This Week On Galileo - June 2-7, 1998
The encounter period winds down Tuesday, June 2, as Galileo's activity shifts from gathering science information to processing and transmitting to Earth the information that has been gathered and stored on board during the last few days. The single remaining observation, initiated on Monday, an observation of the Io torus performed jointly by the ultraviolet spectrometer and extreme ultraviolet spectrometer, is completed on Tuesday.
The processing and sending to Earth of science information comprises the bulk of Galileo's activity for the rest of the week. This procedure, also known as playback, is interrupted twice to perform engineering and navigation activities. The first is a performance test on the attitude control system's gyroscopes. This test is one of many to come and the results will be used to evaluate how the anomalous behavior of one of the spacecraft's two gyroscopes is changing, if at all. If significant changes are noticed, adjustments will be made to computer software modifications that have been put in place to allow the attitude control computer to correct and use output from the anomalous gyroscope. The second interruption occurs when the spacecraft executes a flight path adjustment to correct errors accumulated since the last adjustment, a few days prior to the close flyby of Europa.
On the playback schedule we find four observations, one of Io taken by the near infrared spectrometer in conjunction with the ultraviolet spectrometer, and three of Europa, two taken by the photopolarimeter radiometer and one by the camera. The Io observation is one of the second highest resolution observations of that satellite planned during the Europa phase of the Galileo Europa Mission. The Pele, Marduk and Reiden volcanic regions are targeted for observation. The photopolarimeter radiometer Europa observations gather information on surface temperatures and thermal characteristics that will be used to determine how compact the surface is, how old it is, what makes it up and how it got the way it is.