Magnetic Tremors Pinpoint The Impact Epicenter Of Earthbound Space Storms

Magnetic Tremors Pinpoint The Impact Epicenter Of Earthbound Space Storms

  2:22:00 AM    Science Lover

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Using data from NASA's THEMIS mission, a team of University of Alberta researchers has pinpointed the impact epicenter of an earthbound space storm as it crashes into the atmosphere, and given an advance warning of its arrival.

Artist's concept of a solar storm breaking through the earth's magnetic field. (Credit: NASA)

The team's study reveals that magnetic blast waves can be used to pinpoint and predict the location where space storms dissipate their massive amounts of energy. These storms can dump the equivalent of 50 gigawatts of power, or the output of 10 of the world's largest power stations, into Earth's atmosphere.

The energy that drives space storms originates on the sun. The stream of electrically charged particles in the solar wind carries this energy toward Earth. The solar wind interacts with Earth's magnetic field. Scientists call the process that begins with Earth's magnetic field capturing energy and ends with its release into the atmosphere a geomagnetic substorm.

"Substorm onset occurs when Earth's magnetic field suddenly and dramatically releases energy previously captured by the solar wind," said David Sibeck, project scientist for the Time History of Events and Macroscale Interactions During Substorms (THEMIS) mission at NASA Goddard Spaceflight Center in Greenbelt, Md.

Physicists Jonathan Rae and Ian Mann lead the University of Alberta research team that recently located a substorm's epicenter of the impact. The team uses ground-based observatories spread across northern Canada and the five satellites of the THEMIS mission to detect magnetic disturbances as storms crash into the atmosphere. Using a technique the researchers call "space seismology," they look for the eye of the storm hundreds of thousands of miles above Earth.

"We see the benevolent side of space storms in the form of the Northern Lights," said Mann. "When electrically charged particles speed toward Earth and buffet the atmosphere, the result is often a dancing, shimmering light over the polar region." But there is also a hazardous side. Earth's atmosphere protects us from the damaging direct effects of the radiation from space storms, but in space there is nowhere to hide. High-energy, electrically charged particles released by space storms can damage spacecraft. On Earth, disturbances caused by the particles and the electrical currents they carry can interrupt radio communications and global positioning system (GPS) navigation, and damage electric power grids.

Rae and Mann's team has also determined that the magnetic tremors show that the space storm impact into the atmosphere has a unique epicenter, with the eye of the storm located in space beyond the low-Earth orbits of most communication satellites.

Guided by Earth's magnetic field, the magnetic tremors rocket through space toward Earth. These geomagnetic substorms trigger magnetic sensors on the ground as they impact the atmosphere. The effects of these storms, and the most spectacular displays of the Northern Lights, follow a few minutes later.

The objective of NASA's pioneering multi-spacecraft THEMIS mission is to determine what causes geomagnetic substorms. In addition to a well-instrumented fleet of five spacecraft, THEMIS operates a network of ground observatories stretching across Canada and the United States to place the spacecraft observations in their global context. All night long, every night, the observatories take 3-second time resolution snapshots of the aurora and measure corresponding variations in Earth's magnetic field strength and direction every half second.

An analysis of the auroral movies and magnetic variations by Dr. Jonathan Rae from the University of Alberta pinpointed just when and where one substorm explosively released its magnetic energy. "Undulating auroral features and ripples in Earth's magnetic field began at the same time and propagated away from Sanikulaq, Nunavut, Canada at speeds on the order of 60,000 miles per hour, much like the blast wave from a gigantic explosion," said Sibeck. Dr. Rae and his team presented the results on May 25 at the American Geophysical Union meeting in Toronto.

Probing the eye of a space storm and recognizing the advance warning signs are crucial for researchers trying to understand and predict space weather. Key questions about when and how space storms start are still challenging researchers on the THEMIS team. Like forecasters on Earth who predict severe weather, the University of Alberta researchers are using their "space seismology" technique to investigate methods to forecast space storms.

THEMIS is a NASA-funded mission and involves scientists from Canada, the United States, and Europe. Current Canadian activity is funded by the Canadian Space Agency.

