Discovery of exoplanet with CO2 may lead to detection of other "Earths"

Washington, Dec 9 (ANI): The discovery of carbon dioxide (CO2) in the atmosphere of a Jupiter-like planet 63 light-years away has fuelled hopes for the detection of habitable exoplanets in the future.

According to a report in National Geographic News, Mark Swain of NASA's Jet Propulsion Laboratory in Pasadena, California, said that CO2 is a biomarker, a molecule associated with life as we know it.

This first discovery of the molecule on a far-flung planet, he said, is a step toward eventually finding biomarkers on smaller, more Earthlike worlds.

Last March, Swain and colleagues had announced the first detection of another biologically important chemical, methane, on the same exoplanet, as well as confirmation of water vapor.

"Methane is a potential marker (of life), as is water, as is carbon dioxide," Swain said. "So, three of the biggies we've already detected," he added.

Swain and colleagues made the CO2 discovery while studying radiation from an exoplanet dubbed HD 189733b.

The planet periodically transit, or passes in front of its host star, giving observers a measurement of the star and planet's combined light.

By subtracting the light from the star alone from the combined measurement, astronomers can "see" the planet's light.

Reading signatures from this light then told astronomers the chemical composition of the planet's atmosphere.

Swain acknowledges that HD 189733b is too big, gaseous, and hot to host life as we know it.

But, according to him, the fact that we are now able to find biomarkers such as carbon dioxide on worlds so far away means that we'll know what to look for when reading light signatures from smaller, rocky planets like Earth.

Geoff Marcy, an astronomer at the University of California, Berkeley has high hopes that NASA's upcoming Kepler mission will bring the quest for rocky exoplanets closer to its goal.

Set to launch on March 5, the space telescope is designed to find other "Earths" by staring at the constellation Cygnus and detecting stars that dim due to transiting planets.

Cygnus was chosen because it contains a large number of stars and won't be obscured by the sun at any time of the year.

The probe's photometers are sensitive enough to catch minute changes in light that result during a transit by a small planet, and its "eye" can see a hundred thousand stars at once.

According to William Borucki, Kepler mission lead scientist at NASA, "If Kepler finds that most stars have a terrestrial planet in the habitable zone, then there must be billions of such planets in our galaxy and life could be ubiquitous." (ANI)