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O 2 on Ganymede: Spectral characteristics and plasma formation mechanisms
Author(s) -
Calvin Wendy M.,
Johnson Robert E.,
Spencer John R.
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl00450
Subject(s) - absorption (acoustics) , jupiter (rocket family) , ion , absorption spectroscopy , wavelength , spectral line , infrared , materials science , plasma , oxygen , phase (matter) , chemical physics , astrobiology , physics , optics , astronomy , quantum mechanics , space shuttle
Weak absorption features in the visible reflectance spectrum of Jupiter's satellite Ganymede have been correlated to those observed in the spectrum of molecular oxygen. We examine the spectral characteristics of these absorption features in all phases of O 2 and conclude that the molecular oxygen is most likely present at densities similar to the liquid or solid γ‐phase. The contribution of O 2 to spectral features observed on Ganymede in the near‐infrared wavelength region affects the previous estimates of photon pathlength in ice. The concentration of the visible absorption features on the trailing hemisphere of Ganymede suggests an origin due to bombardment by magnetospheric ions. We derive an approximate O 2 formation rate from this mechanism and consider the state of O 2 within the surface.