Saturn's rings: 3-mm observations and derived properties

The Composition of Saturn's Rings

“…This dark material could come from meteoritic bombardment, as proposed by Cuzzi and Estrada (1998). Microwave observations obtained by Epstein et al (1984) showed that the mass fraction of any nonicy silicate material in the A and B rings must be less than 10% if the material is uniformly distributed. Because the amorphous carbon has a higher absorption coefficient (about 5 cm −1 at 3 mm from Mennella et al 1998) than silicate material (0.8 cm −1 from Epstein et al 1984), we estimate from Eq.…”

“…Microwave observations obtained by Epstein et al (1984) showed that the mass fraction of any nonicy silicate material in the A and B rings must be less than 10% if the material is uniformly distributed. Because the amorphous carbon has a higher absorption coefficient (about 5 cm −1 at 3 mm from Mennella et al 1998) than silicate material (0.8 cm −1 from Epstein et al 1984), we estimate from Eq. (1) of Epstein et al (1984) that the amorphouscarbon/ice mass ratio should be less than a few percent if the materials are uniformly mixed.…”

“…Because the amorphous carbon has a higher absorption coefficient (about 5 cm −1 at 3 mm from Mennella et al 1998) than silicate material (0.8 cm −1 from Epstein et al 1984), we estimate from Eq. (1) of Epstein et al (1984) that the amorphouscarbon/ice mass ratio should be less than a few percent if the materials are uniformly mixed. Our spectral modeling is consistent with a ring particle surface made of 7% carbonaceous material intimately mixed ("salt-and-peper" mixture) with the water ice material.…”

“…Water ice has long been accepted as the most prominenting component based on a combination of near-infrared and microwave observations (Pilcher et al 1970, Clark and McCord 1980, Epstein et al 1984. Different investigations directed at different bands have led to different grain size results.…”

Sub-degree CMB anisotropy from space

“…Spacecraft-Planet geometry when an external planet, P , is in the field of view of the COBRAS/SAMBA detectors Several authors reported measurements of the planets brightness temperature at millimeter wavelengths (e.g. Ulich et al 1980;Sholherb et al 1980;Epstein et al 1980;Ulich 1981;De Pater & Matisse 1985;Dowling et al 1987;Rudy et al 1987;De Pater 1989Muhleman et al 1991). The accuracy of planetary absolute calibration is limited by the uncertainty on the intrinsic radiometric temperatures T planet .…”