Earth-Mars Cave Detection Program, Phase 2 – 2008 Atacama Desert Expedition Explorers Club Flag Report J. Judson. Wynne 1,2 , Nathalie A. Cabrol 1,3 , Guillermo Chong Diaz 4 , Edmond A. Grin 1,3 , Murzy D. Jhabvala 5 , Jeffery E. Moersch 6 and Timothy N. Titus 7 1 SETI Institute, Carl Sagan Center, Mountain View, CA; 2 Merriam-Powell Center for Environmental Research, Department of Biological Science, Northern Arizona University, Flagstaff; 3 NASA-Ames, Moffett Field, CA; 4 Departamento de Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile; 5 NASA-Goddard Space Flight Center, Greenbelt, MD; 6 University of Tennessee-Knoxville and 7 U.S. Geological Survey- Astrogeology Branch, Flagstaff, AZ NOTE: The team members listed above are part of a three year study cave thermal behavior in the Atacama Desert, Chile and Mojave Desert, CA; this team received a three-year grant to conduct this project under NASA’s Exobiology program. During Year 1, only Wynne, Chong and Titus will be participating in fieldwork with the assistance of a cave mapping team and other personnel. The Atacama Desert expedition is part of a broader three year study to: (1) characterize thermal behavior of both caves and non-cave features at two Mars analogue sites: the Atacama Desert, Chile and Mojave Desert, California (only the Atacama work will be discussed in this proposal); (2) evaluate the potential to differentiate thermal signatures of deep caves from shallow caves, as well as deep caves from impact craters and collapse pits; and, (3) develop models for Martian caves that simulate Mars atmospheric conditions using thermal behavior data from terrestrial caves. Our overall goal is to define mission and instrumentation requirements for detecting caves on Mars using thermal infrared imagery. Potential Importance of Martian Caves: (A) Caves may be important in detecting evidence of extraterrestrial life because they offer protection from low surface temperatures, unfiltered ultraviolet radiation and violent windstorms, which may degrade and decompose organic materials. (B) A manned mission to Mars will require access to significant H2O deposits for drinking water, oxygen and liquid hydrogen fuel. Caves may provide the best access to these resources without the added expense of developing rover enabled augers and drilling equipment. (C) Future human exploration and possible establishment of a permanent settlement on Mars will require construction of living areas sheltered from harsh surface conditions. Caves with a protective rock ceiling would provide an ideal environment where these shelters may be built. Fig. 1: Thermal behavior data of Cavernas de Quitor (A) with lateral (red) and sinkhole (green) entrances, midpoint (blue), and surface (black) temperatures, and Cueva Mina Chulacao (B) with entrance (red), dark zone (green) and surface (black) temperatures. Data collected from 19 - 30 June 2006, Atacama Desert, Chile. From Wynne et al. [2008a]. Terrestrial Cave Detection: Rinker [1975] provided the baseline for detecting caves in the thermal infrared, and suggested caves could be detected by identifying the thermal signal associated with the mass of air at the entrance contrasted against the surrounding ground surface. We suggest temperature contrast between the rock walls within the cave entrance and external surface rock will be the basis for cave detection [Wynne et al., 2008a, b]. Internal cave surface temperatures represent the mean annual ambient temperature [Cropley 1965; Pflitsch and Piasecki 2003] while ground surface temperature, influenced by direct solar insolation and to a lesser extent by ambient air temperature, fluctuates diurnally and seasonally [Wynne et al., 2007, 2008b]. Optimal thermal detectability will occur when differences between thermal radiance of the cave walls at the entrance and ground surface are greatest. Fig. 2. Hourly temperature data of entrance (red), dark zone (green), and surface (black) for Ice Cave, New Mexico (A) and Cathedral Cave, Arizona (B). Wynne et al. unpublished data.