Radiation rings around Earth
The giant amounts of radiation the Van Allen belts generate can pose serious risks for satellites. To learn more about them, NASA launched twin spacecraft, the Van Allen probes, in the summer of 2012.
The satellites were armed with a host of sensors to thoroughly analyze the plasma, energetic particles, magnetic fields and plasma waves in these belts with unprecedented sensitivity and resolution.
Unexpectedly, the probes revealed a new radiation belt surrounding Earth, a third one made of super-high-energy electrons embedded in the outer Van Allen belt about 11,900 to 13,900 miles (19,100 to 22,300 kilometers) above the planet's surface. This stable ring of space radiation apparently formed on Sept. 2 and lasted for more than four weeks.
"The feature was so surprising, I initially foolishly thought the instruments on the probes weren't working properly, but I soon realized the lab had built such wonderful instruments that there wasn't anything wrong with them, so what we saw must be true," Baker said.
This newfound radiation belt then abruptly and almost completely disappeared on Oct. 1. It was apparently disrupted by an interplanetary shock wave caused by a spike in solar wind speeds.
"More than five decades after the original discovery of these radiation belts, you can still find new unexpected things there," Baker said. "It's a delight to be able to find new things in an old domain. We now need to re-evaluate them thoroughly both theoretically and observationally."