A mission to drill right through Earth’s crust begins this week

DAVID NIELD

This week marks the start of a new project to drill below Earth’s crust into the planet’s mantle – that rocky shell a couple of thousand kilometres thick. Geologists have been trying for almost 60 years to reach this depth, but no one has yet succeeded: the latest mission might just have the technology and the funding to make it happen.

The drill ship JOIDES Resolution will shortly be setting off from Sri Lanka to a point in the southwestern Indian Ocean known as Atlantis Bank. Once it reaches its destination, the ship will lower a drill bit and tunnel through some 1.5 kilometres (almost a mile) of solid rock, taking core samples as it goes. That’s as far as the plan stretches – if the JOIDES Resolution is successful in its mission, future projects will have to take over in the drive to the boundary between Earth’s crust and mantle.

Why Atlantis Bank? Scientists believe the crust-mantle division is marked by a feature known as the Mohorovičić discontinuity, or ‘Moho’ for short. Moho is believed to be particularly near the surface at Atlantis Bank, which should make it easier to reach. There are also fewer hard-to-crack crustal rocks in the region.

Making it down to this unexplored frontier is “one of the great scientific endeavours of the century”, according to expedition co-leader Henry Dick. Dick and his colleagues hope to make it further than the first team to attempt the drill did – oceanographer Walter Munk and a group of fellow geologists got down to 183 metres in 1960 before costs spiralled out of control and the initiative was cancelled.

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