JOVIAN SYSTEM DATA ANALYSIS PROGRAM PROPOSAL SUMMARY

Goal: The goal of this proposed research is to identify and map the non-water-ice constituents and determine the related processes operating on the surfaces of the icy Galilean satellites of Jupiter. We will use the public-domain NIMS data acquired during the primary Galileo mission. We propose four related tasks: 1) Identify and explain non-ice constituents, 2) Map mineralogy, 3) Prepare samples and measure spectra of hydrated salt minerals, and 4) Determine and publish descriptions and corrections for subtles and defects in NIMS data. Approach: Our approach involves detailed processing and analysis of public-domain NIMS and some SSI data and the use of radiative transfer modeling using our unique capabilities. Also, we will conduct studies of the reflectance of hydrated salt materials under cryogenic conditions in our laboratory jointly with two collaborators, James Crowley and Paul Lucey. We will work closely with the laboratory simulations of Europa's ocean chemistry performed by another collaborator, Fraser Fanale, to coordinate and interrelate our efforts and results. The results will be the identification/location of constituent non-ice materials and related processes with increased understanding of the evolution of the satellites and early processes in solar system evolution, perhaps including prebiotic materials and processes. Background: This proposed basic research program is based on our experience and existing capabilities concerning the Galileo NIMS and is built around our early discoveries. The program represents a transition from our mission support activities to a basic research effort. It is very timely, for we have considerable knowledge and tools developed concerning the NIMS data and their properties, but so far we have been able to apply them only sparingly to scientific study of the icy Galilean satellites. Nevertheless, we have produced four major publications and many abstracts and presentations reporting the discovery of a number of non-ice materials present in the surfaces of the icy Galilean satellites. We conducted the basic analysis of the Galileo NIMS reflectance spectra for the icy satellites to support the mission and to demonstrate their value in identifying surface constituents (McCord et al., 1996a,b, 1997a,b,c,d,e,f,g, 1998a,b,c,d,e,f). We discovered five new absorption bands for Callisto and Ganymede and identified CN and CH as well as CO2, SO2 and S-H--bearing molecules as responsible. We also reported the presence of ubiquitous hydrated minerals including salt deposits on Europa as well as suggestions of active chemistry and transient processes involving the surface materials. We find that these materials are correlated in complex ways with surface brightness and morphology, and our comparisons with SSI image data (Hibbitts et al., 1997a,b) indicate that associations with geologic processes exist. Relevancy and perspectives: It is clear that the icy Galilean satellites' (Callisto, Ganymede and Europa) surfaces contain non-ice constituents which are cosmochemically important and which are indicative of important and perhaps wide-spread and current processes. Many of these constituents appear similar to those found in interstellar ice grains, comets and meteorites and suggest a commonality among many cold region objects. Europa is suggested to have a shallow ice crust overlying a liquid ocean and some of the non-ice surface materials found appear to originate in this ocean and give clues to the ocean's properties. In addition to new knowledge about the satellites, our proposed work will greatly improve the communication/dissemination and understanding of the properties and defects of the NIMS data and contribute analytic tools and methods for working with these data and thus will greatly aid other scientists using these data. These new results will support the Cassini and Europa Orbiter missions and all missions to comets and outer solar system icy objects, including Star Dust. They also will be relevant to the study of interstellar grains and to objects around other stars because some of the processes operating and the constituents found seem common. Educational/Public Outreach proposal: We propose a companion E/PO effort in cooperation with the Hawaii State Department of Education. We will develop a section of the DoE Electronic School course "Space and Cosomology" which will be used as the basis for a DoE television series and the introduction of Planetary Sciences into the school curriculum.