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.

The fuel consumption was less than expected, and the success of the mission has raised hopes that the technology can be used to send other craft far deeper into space, where the chemical propulsion systems that power conventional rockets would be too expensive or unworkable.

"Europe has proved that it is able to fly a spaceship with ion propulsion alone," Giorgio Saccoccia, one of the ESA's propulsion specialists, told reporters at the ESA's control center in Darmstadt, in southern Germany.

Launched into Earth orbit from French Guiana on Sept. 27, 2003, atop a conventional booster rocket, the SMART-1 probe made it to within 3,100 miles of the moon Monday, and will now begin spinning its way closer to the surface as it orbits, Bonacina said.

By mid-January the dishwasher-sized spacecraft will be in an elliptical orbit that will take it within 185 miles of the moon's south pole and 1,850 miles from the north pole, Bonacina said.

"Today we have celebrated the successful technology mission, and now we start with science — we want to do imaging of the surface and study the chemistry of the moon," Bonacina said.

The ESA is hoping to use state-of-the-art equipment to take images of the surface from different angles and X-ray and infrared technology to allow scientists to draw up new three-dimensional models of the moon's surface.

SMART-1 will also be looking at the darker parts of the moon's south pole for the first time, and searching dark craters for signs of water, ESA said.

Over the last 13 months, the 809-pound probe has been edging its way toward the moon in a mission controlled from the ESA's operations center in Darmstadt. It measures 3.3 feet on each side, and solar panels, which help provide ion — or solar-electric — propulsion, spread 46 feet.

Unlike conventional rockets, no fuel is "burned"; instead, the solar panels provide electricity to charge the xenon gas atoms, which accelerate away from the spacecraft at high speed and produce forward thrust.

The surprising fuel efficiency of the spacecraft means that the agency might be able to extend its six-month scientific mission by up to a year, if it can find the additional funding, Bonacina said.

When the mission is eventually complete, the probe will crash onto the moon's surface.

The mission marks the second time that ion propulsion has been used as a primary propulsion system. The first was the Deep Space 1 probe launched by NASA (news - web sites) in 1998.

SMART-1, short for "Small Missions for Advanced Research and Technology," was developed for ESA by the Swedish Space Corporation with contributions from some 30 contractors in Europe and the United States. It took off aboard an Ariane-5 rocket in September 2003.

The total cost for the mission is $142.3 million, about a fifth of what is required for a typical major space mission.

  The success of the mission provides a much-needed boost for the European space program, which is still smarting from its failed attempt to land a probe on Mars last year.

The British-built Beagle 2 was launched on the ESA's Mars Express orbiter, and was supposed to touch down on the Red Planet to begin its search for life on Dec. 25, 2003, but scientists have found no trace of the lander.

As the project failed, two U.S. spacecraft landed on Mars and sent back many pictures and extensive scientific data.