A fuel-efficient compact spacecraft has made it into lunar orbit, signaling Europe's first successful mission to the moon and putting the inexpensive probe on course to study the lunar surface, European Space Agency officials said.
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 59kg of the 82kg of xenon fuel it had aboard.
"It works out to something like 2 million kilometers per liter, which is quite an achievement," ESA spokesman Franco Bonacina said Tuesday from the space agency's headquarters in Paris.
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, last year atop a conventional booster rocket, the SMART-1 probe made it to within 5,000km from the moon Monday morning, 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 300km of the moon's south pole and 3,000km 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 367kg probe has been edging its way toward the moon in a mission controlled from the ESA's operations center in Darmstadt. It measures 1m on each side, and solar panels, which help provide ion -- or solar-electric -- propulsion, spread 14m.
Unlike conventional rockets, no fuel is "burned" but 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 be left to crash onto the moon's surface.
The total cost for the mission is 110 million euros (US$142.3 million), about a fifth of that required for a typical major space mission.