UFO'S of UAP'S, ASTRONOMIE, RUIMTEVAART, ARCHEOLOGIE, OUDHEIDKUNDE, SF-SNUFJES EN ANDERE ESOTERISCHE WETENSCHAPPEN

This graphic shows all of the potentially hazardous asteroids (and their orbital paths) around Earth (not to scale). As of 2013, scientists had counted over 1,400 of these potentially hazardous asteroids.

Credit: NASA/JPL-Caltech

Earth is hit every day by small bits of space dust. Slightly larger chunks burn up colorfully in the atmosphere, causing the shooting stars you see in the sky. Occasionally even bigger rocks hit our atmosphere; they are known as fireballs, because the light from them burning up is particularly bright. These tend to smack the Earth a few times a year and may produce a few fragments for rock-hunters to find.

NASA and other organizations do regular scans of the sky to catalog any small bodies that are at risk of crashing into our planet. No imminently threatening bodies have been found yet, but it's clear that sooner or later Earth will be struck by something big. The organizations are actively researching the best ways to protect Earth from asteroids, meteoroids or comets that may come crashing down

Asteroids refer principally to small, rocky bodies. Comets contain more ice and can also pose a threat to Earth. Before fragments enter our atmosphere, they are known as meteroids. During their path in the atmosphere, they are called meteors. If any of these pieces reach the ground, those pieces are called meteorites. The best hunting ground on Earth for meteorites is Antarctica because the ice makes it so easy to see the fragments, and the ground is not disturbed as much as a typical urban area or forest.

The difference between a meteroid and an asteroid is a little vague. In 1961, The International Astronomical Union (the official body for naming objects in space) said a meteroid is much smaller than an asteroid, but bigger than an atom. A 2010 Meteoritics and Planetary Science paper led by Alan Rubin, a geophysicist at the University of California, Los Angeles, suggested that the limit for meteoroids be about 1 meter in size.

**This is the trail of Chelyabinsk asteroid which exploded about 14 miles above ground with a force nearly 30 times more powerful than the Hiroshima atomic bomb in 2013.**
**Credit: Neuromainker via YouTube/Screenshot by Irene Klotz for Discovery News**

Characterizing the threat

It is clear that even small bodies can pose a threat; the asteroid that broke up over Chelyabinsk, Russia, in 2013 was roughly 56 feet (17 meters) across, shattering glass and injuring hundreds of people. In 1908, an estimated 130-foot (40-meter) object exploded over Siberia and flattened trees over 825 square miles (2,137 square kilometers). Around 50,000 years ago, before human civilization began, a rock about 150 feet wide (46 meters) smacked into what is now called Arizona. It left behind Meteor Crater, which is roughly 0.7 miles (1.2 kilometers) wide today.

Even bigger collisions happened far in the past. The dinosaurs were wiped out 66 million years ago by an object about 6 miles (10 km) wide, which left behind a 110-mile (180 km) crater in Mexico known as Chicxulub. But that's nothing compared to evidence of another impactor found in 2014. A rock formation in our planet's crust pointed to a possible impactor 23 to 36 miles (37 to 58 kilometers) across that smacked into Earth 3.26 billion years ago, just a few million years after life evolved.

NASA began tracking near-Earth objects (NEOs) in the 1970s. Its goal is to find objects that are at least tens of meters in size, “which could cause significant harm to populated areas on the Earth if they were to strike without warning,” NASA stated in 2014.

Congress directed NASA in 1994 to find at least 90 percent of potentially hazardous NEOs larger than 0.62 miles (1 kilometer) in diameter, which NASA fulfilled in 2010. Congress also asked NASA in 2005 to find at least 90 percent of potentially hazardous NEOs that are 460 feet (140 meters) in size or larger. That's supposed to be finished by 2020. NASA created a Planetary Defense Coordination Office in 2014 — a year after Chelyabinsk — to better coordinate its efforts, in response to an Office of the Inspector General report. Other space agencies such as the European Space Agency also have their own offices, and the different nations regularly collaborate with each other.

An artist's concept for the Asteroid Impact & Deflection Assessment (AIDA) mission led by the European Space Agency to intentionally strike an asteroid and test deflection capabilities that could protect Earth.
**Credit: ESA**

Scanning the sky

NASA works with several sky surveys to maintain a list of potentially hazardous objects. These include the Catalina Sky Survey (University of Arizona), Pan-STARRS (University of Hawaii), Lincoln Near-Earth Asteroid Research or LINEAR (Massachussetts Institute of Technology) and Spacewatch (University of Arizona). These observatories are constantly upgrading their capabilities to try to catch fainter asteroids.

Asteroids are also observed from space by several telescopes, but the one most regularly used for NEO searches is called NEOWISE. It's the new mission of the Wide-field Infrared Survey Explorer (WISE) telescope, which launched in 2009 and was revived from hibernation in 2013 to search for asteroids. The telescope is expected to keep operating until 2017, when the angle from the sun in its orbit will be too bright to search for asteroids. A follow-up mission called Near Earth Object Camera (NEOCam) has been proposed for 2021, but is competing against five other missions for funding. Mission selection will be announced in September 2016.

There are other NASA missions that are looking to get up close to asteroids to better characterize their composition. Some recent examples: The Dawn mission visited asteroid Vesta between 2011 and 2012, and has now been at Ceres (a dwarf planet) since 2015. OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is expected to depart for asteroid Bennu in 2018 for a sample-return mission, which will come back to Earth in 2023. Additionally, NASA uses data available from other space agency missions that visited asteroids, such as the Japanese Hayabusa (completed) and Hayabusa 2 (in progress).

