Leg 179 of the Ocean Drilling Program (ODP) represents an endeavor aimed at two longstanding gaps in our understanding of the nature of the solid earth. First, we set out to test a new drilling technology that might enable deeper drilling and eventually higher recovery from the deep ocean crust than ever before possible. Our second goal was to prepare a site where researchers can establish a long-term geophysical ocean-bottom observatory as part of the International Ocean Network (ION) program. Both of these primary objectives were accomplished. Initial tests of the hammer drill-in casing system yielded data that will allow future development and implementation of this technology on a regular basis. A nearly 500-m-deep borehole–cased to basement, cemented into the hard rock basement, and left with a reentry cone–was established at the Ninetyeast Ridge. Installation of a downhole observatory at this location will fill one of the six major gaps in global seismic monitoring coverage. Given potential delays in port because of repairs to the drillship, the advisory structure of ODP prioritized the supplementary objectives for Leg 179. The highest priority for these objectives was given to the two-ship offset seismic experiment in coordination with the Sonne. Unfortunately, time constraints prevented completion of these supplementary objectives.

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