NASA's falling six tonne satellite, could land anywhere

NASA has been watching the six tonne satellite closely.  Officials yesterday moved up their prediction for its arrival to Friday, September 23, give or take a day.

Nasa scientists have calculated the satellite will break into 26 pieces as it gets closer to Earth.  The odds of it hitting someone anywhere on the planet are one in 3,200.

The heaviest piece to hit the ground will be about 159kgs (350 pounds) but no one has ever been hit by falling space junk in the past.

Nasa expects to give the public more detailed information early next week. For now, all continents except Antarctica could be hit by satellite debris.

[http://www.metro.co.uk/news/875770-six-tonne-satellite-falling-to-earth-could-land-anywhere]

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Super-massive black hole shreds a star, first time caught on camera

A stunning cosmic jet from a super-massive black hole which shredded then swallowed a star has been captured by astronomers for the first time.

The rare event - one of the most powerful forces in the universe - shows streams of plasma pouring out of the ghostly space monster at the centre of a far off galaxy almost four billion light years from Earth.

The onset of such a spectacular display caused by stellar debris being consumed by the hole has never been observed before.

Known scientifically as 'relativistic jets', they can reach hundreds of thousands of light years in length.

Most galaxies have super-massive black holes - regions of space that suck in everything nearby with their strong gravitation pull - at their core, with masses of millions or even billions of suns.

The destruction of the star was spotted by the Swift Telescope in March after it wandered too close to the huge black hole.

Read more: http://www.dailymail.co.uk/sciencetech/article-2029731/relativistic-jets-Moment-super-massive-blackhole-shreds-star-caught-camera.html

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Space tourism company opens and looking for astronauts

Virgin Galactic is looking for pilots with at least 3,000 hours of flight to become astronauts. Experience in space will be a plus.

Virgin Galactic is a company founded by Sir Richard Branson to conduct commercial flights into space. They are currently in the process of recruiting astronauts.

The company is looking for pilots to operate their craft, called SpaceShipTwo. In addition, the aircraft, WhiteKnightTwo, will carry the spacecraft to the proper launch altitude.

The teams selected would have to fly during the testing phase, currently in progress, and in the commercial operations once they have started.

The company is looking for test pilots who have graduated from reputable flight schools, and with a minimum of 3,000 hours of flight experience. Experience in space will be an advantage, but not necessary.

Virgin Galactic plans to take tourists into space for short suborbital flights at a price of $200,000 (£ 300,000) per person.

SpaceShipTwo is based on the design of SpaceShipOne, the first spacecraft to have proven the feasibility of placing a human being into space.

Source - Pravda

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Russia plans to send a monkey to Mars

Russian scientists have revealed that a monkey may be sent to Mars. Previously, Russia has a long history of scientific discovery and space exploration through the use of animals.

Although the ape will be looked after by a robot on the mission, the decision is expected to spark controversy with animal rights groups.

To this end, monkeys at the Sochi Institute of Medical Primatology, at Vesyoloye near the Black Sea, have begun the selection process for the ultimate medical animal testing experiment. The institute has a long history of involvement in the Russian and Soviet space program. Sochi was the training facility for the first monkeys into space in 1983.

“We have plans to return to space,” said Zurab Mikvabia, director of the Institute of Experimental Pathology and Therapy in Georgia which supplied apes for the programme in the 1980s.

The Institute is in preliminary talks with Russia's Cosmonautics Academy about preparing monkeys for a simulated Mars mission that could lay the groundwork for sending an ape to the Red Planet, he said.

Such an initiative would build on Mars-500, a joint Russian-European project that saw six human volunteers confined in a capsule in Moscow for 120 days earlier this year to simulate a Mars mission.

Mr Mikvabia said: "Earlier this programme was aimed at sending cosmonauts, people (to Mars).

"But given the length of the flight to Mars, and given the cosmic rays for which we don't have adequate protection over such a long trip, discussions have focused recently on sending an ape instead of a person."

Estimates for the length of the journey to Mars vary depending on the type of mission envisioned, but the European Space Agency says its proposal for a round-trip mission would take 520 days, or about a year and a half.

Mars-500 director Viktor Baranov says 520 days "are enough for the flight to Mars - 250 days to fly there, 250 days to come back and a month for the landing on Mars".

