Atmosphereless Bodies Research Articles

Phase curves of meteorites and terrestrial rocks: Laboratory measurements and applications to asteroids

The measurement of the radiation reflected by a particulate surface as a function of the phase angle can be a powerful method for deriving information about the physical and chemical properties of the materials composing the surface layers of atmosphereless bodies of the Solar System. Several theoretical descriptions of the light scattering by a particulate surface have been developed to explain the observations of the phase functions for a number of Solar System bodies (asteroids, satellites of Jupiter, Moon, and Mercury). However, laboratory measurements on naturally occuring materials, both terrestrial and extraterrestrial, are needed to improve the understanding of the physics of the processes involved. The authors report the results of laboratory measurements carried out at the Teramo Observatory to study the reflectance of powdered meteorites and terrestrial rocks at various phase angles. We analyzed the reflectance of 17 meteorites: 14 chondrites (3 C-type, 5 L-type, 4 H-type, 2 LL-type), and 3 achondrites. In addition, a study of the effects on the phase curve of varying the size fraction and the compaction degree has been carried out on terrestrial rocks (peridotite, diabase, quartz-rich sand).

Some photometric techniques for atmosphereless solar system bodies

We discuss various photometric techniques and their absolute scales in relation to the information that can be derived from the relevant data. We also outline a new scattering model for atmosphereless bodies in the solar system and show how it fits Mariner 10 surface photometry of the planet Mercury. It is shown how important the correct scattering law is while deriving the topography by photoclinometry.

Scattering of light by stochastically rough particles with applications to interplanetary dust and planetary regoliths

The single particle phase function and linear polarization for large stochastically deformed spheres have been calculated by Monte-Carlo simulation using the geometric optics approximation /1/. The radius vector of a particle is assumed to obey a bivariate log-normal distribution with three free parameters: mean radius, its standard deviation and the coherence length of the autocorrelation function. All reflections and refractions which include sufficient energy have been included. Real and imaginary parts of the refractive index can be varied without any restrictions. Results and comparisons with some experiments are presented. Applications of this theory to the photometric properties of atmosphereless bodies and interplanetary dust are discussed.

Radiative transfer in the surfaces of atmosphereless bodies. III - Interpretation of lunar photometry

view Abstract Citations (19) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Radiative transfer in the surfaces of atmosphereless bodies. III. Interpretation of lunar photometry. Lumme, K. ; Irvine, W. M. Abstract Narrowband and UBV photoelectric phase curves of the entire lunar disk and surface photometry of some craters have been interpreted using a newly developed generalized radiative transfer theory for planetary regoliths. The data are well fitted by the theory, yielding information on both macroscopic and microscopic lunar properties. Derived values for the integrated disk geometric albedo are considerably higher than quoted previously, because of the present inclusion of an accurately determined opposition effect. The mean surface roughness, defined as the ratio of the height to the radius of a typical irregularity, is found to be 0.9 + or - 0.1, or somewhat less than the mean value of 1.2 obtained for the asteroids. From the phase curves, wavelength-dependent values of the single scattering albedo and the Henyey-Greenstein asymmetry factor for the average surface particle are derived. Publication: The Astronomical Journal Pub Date: July 1982 DOI: 10.1086/113192 Bibcode: 1982AJ.....87.1076L Keywords: Astronomical Photometry; Lunar Craters; Lunar Surface; Radiative Transfer; Asteroids; Electrophotometry; Light Scattering; Lunar Albedo; Natural Satellites; Phase Shift; Regolith; Surface Properties; Surface Roughness; Ubv Spectra; Lunar and Planetary Exploration; Albedo:Moon; Moon:UBV Photometry; Moon Surface:Radiative Transfer full text sources ADS |

Radiative transfer in the surfaces of atmosphereless bodies. II. Interpretation

Radiative transfer in the surfaces of atmosphereless bodies. II. Interpretation

Radiative transfer in the surfaces of atmosphereless bodies. I - Theory. II - Interpretation of phase curves

A generalized theory of radiative transfer is presented which includes single and multiple scattering of light in particulate surfaces, and is applicable to both the surfaces of atmosphereless bodies and to laboratory samples. Single scattering is described in terms of the effects of porosity and roughness, and is formulated by means of a probabilistic method. It is shown that, for low-albedo surfaces, the effects of porosity and roughness are separable, the opposition effect is caused by the former, and the slope of the linear part of the phase curve is mainly controlled by the latter. The theory, which is applicable to all albedos and phase angles, may be used in both surface brightness and integrated brightness studies. The limiting case of roughness and volume density tending to zero yields the results of classical radiative transfer theory.

The atmospheres of the outer planets and satellites

This is a review of recent research results pertaining to the atmospheres of the outer planets and satellites. It includes the atmospheres of Pluto, Triton, Neptune, Uranus, Titan, Saturn, and Io. Io’s neutral torus and plasma torus are covered, but Jupiter and Jupiter’s magnetosphere are not. Jupiter is not included because of the number of specialized reviews which have recently become available for Jupiter. This review includes earlier Voyager 1 and 2 results for Io’s atmosphere and plasma torus as well as early Pioneer 11 results for Saturn and Titan. Neither ring systems nor atmosphereless bodies are reviewed here.