Unique conjunction of planetary probes



The last two of the large planetary probes of the National Aeronautic and Space Administration and the European Space Agency will rendezvous at the end of the year at Jupiter. At that time, Galileo, which has been exploring Jupiter since the end of 1995, and Cassini, which is on its way to Saturn, will simultaneously observe the Jovian system with U.S.- and European-built instruments.

Cassini will monitor the upstream solar wind conditions and image the magnetosphere and the moons of Jupiter; simultaneously, Galileo will report on the changing plasma conditions from inside the magnetosphere (Figure 1). This is a unique opportunity that will benefit the whole community studying the complex behavior of the Jovian system. The geometry of the two spacecraft during the encounter is especially fortunate for dust measurements, which will greatly enhance our understanding of the Jovian dust environment and the science return for both Galileo and Cassini at Jupiter. These measurements will also provide an opportunity to cross-calibrate the dust instruments; this will be useful in the future analysis of the Cassini dust observations at Saturn.