Scientific Seminars

The New Worlds Observer: An Approach to Direct Observation of Exo-Planets

Webster Cash
University of Colorado, USA

2005-06-08    14:30    Merate -

The New Worlds Observer has just completed a study under the auspices of the NASA Institute for Advanced Concepts. The concept employs a starshade - a spacecraft that separates planet light from starlight before it enters the telescope, thereby sidestepping the nearly insuperable problems of scattered light. The starshade can be either a large pinhole camera, or an obscuring disk. To achieve the necessary resolution of 0.1 arcseconds, so that Earth-like planets may be seen at 10pc, the scale of the starshade must be many meters and the separation between the two spacecraft must be tens of thousands of kilometers. Occulting spacecraft have been considered before because an aperture is a perfect lens, introducing no wavefront distortion or non-uniformity. But they have never been developed because of the problem of diffraction. We showed in our study that an extension of the shaped pupil mathematics developed by Vanderbei, Kasdin and Spergel can solve this problem cleanly. Diffraction can be controlled over a large area of space and over a broad bandpass, allowing sensitive observation from the ultraviolet to the infrared. Planetary systems can be explored at the rate of one per week. Planets like the Earth can be seen in a matter of minutes and within a few hours system features as small as Halley's Comet can be detected. Spectroscopic observations can then identify planets with oceans and free oxygen. The New Worlds Observer could enable high quality direct studies of our neighboring star systems at a small fraction of the cost and risk associated with other approaches to the problem.