During the past 50 years, we have witnessed humankind’s first good, detailed look at the planets in our known Solar System.  All of these advances built upon Earth-based telescopic observations.  We predict surface conditions on other Solar System bodies before spacecraft reach them for in situ study.  The dominant type of asteroid identified telescopically in the main asteroid belt is classed as a C-complex asteroid, likely the origin of many of the primitive carbonaceous chondrite meteorites.

In the visible spectral region, one prominent, identifying spectral feature indicating the presence of Fe2+ → Fe3+ in clay minerals is located near 0.7 µm in over half of the C-complex asteroids.  Using its spectral presence, we can constrain the presence and thermal history of these objects in the Solar System.  I will describe the feature, and the implications of the evidence of its presence.  As an illustration, I will then show how we can use the presence of this feature to probe Solar System developmental history through examining the spectra of the jovian outer irregular satellites.