Today Russia is one of the few countries where experiments on primates are carried out.

"Humanity sacrifices more than 100 million animals a year in the name of health and beauty. It's time to think of an alternative to experiments with animals," says Andrei Zbarsky of the international nature conservation group WWF.

The Institute said a robot would accompany the first primate to Mars to feed and look after the ape.

Mr Mikvabia said: "The robot will feed the monkey, will clean up after it. Our task will be to teach the monkey to co-operate with the robot."

"I'm sure scientists will repeat the story of Laika, the first dog in space. Today it's no secret that the dog died from the nervous stress immediately after the rocket launch and its dead body revolved in orbit for two weeks."

Mr Lapin admits that his institute has received some objections from European colleagues concerned about the animal experiments.

A researcher at the institute, Anaida Shaginyan, says "certainly, I feel sorry for the monkeys, they might die, but the experiments are necessary to preserve the lives of the cosmonauts who will fly to Mars in future".

Via - Telegraph & BBC

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Russian X-ray telescope that will open up new space objects

[ScienceNology] - International Orbiting Astrophysical Observatory «Spectrum-Roentgen-Gamma» (AWG) will be equipped Russian X-ray telescope that will open up new space objects.

The project agreement was signed by the AWG at the international air space between the Federal Space Agency (Roskosmos) and the German Aerospace Center (DLR). AHWG Observatory is scheduled to start in 2012 for a term of seven years. It is designed to survey the entire sky specular X-ray telescopes in the hard energy range (0,5-11 keV). Review will be a record due to its high sensitivity, which is a large effective area of mirror systems, high angular resolution optics and extremely large telescopes for such a field of view.

As the press service of the Institute for Space Research (IKI), with the new X-ray Observatory to be found about 100 thousands of new galaxy clusters and more than 3 million new active nuclei of galaxies in the center of which, presumably, are superheavy black holes. Information about large-scale structure of the universe, obtained on the basis of clusters of galaxies is crucial to study its evolution, including, for the understanding of the role it played in the so-called «dark energy». In addition, based on data on AHWG nuclei of active galaxies can be studied the growth and evolution of superheavy black holes.

Earlier X-ray review of the entire sky was made by the satellite ROSAT (Germany / United States / United Kingdom, 1990-1999), but only in the «soft» (0,5-2 keV) energy range and the worst, about 40 times the sensitivity. Because of the strong interstellar or internal absorption at low energies, many interesting X-ray sources were not detected.

The observatory will be equipped with a two AHWG specular X-ray telescopes: eROSITA (Germany) - the basic tool for the mission weighing 760 kg, which works in the energy range 0,5-10 keV, and the unit ART-XC (Russia), weighing 350 kg, supplementary tool in a German hard energy range 6-30 keV.

Orbit, which will work Observatory (in the vicinity of the point of L2) - one of the five existing in the sun - the Earth points where the perturbing gravitational effects on the spacecraft from the Sun and the Earth reduced to a minimum. Point L2 (Libration point) is located on the sun - the Earth at 1.5 million miles of Earth.

First, the observatory will not pass through the Earth's radiation belts, which have to disconnect the equipment from the damaging effects of the flow of charged particles in the electronic components of devices. Secondly, here the most comfortable temperature, because the sun is always located on the one hand, to the Earth to the Moon and very far away, and the heat flow from them do not make any perturbation, temperature at which the work equipment is stable. Finally, the apparatus of the orbit does not go into the Earth's shadow, and solar panels will be able to ensure energy devices.

Home Organization for scientific equipment Observatory - IKI. According to ground-and space complex «AHWG» parent organization - the Scientific-Production Association to them. SA Lavochkin. The project also involved the Russian Federal Nuclear Center - All-Russian Scientific Research Institute of Experimental Physics (Sarov), in cooperation with the IKI is developing the telescope ART-XC. On the German side of the project involved the German Aerospace Center, Institute for Extraterrestrial Physics, and several other institutions of society to them. Max Planck and universities.

Source :  Science and life , 20 August 2009

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Scientists for the first time were able to measure the depth of sunspot

[ScienceNology] - Astronomers from the University of Glasgow for the first time measured the depth of sunspots. This was reported in the press release on the university site, and the work of researchers has never been published.

