In 1992, Larry A. Lebofsky and colleagues published an article in which they detected a spectral feature at 3 micrometres in 773 Irmintraud, a main-belt D-type asteroid.[1] This feature was believed to indicate the presence of water on the surface and to indicate that the D-type asteroid was more likely to be in an altered state rather than in an unaltered, primitive or primordial state.[1]