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Air-fueled Battery Could Last Up To 10 Times Longer: Ground-breaking Technology For Electric Cars

Air-fueled Battery Could Last Up To 10 Times Longer: Ground-breaking Technology For Electric Cars

  9:55:00 AM    Science Lover

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A new type of air-fuelled battery could give up to ten times the energy storage of designs currently available.

Diagram of the STAIR (St Andrews Air) cell. Oxygen drawn from the air reacts within the porous carbon to release the electrical charge in this lithium-air battery. (Credit: Image courtesy of Engineering and Physical Sciences Research Council (EPSRC))

This step-change in capacity could pave the way for a new generation of electric cars, mobile phones and laptops.

The research work, funded by the Engineering and Physical Sciences Research Council (EPSRC), is being led by researchers at the University of St Andrews with partners at Strathclyde and Newcastle.

The new design has the potential to improve the performance of portable electronic products and give a major boost to the renewable energy industry. The batteries will enable a constant electrical output from sources such as wind or solar, which stop generating when the weather changes or night falls.

Improved capacity is thanks to the addition of a component that uses oxygen drawn from the air during discharge, replacing one chemical constituent used in rechargeable batteries today. Not having to carry the chemicals around in the battery offers more energy for the same size battery. Reducing the size and weight of batteries with the necessary charge capacity has been a long-running battle for developers of electric cars.

The STAIR (St Andrews Air) cell should be cheaper than today’s rechargeables, too. The new component is made of porous carbon, which is far less expensive than the lithium cobalt oxide it replaces.

This four-year research project, which reaches its halfway mark in July, builds on the discovery at the university that the carbon component’s interaction with air can be repeated, creating a cycle of charge and discharge. Subsequent work has more than tripled the capacity to store charge in the STAIR cell.

Principal investigator on the project, Professor Peter Bruce of the Chemistry Department at the University of St Andrews, says: “Our target is to get a five to ten fold increase in storage capacity, which is beyond the horizon of current lithium batteries. Our results so far are very encouraging and have far exceeded our expectations.”

“The key is to use oxygen in the air as a re-agent, rather than carry the necessary chemicals around inside the battery,” says Bruce.

The oxygen, which will be drawn in through a surface of the battery exposed to air, reacts within the pores of the carbon to discharge the battery. “Not only is this part of the process free, the carbon component is much cheaper than current technology,” says Bruce. He estimates that it will be at least five years before the STAIR cell is commercially available.

The project is focused on understanding more about how the chemical reaction of the battery works and investigating how to improve it. The research team is also working towards making a STAIR cell prototype suited, in the first instance, for small applications, such as mobile phones or MP3 players.

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Refined Hubble Constant Narrows Possible Explanations For Dark Energy

Refined Hubble Constant Narrows Possible Explanations For Dark Energy

  8:49:00 PM    Science Lover

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This is a Hubble Space Telescope photo of the spiral galaxy NGC 3021. This was one of several hosts of recent Type Ia supernovae observed by astronomers to refine the measure of the universe's expansion rate, called the Hubble constant. Hubble made precise measurements of Cepheid variable stars in the galaxy, highlighted by green circles in the four inset boxes. These stars pulsate at a rate that is matched closely to their intrinsic brightness. (Credit: NASA, ESA, and A. Riess (STScI and JHU))

Whatever dark energy is, explanations for it have less wiggle room following a Hubble Space Telescope observation that has refined the measurement of the universe's present expansion rate to a precision where the error is smaller than five percent.

The new value for the expansion rate, known as the Hubble constant, or Ho (after Edwin Hubble who first measured the expansion of the universe nearly a century ago), is 74.2 kilometers per second per megaparsec (error margin of ± 3.6). The results agree closely with an earlier measurement gleaned from Hubble of 72 ± 8 km/sec/megaparsec, but are now more than twice as precise.

The Hubble measurement, conducted by the SHOES (Supernova Ho for the Equation of State) Team and led by Adam Riess, of the Space Telescope Science Institute and the Johns Hopkins University, uses a number of refinements to streamline and strengthen the construction of a cosmic "distance ladder," a billion light-years in length, that astronomers use to determine the universe's expansion rate.

