NASA's Van Allen Probes Detects an Impenetrable Barrier in Space

Two donuts of seething radiation that surround Earth, called the Van Allen radiation belts, have been found to contain a nearly impenetrable barrier that prevents the fastest, most energetic electrons from reaching Earth.

A cloud of cold, charged gas around Earth, called the plasmasphere and seen here in purple, interacts with the particles in Earth's radiation belts, shown in grey, to create an impenetrable barrier that blocks the fastest electrons from moving in closer to our planet.

Image Credit: NASA/Goddard

The Van Allen belts are a collection of charged particles, gathered in place by Earth’s magnetic field. They can wax and wane in response to incoming energy from the sun, sometimes swelling up enough to expose satellites in low-Earth orbit to damaging radiation.

The discovery of the drain that acts as a barrier within the belts was made using NASA's Van Allen Probes, launched in August 2012 to study the region.

A paper on these results appeared in the Nov. 27, 2014, issue of Nature magazine.

“This barrier for the ultra-fast electrons is a remarkable feature of the belts," said Dan Baker, a space scientist at the University of Colorado in Boulder and first author of the paper.

"We're able to study it for the first time, because we never had such accurate measurements of these high-energy electrons before."

Understanding what gives the radiation belts their shape and what can affect the way they swell or shrink helps scientists predict the onset of those changes. Such predictions can help scientists protect satellites in the area from the radiation.

Visualization of the radiation belts with confined charged particles (blue & yellow) and plasmapause boundary (blue-green surface)

The Van Allen belts were the first discovery of the space age, measured with the launch of a US satellite, Explorer 1, in 1958.

In the decades since, scientists have learned that the size of the two belts can change, or merge, or even separate into three belts occasionally.

But generally the inner belt stretches from 400 to 6,000 miles above Earth's surface and the outer belt stretches from 8,400 to 36,000 miles above Earth's surface.

A slot of fairly empty space typically separates the belts. But, what keeps them separate? Why is there a region in between the belts with no electrons?

Enter the newly discovered barrier. The Van Allen Probes data show that the inner edge of the outer belt is, in fact, highly pronounced. For the fastest, highest-energy electrons, this edge is a sharp boundary that, under normal circumstances, the electrons simply cannot penetrate.

"When you look at really energetic electrons, they can only come to within a certain distance from Earth," said Shri Kanekal, the deputy mission scientist for the Van Allen Probes at NASA's Goddard Space Flight Center in Greenbelt, Maryland and a co-author on the Nature paper. "This is completely new. We certainly didn't expect that."

The team looked at possible causes. They determined that human-generated transmissions were not the cause of the barrier. They also looked at physical causes.

Could the very shape of the magnetic field surrounding Earth cause the boundary? Scientists studied but eliminated that possibility. What about the presence of other space particles? This appears to be a more likely cause.

The radiation belts are not the only particle structures surrounding Earth. A giant cloud of relatively cool, charged particles called the plasmasphere fills the outermost region of Earth's atmosphere, beginning at about 600 miles up and extending partially into the outer Van Allen belt.

The particles at the outer boundary of the plasmasphere cause particles in the outer radiation belt to scatter, removing them from the belt.

ESA Rosetta mission: Philae instruments detect Organic molecules

The ESA Rosetta Philae lander has detected organic molecules on the surface of its comet, scientists have confirmed.

Carbon-containing "organics" are the basis of life on Earth and may give clues to chemical ingredients delivered to our planet early in its history.

The compounds were picked up by the German-built COSAC instrument designed to "sniff" the comet's thin atmosphere.

Other analyses suggest the comet's surface is largely water-ice covered with a thin dust layer.

The European Space Agency (ESA) craft touched down on the Comet 67P on 12 November after a 10-year journey.

Dr Fred Goessmann, principal investigator on the Cosac instrument, which made the organics detection, confirmed the find to reporters, but he added that the team was still trying to interpret the results.

It has not been disclosed which molecules have been found, or how complex they are.

But the results are likely to provide insights into the possible role of comets in contributing some of the chemical building blocks to the primordial mix from which life evolved on the early Earth.

Preliminary results from the MUPUS instrument, which deployed a hammer to the comet after Philae's landing, suggest there is a layer of dust 10-20cm thick on the surface with very hard water-ice underneath.

The ice would be frozen solid at temperatures encountered in the outer Solar System, MUPUS data suggest this layer has a tensile strength similar to sandstone.

"It's within a very broad spectrum of ice models. It was harder than expected at that location, but it's still within bounds," said Prof Mark McCaughrean, senior science adviser to ESA, told reporters.

"People will be playing with [mathematical] models of pure water-ice mixed with certain amount of dust."

He explained: "You can't rule out rock, but if you look at the global story, we know the overall density of the comet is 0.4g/cubic cm. There's no way the thing's made of rock.

"It's more likely there's sintered ice at the surface with more porous material lower down that hasn't been exposed to the Sun in the same way."

After bouncing off the surface at least twice, Philae came to a stop in some sort of high-walled trap.

"The fact that we landed up against something may actually be in our favour. If we'd landed on the main surface, the dust layer may have been even thicker and it's possible we might not have gone down [to the ice]," said Prof McCaughrean.

Scientists had to race to perform as many key tests as they could before Philae's battery life ran out at the weekend.

On re-charge

A key objective was to drill a sample of "soil" and analyse it in COSAC's oven, but, disappointingly, the latest information suggest no soil was delivered to the instrument.

Prof McCaughrean explained: "We didn't necessarily see many organics in the signal. That could be because we didn't manage to pick up a sample, but what we know is that the drill went down to its full extent and came back up again."

