Comparative Planetary Science
A Possible Titan Ground Fog Detection from Huygens SLI Imagery
Christina L. Smith
Brittney A. Cooper, John E. Moores
York University
Titan is known to harbour a thick nitrogen-dominated atmosphere. Clouds have been detected at a variety of altitudes from terrestrial and satellite observations and methane fog has been detected from orbital images of Titan's south pole. Observations from the surface of other planetary bodies, such as Mars, have made direct detections of clouds in their respective atmospheres. This work presents the results of an investigation into image data taken with the Side Looking Imager (SLI) on-board the Huygens Probe after it landed on the surface of Titan, with the aim of evaluating whether atmospheric features, such as clouds or fog banks, could be detected from the surface. In total, 82 SLI images were calibrated, processed and examined for features. The calibrated images, cropped to the region above the horizon, show a smooth vertical radiance gradient, with the maximum radiance detected at the top of the images and the minimum radiance towards the horizon. With mean-frame subtraction, features beyond the vertical radiance gradient were detected. Of the 82 images, 6 mean-frame subtracted images contained an extended horizontal feature with a radiance which was outside the 95% confidence interval of the predicted value from background observations. These features are considered to most likely originate from a fog bank situated close to the horizon that rises and falls over the time of observation.


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