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Metallic hydrogen, once theory, becomes reality

Metallic hydrogen, once theory, becomes reality

Image of diamond anvils compressing molecular hydrogen. At higher pressure the sample converts to atomic hydrogen, as shown on the right. Credit: R. Dias and I.F. Silvera

Nearly a century after it was theorized, Harvard scientists have succeeded in creating the rarest – and potentially one of the most valuable – materials on the planet.

The material – atomic  – was created by Thomas D. Cabot Professor of the Natural Sciences Isaac Silvera and post-doctoral fellow Ranga Dias. In addition to helping scientists answer fundamental questions about the nature of matter, the material is theorized to have a wide range of applications, including as a . The creation of the rare material is described in a January 26 paper published in Science.

“This is the holy grail of high-pressure physics,” Silvera said. “It’s the first-ever sample of metallic hydrogen on Earth, so when you’re looking at it, you’re looking at something that’s never existed before.”

To create it, Silvera and Dias squeezed a tiny hydrogen sample at 495 gigapascal, or more than 71.7 million pounds-per-square inch – greater than the pressure at the center of the Earth. At those extreme pressures, Silvera explained, solid molecular hydrogen -which consists of molecules on the lattice sites of the solid – breaks down, and the tightly bound molecules dissociate to transforms into , which is a metal.

While the work offers an important new window into understanding the general properties of hydrogen, it also offers tantalizing hints at potentially revolutionary new .

“One prediction that’s very important is metallic hydrogen is predicted to be meta-stable,” Silvera said. “That means if you take the pressure off, it will stay metallic, similar to the way diamonds form from graphite under intense heat and pressure, but remains a diamond when that pressure and heat is removed.”

Understanding whether the material is stable is important, Silvera said, because predictions suggest metallic hydrogen could act as a superconductor at room temperatures.

“That would be revolutionary,” he said. “As much as 15 percent of energy is lost to dissipation during transmission, so if you could make wires from this material and use them in the electrical grid, it could change that story.”

Among the holy grails of physics, a room temperature superconductor, Dias said, could radically change our transportation system, making magnetic levitation of high-speed trains possible, as well as making electric cars more efficient and improving the performance of many electronic devices.

The material could also provide major improvements in energy production and storage – because superconductors have zero resistance energy could be stored by maintaining currents in superconducting coils, and then be used when needed.

Metallic hydrogen, once theory, becomes reality
Photos of compressed hydrogen transitioning with increasing pressure from transparent molecular to black molecular to atomic metallic hydrogen. The sketches below show a molecular solid being compressed and then dissociated to atomic hydrogen. Credit: R. Dias and I.F. Silvera

Though it has the potential to transform life on Earth, metallic hydrogen could also play a key role in helping humans explore the far reaches of space, as the most powerful rocket propellant yet discovered.

“It takes a tremendous amount of energy to make metallic hydrogen,” Silvera explained. “And if you convert it back to molecular hydrogen, all that energy is released, so it would make it the most powerful rocket propellant known to man, and could revolutionize rocketry.”

The most powerful fuels in use today are characterized by a “specific impulse” – a measure, in seconds, of how fast a propellant is fired from the back of a rocket – of 450 seconds. The specific impulse for metallic hydrogen, by comparison, is theorized to be 1,700 seconds.

“That would easily allow you to explore the outer planets,” Silvera said. “We would be able to put rockets into orbit with only one stage, versus two, and could send up larger payloads, so it could be very important.”

To create the new material, Silvera and Dias turned to one of the hardest materials on Earth – diamond.

But rather than natural diamond, Silvera and Dias used two small pieces of carefully polished synthetic diamond which were then treated to make them even tougher and then mounted opposite each other in a device known as a .

“Diamonds are polished with diamond powder, and that can gouge out carbon from the surface,” Silvera said. “When we looked at the diamond using atomic force microscopy, we found defects, which could cause it to weaken and break.”

The solution, he said, was to use a reactive ion etching process to shave a tiny layer – just five microns thick, or about one-tenth of a human hair – from the diamond’s surface. The diamonds were then coated with a thin layer of alumina to prevent the hydrogen from diffusing into their crystal structure and embrittling them.