"But there's no independent way to say: This is what the sample looks like before you put it in there."

Scientists are hopeful however that as Comet 67P/Churyumov-Gerasimenko approaches the Sun in coming months, Philae's solar panels will see sunlight again.

This might allow the batteries to re-charge, and enable the lander to perform science once more.

"There's a trade off - once it gets too hot, Philae will die as well. There is a sweet spot," said Prof McCaughrean.

He added: "Given the fact that there is a factor of six, seven, eight in solar illumination and the last action we took was to rotate the body of Philae around to get the bigger solar panel in, I think it's perfectly reasonable to think it may well happen.

"By being in the shadow of the cliff, it might even help us, that we might not get so hot, even at full solar illumination, but if you don't get so hot that you don't overheat, have you got enough solar power to charge the system."

The lander's Alpha Particle X-ray Spectrometer (APXS), designed to provide information on the elemental composition of the surface, seems to have partially seen a signal from its own lens cover - which could have dropped off at a strange angle because Philae was not lying flat.

Fukushima Radiation cesium-134 detected off North American West Coast

Satellite measurements of ocean temperature (illustrated by color) from July 28th to August 4th and the direction of currents (white arrows) help show where radionuclides from Fukushima are transported.  

Large scale currents transport water westward across the Pacific.  Upwelling along the west coast of North America in the summertime brings cold deep water to the surface and transports water offshore.  

Circles indicate the locations where water samples were collected.  

White circles indicate that no cesium-134 was detected.  

Blue circles indicate locations were low levels of cesium-134 were detected.  No cesium-134 has yet been detected along the coast, but low levels have been detected offshore. 

Credit: Woods Hole Oceanographic Institution (WHOI)

Monitoring efforts along the Pacific Coast of the U.S. and Canada have detected the presence of small amounts of radioactivity from the 2011 Fukushima Dai-ichi Nuclear Power Plant accident 100 miles (150 km) due west of Eureka, California.

Scientists at the Woods Hole Oceanographic Institution (WHOI) found the trace amounts of telltale radioactive compounds as part of their ongoing monitoring of natural and human sources of radioactivity in the ocean.

In the aftermath of the 2011 tsunami off Japan, the Fukushima Dai-ichi Nuclear Power Plant released cesium-134 and other radioactive elements into the ocean at unprecedented levels.

Since then, the radioactive plume has traveled west across the Pacific, propelled largely by ocean currents and being diluted along the way.

At their highest near the damaged nuclear power plant in 2011, radioactivity levels peaked at more than 10 million times the levels recently detected near North America.

WHOI marine chemist Ken Buesseler (left) helps two citizen scientists from LUSH Cosmetics gather a water sample in Vancouver, British Columbia, earlier this year. 

Courtesy of Kevin Griffin, WHOI

"We detected cesium-134, a contaminant from Fukushima, off the northern California coast.  The levels are only detectable by sophisticated equipment able to discern minute quantities of radioactivity," said Ken Buesseler, a WHOI marine chemist, who is leading the monitoring effort.

"Most people don't realize that there was already cesium in Pacific waters prior to Fukushima, but only the cesium-137 isotope.  Cesium-137 undergoes radioactive decay with a 30-year half-life and was introduced to the environment during atmospheric weapons testing in the 1950s and '60s."

"Along with cesium-137, we detected cesium-134, which also does not occur naturally in the environment and has a half-life of just two years. Therefore the only source of this cesium-134 in the Pacific today is from Fukushima."

The amount of cesium-134 reported in these new offshore data is less than 2 Becquerels per cubic meter (the number of decay events per second per 260 gallons of water).

This Fukushima-derived cesium is far below where one might expect any measurable risk to human health or marine life, according to international health agencies, and it is more than 1000 times lower than acceptable limits in drinking water set by US EPA.

The offshore radioactivity reported this week came from water samples collected and sent to Buesseler’s lab for analysis in August by a group of volunteers on the research vessel Point Sur sailing between Dutch Harbor, Alaska, and Eureka, California. 

These results confirm prior data described at a scientific meeting in Honolulu in Feb. 2014 by John Smith, a scientist at Fisheries and Oceans Canada in Dartmouth, Nova Scotia, who found similar levels on earlier research cruises off shore of Canada. 

Credit: Curtis Colins

Scientists have used models to predict when and how much cesium-134 from Fukushima would appear off shore of Alaska and the coast of Canada.

They forecast that detectable amounts will move south along the coast of North America and eventually back towards Hawaii, but models differ greatly on when and how much would be found.

ESA ISS Astronaut detects the Orange glow over Africa

ESA Astronaut Alexander Gerst reports that "When light from the Cupola tints the inside of the ISS orange, I can tell we're over Africa without even looking out the window." 

Credit: ESA, Alexander Gerst

Very Large Telescope Interferometer detects exozodiacal light

This artist's view from an imagined planet around a nearby star shows the brilliant glow of exozodiacal light extending up into the sky and swamping the Milky Way. 

This light is starlight reflected from hot dust created as the result of collisions between asteroids, and the evaporation of comets. 

The presence of such thick dust clouds in the inner regions around some stars may pose an obstacle to the direct imaging of Earth-like planets in the future. 

Credit: ESO/L. Calçada

By using the full power of the Very Large Telescope Interferometer an international team of astronomers has discovered exozodiacal light close to the habitable zones around nine nearby stars.

This light is starlight reflected from dust created as the result of collisions between asteroids, and the evaporation of comets.

