The distribution of sulfur dioxide and other infrared absorbers on the surface of Io

Spatially Resolved Spectroscopy of Io's Pele Plume and SO2 Atmosphere

“…The SO 2 frost abundance outside these white regions, at Pele for example, is generally quite low ( 20%). However, recent results from the Galileo NIMS experiment (Carlson et al 1997) Given that R SO 2 and X SO 2 are both poorly known (thereby making X x poorly known), and the magnitude of this uncertainty has previously been absorbed into R x , it does not make sense to use four poorly constrained parameters instead of one to characterize the surface reflectance. Unless the UV surface reflectance derived from the data is to be quantitatively analyzed, which has not been done in the past, using a single unknown (R) is simpler than using four equally unconstrained ones.…”

Model Calculations for Io's Atmosphere at Eastern and Western Elongations

“…For this reason we will focus on a sublimation atmosphere which gives a hemispheric average atmospheric abundance of SO 2 that is consistent with recent observations. Recent Galileo Near Infrared Mapping Spectrometer measurements (Carlson et al 1997) found that surface SO 2 frost coverage on Io is ubiquitous, except over hot spots or volcanoes. Galileo Solid State Imaging (Geissler et al 1999) revealed a decrease in disk average brightness of Io's atmosphere, likely caused by electron impact excitation of gaseous SO 2 , when comparing images taken at 11 and 53 min after Io had been eclipsed by Jupiter's shadow, likely indicating the collapse of a sublimation atmosphere in darkness.…”

Thermal and energetic processing of astrophysical ice analogues rich in SO2

“…However, the abundance of this compound is very low (with an upper limit of 10 −4 ) with respect to SO 2 (Schmitt & Rodriguez 2003). The next candidates as hydrogen bearing species are then water ice and/or hydrate materials whose absorption bands around 3150 cm −1 were tentatively observed (Salama et al 1984;Carlson et al 1997). It is, however, also possible that the detected flux of hydrogen ions comes from the Jovian magnetosphere and not from the satellite.…”