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.
For more information on the Galileo spacecraft and its mission to Jupiter, please visit the Galileo home page
at one of the following URL’s:
http://www.jpl.nasa.gov/galileo
