Researchers have shown plasma waves buffeting the planet’s radiation belts are responsible for scattering charged particles into the atmosphere for the first time that in a recent study on space weather’s impact on Earth.
The study is the detailed analysis of the link between these waves and the fallout of electrons from the planet’s radiation belts so far. The belts are impacted by fluctuations in “space weather” caused by solar activity that can disrupt GPS satellites, communication systems, power grids and manned space exploration.
The solar system and the bulk of the universe comprise matter which is mostly in the form of plasma. Plasma is a very hot gas in which the electrons have been stripped from atoms to form a gas of negatively charged electrons and positively charged ions.
The space physicists at Dartmouth College are part of a NASA-sponsored team that studied the Van Allen radiation belts, which are doughnut-shaped belts of charged particles held in place by the Earth’s magnetosphere, the magnetic field surrounding our planet.
In a quest to better predict the space weather, researchers study the radiation belts from above and below in complementary approaches such as through satellites high over Earth and through dozens of instrument-laden balloons (BARREL, or Balloon Array for Radiation belt Relativistic Electron Losses) at lower altitudes to assess the particles that rain down. The balloons were launched from Antarctica where some of the best observations could be made.
As the falling electrons collide with the atmosphere, they produce X-rays and that is what the balloon instruments recorded. “We are measuring those atmospheric losses and trying to understand how the particles are getting kicked into the atmosphere,” said study co-author Robyn Millan, associateprofessor at Dartmouth’s department of physics and astronomy.
Millan added, “Our main focus has been really on the processes that are occurring out in space. Particles in the Van Allen belts never reach the ground, so they don’t constitute a health threat. Even the X-rays get absorbed, which is why we have to go to balloon altitudes to see them.”
The researchers obtained measurements in Antarctica in 2013 when the balloons and both the Geostationary Operational Environmental Satellite (GOES) and the Van Allen Probe satellites were near the same magnetic field line.
They put the satellite data into their model that tested the wave-particle interaction theory. The results suggested the wave scattering was the cause of the particle fallout. “This is the first real quantitative test of the theory,” Millan added.
The results appeared in the journal Geophysical Research Letters.