Deep Space 1 (DS1), currently scheduled for launch in July or August 1998, is the first mission of NASA's New Millennium program, chartered to flight validate high-risk, advanced technologies important for future space and Earth science programs. DS1's payload of technologies will be rigorously exercised during the two-year mission. Several features of the project present unique or unusual opportunities and challenges in the design of the mission that are likely to be encountered in future missions. The principal mission-driving technology is solar electric propulsion (SEP); this will be the first mission to rely on SEP as the primary source of propulsion. Another important technology for the mission design is the autonomous on-board navigation system, which requires frequent (at least weekly) intervals of several hours during which it collects visible images of distant asteroids and stars for its use in orbit determination and maneuver planning. The mission design accommodates the needs of these and other technologies for operational use and for acquiring sufficient validation data to assess their viability for future missions. DS1's mission profile includes encounters with an asteroid and a comet.