The presence of such large amounts of dust in the inner regions around some stars may pose an obstacle to the direct imaging of Earth-like planets.

Using the Very Large Telescope Interferometer (VLTI) in near-infrared light, the team of astronomers observed 92 nearby stars to probe exozodiacal light from hot dust close to their habitable zones and combined the new data with earlier observations.

Bright exozodiacal light, created by the glowing grains of hot exozodiacal dust, or the reflection of starlight off these grains, was observed around nine of the targeted stars.

From dark clear sites on Earth, zodiacal light looks like a faint diffuse white glow seen in the night sky after the end of twilight, or before dawn.

It is created by sunlight reflected off tiny particles and appears to extend up from the vicinity of the Sun.

This reflected light is not just observed from Earth but can be observed from everywhere in the Solar System.

The glow being observed in this new study is a much more extreme version of the same phenomenon.

While this exozodiacal light, zodiacal light around other star systems, had been previously detected, this is the first large systematic study of this phenomenon around nearby stars.

In contrast to earlier observations the team did not observe dust that will later form into planets, but dust created in collisions between small planets of a few kilometres in size, objects called planetesimals that are similar to the asteroids and comets of the Solar System. Dust of this kind is also the origin of the zodiacal light in the Solar System.

"If we want to study the evolution of Earth-like planets close to the habitable zone, we need to observe the zodiacal dust in this region around other stars," said Steve Ertel, lead author of the paper, from ESO and the University of Grenoble in France.

"Detecting and characterising this kind of dust around other stars is a way to study the architecture and evolution of planetary systems."

Detecting faint dust close to the dazzling central star requires high resolution observations with high contrast.

Interferometry, combining light collected at the exact same time at several different telescopes, performed in infrared light is, so far, the only technique that allows this kind of system to be discovered and studied.

By using the power of the VLTI and pushing the instrument to its limits in terms of accuracy and efficiency, the team was able to reach a performance level about ten times better than other available instruments in the world.

Research paper on exozodiacal light: www.eso.org/public/archives/re… eso1435/eso1435a.pdf 

Complementary research paper on stellar companions: arxiv.org/abs/1409.6105

POLARBEAR Detects Curls in the Universe’s Oldest Light CMB

Measurements of polarization of the cosmic microwave background. 

Credit: POLARBEAR

Cosmologists have made the most sensitive and precise measurements yet of the polarisation of the Cosmic Microwave Background (CMB).

The report, published October 20 in the Astrophysical Journal, marks an early success for POLARBEAR, a collaboration of more than 70 scientists using a telescope high in Chile's Atacama desert designed to capture the universe's oldest light.

"It's a really important milestone," said Kam Arnold, the corresponding author of the report who has been working on the instrument for a decade.

"We're in a new regime of more powerful, precision cosmology." Arnold is a research scientist at UC San Diego's Center for Astrophysics and Space Sciences and part of the cosmology group led by physics professor Brian Keating.

POLARBEAR measures remnant radiation from the Big Bang, which has cooled and stretched with the expansion of the universe to microwave lengths.

This cosmic microwave background, the CMB, acts as an enormous backlight, illuminating the large-scale structure of the universe and carrying an imprint of cosmic history.

Arnold and many others have developed sensitive instruments called bolometers to measure this light.

Arrayed in the telescope, the bolometers record the direction of the light's electrical field from multiple points in the sky.

"It's a map of all these little directions that the light's electric field is pointing," Arnold explained.
POLARBEAR has now mapped these angles with resolution on a scale of about 3 arcminutes, just one-tenth the diameter of the full moon.

The team found telling twists called B-modes in the patterns of polarization, signs that this cosmic backlight has been warped by intervening structures in the universe, including such mysteries as dark matter, composed of substance that remains unknown, and the famously aloof particles called neutrinos, which elude capture making them difficult to study.

This initial report, the result of the first season of observation, maps B-modes in three small patches of sky.

Dust in our own galaxy also emits polarized radiation like the CMB and has influenced other measurements, but these patches are relatively clean, Arnold says. and variations in the CMB polarization due to dust occur on so broad a scale that they do not significantly influence the finer resolution B-modes in this report.

"We are confident that these B-modes are cosmological rather than galactic in origin," Arnold said.

Observations continue, and the data stream will ultimately be fed by additional telescopes comprising the Simons Array. Together they will map wider swaths of the sky, making fundamental discoveries possible.

"POLARBEAR is a real tour de force. With a relatively small, but strong, UC-led team we have surpassed the next-nearest competitors by an order of magnitude in sensitivity."

"We have paved the way towards solving the deepest mysteries in the quest to understand matter and energy at the beginning of time," said Brian Keating.

POLARBEAR is a collaboration of scientists from many institutions including experiment founder, Adrian Lee, professor of physics at UC Berkeley.

NASA aeronautics research tests new wildfire detection tool

NASA researcher Mike Logan plans to use this small unmanned aerial vehicle to check for fires at a Virginia-North Carolina wildlife refuge as part of an agreement with the U.S. Fish and Wildlife Service. 

Credit: NASA Langley/David C. Bowman

NASA's research in unmanned aerial systems (UAS) may soon provide a means for early detection and mitigation of fires in the Great Dismal Swamp National Wildlife Refuge, a nearly 50,000-square-acre region centered on the Virginia-North Carolina border.

NASA's Langley Research Center, in nearby Hampton, Virginia, has signed a one-year agreement with the Department of the Interior's U.S. Fish and Wildlife Service (FWS) to test small UASs for the detection of brush and forest fires.

