The morning launch kicked off NASA's new millennium programme of ``high risk, high payoff'' technology missions that the space agency hopes will lead to frequent, affordable trips into space.

Deep Space 1 is taking the risks so that future missions don't have to,'' said chief engineer and deputy mission manager Marc Rayman at the jet propulsion laboratory in Pasadena, California.

Though ion engines have flown before, Deep Space 1 is the first deep-space probe to rely on such a device for primary propulsion. Ground controllers plan to fire up the engine in a few weeks, once they're sure everything is working.

The solar-powered engine will provide the extra kick needed for the winged, drum-shaped spacecraft, which weighs just over 450 kg, to arendezvous with asteroid 1992 kd next July. It will travel an estimated 725 million km before catching up with the moving asteroid. A small delta rocket started the probe on its budget-priced 152 million dollars journey.