Rock of Love

By Kathy A. Svitil|Monday, May 01, 2000

NASA's had its share of bad luck lately, but the agency just scored a sweet triumph by slipping a probe into orbit around an asteroid that has only 1/1000 the surface gravity of Earth. The NEAR spacecraft is now conducting a yearlong study of Eros, one of the near-Earth asteroids--a family that includes such alums as the rock that probably wiped out the dinosaurs. From its initial vantage point 225 miles above the surface of 21-mile-wide Eros, NEAR has spotted inexplicable bright patches, immense boulders, and strange layers inside a gaping three-mile-wide crater. The layers resemble those produced by volcanoes on Earth, although scientists consider Eros far too small to be geologically active. "It was completely unexpected and makes it quite likely that Eros is the broken-off chunk of a body the size of a planet or moon," says NEAR's lead scientist, Andrew Cheng of the Applied Physics Laboratory at Johns Hopkins University.

In coming months, NEAR will measure Eros's composition and snap even more detailed images than the two shown above. Although Eros poses no immediate threat to Earth, these studies will help astronomers respond to another asteroid that does. "We're practicing how to navigate and operate a spacecraft around an asteroid, which is a necessary step if you're going to do anything about deflecting one," Cheng says.

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