of the inner disk is not clear. It may have originated from planetesimals recently having moved from the outer regions of the system into the inner system, in a process similar to the Late Heavy Bombardment in the history of the Solar System, and subsequently being ground to dust by collisions. Possible Late Heavy Bombardment In 2010–2011, Carey Lisse of the Johns Hopkins University Applied Physics Laboratory and his group analyzed the Spitzer IRS 5–35 μm spectrum of the warm, ~360K circumstellar dust and found that it showed clear evidence for warm, water- and carbon-rich dust at ~3 AU from the central star, in the system's habitable zone, uncoupled and in a separate reservoir from the system's extended sub-mm dust ring at 150 ± 20 AU. Spectral features similar in kind and amplitude to those found for ultra-primitive (i.e., formed very early in the lifetime of the Eta Corvi system) ~10 Myr old cometary material were found (water ice and gas, olivines and pyroxenes, amorphous carbon and metal sulfides), in addition to emissions due to impact produced silica and high temperature/pressure carbonaceous phases. The warm dust is very primitive, and definitely not from an asteroidal parent body. A large amount, at least 3 x 1019 kg, of 0.1 – 1000 μm warm dust is present, in a roughly collisional equilibrium distribution with dn/da ~ a−3.5. This is the equivalent of a 160-kilometer-radius centaur or medium-sized Kuiper belt object of 1.0 g cm−3 density or a "comet" of 260 km radius and 0.40 g cm−3 density. The warm dust mass is much larger than that of a solar system comet (1012 – 1015 kg), but is very similar to the mass of a Kuiper belt object (1019 – 1021 kg). The amount of water tied up in the observed material, ~1019 kg, is > 0.1% of the water in the Earth's oceans, and the amount of carbon is also considerable, ~1018 kg. The team found that the best model for what is going on is that some process (e.g., planetary migration) is dynamically exciting the Eta Corvi-equivalent of the Solar System's Kuiper belt (KB), causing frequent collisions amongst Kuiper belt objects (KBOs) and producing the observed copious Kuiper belt dust. As part of this process, one or more of the excited KBOs was scattered onto an orbit that sent it into the inner system, where it collided with a planetary-class body