This Week on Galileo September 10-16, 2001
This week’s focus for the Galileo spacecraft is again playback of the
recorded data that was acquired during the August 5 flyby of Io and
Jupiter. A variety of observations are planned for return this week, from
the Photopolarimeter Radiometer (PPR), the Near Infrared Mapping
Spectrometer (NIMS), and the Solid State Imaging camera (SSI).
PPR will first see data from Io, with a global day-side map of temperatures
across the surface. This observation represents the first-ever global view
of day-side temperatures by PPR. A second global map of the satellite’s
surface will examine the polarization of the light reflected from the
surface. This will provide insight into the fine structure of the surface
materials. In addition, two observations of Callisto will provide
polarization data from that body at different angles of reflected sunlight.
NIMS is returning a regional map of a portion of Io, looking for thermal
variations and sulphur dioxide distribution on the surface. An observation
of Jupiter, looking in the wake of the Great Red Spot, rounds out the NIMS
data this week.
The SSI science team is expecting a global color mosaic of the face of Io
that faces Jupiter. This observation was recorded approximately 32 hours
after Io closest approach. We will also begin to play back a series of
pictures that track the evolution of a portion of Jupiter’s atmosphere as
the giant planet rotates beneath the spacecraft.
On Wednesday, at the Goldstone tracking station in the Southern California
desert, the spacecraft appears to pass close to Earth’s moon. Although
Galileo is not blocked by the moon, enough thermal energy reflected by the
moon is received in the ground communications antenna to raise the
temperature of the radio receivers. This adds enough noise to the signal we
are trying to receive from the spacecraft that the data can be corrupted.
To protect against this, a special, non-critical data type is transmitted
during this time, so that the high-priority playback data from the
encounter are not jeopardized.
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:
