The wavelength dependence of the lunar phase curve as seen by the Lunar Reconnaissance Orbiter wide‐angle camera

Abstract

[1] The Lunar Reconnaissance Orbiter wide-angle camera measured the bidirectional reflectances of two areas on the Moon at seven wavelengths between 321 and 689 nm and at phase angles between 0°and 120°. It is not possible to account for the phase curves unless both coherent backscatter and shadow hiding contribute to the opposition effect. For the analyzed highlands area, coherent backscatter contributes nearly 40% in the UV, increasing to over 60% in the red. This conclusion is supported by laboratory measurements of the circular polarization ratios of Apollo regolith samples, which also indicate that the Moon's opposition effect contains a large component of coherent backscatter. The angular width of the lunar opposition effect is almost independent of wavelength, contrary to theories of the coherent backscatter which, for the Moon, predict that the width should be proportional to the square of the wavelength. When added to the large body of other experimental evidence, this lack of wavelength dependence reinforces the argument that our current understanding of the coherent backscatter opposition effect is incomplete or perhaps incorrect. It is shown that phase reddening is caused by the increased contribution of interparticle multiple scattering as the wavelength and albedo increase. Hence, multiple scattering cannot be neglected in lunar photometric analyses. A simplified semiempirical bidirectional reflectance function is proposed for the Moon that contains four free parameters and that is mathematically simple and straightforward to invert. This function should be valid everywhere on the Moon for phase angles less than about 120°, except at large viewing and incidence angles close to the limb, terminator, and poles.Citation: Hapke, B., B. Denevi, H. Sato, S. Braden, and M. Robinson (2012), The wavelength dependence of the lunar phase curve as seen by the Lunar Reconnaissance Orbiter wide-angle camera,

A visible and near-infrared photometric correction for Moon Mineralogy Mapper (M3)

“…These variations in emission angles might not be well constrained in the photometric model and in the limb darkening. The simplified model used to derive the phase function does not address the opposition effect in detail and this could be improved in the future by using other models (Hillier et al, 1999;Shkuratov et al, 2011;Hapke et al, 2012).…”

“…The McEwen model was used for the Clementine observations of the Moon and it has been also used by Yokota et al (2011) to correct the data from Spectral Profiler (SP) onboard the Kaguya mission (Matsunaga et al, 2001). More recent studies (Buratti et al, 2011;Hicks et al, 2011;Sato et al, 2011;Hapke et al, 2012) and previous study (Hillier et al, 1999) have used the Lommel-Seeliger approach. A detailed review by Shkuratov et al (2011) addresses the pros and cons of the limb darkening correction.…”

“…For the Lunar Reconnaissance Orbiter Camera (LROC) data, a multiple scattering Hapke function was used (Sato et al, 2011;Hapke et al, 2012). …”

Asteroid Photometry

“…Finally in situ studies rely on using well-sampled planetary observation data sets to derive information about the validity of Hapke's model (cf. Guiness et al, 1997;Verbiscer and Veverka, 1990;Domingue et al, 1997;Helfenstein et al, 1997;Helfenstein and Shepard, 1999;Hapke et al, 2012;Shepard et al, 2001;1993).…”

Pre-flight and On-orbit Geometric Calibration of the Lunar Reconnaissance Orbiter Camera

“…23, we selected a WAC image in a spectrally neutral region of the Moon (near 0 • N, 160 • E). We then photometrically normalized the image using the Hapke LROC model (incidence = 60 • ; emission = 0 • ; and phase = 60 • ) and the GLD100 to remove the effects of the lighting geometry and topography (Hapke et al 2012;Scholten et al 2012;Sato et al 2014). We then orthorectified the two bands (415 and 689 nm) and created a Fig.…”