A theoretical scientist has captured the imagination of the US public with the Jules Verne-style idea of sending a probe to the Earth's core, but his fellow scientists have shown less enthusiasm for the idea.
David Stevenson, a New Zealand-born professor at the California Institute of Technology, admitted that the proposal was meant mainly to generate discussion. He said that he wanted to suggest that humans should learn as much about their home as they do about other planets.
"It was never my intent that my proposal be serious in the sense of an engineering proposal, merely that it be a provocative idea," Dr Stevenson said.
"It doesn't bother me that people called it crazy because it is crazy, or at least immature, in the sense that there are major unanswered technical issues. But I wanted to get the scientific community to acknowledge that no serious attempt had been made to think about missions that go down in the same sense that space missions go up."
Dr Stevenson's "core mission" calls for a probe a little smaller than a football to be sent to the Earth's core in an envelope of molten iron forced by gravity through cracks created with a nuclear explosion. The probe would send back temperature readings and other data during its journey, which would take about a week.
So far, the deepest anyone has drilled beneath the surface of the Earth is 12km, on Russia's Kola Peninsula. Meanwhile, Dr Stevenson said, billions of dollars had been spent on unmanned scientific missions to other planets.