Geologists have dreamed of drilling through the Mohorovi?i? discontinuity between Earth's crust and mantle for more than 50 years. Actual rock from this so-called "Mohole" and observations taken along the way could shed light on many of the most fundamental questions about Earth's history and dynamics that more indirect sampling methods, mainly acoustic, have not been able to answer. The acoustic methods, such as "3-D Seismic" are effective means for creating synoptic images (similar to remote sensing by satellite), but just as a satellite cannot sequence the DNA in a plant or animal spied on Earth's surface, so acoustic and other methods cannot specify mineral composition and other crucial aspects of Earth's interior. Samples taken from the Mohold could prove valuable for defining the limits of life in the deepest part of the crust as well as for understanding mantle-crust interactions and other geological questions The prospect of drilling a hole to earth's mantle, however, is daunting. The most likely site, in the Pacific, would require drilling a hole the depth of 14 Empire State Buildings in 10 Empire State Buildings of water. While continental drillers have drilled this deep and ocean drillers have operated in such deep water, the project would involve integrating the two traditions in an unprecedented way. Risks include safety, environment, and finance (One study estimated the total cost of successfully completing the Mohole could exceed $500 million). Funds from this grant will support efforts by the Integrated Ocean Drilling Program to begin the planning and infrastructure development necessary for successfully drilling a borehole to earth's mantle.