"The acceleration we first reported operates on the scale size of an electron's gyromotion-it is a really local process, maybe only a few hundred meters in size," notes Harlan Spence, director of the UNH Institute for the Study of Earth, Oceans, and Space, principal scientist for the ECT, and coauthor on the Nature Communications paper.
"Now we're seeing this large-scale, global motion involving ultra low-frequency waves pulsing through Earth's magnetosphere and operating across vast distances up to hundreds of thousands of kilometers.
adds, in all likelihood both processes are occurring simultaneously to accelerate particles to relativistic speeds.
Understanding the complex dynamics of the particle acceleration will help scientists make better predictions of space weather conditions and, thus, offer better protections to orbiting satellites crucial to modern-day society.
Having twin spacecraft making simultaneous measurements in different regions of nearby space is a key part of the mission as it allows the scientists to look at data separated in both space and time.
"With the Van Allen Probes, I like to think there's no place for these particles to hide because each spacecraft is spinning and 'glimpses' the entire sky with its detector 'eyes', so we're essentially getting a 360-degree view in terms of direction, position, energy, and time," Spence
, "What we hope for are those serendipitous occasions when nature has accentuated one process above all others, which allows the spacecraft to really see what's going on.