蜜芽传媒

Mary-Ann Ochota asks why scientists have managed to send probes to interstellar space, but haven't yet managed to reach the earth's mantle, which lies just a few miles beneath us. The best place to drill would be at the bottom of the ocean, where the earth's crust is thinnest, but they would still need to drill through about 6.5 km of solid rock before they broke through.

First broadcast on Keep Digging, 4 April 2017.