This Week on Galileo

September 27 - October 3, 1999

Galileo Concludes Survey of Dusk Side of Jupiter's Magetosphere

Galileo concludes this orbit's real time survey of the dusk side of Jupiter's magnetosphere this week, but continues to return high resolution magnetosphere measurements recorded during its encounter a couple of weeks ago. All of these data were acquired by Galileo's suite of Fields and Particles instruments. Processing and return of these data is interrupted three times this week. On Monday, the spacecraft performs a standard gyroscope performance test. On Thursday, a small flight path correction is scheduled. And on Friday, the spacecraft performs a small turn to keep its antenna pointed toward Earth.

Galileo also passes through apojove on Monday of this week, only 13 days since it passed perijove. Apojove occurs when the spacecraft is furthest from Jupiter in a given orbit; perijove occurs when the spacecraft is at its closest approach to Jupiter. During the Europa Campaign there were typically at least 30 days between perijove and the following apojove. This time reduction is evidence of the changes made to the spacecraft's orbit, starting with Galileo's first Callisto flyby back in May 1999, to allow for a flyby of Io on October 10.

The Fields and Particles magnetosphere survey concludes on Monday. For the duration of the survey, measurements were not recorded on board, but rather returned to Earth in near real time, sharing the transmission stream with recorded data. This leg of the survey covered the duskward portion of the magnetosphere. The high resolution magnetosphere data returned this week is part of a series of recordings performed during each of Galileo's previous four encounters. The data captured during these recordings describe the inner magnetosphere and the Io torus (see Note 1) as a function of distance from Jupiter.

Note 1. The Io torus is a region of intense plasma and radiation activity, in which there are strong magnetic and electric fields. Constantly replenished by the volcanic activity on Io, it is a vital part of the Jovian magnetosphere.

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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