Back in 1769 a professor at the University of Glasgow, Alexander Wilson (Alexander Wilson) discovered that sun-spots seem to be concave. This observation was made in the study of spots on the boundary of the solar disk. However, until recently, remained unclear - whether this is just a feature of the observations or stains really has depth.

In the new study, scientists examined the data collected by the mission SOHO. This device was launched in 1995 specifically for observing the Sun and he was able to obtain a large number of photographs lights during the peak of his activity (at present, light is gradually emerging from an abnormally long period of calm).

First, using the observational data more than 25 thousand spots, the researchers built a computer model of these entities. Then, using the obtained models, the astronomers found that the central regions of spots are located about 1500 kilometers below the top. According to researchers, the new findings useful for the creation of improved models of processes occurring on the Sun.

Source : Science and Technology Russia , 21 August 2009

Photo credit to Wikipedia , Sunspots imaged on 2004-06-22

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Pakistan to launch first satellite in 2011

Dr Samar Mubarakmand, a renowned Pakistani nuclear scientist, said that Pakistan would launch its first space satellite in April 2011, local media reported Tuesday.

Talking to a private TV channel on Tuesday, Dr Samar said the satellite, likely to be sent into earth orbit, would monitor mineral and agriculture programs and weather conditions.

He said this project is funded by the Pakistani Planning Commission and there is no scarcity of funds for nuclear and space projects of the country.

Dr Samar said the country's nuclear program was not inferior to any other country in its standard and proficiency.

Dr Samar is a nuclear scientist and nuclear physicist, and was the chairman of Pakistan's National Engineering and Scientific Commission in 2001-2007, according to local news agency NNI.

He largely contributed to the nuclear program of Pakistan and he was awarded three highest civil awards of the country. He got the national fame in May 1998 when he headed the scientists' team which conducted the six nuclear tests in southwest Pakistan's Balochistan province.


A News from China View , 18 August 2009

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Tower of Pisa discovered on Saturn Rings

Planet Saturn has a prominent system of rings, consisting mostly of ice particles with a smaller amount of rocky debris and dust. NASA’s Cassini spacecraft has recently discovered new objects and strange shadows on the rings.

The unusual objects were detected due to a sharp angle of sunlight cast on the rings. Cassini captured the object shaped as a tower on the outside edge of the F ring.

Cassini is a joint robotic spacecraft mission currently studying planet Saturn and its moons.

The shadow cast by the object implies that it is protruding upwards for about 2 kilometers. The object is a little bit inclined that’s why the scientists called it the Tower of Pisa.

However, the object has nothing in common with real towers. By the astronomers’ opinion, the object appeared after a cosmic body, an asteroid or a big meteorite, passed through the ring.

The ‘tower’ can be clearly visible with the aided eye now, due to the advantageous sunlight. This happens once in 15 years. Moreover, this object is not unique. The scientists spotted similar objects on other rings.

Earlier Cassini captured a strange shadow cast on the Saturn rings, though quickly found the source. The shadow was cast by the inner moon of Saturn, Mimas (about 396 kilometers in diameter), NASA said.


Source : Pravda.ru

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India and Russia complete design of new lunar probe

India and Russia have finished the design of a second unmanned lunar orbiter to be sent to the Moon in 2011-2012, the Indian Express newspaper said on Monday.

The paper quoted Madhavan Nair, chairman of the Indian Space Research Organization (ISRO) as saying in Bangalore on Sunday: "Right now, the design has been completed. We had a joint review with Russian scientists here."

"Next...we will go towards prototype building, which will be taken up next year," Nair said.

Chandrayaan-2 is the second Indian mission to the moon that "would have an orbital flight vehicle constituting an Orbital Craft (OC) and a Lunar Craft (LC) that would carry a soft landing system up to Lunar Transfer Trajectory (LTT)," the Indian space official said.

Russia is responsible for the design and construction of a lander and a rover, which could collect samples of the lunar soil, analyze them and send the data back to Earth.

The ISRO and the Russian Federal Space Agency signed in November 2007 an agreement to work together on the Chandrayaan-2 project.

The work started following the launch of India's first unmanned mission to the moon, the Chandrayaan-1, in October last year.

