- A box of gadgetry little bigger than a television will
be hurled into space this weekend on a mission to explain where the moon
came from.
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- After studying rocks brought back by six manned Apollo
missions and three unmanned Russian probes in the 1960s and '70s, scientists
theorised the moon formed 4.5 billion years ago after a Mars-sized planet
collided with Earth. Lighter rocks were thrown into orbit, forming the
moon.
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- But Bernard Foing, the European Space Agency's project
scientist, said it was still just a theory.
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- "With the Apollo lunar missions we only sampled
specific areas, on the near side, near the equator," Dr Foing said.
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- "It's like taking some samples from the Sahara and
saying we understand the whole Earth."
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- It will be the job of Western Europe's first moon-orbiting
probe to map the chemistry of the entire surface, which it is hoped will
reveal how Earth's companion was born.
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- While the Apollo astronauts dashed to the moon in less
than four days, Europe's SMART-1 probe - the Small Mission for Advanced
Research and Technology - will take a leisurely 16 months.
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- Costing ¤110 million ($185 million) - the budget
mission will also test technology that may revolutionise the exploration
of the solar system.
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- To save money, the probe will hitchhike into space on
Sunday, Sydney time, from the Kourou space port in South America, riding
piggyback with two communication satellites.
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- Previous lunar missions, including Apollo, used powerful
but heavy chemical rockets to blast out of Earth's orbit and head for the
moon. However, SMART-1 is equipped with a lightweight experimental ion
motor that will, according to the European Space Agency, produce no more
force than "the weight of a postcard".
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- Power from solar panels will generate an electric field
that will propel charged particles of xenon gas out of the motor at enormous
speed. Each second, the engine will accelerate the little craft only a
fifth of a millimetre per second faster. However, while conventional chemical
rockets burn out in minutes, SMART-1's ion motor will fire for 4000 hours.
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- Month after month, as SMART-1 circles the Earth, it will
gradually pick up speed, spiralling through hundreds of higher and higher
orbits until January 2005, when it will come so close to the moon that
it will be captured by the lunar gravity.
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- If the collision theory is right, the moon should be
rich in light elements, such as aluminium and magnesium, but short of heavy
ones, such as iron.
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- Copyright © 2003 The Sydney Morning Herald
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- http://www.smh.com.au/articles/2003/09/25/1064083129967.html<
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