Open AccessLow‐energy ions dominate the space environments of Earth, Mars, and Venus
Author(s) -
Schultz Colin
Publication year - 2012
Publication title -
eos, transactions american geophysical union
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.316
H-Index - 86
eISSN - 2324-9250
pISSN - 0096-3941
DOI - 10.1029/2012eo130012
Subject(s) - ion , mars exploration program , magnetosphere , astrobiology , ionosphere , physics , satellite , atomic physics , space environment , electric field , ionization , venus , van allen radiation belt , van allen probes , computational physics , plasma , geophysics , astronomy , quantum mechanics
Stretching from the top of the ionosphere to out into space, the terrestrial space environment is packed with low‐energy ions, populated when ultraviolet radiation emanating from the Sun ionizes atmospheric gases in the ionosphere below. These ions, with energies of a few electron volts, play an important role in modifying dynamics within the magnetosphere. Though this view of the space environment is well grounded in theory, the actual detection and quantification of low‐energy ion densities have been more elusive. The difficulty stems from the environmental conditions within which sensors seeking to measure these low‐energy ions must operate. Satellites high above the Earth accumulate surface charges giving positive potentials of tens to hundreds of volts when exposed to sunlight and end up repelling the low‐velocity, low‐energy, positively charged ions that researchers hoped to detect. Using an array of techniques, including a recently developed approach whereby onboard sensors look for distortions in the electric field in the satellite's own wake, André and Cully estimate the density of low‐energy ions.