Published online 19 November 2007 | Nature | doi:10.1038/news.2007.267

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Chikyu 's first mission complete

Deep-sea drilling vessel gets off to a good start.

Wrangling with the drill on the world's biggest research rig.IODP

The ship that will soon drill deep into an underwater earthquake zone completed its first science mission on 16 November. Chikyu, the world's largest research drilling vessel, finished the initial 8-week leg of its research programme with only minor glitches.

Chikyu’s long-term mission is to drill up to 6 kilometres below the sea floor to examine conditions deep in the Nankai trough, an earthquake-generating zone off Japan's Pacific coast. The first sortie aimed to drill at the six sites where the vessel will eventually take its cores and build observatories. Measurements were made to determine the properties of the rocks surrounding each borehole.

The plans were slightly delayed when the bottom 200 metres of the drill, holding the drill bit and the measuring instruments above it, snapped off in one of the holes. Efforts to fish it out failed. Such incidents are not unusual and the crew had a spare for the costly piece of equipment (which is covered by insurance). Work was able to continue, and the researchers drilled into four of the six sites as planned, reaching 1,400 metres at the site where they plan to dig 6 kilometres. "It's a great site and it drilled well," says Harold Tobin of the University of Wisconsin-Madison, one of the chief scientists on the expedition.

The crew for the next leg is already on board; Chikyu is expected be on site drilling until about 2012. 

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