The Bolometric Bond Albedo of Enceladus

Abstract

The bolometric Bond albedo is a fundamental parameter of planets and moons. Here, combined observations from the Cassini spacecraft and the Hubble Space Telescope are used to determine the bolometric Bond albedo of Enceladus. We provide the full-disk reflectance of Enceladus across all phase angles (0° -180°) from 150 nm to 5131 nm, a spectral range that accounts for nearly all incoming solar power. Considering the distribution of the monochromatic Bond albedo over wavelength, we find a value of 0.76 ± 0.03 for Enceladus' bolometric Bond albedo. The corresponding optical characteristics (e.g., geometric albedo and phase function), which are closely related to Enceladus' surface properties, are also investigated. The wavelength-dependent nature of Enceladus' Bond albedo suggests that the bolometric Bond albedos of other icy moons, if they are mainly determined by the visible observations only, should be carefully considered. Our new measurements of bolometric Bond albedo can be used to better determine the radiant energy budget of Enceladus and further constrain the internal heat flow, a critical driving force for the water plumes on Enceladus.