Вісник Астрономічної школи (Oct 2011)

Asymmetry of reflective properties of the hemispheres of Jupiter satellite Europa

  • A. P. Vid'machenko,
  • A. V. Morozhenko,
  • A. I. Klyanchin,
  • V. I. Shavlovskiy,
  • Yu. S. Ivanov,
  • N. M. Kostogryz

DOI
https://doi.org/10.18372/2411-6602.07.1133
Journal volume & issue
Vol. 7, no. 1
pp. 133 – 144

Abstract

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Rotation around the central planet of Europa is synchronous. Leading hemisphere is much brighter and less polluted by “no ice” material than the trailing one. The high albedo of the satellite may indicates that the ice on the surface is clean enough and is formed recently: 1,5–30 million years ago. Comparison of surface images of spacecrafts “Voyager” and “Galileo” with a low spatial resolution did not detect any significant changes during 20 years. But a detailed analysis of observational data with high resolution points to a number of features on the surface, which may indicate a change in the geological structures during this time. Spectral geometric albedo in the wavelength range 346–750 nm of leading and trailing hemispheres of Galilean satellites were defined using of our spectral observations in 2009 and 2010 and the observations of the other authors at different values of orbital and solar phase angles. The high geometric albedo in the red region of Io and Europa spectrum are confirmed; albedo of Io decreases sharply with decreasing of wavelength for λ<500 nm; albedo of Ganymede and Callisto — reduced smoothly; albedo of Europa have an intermediate gradient of reduction. Such behavior of the spectral variation of Europa surface albedo can be explained by deposition of sulfur from Io. Moreover, the sulfur absorption is more strongly on the trailing hemisphere. This indicates that the sulfur on the leading hemisphere is “processed” by meteoritic bombardment much faster and is gone to the sub-surface regolith layer.

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