U.S. Geological Survey
Southwest Biological Science Center
Colorado Plateau
Field Station
Northern Arizona University
Flagstaff, AZ 86001
Tel: 928.523.7757
Fax: 928.556.7500
Email: J. Judson Wynne
Detecting Caves on Earth and Mars Using Thermal Infrared Imaging
Over the past two years, we have been working on techniques to detect caves in the thermal infrared. The objective of this study is to determine the feasibility of identifying caves on Earth using remote sensing techniques, and then assess the feasibility of these techniques for detecting caves on Mars.
On Earth, this technology can be used to identify: 1) caves of high biological conservation priority, and (2) subterranean access points for studying ground-water hydrology. During the last glaciation, surface-dwelling fauna retreated underground seeking more favorable conditions. As our planet is experiencing unparalleled human-induced climatic change, we don’t know how troglomorphic taxa will respond, nor do we know what surface-dwelling taxa will be driven underground. A systematic approach for identifying a large number of caves will assist researcher and land managers in establishing a baseline regarding current faunal assemblages and ecological conditions. With the rapidly increasing human populations, in particular, in the western United States, there are unprecedented demands upon a limited water supply. Access to caves containing active hydrology may be helpful to city and county municipalities to assist them in evaluating and monitoring water quality and potentially availability.
On Mars, caves are important features for exploration for many reasons. Martian caves are important features for the exploration of life because they offer protection from low surface temperatures, unfiltered ultraviolet radiation and violent windstorms, which may degrade and decompose organic materials. Also, because caves can be highly protected environments, it is possible these features may shelter current life forms. A manned mission to Mars currently lacks the fuel capacity for the return trip back to Earth, as well as the ability to bring enough water for a long-term exploration of the Red Planet. Location of significant H2O deposits for conversion to liquid hydrogen fuel and potable water will be required. In addition to the water requirement, future human exploration and possible establishment of a permanent settlement on Mars will require construction of habitation pods that offer protection from harsh surface conditions. By their nature, caves contain a natural protective rock cover that can provide an ideal environment where these shelters may be built.
This project has been quite successful. We have studied the thermal behavior of caves in northern Arizona, western New Mexico, southern California and northern Chile. We have collected and analyzed ground-based hourly temperature data, ground-based thermal imagery, and thermal imagery collected via fixed wing aircraft and hot air balloons. All of this has shown us that detection of caves in the thermal infrared is possible.
Through this work, we have gained considerable insight into detection of terrestrial caves in the thermal infrared. We have observed diurnal and seasonal temperature variations in detection, and have determined caves are most detectable when the temperature contrast between the entrance and ground surface is greatest. However, structural and geological aspects of caves and the surrounding surface may affect thermal behavior and thus detectability.
Preliminary analyses of visual and thermal imagery have also identified possible cave-like structures in several regions on Mars. Many of these features have thermal characteristics similar to some of our study sites here on Earth. While we are not certain whether these features are actually “caves,” these findings are compelling and definitely warrant further research.
We are in the process of launching Phase 2 of the Earth Mars Cave Detection Program. Our objectives of this work include:
• Expanding upon our initial search for Martian caves by selecting additional regions likely to contain caves and/or cave-bearing geology.
• Collecting thermal behavior data and thermal imagery at two Mars analogue sites (Mojave Desert, CA and Atacama Desert, Chile) for both caves and non-cave features including two impact craters.
• Developing thermal behavior models for Martian caves that simulate Mars atmospheric conditions using thermal behavior data from Earth caves.
• Developing and testing a prototype QWIP (Quantum Well Infrared Photodetector)for a Mars orbiter platform.
• Developing and testing robotic concepts for exploring subterranean Mars.
This study has been funded by NASA Exobiology grant NNH04ZSS001N-EXB, NASA Spaceward Bound! Atacama Desert Expedition, Chile , NASA Spaceward Bound! Mojave Desert Expedition, CA , and supported by the USGS-Southwest Biological Science Center, a grant from Friends of L. Ron Hubbard (LRH Explorers Award), and CONAF-Chile, San Pedro De Atacama Field Office.
Publications
Wynne, J.J., T.N. Titus, and G. Chong Diaz (In prep.), Understanding Thermal Behavior of Two Atacama Desert Caves, Chile. Geophysical Research Letters.
Cushing, G.E., T.N. Titus, J.J. Wynne, P.R. Christensen (In Review), Possible Cave Skylights on Mars. Geophysical Research Letters.
Wynne, J.J., M.G. Chapman, C.A. Drost, J.S. Kargel, T.N. Titus, and R.S. Toomey III (2007), Cave Detection on Mars, 2006 NSS Convention Abstracts, Journal of Cave and Karst Studies 68: 169.
Outreach
2007 NAU Department of Biological Sciences Seminar Series, Flagstaff, AZ. Presentation: Astrobiological Implications for Detecting Caves on Mars.
2007 Lowell Observatory, Flagstaff, AZ. Presentation: If there’s life, it’s underground! The search for caves on Mars.
2006 Needlewood Middle School, Brunswick, GA. Gave lecture to 6th graders on astrobiology, Mars and searching for life underground (students instructed: 60).
2006 The Mission Gallery and Coffee House, Grants, NM. Presentation: Astrobiology and the Search for Martian Cave Life (audience size: 10).
2006 Flagstaff Festival of Science Twilight Talk Series, AZ. Presentation: Astrobiology and the Search for Martian Cave Life (audience size: ~45).
Copyright © 2007-2008 J. Judson Wynne. All Rights Reserved.