Heliospheric Maps from Cassini INCA Early in the Cruise to Saturn

Abstract

Abstract We present new energetic neutral atom (ENA) maps from the Ion and Neutral Camera (INCA) instrument on Cassini from the year 2000, prior to Cassini’s encounter with Jupiter. These maps are the first produced for the year 2000 and are the only maps with comprehensive spatial coverage from the peak of solar cycle 23. These ENA maps span the energy range from 5.2 to 55 keV covering the pickup to suprathermal energy range. These maps represent a novel glimpse into the influence of the solar cycle on the structure of the outer heliosphere, specifically on the heliosheath where pickup and suprathermal ions dominate. The observations are consistent with the picture of the heliosheath from previous observations by the Cassini, Interstellar Boundary Explorer (IBEX), and Voyager missions. These maps have some consistent spatial features to maps produced by Cassini during solar cycle 24 such as reduced intensities in the mid-latitude basins. These maps also have distinct spatial features such as enhanced intensities at the poles and reduced intensities at the low-latitude flanks. These maps do not indicate a strong intensity increase in the regions adjacent to the nose and also show an intensity increase in the regions adjacent to the tailward direction.