NASA's new quest: Alien life

Washington: NASA scientists were able to analyse the makeup of distant planets in other solar systems using a technique that could one day be used to find life on other planets

Teams of scientists used the space-based Spitzer infrared telescope to measure the spectra, or light emissions, of two giant, gaseous planets, trillions of km away from Earth.

By breaking the light given off by the planets into different wavelengths, the scientists could analyse their chemical composition, astronomers said on Wednesday.

The two planets - known as HD 189733b, 63 light years away in the constellation Vulpecula, and HD 209458b, 154 light years away in the constellation Pegasus - are so-called hot-Jupiters, gaseous planets like Jupiter, but located much closer to their suns.

At a teleconference, scientists involved in the project said that more powerful telescopes could likely use the same technique to examine smaller, rocky planets, which could be more Earth-like.

Mark Swain, a research scientist at NASA's Jet Propulsion Laboratory, said that the results were a "very important stepping stone" for drawing conclusions about other types of planets that could be hospitable for life.

The scientists had believed they would find water in the planets' atmospheres, but their analysis came up short on answering the water question.

Because hot-Jupiters are believed to contain water in their atmospheres, the astronomers said that several theories could account for the lack of water-based steam on the estimated 815-degree planets.

One explanation could be that dusty clouds obscured the water molecules. Another is that other molecules absorbed the light given off by water molecules, scientists said.

"Just because we don't see it doesn't mean it's not there," NASA scientist Jeremy Richardson said.

The teams said they will continue to refine their techniques to further examine the planets. They may find the elusive water later.

Even without water, they can estimate that "the weather today on 209458 is hot, dry, probably cloudy with a chance of wind," Swain said.

"The mantra is look for water," astronomer Alan Boss said of the hunt for extraterrestrial life.

The results will be published in Nature and the Astrophysical Journal Letters.