Color heterogeneity of the surface of Phobos: Relationships to geologic features and comparison to meteorite analogs

Journal Article · Wed Apr 10 00:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JB02354· OSTI ID:5452909

Murchie, S L; Britt, D T; Head, J W; Pratt, S F; Fisher, P C ^[1]; Zhukov, B S; Kuzmin, A A; Ksanfomality, L V; Zharkov, A V; Nikitin, G E ^[2]; Fanale, F P; Blaney, D L; Bell, J F; Robinson, M S ^[3]

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1. Brown Univ. Providence, RI (USA)
2. Space Research Inst., Moscow (USSR)
3. Univ. of Hawaii, Honolulu (USA)

Multispectral observations of Phobos by the VSK (Videospectrometric) TV cameras and KRFM (Combined Radiometer and Photometer for Mars) UV-visible spectrometer on Phobos 2 have provided new determinations of the satellite's spectral reflectance properties, at greater spatial and spectral resolutions and over a greater geographic range than have previously been available. Images of the ratio of visible and NIR reflectances covering the longitude range 30-250{degrees}W were constructed from 0.40-0.56 {mu}m and 0.78-1.1 {mu}m VSK images. The average color ratio of Phobos was found to be {approximately}0.97{plus minus}0.14, consistent with previously obtained measurements. However, the surface is heterogeneous, with at least four recognizable spectral units whose absolute color ratios were determined to within {approximately}10%: a red unit with a color ratio of 0.7-0.8, a reddish gray unit with a color ratio of 0.8-1.0, a bluish gray unit with a color ratio of 1.0-1.1, and a blue unit with a color ratio of 1.1-1.4. The redder and bluer color units are interpreted to have been excavated by impacts, from an optically and/or compositionally heterogeneous interior overlain by a reddish gray surficial layer. The location of the blue lobe emanating from Stickney correlates with the location of one of the morphologic classes of grooves, as predicted by ejecta reimpact models of groove origin. The large color ratio of blue material is comparable to that of an assemblage of mafic minerals like that forming black chondrites. Qualitative and quantitative comparison of the color ratio and UV-visible spectral properties of bluish gray material with those of meteorites indicates that black chondrites are this material's closest spectral analog. The UV-visible spectra of reddish gray and red materials most resemble spectra of black chondrites but are also comparable to spectra of some carbonaceous chondrites.

• OSTI ID: 5452909
• Journal Information: Journal of Geophysical Research; (United States), Vol. 96:B4; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
MARS PLANET
SATELLITES
SPECTRAL REFLECTANCE
CHONDRITES
COLOR
COMPARATIVE EVALUATIONS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
IMPACT SHOCK
METEORITES
MULTISPECTRAL PHOTOGRAPHY
NEAR INFRARED RADIATION
RADIOMETRIC SURVEYS
SURFACE PROPERTIES
ULTRAVIOLET RADIATION
VISIBLE RADIATION
ELECTROMAGNETIC RADIATION
EVALUATION
GEOPHYSICAL SURVEYS
INFRARED RADIATION
OPTICAL PROPERTIES
ORGANOLEPTIC PROPERTIES
PHOTOGRAPHY
PHYSICAL PROPERTIES
PLANETS
RADIATIONS
STONE METEORITES
SURVEYS
640107* - Astrophysics & Cosmology- Planetary Phenomena