The successful launch of the Chandrayaan-1 on board the Indian-built PSLV-C11 rocket saw India become the third Asian country to send an unmanned probe to the Earth's largest satellite after Japan and China.

The 1,304-kg spacecraft is equipped with 10 scientific instruments to study the Moon from a 100-km orbit. Five of the instruments were built in India, while the other five were the result of cooperation with Europe and the United States.

During the two-year mission, the remote-sensing satellite is expected to create a detailed three-dimensional map of the Moon's surface and investigate its chemical composition. The primary goal is the discovery of water, along with magnesium, aluminum, silicon and titanium, and the radioactive elements radon, uranium and thorium.

The ISRO chief said on Sunday that 95% of the scientific objectives of the Chandrayaan-1 mission had been achieved despite the failure of the spacecraft's on-board star sensor earlier this year.



A news from Rianovosti , 17 August 2009

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Big Wave Theory Offers Alternative to Dark Energy

Mathematicians have proposed an alternative explanation for the accelerating expansion of the universe that does not rely on the mystifying idea of dark energy.

According to the new proposition, the universe is not accelerating, as observations suggest. Instead, an expanding wave flowing throughout space-time causes distant galaxies to appear to be accelerating away from us. This big wave, initiated by the Big Bang that is thought to have sparked the universe, could explain why objects appear to be farther away from us than they should be according to the Standard Model of cosmology.

"We're saying that maybe these expanding waves are actually causing the anomalous acceleration," said Blake Temple of the University of California, Davis. "We're saying dark energy is not really the correct explanation."

The researchers derived a set of equations describing expanding waves that fit Einstein's theory of general relativity, and which could also account for the apparent acceleration. Temple outlines the new idea with Joel Smoller of the University of Michigan in the Aug. 17 issue of the journal Proceedings of the National Academy of Sciences.

While more research will be needed to see if the idea holds up, "the research could change the way astronomers view the composition of our universe," according to a summary from the journal.

To convince other cosmologists, the new model will have to pass muster with further inquiry.

"There are many observational tests of the standard cosmological model that the proposed model must pass, aside from the late phase of accelerated expansion," said Avi Loeb, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics. "These include big bang nucleosynthesis, the quantitative details of the microwave background anisotropies, the Lyman-alpha forest, and galaxy surveys. The authors do not discuss how their model compares to these tests, and whether the number of free parameters they require in order to fit these observational constraints is smaller than in the standard model. Until they do so, it is not clear why this alternative model should be regarded as advantageous."

Inconvenient truths

Dark energy is itself a hasty fix to an inconvenient truth discovered by astronomers in the late 1990s: that the universe is expanding, and the rate of this expansion seems to be constantly picking up speed.

To explain this startling finding, cosmologists invoked dark energy, a hypothetical form of energy that is pulling the universe apart in all directions (note that dark energy is wholly separate from the equally mysterious concept of dark matter - a hypothetical form of matter that populates the universe, interacting gravitationally with normal matter, but which cannot be seen with light). In this interpretation, the whole universe is blowing up like a balloon, and from any given point within it, all distant objects appear to be speeding away from you.

But not everyone is happy with the dark energy explanation.

"It just seems like an unnatural correction to the equations - it's like a fudge factor," Temple told SPACE.com. "The equations don't make quite as much physical sense when you put it in. You just put it in to fit the data."

Temple thinks the idea of an expanding wave makes more sense.

"At this stage we think this a very plausible theory," he said. "We're saying there isn't any acceleration. The galaxies are displaced from where they're supposed to be because we're in the aftermath of a wave that put those galaxies in a slightly different position."

Ripples in a pond

Temple compared the wave to what happens when you throw a rock into a pond. In this case, the rock would be the Big Bang, and the concentric ripples that result are like a series of waves throughout the universe. Later on, when the first galaxies start to form, they are forming inside space-time that has already been displaced from where it would have been without the wave. So when we observe these galaxies with telescopes, they don't appear to be where we would expect if there had never been a big wave.

One potential issue with this idea is that it might require a big coincidence.

For the universe to appear to be accelerating at the same rate in all directions, we in the Milky Way would have to be near a local center, at the spot where an expansion wave was initiated early in the Big Bang when the universe was filled with radiation.

