Detecting Terrestrial Caves by Applying Topographic Analysis Techniques to Thermal Imagery

J.J. Wynne 1, J. Jenness 2, M.D. Jhabvala 3, T.N. Titus 4and D. Billings 5. 1The SETI Institute, Carl Sagan Center, Mountain View, CA and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, jut.wynne@nau.edu; 2Jenness Enterprises, GIS Analysis Application Design, Flagstaff, AZ; 3NASA Goddard Space Flight Center, Instrument Systems and Technology Division, Code 550, Greenbelt, MD; 4U.S. Geological Survey, Astrogeology Sci- ence Center, Flagstaff, AZ; and, 5National Speleological Society, Desert Dog Troglodytes, Los Angeles, CA. Introduction:Since Rinker\u27s [1] groundbreaking work on terrestrial cave detection nearly 50 years ago, our ability to find caves using airborne and spacecraft acquired imagery has improved considerably. Due to superior analytical techniques, improved instrument optics, and high resolution imagery, we have furthered terrestrial cave detection capabilities [2,3,4] and con- firmed cave-like features on the Moon [5,6,7] and Mars [8,9,10]. Lunar caves may serve as the best loca- tions for human habitation [2,4,6], while Martian caves are of great interest as astrobiological targets, access- ing potential water-ice reserves, as well as astronaut bases [2,4]. Further, geothermal vents associated with vapor plumes identified on Saturnian [11], Jovian [12,13] and Neptunian moons [14] hint at additional planetary subterranean access points, and represent high priority targets for future habitability studies. Cave detection is typically most successful when multiple thermal images are acquired during both the warmest (mid-afternoon) and coolest (predawn) times of day [3]. Although data acquisition is logistically easiest on Earth, repeat thermal imagery over short temporal periods is lacking for most terrestrial loca- tions. When searching for caves on other planetary bodies, obtaining multiple images for regions of inter- est within a limited window of time is challenging. Accordingly, researchers must rely on imagery sporad- ically captured from spacecraft platforms where acqui- sition is dictated by fly-by or orbiter mission schedules and tempered by other mission objectives. For extraterrestrial cave detection, we explored two targeting categories using terrestrial analogs. (1) Deep caves, which have sufficient linear length and/or depth to adequately buffer interior environments from harsh surface conditions. On Mars, these caves would be among the best candidates to search for evidence of life. (2) Shallow caves, which extend tens of meters in length, may represent suitable sites for establishing astronaut bases on the Moon and Mars. Within these less protected sites, habitat pods may be constructed or inserted a small distance within the cave entrance. Open Access - Permission by Author(s) See Extended description for more information