This Week on Galileo 24-30 Sep 2001

Two Engineering Activities Are Planned For The Galileo Spacecraft

In addition to the usual array of playback data this week, two engineering
activities are planned for the Galileo spacecraft. On Wednesday, the
spacecraft is turned by 2.76 degrees to keep the communications antenna
pointed towards Earth. On Friday, routine maintenance of the on-board tape
recorder is performed.

In the playback arena, data acquired during our August 5 flyby of Io are
still being returned from that tape recorder. This week we expect to see
data from the Photopolarimeter Radiometer instrument (PPR), the Near
Infrared Mapping Spectrometer (NIMS), the Solid State Imaging camera (SSI),
and the suite of instruments that measure the electromagnetic fields and
study the particles that exist in the Jupiter environment. This is the
third pass over the data on the tape, and the majority of the data being
returned are filling in gaps in previous playback attempts and extending
coverage of certain observations.

The PPR team will be seeing data from an observation of the Loki volcano
and its 120-mile-wide caldera on Io. In addition, a temperature map of a
pole-to-pole strip across the surface of Io will be returned.

NIMS will be returning a night-side view of the Pele, Pillan, and Isum
regions of Io, looking for thermal variations and hot spots. Other
observations will concentrate on the Tvashtar volcano and the Gishbar and
Amirani hot spots.

SSI also views Tvashtar, Gishbar, and Amirani in data returned this week.

Throughout the closest approach to Io, the Fields and Particles instruments
were collecting and recording continuous data, hoping to determine whether
Io has an intrinsic magnetic field, or whether its field is induced by
passage of the satellite through Jupiter’s much stronger magnetic field.
Fields and Particles data are embedded in the data formats of the other
instruments, such as SSI and NIMS, as they record periodically at high
rates. Between those observations, however, the Fields and Particles
instruments have a dedicated data format that allows them to collect data
continuously without using much tape. An alternating high-speed/slow-speed
recording strategy keeps the tape recorder moving continuously for about an
hour, centered around the closest approach to Io, when the most interesting
aspects of the interaction of the satellite with the ambient magnetosphere
occur.