Temple concedes that this is a coincidence, but said it's possible that we are merely in the center of smaller wave that affects the galaxies we can see from our vantage point - we need not be in the center of the entire universe for the idea to work.

By Clara Moskowitz , Space.com staff writer


Source : Space.com , 17 August 2009

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The First Discovery of Life's Building Block in Comet

<-- Red/green stereo anaglyph of Comet Wild 2: Courtesy NASA

NASA/Goddard Space Flight Center reported that scientists said on Monday, 17 August 2009, The amino acid glycine, a fundamental building block of proteins, has been found in a comet for the first time. And this also supports the theory about life arrived from outerspace.

Amino acids are known as the building blocks of life. The 20 amino acids known to exist can be combined to form millions of different proteins.

Experts say they have developed tests that rule out the possibility that the amino acid originated on Earth. They said the glycine collected from the comet has an extraterrestrial carbon isotope signature that indicates it originated on the comet.


By: Bill Steigerwald

NASA scientists have discovered glycine, a fundamental building block of life, in samples of comet Wild 2 returned by NASA's Stardust spacecraft.

"Glycine is an amino acid used by living organisms to make proteins, and this is the first time an amino acid has been found in a comet," said Dr. Jamie Elsila of NASA's Goddard Space Flight Center in Greenbelt, Md. "Our discovery supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts."

Elsila is the lead author of a paper on this research accepted for publication in the journal Meteoritics and Planetary Science. The research will be presented during the meeting of the American Chemical Society at the Marriott Metro Center in Washington, DC, August 16.

"The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare," said Dr. Carl Pilcher, Director of the NASA Astrobiology Institute which co-funded the research.

Proteins are the workhorse molecules of life, used in everything from structures like hair to enzymes, the catalysts that speed up or regulate chemical reactions. Just as the 26 letters of the alphabet are arranged in limitless combinations to make words, life uses 20 different amino acids in a huge variety of arrangements to build millions of different proteins.

Stardust passed through dense gas and dust surrounding the icy nucleus of Wild 2 (pronounced "Vilt-2") on January 2, 2004. As the spacecraft flew through this material, a special collection grid filled with aerogel – a novel sponge-like material that's more than 99 percent empty space – gently captured samples of the comet's gas and dust. The grid was stowed in a capsule which detached from the spacecraft and parachuted to Earth on January 15, 2006. Since then, scientists around the world have been busy analyzing the samples to learn the secrets of comet formation and our solar system's history.

"We actually analyzed aluminum foil from the sides of tiny chambers that hold the aerogel in the collection grid," said Elsila. "As gas molecules passed through the aerogel, some stuck to the foil. We spent two years testing and developing our equipment to make it accurate and sensitive enough to analyze such incredibly tiny samples."

Earlier, preliminary analysis in the Goddard labs detected glycine in both the foil and a sample of the aerogel. However, since glycine is used by terrestrial life, at first the team was unable to rule out contamination from sources on Earth. "It was possible that the glycine we found originated from handling or manufacture of the Stardust spacecraft itself," said Elsila. The new research used isotopic analysis of the foil to rule out that possibility.

Isotopes are versions of an element with different weights or masses; for example, the most common carbon atom, Carbon 12, has six protons and six neutrons in its center (nucleus). However, the Carbon 13 isotope is heavier because it has an extra neutron in its nucleus. A glycine molecule from space will tend to have more of the heavier Carbon 13 atoms in it than glycine that's from Earth. That is what the team found. "We discovered that the Stardust-returned glycine has an extraterrestrial carbon isotope signature, indicating that it originated on the comet," said Elsila.

The team includes Dr. Daniel Glavin and Dr. Jason Dworkin of NASA Goddard. "Based on the foil and aerogel results it is highly probable that the entire comet-exposed side of the Stardust sample collection grid is coated with glycine that formed in space," adds Glavin.

This is an artist's concept of the Stardust spacecraft beginning its flight through gas and dust around comet Wild 2. The white area represents the comet. The collection grid is the tennis-racket-shaped object extending out from the back of the spacecraft. Credit: NASA/JPL -->

"The discovery of amino acids in the returned comet sample is very exciting and profound," said Stardust Principal Investigator Professor Donald E. Brownlee of the University of Washington, Seattle, Wash. "It is also a remarkable triumph that highlights the advancing capabilities of laboratory studies of primitive extraterrestrial materials."