Hubble observations of pulsating stars called Cepheid variables in a nearby cosmic mile marker, the galaxy NGC 4258, and in the host galaxies of recent supernovae, directly link these distance indicators. The use of Hubble to bridge these rungs in the ladder eliminated the systematic errors that are almost unavoidably introduced by comparing measurements from different telescopes.

Riess explains the new technique: "It's like measuring a building with a long tape measure instead of moving a yard stick end over end. You avoid compounding the little errors you make every time you move the yardstick. The higher the building, the greater the error."

Lucas Macri, professor of physics and astronomy at Texas A&M, and a significant contributor to the results, said, "Cepheids are the backbone of the distance ladder because their pulsation periods, which are easily observed, correlate directly with their luminosities. Another refinement of our ladder is the fact that we have observed the Cepheids in the near-infrared parts of the electromagnetic spectrum where these variable stars are better distance indicators than at optical wavelengths."

This new, more precise value of the Hubble constant was used to test and constrain the properties of dark energy, the form of energy that produces a repulsive force in space, which is causing the expansion rate of the universe to accelerate.

By bracketing the expansion history of the universe between today and when the universe was only approximately 380,000 years old, the astronomers were able to place limits on the nature of the dark energy that is causing the expansion to speed up. (The measurement for the far, early universe is derived from fluctuations in the cosmic microwave background, as resolved by NASA's Wilkinson Microwave Anisotropy Probe, WMAP, in 2003.)

Their result is consistent with the simplest interpretation of dark energy: that it is mathematically equivalent to Albert Einstein's hypothesized cosmological constant, introduced a century ago to push on the fabric of space and prevent the universe from collapsing under the pull of gravity. (Einstein, however, removed the constant once the expansion of the universe was discovered by Edwin Hubble.)

"If you put in a box all the ways that dark energy might differ from the cosmological constant, that box would now be three times smaller," says Riess.

"That's progress, but we still have a long way to go to pin down the nature of dark energy."

Though the cosmological constant was conceived of long ago, observational evidence for dark energy didn't come along until 11 years ago, when two studies, one led by Riess and Brian Schmidt of Mount Stromlo Observatory, and the other by Saul Perlmutter of Lawrence Berkeley National Laboratory, discovered dark energy independently, in part with Hubble observations. Since then astronomers have been pursuing observations to better characterize dark energy.

Riess's approach to narrowing alternative explanations for dark energy--whether it is a static cosmological constant or a dynamical field (like the repulsive force that drove inflation after the big bang)--is to further refine measurements of the universe's expansion history.

Before Hubble was launched in 1990, the estimates of the Hubble constant varied by a factor of two. In the late 1990s the Hubble Space Telescope Key Project on the Extragalactic Distance Scale refined the value of the Hubble constant to an error of only about ten percent. This was accomplished by observing Cepheid variables at optical wavelengths out to greater distances than obtained previously and comparing those to similar measurements from ground-based telescopes.

The SHOES team used Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and the Advanced Camera for Surveys (ACS) to observe 240 Cepheid variable stars across seven galaxies. One of these galaxies was NGC 4258, whose distance was very accurately determined through observations with radio telescopes. The other six galaxies recently hosted Type Ia supernovae that are reliable distance indicators for even farther measurements in the universe. Type Ia supernovae all explode with nearly the same amount of energy and therefore have almost the same intrinsic brightness.

By observing Cepheids with very similar properties at near-infrared wavelengths in all seven galaxies, and using the same telescope and instrument, the team was able to more precisely calibrate the luminosity of supernovae. With Hubble's powerful capabilities, the team was able to sidestep some of the shakiest rungs along the previous distance ladder involving uncertainties in the behavior of Cepheids.

Riess would eventually like to see the Hubble constant refined to a value with an error of no more than one percent, to put even tighter constraints on solutions to dark energy.

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Swine Flu Outbreak Illuminated By Avian Flu Research

Swine Flu Outbreak Illuminated By Avian Flu Research

  9:15:00 PM    Science Lover

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A new study by University of Maryland researchers suggests that the potential for an avian influenza virus to cause a human flu pandemic is greater than previously thought. Results also illustrate how the current swine flu outbreak likely came about.

