Andrew Yee
September 9th 05, 04:10 PM
Press Office
British Antarctic Survey
Contact:
Amanda Lynnes, tel: ++44 1223 221414
Linda Capper, tel: ++44 1223 221448
Author Contact:
Dr Richard Horne, tel: ++44 1223 2211542
7 September 2005
PR No. 13/2005
Scientific breakthrough will help protect astronauts and spacecraft
A breakthrough by a team of British, US and French scientists will help
protect astronauts, spacecraft and satellites from radiation hazards
experienced in space.
Reporting in the journal Nature this week, the team describe how their
study of rare and unusual space storms provided a unique opportunity to
test conflicting theories about the behaviour of high energy particles in
the Van Allen radiation belts* -- a volatile region 12000 miles (19,000
km) above the Earth.
Lead author, Dr Richard Horne of the British Antarctic Survey (BAS) says:
"Solar storms can increase radiation in the Van Allen belts to levels that
pose a threat to spacecraft. As modern society relies increasingly on
satellites for business, communications, and security, it is important to
understand the environment that spacecraft operate in so that we can help
protect our space investment.
"For a long time scientists have been trying to explain why the number of
charged particles inside the belts vary so much. Our major breakthrough
came when we observed two rare space storms that occurred almost
back-to-back in October and November 2003. During the storms part of the
Van Allen radiation belt was drained of electrons and then reformed much
closer to the Earth in a region usually thought to be relatively safe for
satellites.
"When the radiation belts reformed they did not increase according to a
long-held theory of particle acceleration. Instead, by using scientific
instruments in Antarctica and on the CLUSTER mission satellites, we showed
that very low frequency radio waves caused the particle acceleration and
intensified the belts.
"This new information will help spacecraft operators and space weather
forecasters who must predict when satellites and missions are most at risk
from radiation events allowing them to take measures to protect
instruments and systems from damage, and astronauts from risks to their
health."
ENDS
Notes for Editors:
Wave Acceleration of electrons in the Van Allen radiation Belts by Richard
B. Horne[1], Richard M. Thorne[2], Yuri Y. Shprits[2], Nigel P.
Meredith[1], Sarah A. Glauert[1], Andy J. Smith[1], Shrikanth G.
Kanekal[3], Daniel N. Baker[3], Mark J. Engebretson[4], Jennifer L.
Posch[4], Maria Spasojevic[5], Umran S. Inan[5], Jolene S. Pickett[6] &
Pierrette M. E. Decreau[7] is published this week in the journal Nature.
[1] British Antarctic Survey, Madingley Road, Cambridge CB3 0ET, UK
[2] Department of Atmospheric and Oceanic Sciences, University of
California Los Angeles, 405 Hilgard Avenue, Los Angeles, California
90095-1565, USA
[3] Laboratory for Atmospheric and Space Physics, University of Colorado,
1234 Innovation Drive, Boulder, Colorado 80303-7814, USA
[4] Department of Physics, Augsburg College, Minneapolis, Minnesota 55454,
USA
[5] STAR Laboratory, Stanford University, Stanford, California 94305, USA
[6] Department of Physics and Astronomy, University of Iowa, Iowa City,
Iowa 52242-1479, USA
[7] LPCE, 3A, Avenue de la recherche scientifique, 45071, Orleans, Cedex
2, France
Pictures:
Data were collected by Automatic Geophysical Observatories in Antarctica
and by CLUSTER satellites. High Quality stills of these and an artists'
impression of the Van Allen Belts are available from the BAS Press Office
above.
* Van Allen radiation belts
The Van Allen radiation belts were the foremost discovery of the space age
after being detected by the first US satellite Explorer I, which was
launched during the International Geophysical Year of 1957-58. They are
composed of energetic charged particles trapped inside the Earth's
magnetic field, which surrounds the Earth like a ring doughnut. They vary
according to solar activity. Other planets with magnetic fields, such as
Jupiter and Saturn, also have radiation belts. At present it is not known
how the radiation belts at the other planets are formed, but the wave
acceleration theory presented here could apply.
The 'old' theory
Until now it was believed that the electrons within the belts were
accelerated by radial diffusion. This can be explained by thinking of the
Earth's magnetic field as elastic bands. If the bands are plucked, they
wobble. If they wobble at the same rate as the particles drifting around
the Earth then the particles can be driven across the magnetic field and
accelerated. This process is known as radial diffusion and is driven by
solar activity. The new research presented here shows that this theory is
now inadequate.
Space storms
Antarctica is our 'window on space'. Magnetic space storms damage
spacecraft, disrupt power supplies, communications & navigation systems
and alter satellite orbits. BAS scientists are attempting to predict Space
Weather through a better understanding of the complex process that take
place when the Earth and Sun's magnetic fields meet. BAS scientists use
several different technologies to measure variations in the Earth's
magnetic field. Data from these studies are used in mathematical models to
test theoretical ideas. This research makes a major contribution to
international global research programmes that involve spacecraft and
networks of ground-based scientific instruments.
Whistler mode chorus waves
During magnetic storms very low frequency radio waves (in the audio range
below 20 kHz) are generated in space by low energy electrons. The waves
can be guided along the magnetic field down to the ground in the polar
regions. Under some conditions the waves can accelerate a small number of
electrons to very high energies and trap them in space. These are the
particles that damage spacecraft. But under other conditions they can
drain the radiation belts by dumping energetic particles down into the
upper atmosphere and change its chemistry as a result.
