Energetic neutral atom imaging at Jupiter and Saturn; results from the Cassini/MIMI instrument

摘要

Summary form only given. Energetic Neutral Atoms (ENA) are emitted from any magnetized, energetic plasma that meets the criteria of 1) including singling ionized ions, and 2) co-mingling with a neutral gas suitable for charge exchange neutralization of the energetic ions. These criteria are met in many laboratory and space plasmas, including the trapped ion populations at Earth, Jupiter and Saturn. This emission has been exploited for the last three years to provide global images of the Earth storm-time ring current (Mitchell et al., 2000). The Magnetospheric Imaging Instrument (MIMI) aboard the Cassini spacecraft includes an Ion and Neutral Camera (INCA); designed to provide global images of the /spl sim/10 to 150 keVucleon ENA emitting ion plasma trapped in Saturn's magnetosphere. In addition, as the Cassini trajectory approached to within 140 R/sub J/ of Jupiter at the end of 2000, the MIMI INCA imager acquired low resolution ENA images of the Jovian inner magnetosphere. Cassini is scheduled for its Saturn orbit insertion burn on July 1, 2004; however, it is anticipated that INCA will return many images of the Saturnian magnetosphere during Cassini's approach to the planet. This paper present MIMI/INCA ENA images of both Jupiter and Saturn, discuss some of the scientific results from analysis of the Jupiter images, and possibly some early interpretation of the Saturn approach images.