 |
|
Mind the gap: Space scientists uncover causes of gap in Van Allen belts
September 27, 2006A team of British and US scientists have discovered that the gap in the Van Allen radiation belts is formed by natural wave turbulence in space, not by lightning. The discovery settles years of controversy among space scientists about the mechanisms responsible for causing the gap and has important implications for space weather forecasting.
High above the Earth's atmosphere, energetic charged particles are trapped in the Earth's magnetic field where they form the Van Allen radiation belts. Energetic electrons, travelling close to the speed of light, occupy two doughnut shaped zones, usually separated by a gap known as the slot region.
The underlying mechanism that clears the slot region of electrons has been the subject of intense scientific debate. Now, based on analysis of wave data collected over 13 months by the CRRES satellite, Dr Nigel Meredith of British Antarctic Survey and colleagues from BAS, the University of California, Los Angeles and the University of Iowa, believe that the gap is most likely formed by natural wave turbulence in space, rather than by lightning as the alternative theory suggests. Their results are published in the Journal of Geophysical Research this week.
According to lead author, Dr Nigel Meredith:
"Last year NASA scientists suggested that lightning-generated radio waves leaking out into space are responsible for the gap between the two belts by dumping particles into the atmosphere. Since lightning occurs far more often over land than water, waves in space should also occur more over land. However, after analysing satellite data we found that there is no land-ocean variation at frequencies less than 1 kiloHertz where the waves are most intense. Instead, wave activity increases during geomagnetic disturbances driven by the Sun, suggesting that natural wave turbulence is responsible for the gap."
"The results are important, because a better understanding of the radiation belts will help modellers forecast space weather more accurately, helping to protect both astronauts and satellites from radiation hazards."
British Antarctic Survey
According to lead author, Dr Nigel Meredith:
"Last year NASA scientists suggested that lightning-generated radio waves leaking out into space are responsible for the gap between the two belts by dumping particles into the atmosphere. Since lightning occurs far more often over land than water, waves in space should also occur more over land. However, after analysing satellite data we found that there is no land-ocean variation at frequencies less than 1 kiloHertz where the waves are most intense. Instead, wave activity increases during geomagnetic disturbances driven by the Sun, suggesting that natural wave turbulence is responsible for the gap."
"The results are important, because a better understanding of the radiation belts will help modellers forecast space weather more accurately, helping to protect both astronauts and satellites from radiation hazards."
British Antarctic Survey
Rare gamma-ray flare from a distant star disturbs Earth's daytime ionosphere
On Dec. 27, 2004, scientists detected the largest gamma-ray burst ever recorded. It came from a magnetar-a neutron star with an enormous magnetic field-50,000 light years away.
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.
Green light for Lazio-Sirad: the experiment on the International Space Station that will chase earthquakes
Lazio-Sirad is ready to gather data. The experiment is installed on the International Space Station and its aim is to trace the slight variations of the so-called Van Allen belts that seem to occur before earthquakes. At the same time the experiment will gather data that will make possible the development of techniques of protection from radiation for astronauts.
Artemis, one year after launch
A mission brought back from the edge, a world premiere in space, European engineers grappling with the challenge of a launch malfunction: such are the results of Artemis`s first, adventurous year in space. For Artemis is still alive, doggedly advancing towards its working position in geostationary orbit, with ion engines not originally designed for such a task. Already it has demonstrated a new way of relaying data between satellites, premiering laser links in space. One year ago, Artemis was widely thought to be as good as lost; now, the spacecraft promises to perform its mission for advanced telecommunications. Exactly one year ago, due to a malfunction in its upper stage, Ariane 5 left ES
More Van Allen Belts News Articles
| © 2008 BrightSurf.com |