reindeer antler fragments found at the Kushevat Paleolithic site in the Lower Ob region.

In addition to the antler bones, scientists also examined a woolly mammoth (Mammuthus primigenius), a steppe bison (Bison Priscus), Elk (Alces alces), deer (Cervus elephus sibiricus), and, potentially, a musk ox (Ovibos moschatus). Analyses of the bones dated them back to a series of 20 different radiocarbon dates, all ranging from the period between 20 and 40 thousand years ago.

Although this finding solely points to animals, and not humans, inhibiting the Arctic region 40,000 years back, the discovery has now become the basis of further analyses, which currently date human activity in the Ob region back to 40,000 years ago. This is because two reindeer antlers held traces of human activity amongst this group of bones, which have only recently been analyzed.

The question of the initial settlement of the Arctic and Subarctic by an ancient man of the modern type (Homo sapiens sapiens) has long been of interest to scientists. The valley of the Ob River is often considered a potential migration route for Paleolithic man. It is believed that modern man came to Europe and Asia 50,000-60,000 thousand years ago.

What is still unclear is where the modern man lived before and how he crossed the Urals? For a long time, the hypothesis prevailed that 12,000-30,000 years ago, the north of Western Siberia was covered by a large glacier (just like the north of America and Europe). To the south of this glacier was a dammed basin reaching 130 meters.

For this reason, it was believed that looking for archaeological sites dating back to the period of 30-40 thousand years ago in the north was pointless. It was confirmed by the almost complete absence of finds (tools, sites, organic matter).

Thanks to the international research program using AMS dating and optical-stimulating luminescence, researchers from Europe and Russia proved that there was no ice cover in the north of Western Siberia 12,000-30,000 years ago. It was much earlier: 90,000-60,000 years ago north of Salekhard. The level of the ice-dammed basin in the Ob valley did not exceed 60 meters.

This is an entirely different paleogeographic picture. For thirty years, I was convinced that in the north of Western Siberia, there were all the conditions for the existence of an ancient person. Now we had the opportunity to try to prove it: to find traces of Homo sapiens in the north of the Ob 30,000-50,000 years ago, – the project manager, head of the laboratory of the Institute of Geology and Mineralogy named after V.I. V.S commented in a press statement.

As reported by the Barents Observer “the analysis suggests that Homo sapiens and not only Neanderthals inhabited the Arctic Circle in the Upper Paleolithic age. About two decades ago, it was only certain that Neanderthals, and not Homo sapiens, were occupants in the region during the period.”

This was discovered by radiocarbon dating a set of bones unearthed in 2001 at the Yakutia site. The radiocarbon analysis suggested that the Neanderthals had found themselves in the region approximately 28,500-27,000 years ago.

The new AMS analysis has hence provided two major breakthroughs. The first one is that Homo sapiens, as well as Neanderthals, inhabited the Arctic circle during the Paleolithic Age, and the second finding is that Homo sapiens lived north of the Arctic circle already 40,000 years ago.

{ https://mysteriesrunsolved.com/ }

07-08-2022 om 18:15 geschreven door peter