After more than four decades of work on metallic hydrogen, and nearly a century after it was first theorized, seeing the material for the first time, Silvera said, was thrilling.

“It was really exciting,” he said. “Ranga was running the experiment, and we thought we might get there, but when he called me and said, ‘The sample is shining,’ I went running down there, and it was metallic hydrogen.

“I immediately said we have to make the measurements to confirm it, so we rearranged the lab…and that’s what we did,” he said. “It’s a tremendous achievement, and even if it only exists in this diamond anvil cell at high pressure, it’s a very fundamental and transformative discovery.”

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Researchers report possible solution to a long-standing solar mystery

Researchers report possible solution to a long-standing solar mystery

An image of the sun taken with The Helioseismic and Magnetic Imager (HMI) on the Solar Dynamics Observatory spacecraft. HMI is an instrument designed to study oscillations and the magnetic field at the solar surface, or photosphere. HMI observes the full solar disk with a resolution of 1 arcsecond. Credit: NASA

Astronomers from the University of Hawaii Institute for Astronomy (IfA), Brazil, and Stanford University may have solved a long-standing solar mystery.

Two decades ago, scientists discovered that the outer five percent of the sun spins more slowly than the rest of its interior. Now, in a new study, to be published in the journal Physical Review Letters, IfA Maui scientists Ian Cunnyngham, Jeff Kuhn, and Isabelle Scholl, together with Marcelo Emilio (Brazil) and Rock Bush (Stanford), describe the physical mechanism responsible for slowing the sun’s outer layers.

Team leader Jeff Kuhn said “The sun won’t stop spinning anytime soon, but we’ve discovered that the same solar radiation that heats the Earth is ‘braking’ the sun because of Einstein’s Special Relativity, causing it to gradually slow down, starting from its surface.”

The sun rotates on its axis at an average rate of about once per month but that rotation isn’t like, for example, the solid Earth or a spinning disk because the rate varies with solar latitude and distance from the center of the sun.

The team used several years of data from the Helioseismic and Magnetic Imager on NASA’s Solar Dynamics Observatory satellite to measure a sharp down-turn in the sun’s  in its very outer 150km. Kuhn said, “This is a gentle torque that is slowing it down, but over the sun’s 5 billion year lifetime it has had a very noticeable influence on its outer 35,000km.” Their paper describes how this photon-braking effect should be at work in most stars.

This change in rotation at the sun’s surface affects the large-scale  and researchers are now trying to understand how the solar magnetism that extends out into the corona and finally into the Earth’s environment will be affected by this braking.

Gravity sensors might offer earlier warning of earthquakes

earthquake

Ruins from the 1906 San Francisco earthquake, remembered as one of the worst natural disasters in United States history. Credit: Public Domain

A team of researchers from France, the U.S. and Italy has found evidence from the Tohoku-Oki earthquake that sensors that measure changes in gravity might offer a way to warn people of impending disaster faster than traditional methods. In their paper published in the journal Nature Communications, the group describes how they analyzed data from gravity sensors near the epicenter of the Tohoku-Oki quake back in 2011 and found that it was possible to isolate gravitational changes due to the earthquake from the noise of other events.

Current earthquake warning systems rely on a network of seismic —they listen for P-waves below the ground which are generated by an earthquake and send a signal to an alarm if they are heard. Such a system offers those in the vicinity of a quake from a few seconds to perhaps a minute to take safety measures. In this new effort, the researches wondered if it might be possible to detect subtle changes in  near the epicenter of a quake to offer those in harm’s way a little more time to prepare for it—because  waves travel at the speed of light.

Prior research has shown that there are subtle changes in gravitational pull around the epicenter of a quake, due to changes in the density of the rock in the area. But until now, it was not clear if such changes could be picked out from all the other background noise. To find out, the researchers pulled data from gravimeter sensors located approximately 500 kilometers from the epicenter of the Tohoku-Oki quake and compared what they found in the record with data from five  in the same area. They noted also that it took 65 seconds for the P-waves to reach the seismic stations. To find out if the quake data would stand out amongst the noise of other natural events (such as the changing tides) the team looked at measurements taken over the 60 days prior to the quake and then at the data from the day before, the day of, and the day after the quake. In looking at the data, the researchers found that they were able to “see” a small blip—one that stood out enough to confirm a quake had occurred.