The research was funded by the NASA Stardust Sample Analysis program and the NASA Astrobiology Institute. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Stardust mission for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, developed and operated the spacecraft.



Source from NASA/Goddard Space Flight Center

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Huge Storm Detected on Titan

<-- This image of the clouds on Titan (bright area, lower right) was taken with the Gemini North telescope adaptive optics system on April 15, 2008. Credit: Gemini Observatory/AURA; E. Schaller et al.

A paper that describes the first storm observed in the tropical latitudes of Saturn's moon Titan will be published in the journal Nature on August 13. The rain from large clouds such as these is actually liquid methane and may be responsible for forming the channels and other features near the equator observed by the Huygens probe in 2005. The lead author, Dr. Emily Schaller, wrote the paper while working as a Hubble Fellow at the University of Hawaii, Institute for Astronomy.

The huge storm, observed with the NASA Infrared Telescope Facility and the Gemini North telescope on Mauna Kea, Hawaii, covered over almost 1.2 million square miles (three million square kilometers, about the size of India). While the diameter of Earth is 7,926 miles (12,756 km), Titan’s is 3,193 miles (5,150 km), just slightly larger than Mercury, the smallest planet in our solar system.

Titan is the only moon in the solar system with a thick atmosphere, and like Earth, it has a weather cycle, including clouds and rain. However, on Titan, the substance that forms clouds and rains down on the surface is not water but methane (natural gas). It is so cold on Titan (-288°F,
-178°C) that methane is a liquid, and there are “boulders” made of frozen water rather than rock.

Clouds on Titan are generally much smaller and occur much more infrequently than on Earth, which led scientists to wonder how the rivers and channels seen by the Cassini spacecraft and the Huygens probe were formed. “After three years of observing Titan and finding little to no cloud activity, Titan suddenly put on quite a show,” quipped Schaller.

Unlike the large channels on Mars, which were probably carved millions or billions of years ago by liquid water, Titan’s carved surface features, like those on Earth, are still being formed today. Observations over the next several years by telescopes on Earth and by instruments aboard Cassini will continue to reveal more clues about the meteorology and geology of this world, which has many similarities to our own.

The Cassini-Huygens mission was launched in 1997 and arrived at Saturn in July 2004. Cassini completed its initial four-year mission to explore the Saturn system in June 2008. It is now working on an extended mission, seeking answers to new questions raised during its first years at Saturn. The Huygens probe separated from the Cassini orbiter on December 25, 2004, and landed on Titan, Saturn’s largest moon, on January 14, 2005. It continued to transmit information for over an hour despite a hard landing and Titan’s high atmospheric pressure.

The other authors of the paper, “Storms in the tropics of Titan,” are H. G. Roe (Lowell Observatory), and T. Schneider and M. E. Brown (both California Institute of Technology).



A press release from University of Hawaii, Institue for Astronomy , 12 August 2009

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Tiny Flares Responsible for Outsized Heat of Sun's Atmosphere

<-- This false-color temperature map shows solar active region AR10923, observed close to center of the sun's disk. Blue regions indicate plasma near 10 million degrees K. Credit: Reale, et al. (2009)

"Why is the sun's corona so darned hot?" asks James Klimchuk, an astrophysicist at the Goddard Space Flight Center's Solar Physics Laboratory in Greenbelt, Md.

The mystery of why temperatures in the solar corona, the sun's outer atmosphere, soar to several million degrees Kelvin (K) —much hotter than temperatures nearer the sun's surface—has puzzled scientists for decades. New observations made with instruments aboard Japan's Hinode satellite reveal the culprit to be nanoflares.

Nanoflares are small, sudden bursts of heat and energy. "They occur within tiny strands that are bundled together to form a magnetic tube called a coronal loop," says Klimchuk. Coronal loops are the fundamental building blocks of the thin, translucent gas known as the sun's corona.

Scientists previously thought steady heating explained the corona's million degree temperatures. The steady heating model indicates that a coronal loop of a given length and temperature should have a specific density. However, observations showed that coronal loops have much higher density than the steady heating model predicts. Newer models based on nanoflares can explain the observed density. But no direct evidence of the nanoflares existed until now.

