This Week on Galileo

October 4-8, 1999

Galileo Completes Return of Flyby Data

This week Galileo completes return of data acquired during its flyby of Jupiter and Callisto in mid-September. These data are stored on the spacecraft's onboard tape recorder and will be overwritten by new data obtained during its next encounter, starting at the end of this week. The next encounter is the first of two close flybys of Jupiter's volcanic moon Io. The Io flybys were made possible by gradually changing Galileo's orbit about Jupiter during the previous four encounters, which made up the Perijove Reduction Campaign. Data processing and return is interrupted once this week. On Friday, the spacecraft executes a small flight path correction, if necessary.

Data from two observations are returned this week. First to be returned are the remaining portions of a high resolution recording of Jupiter's inner magnetosphere and Io torus performed by the Fields and Particles instruments (Dust Detector, Energetic Particles Detector, Heavy Ion Counter, Magnetometer, Plasma Detector, and Plasma Wave Instrument). The magnetosphere is the region of space in which a planet's magnetic field is stronger than the magnetic field due to the solar wind. The Io torus is a doughnut-shaped region with its inner edge bounded by Io's orbit. It is a region of particularly intense plasma flow and radiation activity inside the Jovian magnetosphere. The Io torus is constantly replenished by volcanic activity on Io.

Data from an observation made by the Plasma Wave instrument are also returned this week. The observation is dedicated to the detection of Chorus emissions. A Chorus signal is measured by the Plasma Wave instrument when charged particles are accelerated due to a particularly efficient type of wave-particle interaction. By detecting and analyzing Chorus emissions, scientists hope to understand a significant process by which energy is transferred from Jupiter's magnetic fields into plasma within the Io torus and from there into outer portions of the magnetosphere.

Together, these observations will contribute toward the study of the dynamic processes that occur in the Io Torus and inner magnetosphere of Jupiter.

Don't forget! Galileo's exciting flyby of Io starts at the end of this week, and with it comes the return of Today on Galileo!

For more information on the Galileo spacecraft and its mission to Jupiter, please visit the Galileo home page.

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Last updated: September 27, 1999

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