More research will have to be done before it can be proven that a network of gravity sensors would truly offer people more time to prepare for a  (depending on how close they are to the ), but the results from this initial study seem promising.

New instrument could search for signatures of life on Mars

New instrument could search for signatures of life on Mars

This artist’s rendition shows how a proposed laser-fluorescence instrument could operate on Mars.

A sensing technique that the U.S. military currently uses to remotely monitor the air to detect potentially life-threatening chemicals, toxins, and pathogens has inspired a new instrument that could “sniff” for life on Mars and other targets in the solar system—the Bio-Indicator Lidar Instrument, or BILI.

Branimir Blagojevic, a NASA technologist at the Goddard Space Flight Center in Greenbelt, Maryland, formerly worked for a company that developed the sensor. He has applied the technology to create an instrument prototype, proving in testing that the same remote-sensing technology used to identify bio-hazards in public places also could be effective at detecting organic bio-signatures on Mars.

BILI is a fluorescence-based lidar, a type of remote-sensing instrument similar to radar in principle and operation. Instead of using radio waves, however, lidar instruments use light to detect and ultimately analyze the composition of particles in the atmosphere.

Although NASA has used fluorescence instruments to detect chemicals in Earth’s atmosphere as part of its climate-studies research, the agency so far hasn’t employed the technique in planetary studies. “NASA has never used it before for planetary ground level exploration. If the agency develops it, it will be the first of a kind,” Blagojevic said.

A Rover’s ‘Sense of Smell’

As a planetary-exploration tool, Blagojevic and his team, Goddard scientists Melissa Trainer and Alexander Pavlov, envision BILI as primarily “a rover’s sense of smell.”

Positioned on a rover’s mast, BILI would first scan the terrain looking for dust plumes. Once detected, the instrument, then would command its two ultraviolet lasers to pulse light at the dust. The illumination would cause the particles inside these dust clouds to resonate or fluoresce. By analyzing the fluorescence, scientists could determine if the dust contained organic particles created relatively recently or in the past. The data also would reveal the particles’ size.

“If the bio-signatures are there, it could be detected in the dust,” Blagojevic said

BILI’s Beauty

The beauty of BILI, Blagojevic added, is its ability to detect in real-time small levels of complex organic materials from a distance of several hundred meters. Therefore, it could autonomously search for bio-signatures in plumes above recurring slopes—areas not easily traversed by a rover carrying a variety of in-situ instruments for detailed chemical and biological analysis. Furthermore, because it could do a ground-level aerosol analysis from afar, BILI reduces the risk of sample contamination that could skew the results.

“This makes our instrument an excellent complementary organic-detection instrument, which we could use in tandem with more sensitive, point sensor-type mass spectrometers that can only measure a small amount of material at once,” Blagojevic said. “BILI’s measurements do not require consumables other than electrical power and can be conducted quickly over a broad area. This is a survey instrument, with a nose for certain molecules.”

With such a tool, which also could be installed on an orbiting spacecraft, NASA could dramatically increase the probability of finding bio-signatures in the solar system, he added. “We are ready to integrate and test this novel instrument, which would be capable of detecting a number organic bio-signatures,” Blagojevic said. “Our goal is increasing the likelihood of their discovery.”

Long Heritage

Blagojevic hopes to further advance BILI by ruggedizing the design, reducing its size, and confirming that it can detect tiny concentrations of a broad range of organic molecules, particularly in aerosols that would be found at the ground level on Mars.

“This sensing technique is a product of two decades of research,” Blagojevic said, referring to the technology created by his former employer, Science and Engineering Services, LLC..

Blagojevic and his team used NASA’s Center Innovation Fund, or CIF, to advance the technology. CIF stimulates and encourages creativity and innovation within NASA, targeting less mature, yet promising new technologies.

Opportunity rover to explore Mars gully

NASA’s Opportunity Mars rover will drive down a gully carved long ago by a fluid that might have been water, according to the latest plans for the 12-year-old mission. No Mars rover has done that before.

