Asteroid Braille (1992 KD) was discovered on May 27, 1992 by astronomers Eleanor Helin and Kenneth Lawrence using the 46 centimeter (18 inch) Shmidt telescope at Palomar Observatory, while scanning the skies as part of the Palomar Planet-Crossing Asteroid Survey. Braille became the target of NASA's Deep Space 1 spacecraft on July 29, 1999 when the spacecraft flew within an estimated 26 kilometers (16 miles) of the asteroid. The spacecraft's infrared sensor confirmed that the small asteroid is similar to Vesta, a rare type of asteroid and one of the largest bodies in the main asteroid belt, which lies between Mars and Jupiter.
"This clear link between Vesta and Braille is an important finding," said Dr. Laurence Soderblom of the U.S. Geological Survey, team leader for Deep Space 1 experiments using the spacecraft's integrated spectrometer and imaging instrument. Scientists are now wrestling with a thorny question: Is the near-Earth asteroid Braille a chip off Vesta's old block, or are the two asteroids siblings which originated elsewhere, perhaps thrown off a larger body that has long since been destroyed?
The scientists made their finding from three sets of data collected by the spacecraft's infrared camera. Called spectra (data obtained when the instrument breaks light into component colors, much like a prism does) the data sets cover different parts of the asteroid and were taken just after closest approach.
Braille's longest side is now estimated at 1.3 miles (2.2 kilometers) and its shortest side appears to be 0.6 miles (1 kilometer). This elongated asteroid was expected to be irregular, and two photographs taken approximately 15 minutes after closest encounter have helped to confirm this.
By contrast, Vesta, discovered in 1807, has a diameter of about 310 miles (500 kilometers). The fourth asteroid ever discovered, Vesta shares with Braille a high visual reflectivity. In fact, Vesta is the most reflective of the main-belt asteroids.
Apart from flyby findings, project scientists have determined that in about 4,000 years Braille will join the hundreds of other asteroids that drift in and out of Earth's orbit.
The flyby, at 12:46 am EDT on July 29, occurred at an estimated distance of 16 miles (26 kilometers), although the exact distance is still being measured.
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