Experimental Research using Thermography To Locate Heat Signatures from Caves

We have long known that there are thermal differences between cave entrances and the surrounding landscape. Speleologists traditionally ridge walked in cave-likely temperate regions in cold mid-winter with a falling barometer in order to visually detect 'fog-plumes' of escaping subterranean air from crevices and unknown earth openings in order to locate caves. We are experimenting with a high-technology solution to this cave detection method applying infrared thermography, a useful tool in fire detection, human body location and other building examination remote sensing to the surface of the earth. Early trials during 2005 with a ThermaCAM TM B20 HSV infrared camera, even under foliage-filled and warm atmospheric conditions, resulted in promising results in initial trials in New Mexico, West Virginia and Greece. Further research is underway at Fisher Cave, Franklin County, Missouri and in the Atacama Desert-- San Pedro de Atacama, Chile. The research in the Atacama is undertaken as a member of the NASA Atacama Desert Chile Science Team 2006. The aim of this research is to develop protocol for the use of infrared thermography to locate caves on Mars. As life might exist in caves on Mars, sheltered from radiation, this is an area of great interest to NASA astrobiologists and other scientists. This research began by documenting temperatures of cave openings and surrounding substrates. Atmospheric, ambient conditions (temperature, relative humidity, specific humidity and dew point) were recorded inside Fisher Cave, at the entrance and at intervals up to 183 meters. Normal images were contrasted with thermograms showing full temperature gradients of the openings. At 118 meters, the opening could no longer be seen with the naked eye. The thermograms showed distinct images of cave openings. Trials continued to 388 meters. In excess of 300 meters, thermograms showed the distinct cave opening of Fisher Cave. At 388 meters, the thermograms showed signatures that could be that of a cave entrance. The initial results indicate that individual cave entrances have separate and unique temperature gradients. Thus, individual cave thermograms are a "fingerprint" or signature of that cave. Thermograms can be used to isolate and identify caves entrances from surrounding terrain features. Once standardized procedures have been established, thermograms may become an important tool for cave location and exploration terrestrially and via remote sensing on other planets.