The research is part of the NASA Aeronautics Research Mission Directorate's UAS Integration in the National Airspace System (NAS) project.

"The U.S. Fish and Wildlife Service is evaluating the feasibility of airborne unmanned platforms and their ability to offer a safer and more cost-effective alternative for surveillance of potential areas of interest immediately following thunderstorm activity," said Great Dismal Swamp Refuge Manager Chris Lowie.

"The agency hopes to see a significant decrease in cost to survey the Great Dismal Swamp, as well as a reduction in time to detect nascent fires, which could potentially save millions of dollars to the taxpayer in firefighting costs," added Lowie.

Mike Logan, the research lead at Langley, came up with the idea after a forest fire in 2011 that lasted almost four months and cost more than $10 million to extinguish.

Smoke from that fire, which was caused by a lightning strike, traveled as far north as Maryland only three years after another $10-million blaze in 2008, according to FWS.

"I made a phone call to the local fire captain after days of inhaling peat bog smoke," said Logan. "I learned most fires are caused by lightning strikes and the only way they can spot them is by hiring an aircraft to do an aerial survey of the huge swamp. So I figured why not use a UAV as a fire detector?"

After approval from the Federal Aviation Administration, the team at Langley plans to fly a lightweight UAS equipped with cameras and transmitters over the wildlife refuge.

"One is an out-of-the-nose camera that can see smoke plumes as they are rising," Logan explained.

"The other is an infrared camera housed in the body of the plane that points down. It can find hot spots by detecting heat signatures."

Although the aircraft can fly as fast as 40 miles an hour, when used in this capacity it will be flown slower while it transmits video, allowing individuals on the ground to observe what is occurring in the live video.

The transmissions can be viewed on a laptop computer in a mobile ground station.

Logan says the drone, which weighs about 15 pounds and has an almost six-foot wingspan, has a range of about eight miles and can stay aloft as long as an hour, before the batteries need recharging.

The aircraft also can be programmed to fly on its own, but a safety pilot will monitor operations during the tests.

"This kind of application for unmanned aerial systems shows just one public benefit," said Dave Hinton, Langley associate director for UAS technologies and applications.

"They can be used to detect fires or locate people who are lost."

ESA CryoSat-2 and Jason-1 Satellites detect 'thousands' of new ocean-bottom mountains

ESA CryoSat-2 and NASA's Jason-1 satellites capture new gravity data.

ESA's CryoSat-2 and NASA's Jason-1 satellites capture new gravity data gives us our clearest view yet of the shape of the ocean floor

It is not every day you can announce the discovery of thousands of new mountains on Earth, but that is what a US-European research team has done.

What is more, these peaks are all at least 1.5km high.

ESA's CryoSat-2 Earth Observation satellite.

Credit: ESA

The reason they have gone unrecognised until now is because they are at the bottom of the ocean.

Prof Dave Sandwell (UCSD) and colleagues used Cryosat-2 and Jason-1 radar satellites to discern the mountains' presence under water and report their findings in Science Magazine.

"In the previous radar dataset we could see everything taller than 2km, and there were 5,000 seamounts," Prof Sandwell told reporters.

"With our new dataset, and we haven't fully done the work yet, I'm guessing we can see things that are 1.5km tall.

"That might not sound like a huge improvement but the number of seamounts goes up exponentially with decreasing size.

"So, we may be able to detect another 25,000 on top of the 5,000 already known," the Scripps Institution of Oceanography researcher explained.

The new detailed map of the sea floor is available here.

Knowing where the seamounts are is important for fisheries management and conservation, because it is around these topographic highs that wildlife tends to congregate.

The roughness of the seafloor is important also as it steers currents and promotes mixing, behaviours that are critical to understanding how the oceans transport heat and influence the climate.

But our knowledge of the seafloor is poor; witness the problems they have had searching for the missing Malaysia Airlines jet MH370, which is believed to have crashed west of Australia.

Seeing fracture zones tells scientists about the movement of the continents
The problem is that saltwater is opaque to all the standard techniques that are used to map mountains on land.

Ship-borne echosounders can gather very high-resolution information by bouncing sound off bottom structures, but less than 10% of the global oceans have been properly surveyed in this way because of the effort it involves.

NASA's Swift satellite detects the X100,000 "superflare" - Video

NASA's Swift satellite detected the "superflare" blasted by a red dwarf star in a binary system called DG Canum Venaticorum (DG CVn). 

In comparison, the largest flare ever recorded from our Sun was an X45, 10,000 times less powerful.

"We used to think major flaring episodes from red dwarfs lasted no more than a day, but Swift detected at least seven powerful eruptions over a period of about two weeks," said Stephen Drake, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who gave a presentation on the "superflare" at the August meeting of the American Astronomical Society’s High Energy Astrophysics Division. "This was a very complex event."

At its peak, the flare reached temperatures of 360 million degrees Fahrenheit (200 million Celsius), more than 12 times hotter than the center of the sun.

ESA GOCE and NASA GRACE detect Gravity Anomaly in Antarctic Ice Loss

Changes in Earth’s gravity field resulting from loss of ice from West Antarctica between November 2009 and June 2012 (mE = 10–12 s–2). 

 A combination of data from ESA’s GOCE mission and NASA’s Grace satellites shows the ‘vertical gravity gradient change’. 

Credit: ESA

Although not designed to map changes in Earth's gravity over time, ESA's extraordinary satellite has shown that the ice lost from West Antarctica over the last few years has left its signature.

Artist rendering of ESA's GOCE satellite in orbit. 

Credit: ESA

More than doubling its planned life in orbit, GOCE spent four years measuring Earth's gravity in unprecedented detail.

