By Sid Perkins
Blast a crack in Earth’s crust, pour in a few thousand tons of rock-busting molten iron, and then toss in a grapefruit-size instrument designed to ride the plunging elevator of liquid metal to the planet’s core.
That scenario sounds like science fiction. Even its author, geophysicist David J. Stevenson of the California Institute of Technology in Pasadena, calls the proposal “highly speculative.” However, in the May 15 Nature, he contends that such a mission to explore Earth’s interior is technically feasible.