It sounds like something from a bad black and white sci-fi movie, but Californian Scientist Prof. Dave Stevenson is planning to send a probe, approx. the size of a grapefruit, to the centre of the Earth to measure various things suchs as temperature and material composition. They are proposing cracking the Earth’s surface using TNT with the equivalent power of a Nuclear Bomb (Did the Earth move for you?). If you wish to find out more you can the details here or there. So watch out for unexpected Earthquakes and volcanoes erupting.