The longest-active rover on Mars also will, for the first time, visit the interior of the crater it has worked beside for the last five years. These activities are part of a two-year extended mission that began Oct. 1, the newest in a series of extensions going back to the end of Opportunity’s prime mission in April 2004.

Opportunity launched on July 7, 2003 and landed on Mars on Jan. 24, 2004 (PST), on a planned mission of 90 Martian days, which is equivalent to 92.4 Earth days.

“We have now exceeded the prime-mission duration by a factor of 50,” noted Opportunity Project Manager John Callas of NASA’s Jet Propulsion Laboratory, Pasadena, California. “Milestones like this are reminders of the historic achievements made possible by the dedicated people entrusted to build and operate this national asset for exploring Mars.”

Opportunity begins its latest extended mission in the “Bitterroot Valley” portion of the western rim of Endeavour Crater, a basin 14 miles (22 kilometers) in diameter that was excavated by a meteor impact billions of years ago. Opportunity reached the edge of this crater in 2011 after more than seven years of investigating a series of smaller craters. In those craters, the rover found evidence of acidic ancient water that soaked underground layers and sometimes covered the surface.

The gully chosen as the next major destination slices west-to-east through the rim about half a mile (less than a kilometer) south of the rover’s current location. It is about as long as two football fields.

“We are confident this is a fluid-carved gully, and that water was involved,” said Opportunity Principal Investigator Steve Squyres of Cornell University, Ithaca, New York. “Fluid-carved gullies on Mars have been seen from orbit since the 1970s, but none had been examined up close on the surface before. One of the three main objectives of our new mission extension is to investigate this gully. We hope to learn whether the fluid was a debris flow, with lots of rubble lubricated by water, or a flow with mostly water and less other material.”

The team intends to drive Opportunity down the full length of the gully, onto the crater floor. The second goal of the extended mission is to compare rocks inside Endeavour Crater to the dominant type of rock Opportunity examined on the plains it explored before reaching Endeavour.

“We may find that the sulfate-rich rocks we’ve seen outside the crater are not the same inside,” Squyres said. “We believe these sulfate-rich rocks formed from a water-related process, and water flows downhill. The watery environment deep inside the crater may have been different from outside on the plain—maybe different timing, maybe different chemistry

The rover team will face challenges keeping Opportunity active for another two years. Most mechanisms onboard still function well, but motors and other components have far exceeded their life expectancy. Opportunity’s twin, Spirit, lost use of two of its six wheels before succumbing to the cold of its fourth Martian winter in 2010. Opportunity will face its eighth Martian winter in 2017. Use of Opportunity’s non-volatile “flash” memory for holding data overnight was discontinued last year, so results of each day’s observations and measurements must be transmitted that day or lost.

In the two-year extended mission that ended last month, Opportunity explored the “Marathon Valley” area of Endeavour’s western rim, documenting the geological context of water-related minerals that had been mapped there from orbital observations. Last month, the rover drove through “Lewis and Clark Gap,” a low point in the wall separating Marathon Valley from Bitterroot Valley. A recent color panorama from the rover features“Wharton Ridge,” which extends eastward from the gap.

This week, Opportunity is investigating rock exposures next to “Spirit Mound,” a prominent feature near the eastern end of Bitterroot Valley. The third main science goal of the new extended mission is to find and examine rocks from a geological layer that was in place before the impact that excavated Endeavour Crater. The science team has not yet determined whether the mound area will provide rocks that old.

NASA inflates spare room in space

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NASA on Saturday successfully expanded and pressurized an add-on room at the International Space Station two days after aborting the first attempt when it ran into problems.

The flexible habitat, known as the Bigelow Expandable Activity Module (BEAM), completed slowly extending 67 inches (170 centimeters) at 4:10 pm (2010 GMT) following more than seven hours during which astronaut Jeff Williams released short blasts of air into the pod’s walls from the orbiting lab using a manual valve.

After the expansion was completed, he opened eight air tanks inside BEAM, pressurizing the pod to a level close to the space station’s 14.7 pounds per square inch.

“The module is fully expanded at this point and fully pressurized,” NASA spokesman Daniel Huot said. “A very successful day today with the expansion of the first expandable human-rated habitat to ever be flown into space.”

