The base of the jovial groove as the little group walked was a lilting, repeating riff on the kora, the 21-string harp-lute that a musician played with its base propped against his torso, plucking with his thumbs. â
The Vanguard team was still working on a test vehicle (TV-2) designed to test the first stage of the rocket when they learned of the launch of the world's first artificial satellite, Sputnik I, by the USSR on October 4, 1957. On December 2, the Department of Defense announced the imminent launch of TV-3.
Dawn is not the first NASA spacecraft to use ion propulsion. The agency's Deep Space 1 spacecraft, launched in 1998 to test new technologies and capture data about a comet, was the first to use an alternative to traditional propulsion. The Dawn spacecraft, however, has used ion propulsion to travel much farther and to study two extraterrestrial objects.