The ion engine on board NASA's Deep Space 1 spacecraft has again fired successfully, placing the $152 million New Millennium spacecraft en route for a 13km fly-by of the asteroid 1992 KD in July.
The ion engine - one of several new technologies being demonstrated on the mission - has operated for more than 850h.
An intelligent flight control system known as the autonomous optical navigation system has also proved successful, enabling the spacecraft to become the first to calculate its own location without the aid of flight controllers.
Using flight programme star charts and data gathered by its on-board camera, the navigation system computed its own location and course (Flight International, 11-17 November 1998).
Source: Flight International