Approximately 30 people attended the annual Planetary Mappers Meeting, locally hosted by Dr. Kevin Williams at the Center for Earth and Planetary Studies. The meeting room was in the National Air and Space Museum, providing an apt setting for our discussions of extraterrestrial geologic studies.

The progress of current Mars maps was presented on June 23. Mappers increasingly use data collected by the Thermal Emission Imaging System (THEMIS); daytime infrared (IR) and visible images are particularly useful for constraining and mapping geologic relations. J. Grant, K. Williams, and C. Fortezzo presented a series of 1:500K-scale maps in the Margaritifer Terra region, focusing on the spatial and temporal distribution of channeled and standing water in the region. Maps in this region range from those just proposed in 2005, to those recently submitted for review. Combined THEMIS (visible and daytime IR) and Mars Orbiter Laser Altimeter (MOLA) data have proved to be a powerful combination in this area. K. Shockey and J. Zimbelman presented their progress in understanding the Medusae Fossae Formation; this led to a discussion about what limits the size of a mappable unit. In a first for the USGS Planetary Mapping program, P. Mouginis-Mark will be generating a geologic map based entirely on THEMIS visible images (~19 m/pixel) and Mars Orbiter Camera (MOC) narrow-angle images (<6 m/pixel). The Olympus Mons caldera map will be generated at a scale of 1:200,000. K. Tanaka and K. Herkenhoff discussed their mapping of the polar regions of Mars. D. Crown, M. Farley and T. Gregg focused on their work around the Hellas region; D. Crown also discussed his investigations near the dichotomy boundary to understand the formation of debris aprons.

On June 24, we discussed the status of mapping on Io, Europa, Ganymede, the Moon, and Venus. D. Williams is leading a team to generate a global geologic map of Io; the changing nature of this planet requires that a single paper map will be published, with electronic layers in GIS format for individual, variable features. K. Tanaka described progress of the global geologic map of Europa, which is an effort led by R. Greeley. Ganymede is also the subject of a global geologic map; W. Patterson stated that the map was being generated in 60° x 60° quadrangles by separate co-investigators. L. Gaddis is PI on a pilot project for remapping the Moon. J. Skinner reported that they have begun mapping a 1:2,500,000-scale quadrangle centered on Copernicus and are using Clementine and Lunar Orbiter IV data as the base map. Results of recent Venus mapping were presented by J. Head, M. Ivanov, and V. Hansen.

During scheduled discussion, the mappers deliberated and reached consensus on the following diverse topics. First, the annual meeting in 2006 will be held on June 24 and 25. We tentatively chose that it will be held in Pocatello or Boise, Idaho in 2006 and at the Planetary Science Institute in Tucson, Arizona in 2007. Second, the Geologic Mapping Subcommittee (GEMS) panel will create and distribute a "New Mappers Handbook" to inform new and present mappers about where to find pertinent information online (and elsewhere) about the current mapping program. Third, the size of the "smallest mappable unit" in a map should be governed by the map resolution. The resolution of the map was initially chosen to maximize the scientific story within the map area; therefore, if a unit is too small to be clearly mapped at this scale, it should not be officially included. However, it is important to note that the use of figures in the map text is encouraged. In the event where a possible or likely unit is identified in the map area, but is too small to be clearly identified on the final printed map, the mapper is encouraged to include as many figures as necessary within the text to reveal the complexity in the region. We agreed that maps should continue to be science-driven. However, some concern was expressed regarding the funding of characterization products (e.g., a global Thermal Emission Spectrometer (TES) map of Mars). What program officially funds these, if any, and where should proposals to produce these be submitted? GEMS agreed to talk with program managers at NASA to determine the appropriate venue for these products. Finally, we noted that USGS should provide new Mars mapping projects with processed THEMIS images that mappers can mosaic themselves; Geographic Information Systems software provides excellent tools for generating dynamic image mosaics.

The meeting concluded with a behind-the-scenes tour of the Smithsonian Natural History Museum's meteorite collection, led by curator Tim McCoy. Mappers were treated to a wealth of meteorite samples, including some from Mars. We all thoroughly enjoyed seeing—and carefully holding with our latex-gloved hands—these beautiful pieces of geologic significance.