Scientists are now armed with the most accurate gravity model ever produced.

This is leading to a much better understanding of many facets of our planet, from the boundary between Earth's crust and upper mantle to the density of the upper atmosphere.

The strength of gravity at Earth's surface varies subtly from place to place owing to factors such as the planet's rotation and the position of mountains and ocean trenches.

Changes in the mass of large ice sheets can also cause small local variations in gravity.

Recently, the high-resolution measurements from GOCE over Antarctica between November 2009 and June 2012 have been analysed by scientists from the German Geodetic Research Institute, Delft University of Technology in the Netherlands, the Jet Propulsion Lab in USA and the Technical University of Munich in Germany.

Remarkably, they found that the decrease in the mass of ice during this period was mirrored in GOCE's measurements, even though the mission was not designed to detect changes over time.

Using gravity data to assess changes in ice mass is not new.

The NASA, DLR (Germany) Grace satellite, which was designed to measure change, has been providing this information for over 10 years.

However, measurements from Grace are much coarser than those of GOCE, so they cannot be used to look at features such as Antarctica's smaller 'catchment basins'.

For scientific purposes, the Antarctic ice sheet is often divided into catchment basins so that comparative measurements can be taken to work out how the ice in each basin is changing and discharging ice to the oceans. Some basins are much bigger than others.

By combining GOCE's high-resolution measurements with information from Grace, scientists can now look at changes in ice mass in small glacial systems, offering even greater insight into the dynamics of Antarctica's different basins.



They have found that that the loss of ice from West Antarctica between 2009 and 2012 caused a dip in the gravity field over the region.

In addition, GOCE data could be used to help validate satellite altimetry measurements for an even clearer understanding of ice-sheet and sea-level change.

Using gravity data to assess changes in ice mass is not new. The NASA, DLR (Germany) Grace satellite, which was designed to measure change, has been providing this information for over 10 years.

However, measurements from Grace are much coarser than those of GOCE, so they cannot be used to look at features such as Antarctica's smaller 'catchment basins'.

For scientific purposes, the Antarctic ice sheet is often divided into catchment basins so that comparative measurements can be taken to work out how the ice in each basin is changing and discharging ice to the oceans. Some basins are much bigger than others.

By combining GOCE's high-resolution measurements with information from Grace, scientists can now look at changes in ice mass in small glacial systems, offering even greater insight into the dynamics of Antarctica's different basins.

They have found that that the loss of ice from West Antarctica between 2009 and 2012 caused a dip in the gravity field over the region.

In addition, GOCE data could be used to help validate satellite altimetry measurements for an even clearer understanding of ice-sheet and sea-level change.

Using 200 million measurements collected by ESA’s CryoSat mission between January 2011 and January 2014, researchers from the Alfred Wegener Institute in Germany have discovered that the Antarctic ice sheet is shrinking in volume by 125 cubic kilometres a year. 

The study, which was published in a paper published on 20 August 2014 in the European Geosciences Union’s Cryosphere journal, also showed that Greenland is losing about 375 cubic kilometres a year. 

Credit: ESA

ESA's CryoSat satellite, which carries a radar altimeter, has recently shown that since 2009 the rate at which ice is been lost from the West Antarctic Ice Sheet every year has increased by a factor of three.

And, between 2011 and 2014, Antarctica as a whole has been shrinking in volume by 125 cubic kilometres a year.

Johannes Bouman from the German Geodetic Research Institute said, "We are now working in an interdisciplinary team to extend the analysis of GOCE's data to all of Antarctica.

"This will help us gain further comparison with results from CryoSat for an even more reliable picture of actual changes in ice mass."

This new research into GOCE's gravity data revealing ice loss over time is being carried out through ESA's Earth Observation Support to Science Element.

ESO ALMA: Detection of organic molecule iso-propyl cyanide in interstellar clouds

The image shows dust and molecules in the central region of our galaxy. 

The background image shows the dust emission in a combination of data obtained with the APEX telescope and the Planck space observatory at a wavelength around 860 micrometers. 

The organic molecule iso-propyl cyanide with a branched carbon backbone (i-C3H7CN, left) as well as its straight-chain isomer normal-propyl cyanide (n-C3H7CN, right) were both detected with the Atacama large millimeter/submillimeter array in the star-forming region Sgr B2, about 300 light years away from the Galactic center Sgr A*. 

Credit: MPIfR/A. Weiss (background image), University of Cologne/M. Koerber (molecular models), MPIfR/A. Belloche (montage)

Scientists from the Max Planck Institute for Radio Astronomy, Cornell University, and the University of Cologne have for the first time detected a carbon-bearing molecule with a "branched" structure in interstellar space.

The molecule, iso-propyl cyanide (i-C3H7CN), was discovered in a giant gas cloud called Sagittarius B2, a region of ongoing star formation close to the center of our galaxy that is a hot-spot for molecule-hunting astronomers.

The branched structure of the carbon atoms within the iso-propyl cyanide molecule is unlike the straight-chain carbon backbone of other molecules that have been detected so far, including its sister molecule normal-propyl cyanide.

The discovery of iso-propyl cyanide opens a new frontier in the complexity of molecules found in regions of star formation, and bodes well for the presence of amino acids, for which this branched structure is a key characteristic.

The results are published in this week's issue of Science.

While various types of molecules have been detected in space, the kind of hydrogen-rich, carbon-bearing (organic) molecules that are most closely related to the ones necessary for life on Earth appear to be most plentiful in the gas clouds from which new stars are being formed.

