The annual Planetary Geologic Mappers Meeting was held this year in Flagstaff, Arizona at the USGS. Mappers presented their work on June 17 and 18, 2004; on Saturday, June 19, Noel Gorelick of Arizona State University led a Mars Odyssey Thermal Emission Imaging System (THEMIS) data-use workshop. Approximately 40 attendees were at the meeting, and about 15 people (both NASA-funded mappers and interested USGS staff) attended the THEMIS workshop on Saturday. Several others, who were unable to attend, sent their maps to the USGS and these maps were posted for viewing and discussion.

Presentations made on June 17 demonstrated the richness and breadth the mapping program is achieving through mapping of the outer planets' satellites. P. Figueredo presented an interesting technique developed in GIS by T. Hare to create a stratigraphy for Europa using lineaments (which are ubiquitous) rather than impact craters (which are remarkably few). W. Patterson showed preliminary maps of portions of Ganymede. Mapping Ganymede poses challenges caused by gross variations in available image resolution across the planet. Even though tectonic terrains are easily identified, geologic units are much more difficult to discern. The Geologic Mapping Subcommittee (GEMS) panel noted that as these mapping efforts mature, guidelines may need to be issued for uniform generation of unit names, descriptions, and correlation charts for the outer-planet satellites. L. Keszthelyi presented the unique challenges involved with mapping volcanically active Io. Although this mapping is still in the early states, Keszthelyi indicated that generating a map of Io can really only be done using multiple GIS layers so that the user will be able to specify a time, as well as a place, for an Ionian geologic map. L. Gaddis presented the progress being made on a pilot lunar quadrangle map at 1:2,500,000 scale of the Copernicus region based on Lunar Orbiter, Clementine, and Lunar Prospector data sets. This project was funded as a test case, to determine the feasibility and functionality of a revised Lunar Mapping Program. To date, Gaddis and colleagues have identified a scheme for dividing the planet into mappable quads, based on the original lunar mapping program, and have determined that Clementine data will provide the best base maps.