Callisto 3 Science Summary

The science to be done during this 9 day encounter can be divided into 3 groups, Jupiter's atmosphere, studies of the satellite properties, and Jupiter's magnetic field.

Jupiter's Atmosphere

The target area on Jupiter is in longitude which is between latitudes 13 degrees S and 3 degrees N; this includes a region with a strong jet stream, similar to the northern counterpart into which the Galileo Probe entered last December.

The molecules that make up the top layers of Jupiter's atmosphere will also be mapped out during an "Earth radio occultation". Galileo will be going behind Jupiter as seen from earth, and during that time it will look at how the radio signals from Galileo are bent as they go through Jupiter's atmosphere. That data will help us determine how far down in the atmosphere the different gases are. This also means we will be out of communication with the spacecraft for several hours during that time.

Later, the sun will appear to go behind Jupiter, allowing Galileo to view it completely in the dark, looking for lightning flashes.

The Satellites

The main focus of study will be Callisto (the Galilean moon the furthest out from Jupiter) from about 1100km (680 miles), and Europa from about 34000km (21000 miles). Also, this week Galileo will come the closest to Io during the remainder of the mission this week at 245,000 km (150,000 miles). The best opportunity of the mission to view Jupiter's thin rings will be in this encounter, during the solar occultation when Galileo will be in Jupiter's shadow. The close distance to Europa allows the instruments to make measurements of the make-up of its surface, looking for solids other than water ice, and to look for indirect evidence of icy volcanoes.

Galileo will monitor Io during this encounter for volcanic activity to see how frequently eruptions occur and how long they last. Differences even from the September encounter are expected.

Jupiter's Magnetic Field

In this encounter, Galileo will pass through Jupiter's northern auroral zone. Some lines of Jupiter's magnetic field cause plasma (hot ionized gases) to be driven into Jupiter's atmosphere and cause aurora. Galileo will for the first time actually pass through these lines andwill take measurements that can help us understand how the aurora are generated.

A general study of Jupiter's magnetic environment inside the region influenced by particles from Io will continue from previous orbits.

Return to Countdown to Callisto 3 Home Page
Return to Project Galileo Homepage