Asteroids are ancient cosmic fragments left over from the formation of the solar system and may hold clues to that early time, which is why they are of such great interest to scientists. Most asteroids orbit the Sun in a "belt" of debris between Mars and Jupiter, but there are some whose orbits cross or come close to that of Earth.

On July 28, 1999, the Deep Space 1 spacecraft flew by asteroid Braille only about 26 kilometers above the surface, which is about twice as high above the asteroid as a jet plane flies above the Earth.

During the close flyby, the spacecraft took images, measured such basic physical properties of the asteroid as its mineral composition, size, shape, and brightness; and it searched for changes in the solar wind as it interacted with the asteroid to investigate whether it had a magnetic field. Solar wind is a field of high energy particles that emanates from the Sun.

Artist's rendering by Don Foley(copyright)