British Antarctic Survey is a world leader in research into global issues
in an Antarctic context. It is the UK's national operator and is a
component of the Natural Environment Research Council. It has an annual
budget of around £40 million, runs eight research programmes and operates
five research stations, two Royal Research Ships and five aircraft in and
around Antarctica. More information about the work of the Survey can be
found at:
http://www.antarctica.ac.uk
British Antarctic Survey
Contact:
Amanda Lynnes, tel: ++44 1223 221414
Linda Capper, tel: ++44 1223 221448
Author Contact:
Dr Richard Horne, tel: ++44 1223 2211542
7 September 2005
PR No. 13/2005
Scientific breakthrough will help protect astronauts and spacecraft
A breakthrough by a team of British, US and French scientists will help
protect astronauts, spacecraft and satellites from radiation hazards
experienced in space.
Reporting in the journal Nature this week, the team describe how their
study of rare and unusual space storms provided a unique opportunity to
test conflicting theories about the behaviour of high energy particles in
the Van Allen radiation belts* -- a volatile region 12000 miles (19,000
km) above the Earth.
Lead author, Dr Richard Horne of the British Antarctic Survey (BAS) says:
"Solar storms can increase radiation in the Van Allen belts to levels that
pose a threat to spacecraft. As modern society relies increasingly on
satellites for business, communications, and security, it is important to
understand the environment that spacecraft operate in so that we can help
protect our space investment.
"For a long time scientists have been trying to explain why the number of
charged particles inside the belts vary so much. Our major breakthrough
came when we observed two rare space storms that occurred almost
back-to-back in October and November 2003. During the storms part of the
Van Allen radiation belt was drained of electrons and then reformed much
closer to the Earth in a region usually thought to be relatively safe for
satellites.
"When the radiation belts reformed they did not increase according to a
long-held theory of particle acceleration. Instead, by using scientific
instruments in Antarctica and on the CLUSTER mission satellites, we showed
that very low frequency radio waves caused the particle acceleration and
intensified the belts.
"This new information will help spacecraft operators and space weather
forecasters who must predict when satellites and missions are most at risk
from radiation events allowing them to take measures to protect
instruments and systems from damage, and astronauts from risks to their
health."
ENDS
Notes for Editors:
Wave Acceleration of electrons in the Van Allen radiation Belts by Richard
B. Horne[1], Richard M. Thorne[2], Yuri Y. Shprits[2], Nigel P.
Meredith[1], Sarah A. Glauert[1], Andy J. Smith[1], Shrikanth G.
Kanekal[3], Daniel N. Baker[3], Mark J. Engebretson[4], Jennifer L.
Posch[4], Maria Spasojevic[5], Umran S. Inan[5], Jolene S. Pickett[6] &
Pierrette M. E. Decreau[7] is published this week in the journal Nature.
[1] British Antarctic Survey, Madingley Road, Cambridge CB3 0ET, UK
[2] Department of Atmospheric and Oceanic Sciences, University of
California Los Angeles, 405 Hilgard Avenue, Los Angeles, California
90095-1565, USA
[3] Laboratory for Atmospheric and Space Physics, University of Colorado,
1234 Innovation Drive, Boulder, Colorado 80303-7814, USA
[4] Department of Physics, Augsburg College, Minneapolis, Minnesota 55454,
USA
[5] STAR Laboratory, Stanford University, Stanford, California 94305, USA
[6] Department of Physics and Astronomy, University of Iowa, Iowa City,
Iowa 52242-1479, USA
[7] LPCE, 3A, Avenue de la recherche scientifique, 45071, Orleans, Cedex
2, France
Pictures:
Data were collected by Automatic Geophysical Observatories in Antarctica
and by CLUSTER satellites. High Quality stills of these and an artists'
impression of the Van Allen Belts are available from the BAS Press Office
above.
* Van Allen radiation belts
The Van Allen radiation belts were the foremost discovery of the space age
after being detected by the first US satellite Explorer I, which was
launched during the International Geophysical Year of 1957-58. They are
composed of energetic charged particles trapped inside the Earth's
magnetic field, which surrounds the Earth like a ring doughnut. They vary
according to solar activity. Other planets with magnetic fields, such as
Jupiter and Saturn, also have radiation belts. At present it is not known
how the radiation belts at the other planets are formed, but the wave
acceleration theory presented here could apply.
The 'old' theory
Until now it was believed that the electrons within the belts were
accelerated by radial diffusion. This can be explained by thinking of the
Earth's magnetic field as elastic bands. If the bands are plucked, they
wobble. If they wobble at the same rate as the particles drifting around
the Earth then the particles can be driven across the magnetic field and
accelerated. This process is known as radial diffusion and is driven by
solar activity. The new research presented here shows that this theory is
now inadequate.
Space storms
Antarctica is our 'window on space'. Magnetic space storms damage
spacecraft, disrupt power supplies, communications & navigation systems
and alter satellite orbits. BAS scientists are attempting to predict Space
Weather through a better understanding of the complex process that take
place when the Earth and Sun's magnetic fields meet. BAS scientists use
several different technologies to measure variations in the Earth's
magnetic field. Data from these studies are used in mathematical models to
test theoretical ideas. This research makes a major contribution to
international global research programmes that involve spacecraft and
networks of ground-based scientific instruments.
Whistler mode chorus waves
During magnetic storms very low frequency radio waves (in the audio range
below 20 kHz) are generated in space by low energy electrons. The waves
can be guided along the magnetic field down to the ground in the polar
regions. Under some conditions the waves can accelerate a small number of
electrons to very high energies and trap them in space. These are the
particles that damage spacecraft. But under other conditions they can
drain the radiation belts by dumping energetic particles down into the
upper atmosphere and change its chemistry as a result.
British Antarctic Survey is a world leader in research into global issues
in an Antarctic context. It is the UK's national operator and is a
component of the Natural Environment Research Council. It has an annual
budget of around £40 million, runs eight research programmes and operates
five research stations, two Royal Research Ships and five aircraft in and
around Antarctica. More information about the work of the Survey can be
found at:
http://www.antarctica.ac.uk