New Technique Can Identify Molecules on Exoplanets

Researchers at the American space agency NASA have recently announced that they managed to create a new method of using modest, ground-based telescopes for producing amazing new science. The technique was just recently used on an exoplanet some 63 light-years away, with the 30-year-old, 3-meter-diameter (10-foot) NASA Infrared Telescope Facility, atop Mauna Kea, in Hawaii. The method makes it easy to identify specific molecules in the atmosphere of exoplanets, as evidenced by the fact that the small telescope was able to find an organic molecule around the Jupiter-size planet it observed. “The fact that we have used a relatively small, ground-based telescope is exciting because it implies that the largest telescopes on the ground, using this technique, may be able to characterize terrestrial exoplanet targets,” says Mark Swain, the leader of the new investigation, and a scientist at the NASA Jet Propulsion Laboratory (JPL), in Pasadena, California. Details of this work appear in the February 3 issue of the esteemed scientific journal Nature. Swain was lead author of the paper. “Given favorable observing conditions, this work suggests we may be able to detect organic molecules in the atmospheres of terrestrial planets with existing instruments,” he adds, stating that the ITF is ranked only 40th in a top of the world's ground-based telescopes, which carries considerable implications for the possibilities offered by the other 39 larger facilities. The data collected with the ITF provided new info on the exoplanet's atmospheric composition and conditions, something that has never before been achieved using a telescope on the ground. The organic molecules detected around the planet HD189733b belonged to methane and carbon, the JPL team reports. Such a discovery was made possible through the use of a new calibration method that is capable or removing systematic observation errors from the picture. These errors are produced as light coming from the target passes through our planet's atmosphere. Further mistakes get passed on as the telescope moves during observations, in tune with the planet's motion. “As a consequence of this work, we now have the exciting prospect that other suitably equipped yet relatively small ground-based telescopes should be capable of characterizing exoplanets. On some days we can't even see the sun with the telescope, and the fact that on other days we can now obtain a spectrum of an exoplanet 63 light-years away is astonishing,” concludes ITF support scientist John Rayner. He is also the NASA expert who built the SpeX spectrograph, the instrument used for the new measurements.