This Week on Galileo

July 26-August 1, 1999

Galileo Continues Playback

Galileo continues playing back pictures and other science information from a second pass through data stored on its onboard tape recorder. These data were acquired during the spacecraft's encounter with Jupiter and the planet's four Galilean moons at the beginning of this month. This second data return opportunity allows the replay of data lost in transmission to Earth, reprocessing of data using different parameters, or return of new additional data. Data playback is interrupted twice this week. On Wednesday, the spacecraft executes a standard gyroscope performance test. On Thursday, it performs a small turn to keep its radio antenna pointed toward Earth.

Six observations are on this week's data return schedule. One observation was made by the Fields and Particles instruments, three by the Solid-State Imaging camera, one by the Photopolarimeter Radiometer, and one by the Near-Infrared Mapping Spectrometer. All of the observations capture data related to Jupiter's volcanic moon Io.

The Fields and Particles instruments return the second half of a two hour observation that was recorded as the spacecraft flew through the Io torus. The torus is a region of intense plasma and radiation activity that is constantly replenished by the volcanic activity on Io. It is a vital part of the dynamics of the Jovian magnetosphere. The observation contains measurements of plasma and magnetic and electric fields within the torus.

The Solid-State imaging camera returns observations containing the highest resolution images of Io obtained to date by Galileo. They capture different views of Io at resolutions of 2.6 kilometers (1.6 miles), 1 to 1.5 kilometers (0.6-0.9 miles), and 1.3 kilometers (0.8 miles) per picture element. The images will also provide science planners with information that will be used in planning future observations of Io.

The Photopolarimeter Radiometer observation is one in a series of three that will provide information to help identify and characterize relatively large regions of Io where surface temperatures are higher than their surroundings. In addition, the measurements will provide insight into how different regions of Io's surface retain heat.

Finally, the Near-Infrared Mapping Spectrometer returns an observation designed to obtain high-resolution spectral and spatial measurements of Io's surface. These measurements will be used to construct the highest resolution map of Io made to date by the Spectrometer instrument. Previous maps of Io of this type have revealed new hot spots, typically corresponding to changes in volcanic activity.

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

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Last updated: July 26, 1999

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