Tuesday, January 31, 2012 5:38:14 AM
Our Planet's Killer Electrons Shoot Toward Space, Not Earth
Solar wind presses against Earth's magnetic field, giving it a bow shock much like that of a boat in the water. During heavy solar ejections, the pressure can shove the magnetosphere into the Van Allen radiation belts, releasing dangerously charged electrons into space.
CREDIT: NASA
by Nola Taylor Redd, SPACE.com Contributor
Date: 30 January 2012 Time: 07:00 AM ET
As the sun heads toward its 2013 maximum, the corresponding increase in space weather may temporarily strip the radiation belts around Earth of their charged electrons. But a new study of data recorded by 11 independent spacecraft reveals that the deadly particles are blown into space rather than cast into our planet's atmosphere, as some scientists have suggested.
Streams of highly charged electrons zip through the Van Allen radiation belts [ http://www.space.com/2815-james-van-allen-science-paper.html ] circling Earth. When particles from the sun collide with the planet's magnetic field, which shields Earth from the worst effects, the resulting geomagnetic storms [ http://www.space.com/14325-post-skywatching-photos-auroras-january-2012.html ] can decrease the number of dangerous electrons.
Where those particles go is something physicists have long puzzled over — and since they could wreak havoc on sensitive telecommunication satellites and pose a risk to astronauts in space, it's an important question, researchers say.
At the heart of the geomagnetic storm mystery are strange dips, known as dropouts, in the number of charged particles in the radiation belts [ http://www.space.com/2971-mysterious-radio-hiss-blamed-space-weather.html ]. These lapses can happen multiple times per year, but when the sun is going through an active period — as it is now — the number can increase to several times per month, scientists involved in the new study explained. [Amazing auroras from geomagnetic storms [ http://www.space.com/13384-spellbinding-northern-lights-photos-october-2011.html ]]
Astronomers have previously suggested that the missing particles could have been ejected toward Earth, where they might have been absorbed by the atmosphere. This activity still could explain some of the loss, particularly that which occurs when no geomagnetic storm has been detected, but not all of it.
A team of scientists from the University of California, Los Angeles, observed a geomagnetic storm in January 2011 with a plethora of instruments. They noticed that as intense solar activity pushes against the outer edge of Earth's magnetic field [ http://www.space.com/8961-head-crash-spotted-solar-wind-earth-magnetic-field.html ] on the daylight side, the lines can cross, allowing the damaging electrons to escape into space.
"Those particles are entirely lost," lead scientist Drew Turner told SPACE.com. The research is detailed in the Jan. 29 edition of the journal Nature Physics.
Although material ejected from the sun can deplete the Earth's outer radiation belt, it can also resupply the belt with more charged particles in only a few days, Turner said.
Previous studies have found that the volume of electrons can spike after a solar event. When the belts are first almost depleted, Turner's observations imply a larger influx than previously accounted for.
The team used 11 different satellites, including NASA's five Themis spacecraft and two weather satellites operated by the National Oceanic and Atmospheric Administration and the European Organization for the Exploitation of Meteorological Satellites, to study a small geomagnetic storm. The abundance of spacecraft allowed them to capture a complete picture of the interactions between Earth's magnetic field and the particles streaming from the sun.
"It's impossible to get the sense of the entire process with one pinpoint of information," Turner said.
He called the lineup of the various crafts "lucky."
The upcoming launch of NASA's Radiation Belt Storm Probes Mission (RBSP), scheduled for August 2012, may help to remove some elements of chance from further studies.
"RBSP will provide two more points of view with perfect instruments for radiation belt studies," he said.
Copyright © 2012 TechMediaNetwork.com
http://www.space.com/14400-killer-electrons-radiation-belt-space.html [with comments]
===
THEMIS satellite tracks mass electron escape
Posted on January 30, 2012 - 13:59 by Trent Nouveau
When scientists discovered two great swaths of radiation encircling Earth in the 1950s, it spawned exaggerated fears about "killer electrons" and space radiation effects.
The Cold War-era fears were soon allayed, as the radiation doesn't reach Earth, though it can affect satellites and humans moving through the belts. ?? Nevertheless, numerous mysteries about the zone - dubbed the Van Allen Radiation belts - remain to this day. Filled with electrons and energetic charged particles, the radiation belts swell and shrink in response to incoming solar energy, but scientists are not quite sure how.
