Congratulations to the European Space Agency! Its SMART-1 spacecraft has arrived in orbit around the Moon.

Almost more impressive than reaching its destination was the slow and steady way the SMART-1 craft puttered its way there — flying 13 months in ever expanding circles around the earth using a cutting-edge ion propulsion system.

The spacecraft used only 130 pounds of the 181 pounds of xenon fuel it had aboard, according to European Space Agency spokesman Franco Bonacina in Paris. That translates to more than 5 million miles per gallon.

This is only the second time that Ion propulsion has been used as the primary drive for a probe. NASA's 1998 Deep Space 1 probe was the first.

The ESA hopes to find water in the dark craters at the Moon's south pole.