A space probe that uses remote-sensing and direct-sensing instruments to explore a planetary system, observe a planet, its atmosphere, magnetosphere, satellites, and any rings. Such a mission usually lasts for several years. Examples include the Galileo probe that explored the planet Jupiter and its system, including rings and satellites, from 1995, and Cassini, scheduled to reach the planet Saturn in 2004. A planetary system explorer is placed into a low-inclination orbit, such as an equatorial one, because this provides coverage of the planet and its magnetosphere and a good observation of orbiting moons in the equatorial plane.
Subjects: Astronomy and Astrophysics.