Blog, Robots & Dinosaurs

A (short) journey to the center of the Earth


If anyone has seen lately the remake of Total Recall, they will absolutely remember the sophisticated mechanism to travel from the UK to Australia (and the tri-boobed mutant, of course). The travelling system worked more or less this way: there was a tunnel crossing the planet from London to Sydney. A huge capsule with the design of a suppository-spacecraft was dropped into the tunnel until reaching the center of the Earth. Then when the gravity was at its zero the capsule lighted its engines and flew vertically approaching Australia from the underground.

Despite the fact that this was the only interesting part of the movie, it was quite clear to everybody that not even in two millions years we will be capable of drilling the Earth just to fly cheaper to down under. And of course the laws of physics have been violated in a dozen ways. Some guy even tried to explain the absurd physics behind the shaft. In a few words: the center of the Earth is supposed to be filled with liquid metal. So tremendously dense and hot. Crossing it would be like eating a panzerotto just taken out of the oven. Do it at hypersonic speed is just a bad idea.

Furthermore, the pressure in the very center of Earth is so incredibly high that the iron won’t liquefy even if the temperature reaches more than 5000ºC. And yes, 5000ºC is the same temperature of the surface of the Sun. So this combination of heat and pressure convert our planet core in a hot, huge flipper ball.

So I was wondering, if we are sat over a big metal ball with the temperature of the sun, aren’t we curious enough to go and know it? I mean, we have landed on the moon, built space stations, taken pictures of galaxies million of light years far from our planet, but how much do we know about our own home?

Not much really. Our journey to the center of the Earth did not get very far. Some years after touching the lunar surface and coming back, the Russians started a project to dig a big hole vertically underground. The name of the project was Kola Superdeep Borehole and the goal of the mission was studying the interior of our planet. Well, they started digging and digging until they reached the unbelievable depth of… 12km! (7.5 miles)

12 km is a quarter marathon, or the total size of the quadrilatero della moda of Milan. Try to put it in perspective with the size of the Earth (5000 km or 3100 miles to the core) and we have an idea of how much work we have ahead before start to understand what lies under our feet.

But why did the Soviets stopped so early? Because of the heat. At 12 km they expected 100ºC but instead they found an impressive temperature of 180ºC. So in spite of thinking that it was a good place to bake pizza, they decided that was to hot too keep on drilling when their tools started to melt.

It has to be said, also the Americans tried to drill a hole into the ground, but cheating. Instead of starting from the sea level, they began to drill out of Guadalupe Island where the sea bottom is at 3.6 km. This project (named Mohole) was actually a submarine drilling, but it did not dig very much, as it went only 180 meters deep.

Sorry kids, but it seems that no one is still interested in following the Jules Verne adventure. At least on this planet, because the interstellar drilling is on the roadmap of many agencies… Are we ready to write a journey to the center of Titan?
Photo by William Truebridge.

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