Engineering: Getting There the Hot Way

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Taking leave of their own problems for a while, five nuclear scientists at the Atomic Energy Commission's Los Alamos Scientific Laboratory were discussing the difficulties of Project Mohole, the National Science Foundation's plan to bore through six miles of the earth's crust northeast of Hawaii. What kind of drill would stand up to the job?

The talk turned to molybdenum, which is not the hardest metal known to man but has the advantage of not even beginning to melt at temperatures up to 4,700°F. Eventually the atom experts decided to put their drilling theories to a test; they constructed a 2-in. cylindrical drill bit of molybdenum, and to their surprise their very first demonstration was a success. With a 5-kw. generator, they heated the face of the bit to 2,190°F, then forced it down against a specimen of hard basalt rock. Like a hot pick thrusting through ice, the bit ate into the rock at the rate of 50 ft. a day—a rate that the experimenters figured could be doubled by heating the bit to a still higher temperature and by putting a little more pressure on the drill from the top.

The Los Alamos men are already speculating beyond Mohole. They feel that their drill can be put to work some day to tap the geothermal energy that abounds deep in the earth, causing hot springs and geysers. As for immediate uses, the inventors are uncertain, but they answer at least one request a day for information about their molybdenum bit from miners and wildcatters.