Location of the bow shock and ion composition boundaries at Venus - initial determinations from Venus Express ASPERA-4
Vari ; - ASI Sponsor
Jan - 1992
journal :
type: Article Journal
Abstract
The general scientific objective of the ASPERA-4 (Analyzer of Space Plasmas and Energetic Atoms) experiment is to study the solar wind - atmosphere interaction and characterise the plasma and neutral gas environment in the near-Venus space through energetic neutral atom (ENA) imaging and local charged particle measurements. The studies to be performed address the fundamental question: How strongly do the interplanetary plasma and electromagnetic fields affect the Venusian atmosphere? The ASPERA-4 instrument comprises four sensors; two ENA sensors, electron and ion spectrometers. The Neutral Particle Imager (NPI) provides measurements of the integral ENA flux (0.1 - 60 keV) with no mass and energy resolution but relatively high angular resolution. The Neutral Particle Detector (NPD) provides measurements of the ENA flux, resolving velocity (0.1 - 10 keV) and mass (H and O) with a coarse angular resolution. The electron spectrometer (ELS) is a standard top-hat electrostatic analyzer in a very compact design. These three sensors are located on a scanning platform providing a 4p coverage (maximum possible). The instrument also contains an ion mass composition sensor, IMA (Ion Mass Analyzer). Mechanically, IMA is a separate unit electrically connected with the ASPERA-4 main unit. IMA provides ion measurements in the energy range 0.01 - 36 keV/q for the main ion components H+, H+ 2 , He+, O+, O+ 2 , and CO+ 2 ion group with M/q > 40 amu/q.
keywords : VENUS EXPRESS