Paris, 25 Feb 2005
"Walking on the moon" is a song evoking one of mankind's earliest dreams. In July 1969 it became reality when, stepping out of his Lunar Module, Neil Armstrong pronounced the now historic words: 'One small step for man but a giant leap for mankind.' Today another lunar exploration mission is paving the way for a return to the Moon. Launched from Kourou in September 2003, the European Space Agency's SMART-1 satellite started orbiting the Moon last November.
"Our objective is to survey its surface nature and chemical composition, observing it from a polar orbit," explains the mission's project scientist Bernard Foing. "Piecing together many mosaics, we will for instance produce a high-resolution map of the Moon."
The Euronews 'Space' magazine has visited the SMART-1 Science and Technology Operations centre based at ESA's Research and Technology Centre at Noordwijk in the Netherlands. It is from there that are programmed the observations by the seven science and technology instruments on board the satellite. According to Jim Volp, operations engineer, it is much like remotely driving a car from a great distance. "We are not worried about the engine or the car parts, but we are more concerned with the passengers, the science payload. Instruments may want to point at different things, one looking to the left, the other at the same time to the right. We need to harmonise things."
Fully operational since arriving in orbit around the Moon, the morale of the project and science teams is high. The mission was originally due to end next August but on 15 February it was given an extra lease of life with a year's extension. The spacecraft will now lower its orbit around the Moon for a second phase of science observations.
An essential reason for the extension is the spacecraft's very efficient solar-electric propulsion and navigation. This small motor producing an ion plasma jet from the sun's energy and xenon gas gently carried the satellite up to its lunar orbit.
"The thrust is only 7 grams, the weight of a postcard," recalls Bernard Foing. "By operating continuously with this thrust – much like blowing on one's hand for six months - it has been possible to spiral up to the Moon." The magical journey of ever-increasing circles have conveyed the small one-meter cube-shaped SMART-1, only 370 kg, over several million kilometres until it was caught by the Moon's gravity.
By studying the surface geology and chemistry, the SMART-1 mission will also improve our understanding of the Moon's origins and early evolution. It is believed to have been formed from aggregated debris ejected from the Earth when it was hit by an asteroid more than 4 billion years ago.
Looking at the darker parts of the Moon's south pole for the first time, the satellite will also attempt to bring a definitive answer to a long-standing question about the existence of water on the Moon. Water in a frozen state, brought as icy particles in asteroids or comets, could be present. Water-ice may be present at the bottom of some lunar craters, says Bernard Foing
"In the region of the south pole, there are many craters," says Bernard Foing displaying a large model of the lunar surface. "Some craters are very special in that the Sun's rays never reach their bottom. Temperatures there can be the coldest in the solar system, at minus 200 C, so cold as to permanently trap any water-ice. But along the crater perimeters, there are peaks that are constantly illuminated by the Sun."
These are ideal conditions to re-launch lunar exploration. "Having permanently lit areas and water nearby has an enormous impact for future missions. We can send rovers to these peaks of eternal light, set up lunar bases which will have solar power, with water-ice available in the craters."
SMART-1 data are being made available to other international lunar missions. "Our satellite is thus helping to define and plan the next generation of robotic and manned missions to the Moon." For Bernard Foing and the SMART-1 team, the prospect of walking – once again - on the Moon and perhaps living there permanently is no longer a dream. But a near certainty.
European Space Agency
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European Space Agency