The Deep Impact flyby spacecraft includes a 1.08 to 4.5 μm infrared (IR) spectrometer.
Although ice was not observed on surface in the impact region, strong absorptions near 3 μm due
to water ice are detected in measurements of the ejecta from the impact event. Absorptions from
water ice occur throughout the IR dataset beginning three seconds after impact through the end
of observations, ~45 minutes after impact. Spatially and temporally resolved IR spectra of the
ejecta are analyzed in conjunction with laboratory impact experiments. The results imply an
internal stratigraphy for Tempel 1 consisting of devolatilized materials transitioning to unaltered
components at a depth of approximately one meter. At greater depths, which are thermally
isolated from the surface, water ice is present. Up to depths of 10 to 20 m, the maximum depths
excavated by the impact, these pristine materials consist of very fine grained (1±1 μm) water ice
particles, which are well-separated from refractory components.