Two active regions appear as bright areas on this full-disk image of the sun, taken with the Hinode spacecraft's X-Ray Telescope. Credit: NASA -->

Observations from the NASA-funded X-Ray Telescope (XRT) and Extreme-ultraviolet Imaging Spectrometer (EIS) instruments aboard Hinode reveal that ultra-hot plasma is widespread in solar active regions. The XRT measured plasma at 10 million degrees K, and the EIS measured plasma at 5 million degrees K. "These temperatures can only be produced by impulsive energy bursts,"says Klimchuk, who presented the findings on August 6 at the International Astronomical Union General Assembly meeting in Rio de Janeiro, Brazil.

"Coronal loops are bundles of unresolved strands that are heated by storms of nanoflares."

Coronal heating is a dynamic process. The brightness of the observed X-ray and ultraviolet emission is strongly dependent on the density of the coronal plasma. Where there's low density, there isn't much brightness. Where there's high density, there's a lot of brightness. The corona is mostly bright at about 1 million degrees K.

Klimchuk and colleagues constructed a theoretical model to explain how plasma evolves within these coronal tubes and what causes temperatures to skyrocket. "We simulate a burst of heating and see how the corona responds," says Klimchuk. "Then we make predictions about how much emission we should see from plasma of different temperatures."

Klimchuk surmises that when a nanoflare suddenly releases its energy, the plasma in the low-temperature, low-density strands becomes very hot—around 10 million degrees K—very quickly. The density remains low, however, so the emission, or brightness, remains faint. Heat flows from up in the strand, where it's hot, down to the base of the coronal loop, where it's not as hot. This heats up the dense plasma at the loop’s base. Because it is so dense at the base, the temperature only reaches about 1 million degrees K. This dense plasma expands up into the strand. Thus, a coronal loop is a collection of 5-10 million degree K faint strands and 1 million degree K bright strands.

"What we see is 1 million degree K plasma that has received its energy from the heat flowing down from the superhot plasma," says Klimchuk. "For the first time, we have detected this 10 million degree plasma, which can only be produced by the impulsive energy bursts of nanoflares."

The Hinode observations and the scientists' analysis verify that nanoflares are occurring on the sun and that they explain much and perhaps most coronal heating. The observations also confirm "there is some nanoflare activity everywhere" in the sun's active regions, says Klimchuk.

Nanoflares are responsible for changes in the X-ray and ultraviolet (UV) radiation that happen as an active region evolves. X-ray and UV get absorbed by Earth's upper atmosphere, which heats up and expands. Changes in the upper atmosphere can affect the orbits of satellites and space debris by slowing them down, an effect known as "drag." It is important to know the changing orbits so that maneuvers can be made to avoid space collisions. The X-ray and UV also affect the propagation of radio signals and thereby adversely affect communication and navigation systems.

The discovery that nanoflares play an important and perhaps dominant role in coronal heating paves the way to understanding how the sun affects Earth, our place in the universe.


Source : NASA / Goddard

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Halos may help us see dark matter

New calculations suggest that the halos caused when dark matter particles collide could be frequent enough to help us detect them within a year.

Previous studies had suggested that such quantum collisions - termed annihilations - would be few and far between, and so the gamma rays they emit would be hard to pick up even by orbiting satellite telescopes such as NASA's Fermi.

But the team's analysis of data from previous observations picked up more collisions than expected. They theorised that this might be down to an attractive force, the Sommerfeld effect, pulling dark matter particles more closely together and so making collisions more likely.

By applying these new calculations to a model of a dark matter cloud the size of our Milky Way the researchers were able to predict that Fermi should be able to detect a few subhalos caused by these collisions in its first year of operation, and find at least ten after five years.

Such observations would give the first direct evidence for the existence of dark matter - something that would rate as one of the all-time great physics discoveries.



Source : University of Oxford , 12 Aug 2009

The work was carried out by Michael Kuhlen of the Institute for Advanced Study in Princeton, Piero Madau of the University of California, Santa Cruz, and Joseph Silk of the University of Oxford.

Illustration of the Milky Way, image: NASA/JPL-Caltech

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