H.3.4 Outer magnetosphere

NASA has defined a severe charging environment [RD.53] based on the 90^th percentile of severe environments. However, this is not the one adopted as the ECSS Standard.

Table H-5 gives typical plasma parameters for the geostationary environment for quiet and substorm periods.

The outer boundary of the magnetosphere, the magnetopause, is controlled by the balance between the pressure of the magnetic field and that of the solar wind. Along the EarthSun line, the magnetopause is closest to the Earth and its position can be expressed approximately [RD.54] as:

(H-2)

where

L_m is the distance from the centre of the Earth to the magnetopause, at
the subsolar point, in Earthradii;

B₀ is the strength of the terrestrial internal magnetic field, at surface of
the Earth, on the equator = 3 ⨉10⁴ nT;

μ_o is the permeability of free space;

n is the density of the solar wind;

m is the mass of the proton;

V is the velocity of the solar wind.

L_m is typically 10 Earthradii away from the subsolar point. The magnetopause flares out on the flanks and is effectively infinite in length in the antisolar direction. This boundary is described in more detail in clause 5.