This Week On Galileo - April 13-19, 1998
Processing and transmission to Earth of pictures and other science information, a process also known as playback, is the sole order of business this week on Galileo. The data was gathered and stored on the spacecraft's onboard tape recorder during the last few days of March as the spacecraft flew through the Jupiter system and within 1,645 kilometers (1022 miles) of the surface of Jupiter's moon Europa.
Most of the data return this week was obtained by the spacecraft camera, or Solid State Imaging (SSI) subsystem, during the close flyby of Europa. Among the pictures returned this week we find a couple containing the Mannann'an crater. Taken from slightly different angles, this pair of images will be combined to form a stereo image of the region. A similar pair of pictures containing a region of dark spots on Europa is also returned this week. This pair will also be combined to form a stereo image of the region. Regional coverage of this same dark spot area was obtained in November 1997. Another SSI observation provides photometric information describing Europa's surface. These photometric measurements will tell us how intensely light is reflected from the surface and provide additional information on its makeup. Finally, a picture of a region of triple-bands is returned. These triple-band features are believed to be formed when Europa's surface cracks, material upwells from below the surface and spills to both sides of the central crack. They are considered evidence for the possible existence of a sub-surface ocean or, at the least, soft ice.
Sprinkled throughout the week, similar to last week's playback schedule, is information from the fields and particles instruments describing the interaction of Jupiter's magnetosphere with Europa. Remember that Jupiter's magnetosphere is that region of space where Jupiter's magnetic and electric fields dominate those fields generated by the solar wind. The charged particles that make up the magnetosphere co-rotate with Jupiter, at a rate of about 1 revolution every 10 hours, and get disturbed as they sweep past each of the satellites in orbit around Jupiter. Each new bit of data describing this interaction will help scientists understand the phenomena at work.