Astronauts will now perform a series of tests to ensure the pod does not leak air and conduct other preparations before entering it through the station’s Tranquility module for the first time in approximately a week, NASA said.

The inflation process may be better described as “unfolding” since it takes very little air to bring the pod to full size, experts said. Only about 0.4 pounds per square inch (psi) is needed to expand BEAM to its full shape.

The expansion caused a popping sound not unlike that of popcorn as the structure slowly filled out, live video feed from the space station on NASA television showed.

NASA is testing expandable habitats astronauts might use on the Moon or Mars in the coming decades.

Efforts to inflate the flexible habitat got under way around 9 am (1300 GMT) after the first attempt failed on Thursday because of too much friction between the pod wall’s fabrics, possibly because it had been left packed longer than originally planned.

Astronauts are expected to re-enter the module several times a year throughout the two-year technology demonstration to retrieve sensor data and assess conditions inside the unit, including how well it protects against space radiation, the US space agency said.

Bigelow Aerospace developed the first-of-its-kind habitat as part of an $18 million contract with NASA.

Fully expanded, the module is 13 feet long (four meters) by 10.5 feet (3.23 meters) wide.

Expandable habitats’ benefit lies in the little space they take up in spacecrafts’ cargo holds while providing greater living and working space once inflated.

But key questions that remain to be answered include how well such pods would protect people against solar radiation, debris and the temperature extremes of space.

India’s budget mini space shuttle blasts off 

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India successfully launched its first mini space shuttle on Monday as New Delhi’s famously frugal space agency joined the global race to make rockets as reusable as airplanes.

The shuttle was reportedly developed on a budget of just one billion rupees ($14 million), a fraction of the billions of dollars spent by other nations’ space programmes.

The Reusable Launch Vehicle, or RLV-TD, which is around the size of a minibus, hurtled into a blue sky over southeast India after its 7:00am (0130 GMT) lift off.

After reaching an altitude of about 70 kilometres (43 miles), it glided back down to Earth, splashing into the Bay of Bengal 10 minutes later.

The test mission was a small but crucial step towards eventually developing a full-size, reusable version of the shuttle to make space travel easier and cheaper in the future.

“We have successfully accomplished the RLV mission as a technology demonstrator,” Indian Space Research Organisation (ISRO) spokesman Devi Prasad Karnik told AFP.

The worldwide race for reuseable rockets intensified after NASA retired its space shuttle programme in 2011.

They are seen as key to cutting costs and waste in the space industry, which currently loses millions of dollars in jettisoned machinery after each launch.

Internet tycoon Elon Musk’s SpaceX and Blue Origin of Amazon owner Jeff Bezos have already successfully carried out their own test launches.

Musk told reporters in April that it currently costs about $300,000 to fuel a rocket and about $60 million to build one.

SpaceX first landed its powerful Falcon 9 rocket in December while Blue Origin’s New Shepard successfully completed a third launch and vertical landing in April this year.

But ISRO hopes to develop its own version, primarily to cash in on the huge and lucrative demand from other countries to send up their satellites.

Mission to Mars

The Indian space agency is no stranger to stellar achievements on a shoestring budget.

It made global headlines in 2013 after sending an unmanned rocket to orbit Mars at a cost of just $73 million. NASA’s Maven Mars mission had a $671 million price tag.

The launch and its low cost were a source of immense pride in India, which beat rival China in becoming the first Asian country to reach the Red Planet.

K. Sivan, a scientist involved in the latest project, said the seven-metre (23-foot) long shuttle survived the test flight, and scientists hope subsequent models six times as big, to be built over the next decade, will glide safely back to land.

“We have located the place where the vehicle is floating. The landing was soft and the vehicle did not break,” Sivan told AFP.

“The mission went off as planned and data from the experiment showed that we have achieved its objectives and demonstrated the RLV technology.”

Prime Minister Narendra Modi praised the “industrious efforts” of ISRO scientists.

“Dynamism & dedication with which our scientists & @isro have worked over the years is exceptional and very inspiring,” Modi said on Twitter.

Modi has often hailed India’s budget space technology, quipping in 2014 that a local rocket that launched four foreign satellites into orbit had cost less to make than Hollywood film “Gravity”.