Indeed, what appears to be the same type of incoming energy has caused entirely different responses on different occasions, with increased particles in some cases and particle loss in others.
Unsurprisingly, there is no shortage of theories about what causes the belts to swell or shrink - with little hard evidence to distinguish between them.
To be sure, it was quite difficult to determine if, when the belts shrink, particles escape up and out into interplanetary space or down toward Earth.??
However, a new study using multiple spacecraft simultaneously has managed to successfully track the particles and determine the escape direction for at least one event: up.
"For a long time, it was thought particles would precipitate downward out of the belts," explained Drew Turner, a scientist at the University of California, Los Angeles. "But more recently, researchers theorized that maybe particles could sweep outward. Our results for this event are clear: we saw no increase in downward precipitation."
While it may sound like a simple detail, such knowledge is hardly esoteric. Yes, the study of particle losses in the belts has so far provided more mystery and potential theories than concrete information. But understanding the radiation belts - and how they change as particles and energy enters or exits - is a crucial part of protecting satellites that fly through the region.
The Van Allen belts fit into a larger system that stretches from the sun to Earth. The sun emits a constant stream of solar wind, not to mention the occasional larger bursts - such as explosions from the sun's atmosphere called coronal mass ejections (CMEs) or shock fronts caused by fast solar winds overtaking slower winds known as corotating interaction regions (CIRs).
When these bursts of energy move toward Earth, they can affect Earth's own magnetic environment, known as the magnetosphere, while creating a geomagnetic storm. Sometimes these storms can cause a sudden drop in the radiation belt particles, seemingly emptying in only a few hours. This "drop out" can last for days. What causes the drop out, why it lasts so long, and just how the particles even leave remain unanswered questions.
Solving such a mystery requires numerous spacecraft measuring changes at several points in space to determine whether an event in one place affects an event elsewhere. ??The Radiation Belt Storm Probes (RBSP), scheduled to launch in August 2012, are specifically geared for such observations, but in the meantime, a team of scientists have combined two disparate sets of a spacecraft to generate an early multipoint view of the radiation belts during an event when the belts experienced a sudden loss of particles.
"We are entering an era where multi-spacecraft are key," said Vassilis Angelopoulos, a space scientist at UCLA. ??"Being able to unite a fleet of available resources into one study is becoming more of a necessity to turn a corner in our understanding of Earth's environment."
By harnessing the observation abilities of the three THEMIS, two GOES, and six POES spacecraft, researchers could observe events in the Van Allen radiation belts from numerous viewpoints simultaneously.
In this case, the team observed a small geomagnetic storm on January 6, 2011 using the three NASA THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft, two GOES (Geostationary Operational Environment Satellite), and six POES (Polar Operational Environmental Satellite).
The THEMIS and GOES spacecraft orbit around Earth's equatorial region, while the POES spacecraft orbit at lower altitude near the poles and travel through the radiation belts several times per day. All are equipped to study the energetic particles in the region. The observations provided an unprecedented view of a geomagnetic storm from numerous viewpoints simultaneously – and the team determined (unequivocally) that particles escaped the radiation belts by streaming out into space, not by raining down toward Earth.
During this storm, electrons moving near the speed of light dropped out for over six hours. In that time period POES saw no increase in electrons escaping downward from the belts. On the other hand, the spacecraft did monitor a low-density patch of the belt that first appeared at the outer edges of the belts and then moved inward. ??This sequence is consistent with the notion that particles were streaming outward, just as the low density region of cars leaving from the front of a traffic jam moves backward over time as more and more cars are able to move forward and escape.
"This was a very simple storm... It's not an extreme case, so we think it's probably pretty typical of what happens in general and ongoing results from concurrent statistical studies support this," added Turner.
And if electrons typically escape the radiation belts by streaming outward, it does seem quite likely that some kind of waves abet their outward motion - enabling them to reach the outer escape boundary.
