Category Archives: Space Science

Interesting results from cluster spacecraft

Recent results from Cluster shed some light on the mechanism that brings particles from the solar wind into the Earth’s magnetosphere, creating the Aurora and radiation belts. The basic mechanism is vortices generated in the sheared flow region between the magnetosphere and the solar wind. The mechanism behind the vortices is called the Kelvin-Helmholtz instability, and it’s fairly generic to low velocity sheared flows, as the discussed in the article.

The same mechanism will affect any craft powered by mini-magnetospheric plasma propulsion (M2P2), but the particle transport will be the other way – from inside the magnetic bubble to outside (since the inner particle density will be higher than the solar wind particle density, at least in the tail region). This will cause loss of ions from the bubble, and may turn out to be the limiting factor for M2P2.

There is a nice picture of Kelvin-Helmholtz waves in the Earth’s atmosphere here.