Enceladus, one out of currently 62 satellites of Saturn, orbits the planet at a distance of 3.95 Saturn radii RS (1RS = 60,268 km) and is embedded in the radiation belts of Saturn’s inner magnetosphere. Even with a small radius REnc of only 252 km and an apparent similarity to other icy moons, this moon is by far the most important internal source of dust, neutral gas and plasma in the saturnian system and especially in the magnetosphere. As already inferred from data of the first flybys of the Pioneer 11 (1979), Voyager 1 (1980) and Voyager 2 (1981) spacecraft, respectively (Smith et al., 1981; Krimigis et al., 1982), this moon plays the same role Io does for the jovian system. The Cassini spacecraft, in orbit around Saturn since July 2004, has flown by Enceladus 14 times between 2005 and 2010. Data from Cassini instrument teams identified a plume of water geysers above the so called “tigerstripes” on the south pole of the moon (Dougherty et al., 2006; Porco et al., 2006). This discovery is one of the most important findings to better understand the saturnian magnetosphere. The material released in the form of water gas, ice molecules and dust (Waite et al., 2006; Spahn et al., 2006) from those geysers is the main source of the E-ring and the neutral torus and is the major plasma source of water group ions in the magnetosphere. A summary of Enceladus findings from Cassini measurements is very well presented by Spencer et al. (2009).
Saturn
62 satellites
Enceladus
distance
3.95 Saturn radii RS
Saturn radii RS
1RS
60,268 km
km
Enceladus
radius REnc
252 km
km
Pioneer 11
first flybys
1979
Voyager 1
first flybys
1980
Voyager 2
first flybys
1981
Cassini spacecraft
orbit around Saturn
since July 2004
Cassini spacecraft
flown by Enceladus
14 times
Cassini spacecraft
flown by Enceladus 14 times
between 2005 and 2010