"Understanding the production of organic material at the early stages of star formation is critical to piecing together the gradual progression from simple molecules to potentially life-bearing chemistry," says Arnaud Belloche from the Max Planck Institute for Radio Astronomy, the lead author of the paper.

The search for molecules in interstellar space began in the 1960's, and around 180 different molecular species have been discovered so far.

Each type of molecule emits light at particular wavelengths, in its own characteristic pattern, or spectrum, acting like a fingerprint that allows it to be detected in space using radio telescopes.

Until now, the organic molecules discovered in star-forming regions have shared one major structural characteristic: they each consist of a "backbone" of carbon atoms that are arranged in a single and more or less straight chain.

The new molecule discovered by the team, iso-propyl cyanide, is unique in that its underlying carbon structure branches off in a separate strand.

"This is the first ever interstellar detection of a molecule with a branched carbon backbone," says Holger Müller, a spectroscopist at the University of Cologne and co-author on the paper, who measured the spectral fingerprint of the molecule in the laboratory, allowing it to be detected in space.

But it is not just the structure of the molecule that surprised the team, it is also plentiful, at almost half the abundance of its straight-chain sister molecule, normal-propyl cyanide (n-C3H7CN), which the team had already detected using the single-dish radio telescope of the Institut de Radioastronomie Millimétrique (IRAM) a few years ago.

"The enormous abundance of iso-propyl cyanide suggests that branched molecules may in fact be the rule, rather than the exception, in the interstellar medium," says Robin Garrod, an astrochemist at Cornell University and a co-author of the paper.

The central region of the Milky Way above the antennas of the ALMA observatory. 

The direction to the Galactic center is halfway between Antares, the brightest star visible in the picture and the tip of an ALMA antenna in the foreground (second from right). 

Credit: Y. Beletsky (LCO)/ESO

The team used the Atacama Large Millimeter/submillimeter Array (ALMA), in Chile, to probe the molecular content of the star-forming region Sagittarius B2 (Sgr B2).

This region is located close to the Galactic Center, at a distance of about 27,000 light years from the Sun, and is uniquely rich in emission from complex interstellar organic molecules.

"Thanks to the new capabilities offered by ALMA, we were able to perform a full spectral survey toward Sgr B2 at wavelengths between 2.7 and 3.6 mm, with sensitivity and spatial resolution ten times greater than our previous survey," explains Belloche.

"But this took only a tenth of the time." The team used this spectral survey to search systematically for the fingerprints of new interstellar molecules.

"By employing predictions from the Cologne Database for Molecular Spectroscopy (CDMS), we could identify emission features from both varieties of propyl cyanide," says Müller.

As many as 50 individual features for i-propyl cyanide and even 120 for n-propyl cyanide were unambiguously identified in the ALMA spectrum of Sgr B2.

The two molecules, each consisting of 12 atoms, are also the joint-largest molecules yet detected in any star-forming region.

Journal Reference:
Arnaud Belloche, Robin T. Garrod, Holger S. P. Müller, and Karl M. Menten. "Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanide." Science, 26 September 2014: 1584-1587 DOI: 10.1126/science.1256678

Evidence of 'oceans worth' of water in Earth's mantle detected

Schematic cross section of the Earth’s interior highlighting the transition zone layer (light blue, 410-660 km depth), which has an anomalously high water storage capacity. 

The study by Schmandt and Jacobsen used seismic waves to detect magma generated near the top of the lower mantle at about 700 km depth.

Dehydration melting at those conditions, also observed in the study’s high-pressure experiments, suggests the transition zone may be nearly saturated with H2O dissolved in high-pressure rock. 

Credit: Steve Jacobsen/Northwestern University

Researchers have found evidence of a potential "ocean's worth" of water deep beneath the United States.

Although not present in a familiar form, the building blocks of water are bound up in rock located deep in the Earth's mantle, and in quantities large enough to represent the largest water reservoir on the planet, according to the research.

For many years, scientists have attempted to establish exactly how much water may be cycling between the Earth's surface and interior reservoirs through the action of plate tectonics.

Northwestern University geophysicist Steve Jacobsen and University of New Mexico seismologist Brandon Schmandt have found deep pockets of magma around 400 miles beneath North America, a strong indicator of the presence of H₂O stored in the crystal structure of high-pressure minerals at these depths.

"The total H₂O content of the planet has long been among the most poorly constrained 'geochemical parameters' in Earth science. Our study has found evidence for widespread hydration of the mantle transition zone," says Jacobsen.

For at least 20 years geologists have known from laboratory experiments that the Earth's transition zone, a rocky layer of the Earth's mantle located between the lower mantle and upper mantle, at depths between 250 and 410 miles, can, in theory, hold about 1 percent of its total weight as H₂O, bound up in minerals called wadsleyite and ringwoodite.

However, as Schmandt explains, up until now it has been difficult to figure out whether that potential water reservoir is empty, as many have suggested, or not.

If there does turn out to be a substantial amount of H₂O in the transition zone, then recent laboratory experiments conducted by Jacobsen indicate there should be large quantities of what he calls "partial melt" in areas where mantle flows downward out of the zone.

This water-rich silicate melt is molten rock that occurs at grain boundaries between solid mineral crystals and may account for about 1 percent of the volume of rocks.

"Melting occurs because hydrated rocks are carried from the transition zone, where the rocks can hold lots of H₂O, downward into the lower mantle, where the rocks cannot hold as much H₂O."

"Melting is the way to get rid of the H₂O that won't fit in the crystal structure present in the lower mantle," says Jacobsen.

