Plasma Environment and Models for L2

The second Lagrange point, 1.5 million miles f?om the Earth in the anti-solar direction, is becoming an increasingly important destination for scientific spacecraft. The quasi-stable gravity field requires little energy resources for station keeping and astronomical missions-infrared and microwave in particular-find the minimal impact from Earth albedo radiation and limited restrictions on viewing directions a tremendous advantage in their mission design. Spacecraft design for L2 missions will have to consider the plasma environments of the ambient solar wind, magnetosheath, and magnetotail from energies of a few 10s of an eV through 10's of keV in addition to enhanced energetic particle populations from 10's to 1000 keV during solar energetic particle events. This paper describes the low energy charged particle environments at L2 distances that must be addressed by spacecraft designers and modeling efforts to develop environment specification tools for the L2 plasma environment.