This graphic shows why the Type A virus can't be eradicated.
(Credit: Image courtesy of University of Maryland)

As of now, avian flu viruses can infect humans who have contact with birds, but these viruses tend not to transmit easily between humans. However, in research recently published in the Proceedings of the National Academy of Sciences, Associate Professor Daniel Perez from the University of Maryland showed that after reassortment with a human influenza virus, a process that usually takes place in intermediary species like pigs, an avian flu virus requires relatively few mutations to spread rapidly between mammals by respiratory droplets.

"This is similar to the method by which the current swine influenza strain likely formed," said Perez, program director of the University of Maryland-based Prevention and Control of Avian Influenza Coordinated Agricultural Project, AICAP. "The virus formed when avian, swine, and human-like viruses combined in a pig to make a new virus. After mutating to be able to spread by respiratory droplets and infect humans, it is now spreading between humans by sneezing and coughing."

Image via Wikipedia

In his study, Perez used the avian H9N2 influenza virus, one that is on the list of candidates for human pandemic potential. Using reverse genetics, a technique whereby individual genes from viruses are separated, selected, and put back together, Perez and his team created a hybrid human-avian virus. Their research hybrid has internal human flu genes and surface avian flu genes from the H9N2 virus. Though it comes from a different strain of avian flu than the one that contributed to the hybrid virus now causing the swine flu outbreak, Perez's research virus is similar in origin to the swine flu virus, in that both involved a combination of avian and human influenza viruses.

Perez infected ferrets (considered a good model for human influenza transmission) with the virus he created, and allowed the virus to mutate in the species. Before long, healthy ferrets that shared air space but not physical space with the infected ferret had the virus, showing that the virus had mutated to spread by respiratory droplets.

When the genetic sequences of the mutant virus and original hybrid virus were compared, the only differences were five amino acid mutations, three on the surface, and two internally. Two of the surface mutations were determined to be solely responsible for supporting respiratory droplet transmission. Because so few mutations were necessary to make the hybrid H9N2 transmissible this way, they concluded that after an animal-human hybrid influenza virus forms in nature, a human pandemic of this virus is potentially just a few mutations away.

"We do not know if the mutations we saw in the lab are the same that have made the H1N1 swine flu transmissible by respiratory droplets," Perez said. "We will be doing more research on the current swine flu strain to study its specific genetic mutations."

Perez found that one of the two of the genetic mutations in his lab strain that enabled respiratory transmission between mammals was on the tip of the HA surface protein, one of the sites where human antibodies created in response to current vaccines would bind.

"Because the binding site of the mutant virus is different from the virus upon which the vaccine is modeled, it may mean that current vaccine stocks would not be as effective against the H9N2 mutant strain as previously anticipated," said Perez. "We should keep this in mind when designing vaccines for an avian flu pandemic in humans."

However, scientists cannot predict what the actual mutations will look like if and when they occur in nature, or even which strain of avian influenza will mutate to infect mammals.

"This is just the tip of the iceberg," said Perez. "Many more studies have to be done to see which combinations of mutations cause this type of transmission before we can design the appropriate vaccines."

Perez will be talking this week with the NIH and the CDC to discuss his team's role in researching the current swine flu virus strain. Perez will likely do studies related to vaccine development, virus transmission between humans and animals, and the pathogenesis of the virus.

A virus vaccine is derived from the virus itself. The vaccine consists of virus components or killed viruses that mimic the presence of the virus without causing disease. These prime the body's immune system to recognize and fight against the virus. The immune system produces antibodies against the vaccine that remain in the system until they are needed. If that virus, or in some cases a closely similar one is later introduced into the system, those antibodies attach to viral particles and remove them before they have time to replicate, preventing or lessening symptoms of the virus.

The immune system also retains antibodies to a virus after being infected with it, so humans have general immunity to human strains of avian influenza strains. But humans do not generally have immunity to avian flu strains because they have not been infected by them before. The surface proteins are sufficiently different to escape the human immune response. Avian flu strains are therefore more dangerous for humans because the human immune system cannot recognize the virus or protect against it.

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