"Is it possible that Pluto will ever collide with Neptune because their orbits appear to cross? If so, what will happen?"
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Thermal Behavior and Detection of Caves on Earth and Mars (2)
PI: Nathalie Cabrol
Preliminary results from terrestrial caves study have shown they are detectable in the thermal infrared. Diurnal and seasonal temperature variations have been determined. They are most detectable when the temperature contrast between the entrance and ground surface is greatest. However, geology and structure and surrounding surface may affect thermal behavior, thus detectability. Non-cave features may confound our ability to accurately target candidate sites for exploration, and they require thermal characterization as well. Analysis of visual and thermal imagery reveal possible cave-like structures on Mars, some with thermal characteristics similar to terrestrial sample sites. To best detect caves on Mars, we must first identify the range of conditions under which they are detectable on Earth, develop simulation models to predict conditions for optimal detectability on Mars, and be able to distinguish caves from non-cave features. Our goal is to define mission and instrumentation requirements for detecting caves on Mars using a combined thermal infrared-visual imagery interpretation approach. We will: 1) Characterize cave thermal behavior and evaluate the potential to differentiate thermal signatures of deep caves from shallow caves, as well as deep caves from impact craters and collapse pits at Mars analog sites. We will collect thermal data for both caves and non-cave features. We will acquire ground-based temperature data to: Capture the variability of cave structure and geological substrate using both data collected during the pilot phase of this study and this project and; characterize thermal behavior of non-cave features that may result in false positives; 2) Develop models for Martian caves that simulate atmospheric and environmental conditions using thermal behavior data and structural characteristics from terrestrial caves. We will model surface and subsurface temperatures of caves and surrounding terrain, Mars atmospheric conditions (lower pressure, density, and heat capacity), entrance structure, albedo associated with Martian geological formations where caves are likely to occur, and varying surface temperatures to reflect seasonality and diurnality. The goal is to identify the detectability of a cave given structure type and geological substrate. The developed models will be used to identify times to conduct overflights using the QWIP thermal imaging sensor. Overflights will allow us to determine detectability and resolvability of each cave in the thermal infrared; 3) Document regions on Mars likely to contain caves and cave-bearing geology. Visible and multispectral imagery from orbital missions will be examined within these areas to begin the process of prioritizing potential regions for high-resolution thermal image capture. This project is relevant to the NASA Exobiology program because systematic thermal detection of caves on Mars will enable us to explore the most promising locality to search for extinct and/ or extant life.
