A gigantic, daisy-shaped space shield could let astronomers use an orbiting telescope for searching Earth-like planets in other solar systems, an astronomer reported on Wednesday.

With this thin plastic "starshade," researchers could use a telescope trailing thousands of kilometers behind it for imaging light from distant planets skimming by the giant petals, while not being swamped by light from the parent stars, said Webster Cash, a professor at the University of Colorado, in the July 6 edition of the journal Nature.

Researchers thus could identify such features as oceans, continents, polar caps and cloud banks on remote planets, and even detect biomarkers like methane, oxygen and water if they exist.

By now, it is difficult for astronomers to observe extrasolar Earth-like planets as those planets are too close to their parent stars and too dim compared with the stars.

Scientists would launch the telescope and starshade together into an orbit roughly 1.6 million km from the Earth, and then remotely unfurl the starshade and use small thrusters to move it into lines of sight of nearby stars thought to harbor planets, said Cash.

Roughly half the size of a football field, the starshade will be equipped with thrusters to move into the line of sight of distant stars.

The thrusters would be intermittently turned on to hold the starshade steady during the observations of the planets, which would appear as bright specks.

"We would use the starshade as a giant hand to suppress the light emanating from a central star by a factor of about 10 billion," said Cash.

"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 said.

Dubbed the "New Worlds Observer," Cash's design has been selected by U.S. National Aeronautics and Space Administration after initial study.

If Earth-like planets exist, the starshade could find them within the next decade, forecast Cash.

Source: Xinhua