JOURNEY TO THE CENTRE OF THE EARTH

… or as far as we can get, anyway. The current world record for deep drilling was set by the Kola Superdeep project, begun in 1970 in a cold corner of the Soviet Union. But it was limited by drilling techniques of the day, and Earth held on to many of its secrets. A brand new drilling method hopes to undercover at least some of them…

CRUST: Igneous, metamorphic and sedimentary rocks.

MANTLE: Sticky porridge fills the planet.

CORE: The pressure is extreme at the centre of Earth.

With an ear-splitting screech, the four rotating drill-heads hit the hard and ancient rock of the Russian Kola Peninsula. Scientists, engineers and workers gather in a ring around the equipment to watch the first metres of the hole open up. It is a proud day for the Soviet Union.

Earth’s depths are unknown territory

When the Russians initiated their Kola Superdeep Borehole on 24 May 1970, their aim was to reach a depth of 15 kilometres – the number ‘15,000’ was even inscribed in tall digits on the drill tower building. Everybody expected challenges en route, given the technology was being put to the ultimate test. But over the next two decades, the Russians came to realise that Earth is less willing to reveal its deepest secrets than anyone had imagined.

Officially, the Russians were aiming to learn more about Earth and its underground resources. But politics were also central to getting the Kola Superdeep under way. The Kola Superdeep was begun less than a year after the Soviet Union had lost the most important battle of the space race – and perhaps of the entire Cold War – when American astronaut Neil Armstrong set foot on the Moon. So the Russians figured to beat the Americans in the other direction, in a downward race towards Earth’s interior. The ultimate aim of this