The ASPERA-3 (Analyser of Space Plasma and Energetic Atoms) instrument of Mars Express is designed to study the solar wind-Mars atmosphere interaction and to characterise the plasma and neutral gas environment in near-Mars space through energetic neutral atom (ENA) imaging and local charged-particle measurements. The studies address the fundamental question: how strongly do the interplanetary plasma and electromagnetic fields affect the martian atmosphere? This question is directly related to the problem of martian dehydration. The instrument comprises four sensors; two ENA sensors, and electron and ion spectrometers. The Neutral Particle Imager (NPI) measures the integral ENA flux (0.1-60 keV) with no mass and energy resolution but with high angular resolution. The Neutral Particle Detector (NPD) measures the ENA flux, resolving energy (0.1-10 keV) and mass (H and O) with a coarse angular resolution. The electron spectrometer (ELS) is a standard top-hat electrostatic analyser of a very compact design. These three sensors are mounted on a scanning platform providing 4π coverage. The instrument includes an ion mass composition sensor, IMA (Ion Mass Analyser). Mechanically, IMA is a separate unit connected by a cable to the ASPERA-3 main unit. IMA provides ion measurements in the energy range 0.01-40 keV/q for the main ion components H+, He 2+, He+O+ with 20-80 amu/g.
|Number of pages
|European Space Agency, (Special Publication) ESA SP
|Published - Aug 2004