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As the sun approaches solar maximum in 2013, new light has been shed upon the effect of solar events on our planet’s magnetosphere, according to a study to be published in Nature Physics on Jan. 29.
Astronomers at the University of California-Los Angeles (UCLA) have discovered that most of the electrons in the Earth’s outer radiation belt vanish at the start of a geomagnetic storm, only to reappear a few hours later. This doughnut-shaped region is full of energetic electrons traveling at almost light speed.
“It’s a puzzling effect,” said study co-author Vassilis Angelopoulos in a press release. “Oceans on Earth do not suddenly lose most of their water, yet radiation belts filled with electrons can be rapidly depopulated.”
Originally noticed by scientists in the 1960s, the team elucidated this mystery using data collected from a fleet of orbiters, including NASA’s THEMIS spacecraft (Time History of Events and Macroscale Interactions during Substorms).
“What we are studying was the first discovery of the space age,” said study co-author Yuri Shprits in the release. “People realized that launches of spacecraft didn’t only make the news, they could also make scientific discoveries that were completely unexpected.”
A 2006 study suggested that the electrons could be lost to the interplanetary medium. However, the new research shows that some of the electrons fall into our atmosphere, but most are pushed away from Earth as solar wind particles from geomagnetic storms begin to bombard the radiation belt.
“This is an important milestone in understanding Earth’s space environment,” said study lead author Drew Turner in the release. “We are one step closer toward understanding and predicting space weather phenomena.”
When the sun undergoes events such as coronal mass ejections, highly charged particles strike Earth’s magnetic field, causing geomagnetic storms that can damage satellites needed for weather monitoring, communications, and global positioning. Understanding the effects of solar activity on Earth’s radiation belts can help to protect these satellites and astronauts traveling through the belts who are highly at risk from such radiation.
“While most satellites are designed with some level of radiation protection in mind, spacecraft engineers must rely on approximations and statistics because they lack the data needed to model and predict the behavior of high-energy electrons in the outer radiation belt,” Turner said.
“As a society, we’ve become incredibly dependent on space-based technology,” he concluded. “Understanding this population of energetic electrons and their extreme variations will help create more accurate models to predict the effect of geomagnetic storms on the radiation belts.”
UCLA researchers are now working with scientists at Russia’s Moscow State University to measure these high-energy electrons with greater accuracy using the Lomonosov spacecraft, which is planned to launch this spring.
