资源环境科技发展态势分析平台

We use nighttime Cassini Composite Infrared Spectrometer (CIRS) data to look for discrete regions of elevated nighttime temperatures indicative of endogenic activity on Dione's surface. This is achieved by producing low latitude and midlatitude (less than 60 degrees) maps of Dione's nighttime surface temperature, derived from 10 to 1,100-cm(-1) CIRS data. The surface temperatures observed do not show evidence of any small discrete regions of elevated nighttime temperatures and are comparable to temperatures predicted by a passive thermophysical model of Dione's surface. Thus, we conclude that no evidence for activity exists on Dione at midlatitude to low latitude. Using the derived surface temperature maps, we set upper limits for the temperature at which a 50-, 100-, or 200-km(2) hot spot would remain undetected by this study. We find the mean temperature of such a hot spot would be 117.147.2K (-249F), 104.827.7K (-272F), and 95.419.5K (-288F) for a 50-, 100-, and 200-km(2) hot spot, respectively, corresponding to endogenic emission of 1.07, 0.68, and 0.47GW.

Plain Language Summary We use data from National Aeronautics and Space Administration's Cassini spacecraft to map the nighttime surface temperature of one of its large icy moons Dione. These maps show no evidence of small very hot regions, which (if present) would provide evidence of activity on Dione. Instead, the surface temperatures we do see are comparable with those we would expect to see on Dione if it were inactive. So we find no evidence for activity on Dione in this study. However, it is possible that very small regions of high surface temperatures would not be detected in this work. We use the observed surface temperatures to define how hot a small region (50, 100, or 200km(2)) could be and remain undetected. The results show such a region would have a mean temperature of 117.147.2K (-249F), 104.8 +/- 27.7K (-272F), and 95.4 +/- 19.5K (-288F) for a 50-, 100-, and 200-km(2) hot spot, respectively, corresponding to endogenic emission of 1.07, 0.68, and 0.47GW.