March 26, 2008 In another first for NASA's Hubble Space Telescope (HST), an organic molecule has been detected in the atmosphere of a Jupiter-sized planet orbiting a star 63 light-years (or somewhere in the vicinity of 370 trillion miles) away. Given that the molecule found was methane, a key chemical player in the "primeval soup" from which life was formed on this planet, the discovery represents a significant breakthrough in the search for life outside our solar system.
"This is a crucial stepping stone to eventually characterizing prebiotic molecules on planets where life could exist," said Mark Swain of NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., who led the team that made the discovery. Swain is lead author of a paper appearing in the March 20 issue of Nature.
Located 63 light-years away in the constellation Vulpecula, the planet HD 189733b is far too hot (at 1,700 degrees Fahrenheit) and too close to its parent star (taking just two days to orbit) to actually harbor life as we understand it, but the discovery made using the Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) validates the observation process which will be used to examine Earth-like planets in the future.
Spectroscopy is a method of detecting molecular markers by splitting the light emitted from stars. In this case, light traveling from HD 189733b's parent star that has passed through the planet's atmosphere can be analyzed to reveal insights into its chemical make-up.
"These measurements are an important step to our ultimate goal of determining the conditions, such as temperature, pressure, winds, clouds, etc., and the chemistry on planets where life could exist. Infrared spectroscopy is really the key to these studies because it is best matched to detecting molecules," said Swain.
The find also confirms an earlier observation made by NASA's Spitzer Space Telescope in 2007 that water molecules are present in the planet's atmosphere. "With this observation there is no question whether there is water or not - water is present," said Swain.
Swain's co-authors on the paper include Gautam Vasisht of JPL and Giovanna Tinetti of University College, London.