SMART-1 is the first of the small missions for advanced research and technology as part of ESA's science programme “Cosmic vision”. It was successfully launched on September 27, 2003 and is presently traveling towards its destination, the Moon. The main objective of the mission, to demonstrate solar electric primary propulsion for future Cornerstones (such as Bepi-Colombo), has already been achieved. At the time of writing the electric propulsion system has been working already for more than 3400 h and has provided a Delta-V to the spacecraft of more than 2500 m/s. The other technology objectives are also being fulfilled by the verification of the proper functioning of such on-board experiments like the X-Ka band transponder, the X-ray spectrometer, the near IR spectrometer, the laser link, etc. The scientific objectives are related to lunar science and will be fulfilled once the spacecraft enters its operational lunar orbit, currently expected for January 2005. SMART-1 lunar science investigations will include studies of the chemical composition of the Moon, of geophysical processes, environment and high-resolution studies in preparation for future steps of lunar exploration. SMART-1 has been an innovative mission in many aspects and we are now drawing some preliminary conclusions about the lessons to be learnt. The paper describes the spacecraft and the technology elements with particular emphasis to the technology nature of the mission. The on-board avionics employs many novel designs for spacecraft, including a serial CAN bus for data communication, autonomous star trackers and extensive use of auto-code generation for implementing the attitude control system and the failure, detection, isolation and recovery (FDIR). Finally, the orbital operation phase currently ongoing, including the routine electric propulsion operations and the instrument commissioning, is providing a wealth of data and lesson-learnt useful for future autonomous planetary missions.