© 2012 DD&M Inc.
http://www.tgdaily.com/space-features/61115-themis-satellite-tracks-mass-electron-escape [no comments yet]
===
from elsewhere this string, (linked in) http://investorshub.advfn.com/boards/read_msg.aspx?message_id=71521718 and preceding (and any future following)
Solar wind presses against Earth's magnetic field, giving it a bow shock much like that of a boat in the water. During heavy solar ejections, the pressure can shove the magnetosphere into the Van Allen radiation belts, releasing dangerously charged electrons into space.
CREDIT: NASA
by Nola Taylor Redd, SPACE.com Contributor
Date: 30 January 2012 Time: 07:00 AM ET
As the sun heads toward its 2013 maximum, the corresponding increase in space weather may temporarily strip the radiation belts around Earth of their charged electrons. But a new study of data recorded by 11 independent spacecraft reveals that the deadly particles are blown into space rather than cast into our planet's atmosphere, as some scientists have suggested.
Streams of highly charged electrons zip through the Van Allen radiation belts [ http://www.space.com/2815-james-van-allen-science-paper.html ] circling Earth. When particles from the sun collide with the planet's magnetic field, which shields Earth from the worst effects, the resulting geomagnetic storms [ http://www.space.com/14325-post-skywatching-photos-auroras-january-2012.html ] can decrease the number of dangerous electrons.
Where those particles go is something physicists have long puzzled over — and since they could wreak havoc on sensitive telecommunication satellites and pose a risk to astronauts in space, it's an important question, researchers say.
At the heart of the geomagnetic storm mystery are strange dips, known as dropouts, in the number of charged particles in the radiation belts [ http://www.space.com/2971-mysterious-radio-hiss-blamed-space-weather.html ]. These lapses can happen multiple times per year, but when the sun is going through an active period — as it is now — the number can increase to several times per month, scientists involved in the new study explained. [Amazing auroras from geomagnetic storms [ http://www.space.com/13384-spellbinding-northern-lights-photos-october-2011.html ]]
Astronomers have previously suggested that the missing particles could have been ejected toward Earth, where they might have been absorbed by the atmosphere. This activity still could explain some of the loss, particularly that which occurs when no geomagnetic storm has been detected, but not all of it.
A team of scientists from the University of California, Los Angeles, observed a geomagnetic storm in January 2011 with a plethora of instruments. They noticed that as intense solar activity pushes against the outer edge of Earth's magnetic field [ http://www.space.com/8961-head-crash-spotted-solar-wind-earth-magnetic-field.html ] on the daylight side, the lines can cross, allowing the damaging electrons to escape into space.
"Those particles are entirely lost," lead scientist Drew Turner told SPACE.com. The research is detailed in the Jan. 29 edition of the journal Nature Physics.
Although material ejected from the sun can deplete the Earth's outer radiation belt, it can also resupply the belt with more charged particles in only a few days, Turner said.
Previous studies have found that the volume of electrons can spike after a solar event. When the belts are first almost depleted, Turner's observations imply a larger influx than previously accounted for.
The team used 11 different satellites, including NASA's five Themis spacecraft and two weather satellites operated by the National Oceanic and Atmospheric Administration and the European Organization for the Exploitation of Meteorological Satellites, to study a small geomagnetic storm. The abundance of spacecraft allowed them to capture a complete picture of the interactions between Earth's magnetic field and the particles streaming from the sun.
"It's impossible to get the sense of the entire process with one pinpoint of information," Turner said.
He called the lineup of the various crafts "lucky."
The upcoming launch of NASA's Radiation Belt Storm Probes Mission (RBSP), scheduled for August 2012, may help to remove some elements of chance from further studies.
"RBSP will provide two more points of view with perfect instruments for radiation belt studies," he said.
Copyright © 2012 TechMediaNetwork.com
http://www.space.com/14400-killer-electrons-radiation-belt-space.html [with comments]
===
THEMIS satellite tracks mass electron escape
Posted on January 30, 2012 - 13:59 by Trent Nouveau
When scientists discovered two great swaths of radiation encircling Earth in the 1950s, it spawned exaggerated fears about "killer electrons" and space radiation effects.
The Cold War-era fears were soon allayed, as the radiation doesn't reach Earth, though it can affect satellites and humans moving through the belts. ?? Nevertheless, numerous mysteries about the zone - dubbed the Van Allen Radiation belts - remain to this day. Filled with electrons and energetic charged particles, the radiation belts swell and shrink in response to incoming solar energy, but scientists are not quite sure how.
