Fig. 11. Influence of Terrain Type on Spectrum Slope on Ganymede.
In 11a, circle diameter increases linearly with the fraction of bright
crater material in the field of view. The largest circles indicate a pure
bright crater spectrum. Both Voyager1 and 2 data are shown but not distinguished:
all the spectra with more than 25% bright crater material are from Voyager2,
however. The small slope of the bright crater spectra is readily seen.
11b is similar except that the fraction of dark (cratered) terrain rather
than bright crater material is indicated. Only Voyager2 data are shown,
in order that the vague slope/terrain correlation visible here is not obscured
by slight slope differences between the Voyager1 and 2 spectra. Spectra
with more that 25% bright crater material have also been excluded, so that
the smallest circles indicate pure light (mostly grooved) terrain spectra.
The largest circles represent pure dark terrain spectra.
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