Some planned missions will take even more daring steps at asteroids. NASA has been working on concepts for an Asteroid Redirect Mission (ARM) that would have a robot move a small body into the moon's orbit, for astronauts to study. Also: NASA, the European Space Agency and other partners are planning a mission called AIDA, or Asteroid Impact and Deflection Assessment. The goal is to change the path of a small moon orbiting the asteroid Didymos using a kinetic impactor.

A kinetic impactor (perhaps with a nuclear bomb inside) would deflect the orbit, tugging the asteroid slowly using a spacecraft, redirecting it with solar heat, or blasting it with a laser. That is just one idea. There is ongoing research as to what sort of asteroid deflection technique would be best. The best approach depends on many factors, such as cost, the composition of the asteroid, time to impact and technology maturity. Studies are ongoing in these fields; in 2007, NASA said that non-nuclear kinetic impactors had the most mature technology.

IN BRIEF

Physicists assert that they have observed quantum spin liquid state again; however, this time, they have done so in a material where it was thought to be impossible. If verified, it could transform how we understand quantum computing.

Back in April, the physics world freaked out when scientists confirmed that they’d made the first direct observation of a brand-new state of matter – known as quantum spin liquid – for the first time.

But now a team of physicists has just announced that they’ve observed quantum spin liquid state again… and this time in a material where it should be impossible.

The discovery could change our understanding of how to make quantum computing work.

“We have proved empirically that interesting quantum states like spin liquids can also occur in considerably more complex crystals with different constellations of magnetic interactions,”said lead researcher Christian Balz, from the Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) in Germany.

“This could be important for the advancement of quantum computers in the future because spin liquids are one of the possible building blocks for carrying the smallest unit of quantum information, known as a qubit,” added one of the senior researchers Bella Lake.

Let’s back up a second, because all this isn’t as confusing as it sounds.

WHAT IS QUANTUM SPIN?

Spin in the quantum world doesn’t actually mean an electron is physically spinning. It refers to a type of intrinsic angular momentum that simply describes how an electron is behaving. In quantum computing we often simplify this by saying the spin state is down, up, or in superposition (both at the same time).

Quantum spin liquid is a state of matter that, very simply, occurs when the spin of electrons continue to fluctuate in a fluid manner even at very low temperatures, when they should be frozen in place.

It’s like atoms inside regular materials. When they’re in a fluid state, they’re moving freely. But when temperatures drop, they’ll freeze in place in a solid arrangement. That should happen with spin orientation in magnetic materials, but in quantum spin liquid state, it doesn’t.

Even though it was predicted in 1973, the new state of matter was only observed for the first time this year, in a two-dimensional, graphene-like material.

That discovery made a lot of sense, because the material fit our understanding of how spin liquid state arises.

Basically, the criteria is that a material has to have has anti-ferromagnetic – or antiparallel – interactions, which, as the name suggests, is the opposite to ferromagnetic interactions in materials such as iron and nickel.

It means that if one electron has a ‘down’ spin, the one next to it has to have an ‘up’ spin, and so on.

Anti-ferromagnetic materials on their own don’t necessarily enter quantum spin liquid state, unless they also happen to have a triangular atomic arrangement, which makes this alignment impossible.

So, just imagine three atoms at the corner of a triangle – they’re never all going to be in parallel alignments because as soon as one changes to match the one to its right, the one on its left will have to change, and so on and so on. They’ll keep flipping their alignment even at absolute zero temperature – hence, quantum spin liquid state.

But the new research suggests that our criteria isn’t quite right, because the German team were able to observe the new state of matter occurring in a material that doesn’t fit that profile.

THE IMPOSSIBLE SPIN?

The material in question is a monocrystal of calcium chromium oxide (Ca10Cr7O28).

Calcium-chromium oxide is made up of what are known as Kagomé lattices – named after the pattern of triangles and hexagons woven in Japanese baskets.

Basically that means the material has a complex mix of anti-ferromagnetic interactions, but also much stronger ferromagnetic interactions, which, according to conventional understanding, should prevent quantum spin liquid behaviour.

But through a range of scattering and spectrometry experiments in Germany, France, England, Switzerland, and the US, the team was able to show that this wasn’t the case – quantum spin liquid state was happening even at temperatures as low as 20 millikelvin (around –273 degrees Celsius).

So what’s going on here? Fortunately, the team has already come up with a hypothesis to explain why this material could behave like a quantum spin liquid without breaking our conventional understanding of the state of matter.

Using numerical simulations, they’ve shown that competition is the key to the strange behaviour – different magnetic interactions in the materials are competing with each other, and keeping the spins flip-flopping around.

You can see that happening in the illustration below, which shows the competing interactions on each atom (the grey and black balls). The green and red sticks represent ferromagnetic interactions, while the blue sticks represent anti-ferromagnetic interactions, which are forcing the spins to keep changing.

HZB

“The work expands our understanding of magnetic materials, and also shows us that there are potentially far more candidates for spin liquids than expected,”said Lake.

The research has been published in Nature Physics, and now needs to be verified by other teams before we say for sure that quantum spin liquid state can exist in these new types of materials.

But it’s a pretty exciting study that hugely widens the potential pool of materials that we could use in future to build quantum computers.

We can’t wait to find out more.

Science Alert Read more articles from Science Alert

{ http://futurism.com/ }