Open AccessEffect of diffuse sky brightness on the spectrophotometry of rough Martian surfaces
Author(s) -
Thomas Nicolas,
Jorda Laurent,
Markiewicz Wojciech J.
Publication year - 2000
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000je001222
Subject(s) - martian , brightness , mars exploration program , martian surface , flux (metallurgy) , diffuse sky radiation , sky , atmosphere of mars , optics , astrobiology , surface brightness , physics , atmosphere (unit) , scattering , geology , materials science , astrophysics , meteorology , metallurgy , galaxy
The Martian Surface is illuminated both by the direct solar flux and by a diffuse flux originating from scattering by dust in the Martian atmosphere. The fact that the diffuse flux varies in intensity and color across the sky leads to nonsolar total illumination of surfaces. This, in turn, can lead to interesting phenomena such as the apparent color changes of rock surfaces with time of day [ Thomas et al. , 1999]. A further consequence is the possibility that two surfaces, in an identical orientation and of identical color when illuminated by a direct beam, can change color relative to one another when viewed under Martian conditions if the two surfaces are of different surface roughness. This is a natural consequence of microshadowing combined with the diffuse illumination of those shadows. In this paper, we demonstrate the phenomenon with a numerical model, show an example from the Mars Pathfinder landing site where it could be of significance, and discuss its implications for spectrophotometric studies of Martian rocks.