Down to it. (Letters)."Going Down? Probe could ride to Earth's core in a mass of molten iron" (SN: 5/17/03, p. 307) neglects the most difficult problem associated with sending a probe to the vicinity of Earth's core: sending the information back. Even a few feet of earth will stop conventional radio waves Radio waves Electromagnetic energy of the frequency range corresponding to that used in radio communications, usually 10,000 cycles per second to 300 billion cycles per second. . Extra-low-frequency transmissions would do the job, but a transmission could take years. AUGUSTO SOUX, SAN DIEGO San Diego (săn dēā`gō), city (1990 pop. 1,110,549), seat of San Diego co., S Calif., on San Diego Bay; inc. 1850. San Diego includes the unincorporated communities of La Jolla and Spring Valley. Coronado is across the bay. , CALIF. David J. Stevenson David J. Stevenson (born September 2,1948) is a professor of planetary science at Caltech. Originally from New Zealand, he received his Ph.D. from Cornell University in physics, where he proposed a model for the interior of Jupiter. of the California Institute of Technology California Institute of Technology, at Pasadena, Calif.; originally for men, became coeducational in 1970; founded 1891 as Throop Polytechnic Institute; called Throop College of Technology, 1913–20. in Pasadena envisions a probe that sends data via encoded vibrations at low frequencies. Sensitive detectors at Earth's surface can pick up small seismic waves that would be produced by a 10-watt vibrating vibrating, v using quivering hand motions made across the client's body for therapeutic purposes. source, he notes. Over the course of a mission, the probe would send out about 100 million vibrations-enough to encode sufficient information about the deep-Earth environment.--S. PERKINS The liquid iron channels already exist--in the form of active volcanoes. ALLAN MORRISON, MANITOBA, CANADA There is a far more interesting way to get to the core than setting off hydrogen bombs and filling the crack immediately afterwards. A better method would be to drop a 100,000-ton hardened-iron mass shaped like a spear from a great height, like an orbit. This would go through the crust pronto pron·to adv. Informal Without delay; quickly. [Spanish, from Latin pr  mptus; see prompt. . To get the spear in orbit, you simply go to the moon with a few robots and mine the needed iron. With a little acceleration, the iron is in orbit, and presto, you're ready for action. Cheers. THOR OLSON, REDMOND, WASH. |
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