Why is SMART-1 testing its ion engine on a trip to the Moon?
First, the Moon is a very interesting scientific target! Secondly, SMART-1 could share the cost of the Ariane-5 launcher with other passengers also going up to the geo-transfer orbit (GTO), from which the Moon can be reached. Last but not least , the necessary spiral orbit which SMART-1 took to reach the Moon from the GTO, is a long and complex trajectory: this allowed SMART-1 to test fully and properly the ion engine in conditions representative of a fully fledged deep-space mission.
