January 24 - 30, 2000
Galileo Continues Returning Data From Its Onboard Tape Recorder
Galileo flies through apojove this week as it continues to return data stored on its onboard tape recorder. Apojove occurs on Friday and is the point at which the spacecraft is farthest from Jupiter in a given orbit. The data returned this week were acquired by Galileo during a flyby of Jupiter's icy moon Europa on January 3, 2000. Galileo is fairly busy this week as it halts data playback several times to perform engineering and navigation activities.
On Monday, the spacecraft will perform a test to determine the status of the Ultraviolet Spectrometer (UVS) instrument. UVS has been turned off for Galileo's past two encounters to protect it from additional radiation damage. Engineers hope that the instrument's damaged electronic components will have had a chance to anneal, restoring the instrument's functionality. Annealing is the process through which heat is applied to a cooling material to relieve stresses, change properties, improve machinability, or in this case, for realignment of atoms in a distorted crystal. On Friday, the spacecraft performs a flight path adjustment, if necessary. Finally, on Saturday, the spacecraft performs standard maintenance on its onboard tape recorder.
This week's playback continues last week's return of images of Europa taken by the Solid-State Imaging camera (SSI). The images were designed to capture sharp-edged ridges on Europa, a multi-ring impact feature named Callanish, and a region of mottled (or blotchy-looking) terrain. Also continuing from last week is the playback of portions of a high resolution recording performed by the Fields and Particles instruments during the spacecraft's closest 60 minutes to Europa. The data contained in the recording will allow scientists to refine and interpret estimates of Europa's recently-detected induced magnetic field. The presence of the field indicates the presence of an electrically conducting layer of material inside Europa, yet another piece of circumstantial evidence that liquid water is present beneath Europa's surface.
Next on the playback schedule is the return of images taken by SSI of three of Jupiter's smaller moons: Amalthea, Thebe, and Metis. The images will provide the best resolution views of these moons, almost a factor of two better than the best previous images in the case of Amalthea and Metis. The increased resolution should aid scientists significantly in improving the knowledge of the shape and surface conditions of these smaller moons.
Toward the end of the week, the spacecraft returns two observations of Io. The first was performed by the Near-Infrared Mapping Spectrometer (NIMS) and captured a near-global observation of the hemisphere of Io that contains the volcanic region of Loki. The second observation made by SSI consists of a series of color images of the same hemisphere.