He adds:
"When a rock starts to melt, whatever H₂O is bound in the rock will go into the melt right away. So the melt would have much higher H₂O concentration than the remaining solid. We're not sure how it got there."

"Maybe it's been stuck there since early in Earth's history or maybe it's constantly being recycled by plate tectonics."

Seismic Waves
Melt strongly affects the speed of seismic waves, the acoustic-like waves of energy that travel through the Earth's layers as a result of an earthquake or explosion.

This is because stiff rocks, like the silicate-rich ones present in the mantle, propagate seismic waves very quickly.

According to Schmandt, if just a little melt, even 1 percent or less, is added between the crystal grains of such a rock it causes it to become less stiff, meaning that elastic waves propagate more slowly.

"We were able to analyse seismic waves from earthquakes to look for melt in the mantle just beneath the transition zone," says Schmandt.

Brandon Schmandt (University of New Mexico, left) and Steve Jacobsen (Northwestern University, right) combined seismic observations from the US-Array with laboratory experiments to detect dehydration melting of hydrous mantle material beneath North America at depths of 700-800 km. 

Credit: University of New Mexico/Northwestern University

"What we found beneath the U.S. is consistent with partial melt being present in areas of downward flow out of the transition zone."

"Without the presence of H₂O, it is very difficult to explain melting at these depths. This is a good hint that the transition zone H₂O reservoir is not empty, and even if it's only partially filled that could correspond to about the same mass of H₂O as in Earth's oceans," he adds.

Jacobsen and Schmandt hope that their findings, published in the June issue of the journal Science, will help other scientists to understand how the Earth formed and what its current composition and inner workings are, as well as establish how much water is trapped in mantle rock.

"I think we are finally seeing evidence for a whole-Earth water cycle, which may help explain the vast amount of liquid water on the surface of our habitable planet. Scientists have been looking for this missing deep water for decades," says Jacobsen

Schematic representation of seismometers placed in the US-Array between 2004 and 2014 and used in the study by Schmandt and Jacobsen to detect dehydration melting at the top of the lower mantle beneath North America. 

Credit: NSF-Earthscope

Crystals of laboratory-grown hydrous ringwoodite, a high-pressure polymorph of olivine that is stable from about 520-660 km depth in the Earth’s mantle. 

The ringwoodite pictured here contains around one weight percent of H2O, similar to what was inferred in the seismic observations made by Schmandt and Jacobsen. 

Credit: Steve Jacobsen/Northwestern University

Subaru Telescope: Traces of One of Universe's First Stars Detected

The most massive stars in the early universe would eject material high in iron when they exploded. 

Astronomers can read the composition of the next generation of stars to determine what made up their ancestors.

Credit: National Astronomical Observatory of Japan

An ancient star in the halo surrounding the Milky Way galaxy appears to contain traces of material released by the death of one of the universe's first stars, a new study reports.

The chemical signature of the ancient star suggests that it incorporated material blasted into space by a supernova explosion that marked the death of a huge star in the early universe, one that may have been 200 times more massive than the sun.

"The impact of very-massive stars and their explosions on subsequent star formation and galaxy formation should be significant," lead author Wako Aoki, of the National Astronomical Observatory of Japan, told Space.com by email.

Hidden giants
The first stars in the cosmos, known as Population III stars, formed from the hydrogen and helium that dominated the early universe.

Through nuclear fusion, other elements were forged in their hearts. At the end of their lifetimes, supernovas scattered these elements into the space around them, where the material was folded into the next generation of stars.

The universe's first massive stars would have been short-lived, so to determine their composition, scientists must examine the makeup of their offspring, stars that formed from the material distributed by their explosive deaths.

While numerical simulations have suggested that at least some of the first stars should have reached enormous proportions, no previous observational evidence had managed to confirm their existence.

Aoki and a team of scientists used the Subaru Telescope in Hawaii to perform follow-up observations of a large sample of low-mass stars with low quantities of what astronomers term "metals," elements other than hydrogen and helium. 

They identified SDS J0018-0939, an ancient star only 1,000 light-years from Earth.

"The low abundance of heavy elements suggests that this star is quite old — as old as 13 billion years," Aoki said.
(Scientists think the Big Bang that created the universe occurred approximately 13.8 billion years ago.)

The chemical composition of SDS J0018-0939 suggests it gobbled up the material blown off of a single massive ancient star, rather than several smaller bodies.

If multiple supernovas had provided the material that constructed the star, the "peculiar abundance ratios" in its interior would have been erased, Aoki said.

Volker Bromm of the University of Texas, Austin agrees, saying that SDS J0018 likely evolved from the material from a single star, which could have been more than 200 times as massive as the sun.

Bromm, who has performed theoretical studies on the properties of the first generation of stars and their supernova explosions, did not participate in the new study.

He authored a corresponding "News & Views" article that appeared with the research online today (Aug. 21) in the journal Science.

Signs of low-mass first-generation stars have appeared to be more plentiful in their descendants, which contain large amounts of carbon and other light elements, but until these results, scientists had detected no traces of their very massive siblings.

The scarcity suggested that low-mass stars were more numerous in the early universe.

"We have come to understand that the first stars had a range of masses, from a few solar masses, all the way up to 100 solar masses, or even more," Bromm told reporters.

"The typical, or average, mass is predicted to be somewhere close to a few tens of solar masses.".

NASA SDO: EUNIS mission - Coronal Heating theory detected

NASA's Solar Dynamics Observatory captured this image of what the sun looked like on April 23, 2013, at 1:30 p.m. EDT when the EUNIS mission launched. 

