Over 20 years ago, scientists proposed that wind existed in space, but until recently have been unable to prove it. Now, however, scientists at the European Geosciences Union (EGO) have detected a plasmaspheric wind that contributes to the loss of material from the Earth’s plasmasphere, a region of space extending above its atmosphere.
To detect the space wind, scientists analyzed properties of charged particles by using information collected in the Earth’s plasmasphere by ESA’s Cluster spacecraft. The research team also created a filtering technique to eliminate noise sources that would allow them to look for specific plasma motion. After carefully scrutinizing data, researchers found a slow, but steady, wind releasing about 90 tons of plasma into Earth’s outer magnetosphere every day. This plasma motion is present at all times, even when the Earth’s magnetic field is not being disturbed by energy particles coming from the Sun.
“The plasmaspheric wind is a weak phenomenon, requiring for its detection sensitive instrumentation and detailed measurements of the particles in the plasmasphere and the way they move,” said Iannis Dandouras of the Research Institute of Astrophysics and Planetology in Toulouse, France.
The scientists now believe that this space wind not only contributes to the loss of material that occurs from Earth’s top atmospheric layer, but is also the source of plasma for the outer magnetosphere above it.
“The plasmaspheric wind is an important element in the mass budget of the plasmasphere, and has implications on how long it takes to refill this region after it is eroded following a disturbance of the planet’s magnetic field," explained Dandouras.
So why is this so important? The Earth’s plasmasphere is the most important plasma reservoir inside the magnetosphere and plays an important role in governing the Earth’s radiation belts, which are hazardous to satellites and astronauts travelling through them. The plasmasphere is also responsible for the delay in production of GPS signals passing through it. Understanding how space wind works may give us insight in how to deal with those particular issues, as well as give us a better knowledge of weather patterns in space.