Active volcanoes on Io from ground-based observations of Jupiter and mutual satellite occultations
National Aeronautics and Space Administration Planetary Data Archiving, Restoration, and Tools Program
Non PSI Personnel: Robert Howell (Co-Investigator, University of Wyoming), John Spencer (Collaborator, Southwest Research Institute)
Project Description
Most studies of the temporal and spatial variability of Ionian volcanoes have been forced to rely exclusively on spacecraft data, primarily Galileo (Davies, et al., 2012ab; Veeder, et al., 2012; Hamilton, et al., 2013), because only spacecraft data is generally available on the PDS in physical units and with relevant location information. However, ground-based observations, while at a lower spatial resolution, give the longest temporal baseline and often the highest temporal resolution of any data set. It was, for example, only
the ground-based data that allowed the discovery of the semi-periodic nature of Loki, the most powerful volcano on Io (Rathbun et
al., 2002). Many fundamental questions about Io’s volcanoes have not been addressed because the ground-based data have not been available in an accessible public archive. We propose here to make the data available to the entire scientific community, not just those who have the specialized tools to deal with arcane photometric calibration and timing/ephemeris/location information.
The first set of data consists of observations of Io in eclipse and while being occulted by Jupiter. We will create occultation lightcurves in PDS table format to share with the community. These lightcurves show a step whenever a volcano is occulted by Jupiter’s limb. The height of the step indicates the strength of the volcano while the timing indicates, in one-dimension, the location of the volcano on the surface. We will share a program that determines this location based on the time of the observation of the step.
The second set of data is mutual satellite occultations of Io from 1985 through 2015. Mutual events provide the highest spatial resolution available from ground-based data, and in addition this long time span provides a unique record of longer-term variations.
We will share lightcurves from the mutual occultations as well as tomographic reconstructions (2-dimensional images) of the brightness of any active volcanoes observed.
Finally, we will test multiple ephemerides to determine which is the most accurate. Our resulting data and ancillary programs will be shared in the PDS and on GitHub, in easy to use formats, such as tables and 2D images, which are calibrated in physical units and include spatial information.
