"The prime object of this mission was to test the ion propulsion," mission manager Gerhard Schwehm said.
"This is a very efficient means to get a spacecraft over large distances with a very small mass of fuel. It worked really well."
Instead of burning rocket fuel, the PPS-1350 engine from French aerospace firm Snecma generates a stream of electrically charged atoms called ions. That creates minuscule amounts of thrust - roughly enough to hold up a postcard.
Riding that small, steady push, SMART-1 made it to the moon in 14 months, gradually accelerating and raising its orbit around the earth until it was high enough to be grabbed by the moon's gravity.
http://www.shanghaidaily.com/art/2006/08/31/290660/SMART_1_to_crash_on_moon__039_s_surface.htm
more here
http://www.esa.int/SPECIALS/SMART-1/index.html
High enough? From memory, the Earth's gravitational effect, in relation to the Moon is something just under
90% of the distance between to the two masses. Say 250K miles, that means it has to be about
25K miles from the Moon to be captured by it.
Or did I miscalculate?