The cosmic dust analyser onboard cassini: ten years of discoveries

Saturn suprathermal O2+ and mass‐28+ molecular ions: Long‐term seasonal and solar variation

“…[] and Srama et al . [] (~11 and ~17, respectively) are similar to the photometrically derived E ring vertical integrated brightness variation which is proportional to R ~15 between the A ring and Enceladus' orbit [ Baum and Kreidl , ; Showalter et al ., ; Johnson et al ., ]. The estimated nominal total grain density of the E‐ring population at ~3 Rs will therefore be on the order of about one one‐hundredth its value at ~4 Rs, or n d (3 Rs) ≃ 0.14/100 cm −3 ~ 1.4 × 10 −3 cm −3 .…”

“…Rough overall averaging of these values results in n d (4 Rs) >~0.14 cm À3 . Radial variation power-law slopes of E-ring grain density at ≤3.95 Rs derived from Cassini data in Wang et al [2006] and Srama et al [2011] (~11 and~17, respectively) are similar to the photometrically derived E ring vertical integrated brightness variation which is proportional to R~1 5 between the A ring and Enceladus' orbit [Baum and [Showalter et al, 1991;Tseng et al, 2012]. c Grain number densities attributed to Kempf et al [2008].…”

“…The A, B, C, F, and G rings are several tens of meters thick, and the E ring, with a vertical full width half maximum of ~4200 km [ Kempf et al ., ], are all centered on Saturn's rotational equatorial plane. The broad E ring, with equatorial brightness peaking at Enceladus' orbit and fed by its plumes, is observed vertically up to about ±4 Rs and equatorially from ~2.3 to ~20 Rs [ Srama et al ., ], where the A ring and Titan, respectively, absorb grains and block further radial ring expansion [ Horányi et al ., ; Juhász and Horányi , ; Kempf et al ., ; S. Kempf, personal communication, 2013]. The equatorial trans‐A‐ring‐Enceladus region, from the outer edge of the A ring to Enceladus' orbit, also contains the moons Janus, Epimetheus, and Mimas as well as the narrower F and G rings at 2.33 and 2.72–2.85 Rs, respectively.…”

Cosmic dust in space and on Earth

“…Since then we have seen the in situ analysis of dust by missions including Galileo, whose impactionization Dust Detector analysed dust as it passed through Jupiter's gossamer ring system (Krüger et al 2009), and Cassini, whose Cosmic Dust Analyzer instrument studied dust particles during both its flyby of Jupiter and its orbits of Saturn and its rings and moons (Srama et al 2011). The rings of Saturn are one of the most famous dusty features of the solar system but, as well as characterizing dust particles in and around Saturn's rings, this instrument has also detected particles ejected in jets from Saturn's moon Enceladus, finding evidence for hydrothermal activity beneath its icy crust (Hsu et al 2015).…”

Discovery of suprathermal Fe+ in Saturn's magnetosphere

“…Enceladus' orbit is at ~3.95 Rs , and its ejecta contribute over time to form Saturn's E ring and OH torus. Long‐term CDA measurements have detected E ring particles far beyond the classical, optically determined 3–8 Rs equatorial E ring, that is, ~2–4 Rs away from the ring plane, outward to ~20 Rs , and inward almost to the outer edge of the A ring [see, e.g., Srama et al , , Figure 10]. Icy matter between the F ring (~2.33 Rs ) and the outer edge of the A ring (~2.27 Rs ) extinguishes the radiation belts [ Kollmann et al , ].…”