title: Results of TV imaging of Phobos (Experiment VSK-Fregat).
abstract: From February to March 1989 the Phobos 2 spacecraft took 37 TV images of Phobos at a distance of 190-1100 km.  These images complement Mariner-9 and Viking data by providing higher-resolution coverage of a large region West of the crater Stickney (40-160 degrees W) and by providing disk-resolved measurements of surface brightness at a greater range of wavelengths and additional phase angles.  These images have supported updated mapping and characterization of large craters and grooves, and have provided additional observations of craters' and grooves' bright rims.  Variations in surface visible/near-infrared color ratio of almost a factor of 2 have been recognized; these variations appear to be associated with the ejecta of specific large impact craters.  Updated determinations of satellite mass and volume allow calculation of a more accurate value of bulk density, 1.90 +/- 0.1 g cm-3.  This is significantly lower than the density of meteoritic analogs to Phobos' surface, suggesting a porous interior perhaps containing interstitial ice.
authors.affiliation: Space Research Institute, USSR Academy of Sciences, Moscow.
authors.forename: G
authors.initials: G
authors.lastname: Avanesov
authors.forename: B
authors.initials: B
authors.lastname: Zhukov
authors.forename: Y A
authors.initials: YA
authors.lastname: Ziman
authors.forename: V
authors.initials: V
authors.lastname: Kostenko
authors.forename: A
authors.initials: A
authors.lastname: Kuzmin
authors.forename: V
authors.initials: V
authors.lastname: Murav'ev
authors.forename: V
authors.initials: V
authors.lastname: Fedotov
authors.forename: B
authors.initials: B
authors.lastname: Bonev
authors.forename: D
authors.initials: D
authors.lastname: Mishev
authors.forename: D
authors.initials: D
authors.lastname: Petkov
authors.forename: A
authors.initials: A
authors.lastname: Krumov
authors.forename: S
authors.initials: S
authors.lastname: Simeonov
authors.forename: V
authors.initials: V
authors.lastname: Boycheva
authors.forename: Y U
authors.initials: YU
authors.lastname: Uzunov
authors.forename: G G
authors.initials: GG
authors.lastname: Weide
authors.forename: D
authors.initials: D
authors.lastname: Halmann
authors.forename: W
authors.initials: W
authors.lastname: Pössel
authors.forename: J
authors.initials: J
authors.lastname: Head
authors.forename: S
authors.initials: S
authors.lastname: Murchie
authors.lastname: Schkuratov YuG
authors.forename: R
authors.initials: R
authors.lastname: Berghänel
authors.forename: M
authors.initials: M
authors.lastname: Danz
authors.forename: T
authors.initials: T
authors.lastname: Mangoldt
authors.forename: U
authors.initials: U
authors.lastname: Pihan
authors.forename: B
authors.initials: B
authors.lastname: Smith
mesh_terms: D001256:Astronomy / Q000379:methods; D003116:Color; D005118:Extraterrestrial Environment; D055593:Geological Phenomena; D005844:Geology; D007053:Ice; D007091:Image Processing, Computer-Assisted; D018535:Mars; D018531:Spacecraft; D013053:Spectrophotometry; D013499:Surface Properties; D013690:Television; D014586:USSR
chemical_list: D007053:Ice