EUNIS focused on an active region of the sun, seen as bright loops in the upper right in this picture. 

Credit: NASA/SDO

Scientists have recently gathered some of the strongest evidence to date to explain what makes the sun's outer atmosphere so much hotter than its surface.

The new observations of the small-scale extremely hot temperatures are consistent with only one current theory: something called nanoflares; a constant peppering of impulsive bursts of heating, none of which can be individually detected, provide the mysterious extra heat

What's even more surprising is these new observations come from just six minutes worth of data from one of NASA's least expensive type of missions, a sounding rocket.

The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) mission, launched on April 23, 2013, gathering a new snapshot of data every 1.3 seconds to track the properties of material over a wide range of temperatures in the complex solar atmosphere.

The sun's visible surface, called the photosphere, is some 6,000 Kelvins, while the corona regularly reaches temperatures which are 300 times as hot.

Jeff Brosius

"That's a bit of a puzzle," said Jeff Brosius, a space scientist at Catholic University in Washington, D.C., and NASA's Goddard Space Flight Center in Greenbelt, Maryland.

"Things usually get cooler farther away from a hot source. When you're roasting a marshmallow you move it closer to the fire to cook it, not farther away."

Brosius is the first author of a paper on these results appearing in the Aug. 1, 2014, edition of The Astrophysical Journal.

Several theories have been offered for how the magnetic energy coursing through the corona is converted into the heat that raises the temperature.

Different theories make different predictions about what kind of, and what temperature, material might be observable, but few observations have high enough resolution over a large enough area to distinguish between these predictions.


NASA's EUNIS sounding rocket mission spotted evidence to explain why the sun's atmosphere is so much hotter than its surface. 

Credit: NASA/Goddard/Duberstein 

The EUNIS sounding rocket, however, was equipped with a very sensitive version of an instrument called a spectrograph.

Spectrographs gather information about how much material is present at a given temperature, by recording different wavelengths of light.

To observe the extreme ultraviolet wavelengths necessary to distinguish between various coronal heating theories, such an instrument can only work properly in space, above the atmosphere surrounding Earth that blocks that ultraviolet light.

The EUNIS team stands in front of the sounding rocket before its second launch on Nov. 6, 2007. 

The mission will launch again for a six-minute flight to observe the sun on December 15, 2012. 

Credit: U.S. Navy

So EUNIS flew up nearly 200 miles above the ground aboard a sounding rocket, a type of NASA mission that flies for only 15 minutes or so, and gathered about six minutes worth of observations from above the planet's air.

During its flight, EUNIS scanned a pre-determined region on the sun known to be magnetically complex, a so-called active region, which can often be the source of larger flares and coronal mass ejections.

As light from the region streamed into its spectrograph, the instrument separated the light into its various wavelengths.

Instead of producing a typical image of the sun, the wavelengths with larger amounts of light are each represented by a vertical line called an emission line.

Each emission line, in turn, represents material at a unique temperature on the sun. Further analysis can identify the density and movement of the material as well.

The EUNIS spectrograph was tuned into a range of wavelengths useful for spotting material at temperatures of 10 million Kelvin; temperatures that are a signature of nanoflares.

Unlike a conventional image, NASA's Extreme Ultraviolet Normal Incidence Spectrograph will provide what's known as "spectra" such as above, which show lines to highlight which wavelengths of light are brighter than others. 

That information, in turn, corresponds to which elements are present in the sun's atmosphere and at what temperature. 

Credit: NASA/EUNIS

Scientists have hypothesised that a myriad of nanoflares could heat up solar material in the atmosphere to temperatures of up to 10 million Kelvins.

This material would cool very rapidly, producing ample solar material at the 1 to 3 million degrees regularly seen in the corona.

However, the faint presence of that extremely hot material should remain. Looking over their six minutes of data, the EUNIS team spotted a wavelength of light corresponding to that 10 million degree material.

To spot this faint emission line was a triumph of the EUNIS instrument's resolution. The spectrograph was able to clearly and unambiguously distinguish the observations representing the extremely hot material.

"The fact that we were able to resolve this emission line so clearly from its neighbours is what makes spectroscopists like me stay awake at night with excitement," said Brosius.

"This weak line observed over such a large fraction of an active region really gives us the strongest evidence yet for the presence of nanoflares."

The EUNIS experiment undergoing tests before launch. 

Credit: NASA

There are a variety of theories for what mechanisms power these impulsive bursts of heat, the nanoflares.

Moreover, other explanations have been offered for what is heating the corona.

Scientists will continue to explore these ideas further, gathering additional observations as their tools and instruments improve.

However, no other theory predicts material of this temperature in the corona, so this is a strong piece of evidence in favour of the nanoflare theory.

Adrian Daw

"This is a real smoking gun for nanoflares," said Adrian Daw, the current principal investigator for EUNIS at Goddard. "And it shows that these smaller, less expensive sounding rockets can produce truly robust science."

In addition to having a lower cost, sounding rockets offer a valuable test bed for new technology that may subsequently be flown on longer-term space missions.

Another advantage of sounding rockets is that the instruments parachute back to the ground so they can be recovered and re-used.

The EUNIS mission will be re-tuned to focus on a different set of solar wavelengths; ones that can also spot the extremely high temperature material representative of nanoflares, and fly again sometime in 2016.

More Information: Pervasive Faint Fe XIX Emission from a Solar Active Region Observed with EUNIS-13: Evidence for Nanoflare Heating - Jeffrey W. Brosius et al. 2014 ApJ 790 112. doi:10.1088/0004-637X/790/2/112