Indeed, what appears to be the same type of incoming energy has caused entirely different responses on different occasions, with increased particles in some cases and particle loss in others.
Unsurprisingly, there is no shortage of theories about what causes the belts to swell or shrink - with little hard evidence to distinguish between them.
To be sure, it was quite difficult to determine if, when the belts shrink, particles escape up and out into interplanetary space or down toward Earth.??
However, a new study using multiple spacecraft simultaneously has managed to successfully track the particles and determine the escape direction for at least one event: up.
"For a long time, it was thought particles would precipitate downward out of the belts," explained Drew Turner, a scientist at the University of California, Los Angeles. "But more recently, researchers theorized that maybe particles could sweep outward. Our results for this event are clear: we saw no increase in downward precipitation."
While it may sound like a simple detail, such knowledge is hardly esoteric. Yes, the study of particle losses in the belts has so far provided more mystery and potential theories than concrete information. But understanding the radiation belts - and how they change as particles and energy enters or exits - is a crucial part of protecting satellites that fly through the region.
The Van Allen belts fit into a larger system that stretches from the sun to Earth. The sun emits a constant stream of solar wind, not to mention the occasional larger bursts - such as explosions from the sun's atmosphere called coronal mass ejections (CMEs) or shock fronts caused by fast solar winds overtaking slower winds known as corotating interaction regions (CIRs).
When these bursts of energy move toward Earth, they can affect Earth's own magnetic environment, known as the magnetosphere, while creating a geomagnetic storm. Sometimes these storms can cause a sudden drop in the radiation belt particles, seemingly emptying in only a few hours. This "drop out" can last for days. What causes the drop out, why it lasts so long, and just how the particles even leave remain unanswered questions.
Solving such a mystery requires numerous spacecraft measuring changes at several points in space to determine whether an event in one place affects an event elsewhere. ??The Radiation Belt Storm Probes (RBSP), scheduled to launch in August 2012, are specifically geared for such observations, but in the meantime, a team of scientists have combined two disparate sets of a spacecraft to generate an early multipoint view of the radiation belts during an event when the belts experienced a sudden loss of particles.
"We are entering an era where multi-spacecraft are key," said Vassilis Angelopoulos, a space scientist at UCLA. ??"Being able to unite a fleet of available resources into one study is becoming more of a necessity to turn a corner in our understanding of Earth's environment."
By harnessing the observation abilities of the three THEMIS, two GOES, and six POES spacecraft, researchers could observe events in the Van Allen radiation belts from numerous viewpoints simultaneously.
In this case, the team observed a small geomagnetic storm on January 6, 2011 using the three NASA THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft, two GOES (Geostationary Operational Environment Satellite), and six POES (Polar Operational Environmental Satellite).
The THEMIS and GOES spacecraft orbit around Earth's equatorial region, while the POES spacecraft orbit at lower altitude near the poles and travel through the radiation belts several times per day. All are equipped to study the energetic particles in the region. The observations provided an unprecedented view of a geomagnetic storm from numerous viewpoints simultaneously – and the team determined (unequivocally) that particles escaped the radiation belts by streaming out into space, not by raining down toward Earth.
During this storm, electrons moving near the speed of light dropped out for over six hours. In that time period POES saw no increase in electrons escaping downward from the belts. On the other hand, the spacecraft did monitor a low-density patch of the belt that first appeared at the outer edges of the belts and then moved inward. ??This sequence is consistent with the notion that particles were streaming outward, just as the low density region of cars leaving from the front of a traffic jam moves backward over time as more and more cars are able to move forward and escape.
"This was a very simple storm... It's not an extreme case, so we think it's probably pretty typical of what happens in general and ongoing results from concurrent statistical studies support this," added Turner.
And if electrons typically escape the radiation belts by streaming outward, it does seem quite likely that some kind of waves abet their outward motion - enabling them to reach the outer escape boundary.
© 2012 DD&M Inc.
http://www.tgdaily.com/space-features/61115-themis-satellite-tracks-mass-electron-escape [no comments yet]
===
from elsewhere this string, (linked in) http://investorshub.advfn.com/boards/read_msg.aspx?message_id=71521718 and preceding (and any future following)
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