'Starshade' may aid space exploration

Thursday, July 6, 2006 Posted: 1554 GMT (2354 HKT)

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The 'starshade' would use thrusters to move into the line of sight of distant stars.
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LONDON, England (Reuters) -- A huge daisy-shaped shield that would block out light from parent stars could be used to find Earth-like planets in other solar systems, an American astronomer said on Wednesday.

He and his team have designed a plastic "starshade" measuring 50 yards (45 meters) in diameter that would orbit in tandem with a trailing telescope and block out light from parent stars to enable scientists to map planetary systems.

Finding other planets is very difficult because their parent stars are about 10 times brighter.

"We think this is a compelling concept, particularly because it can be built today with existing technology," said Professor Webster Cash of the University of Colorado.

"We will be able to study Earth-like planets tens of trillions of miles away and chemically analyze their atmospheres for signs of life," he added in a statement.

The shield, which is known as the New Worlds Observer, is described in the journal Nature. It would be launched into an orbit about 1 million miles from Earth and then opened.

Three thrusters would be used to keep it steady while the telescope trailing thousands of miles behind follows light from distant planets as it hits the space shield.

"The New Worlds Observer is actively being studied in academia, industry and government," Cash said in a letter to Nature.

He added that if Earth-like planets exist, the starshade could find them within the next decade.