On the last day of orbit the Galileo plasma anlyzers (PLS) detected evidence of Jupiter's plasma torus at locations inside Io's orbit during the interval 15:00 to 16:00 UT. These measurements will allow the PLS team to determine densities, temperatures, and flow speeds of the ions. After 16:00 UT the measured ion and electron intensities were dominated by direct penetration of the sensors by high-energy charged particles. The intensity of this penetrating radiation peaked at about 17:08 UT when the spacecraft was at a radial distance from Jupiter 3.7 Rj, or 263,000 km. As the spacecraft approached the orbit of Amalthea, the penetrating radiation declined. The final PLS telemetry packets acquired between 18:20:36 and 18:25:49 UT at radial distances between 1.9 and 1.8 Rj indicate that the intensities had dropped by a factor of approximately 5. Comparison of these recent final measurements from Galileo with measurements gained at similar distances from Jupiter during orbit A34 should provide invaluable information regarding the variability and the spatial distribution of charged particles at these locations that have been infrequently visited by spacecraft.
Last Modified: Monday, 04-Mar-19 at 11:00:10 AM
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