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G. Tinetti (NAI-NRC/Caltech), V. S. Meadows (IPAC/JPL), D. Crisp (JPL), W. Fong (Caltech), T. Velusamy (JPL), M. Allen (JPL/Caltech)
NASA and ESA are currently studying mission concepts for space-based observatories to search for and characterize extrasolar terrestrial planets. Any planet directly detected by this first generation of space-missions will be resolved only as point sources. Basic information can be gleaned from the object's distance from the star and its apparent brightness, but the presence of a planetary atmosphere of unknown composition will complicate the determination of planetary properties. Disk-averaged spectroscopy will be our best tool for discriminating between Jovian/Terrestrial planets, and between Terrestrial planets of different types.
We simulate spectrally-dependent light-curves and disk-averaged spectra of a plausible range of extrasolar terrestrial planets to determine the detectability of biosignatures by proposed space-based observatories. The core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model (SMART by D.Crisp), used to generate a database of synthetic spectra for a variety of atmospheric/surface properties, viewing angles, illuminations and cloud coverage. To simulate a wider range of terrestrial planets than those found in our system SMART can be coupled to a versatile climate model (G. Tinetti and D. Crisp) and a chemistry model, (Kinetics, by M. Allen and Y. Yung).
Our model generates a variety of products including disk-averaged synthetic spectra, light-curves and the spectral variability at visible and IR wavelengths as a function of viewing angle. These results can be processed with an instrument simulator to improve our understanding of the detectable characteristics as viewed by the first generation extrasolar terrestrial planet detection and characterization missions.
These tools were used to simulate an increasingly frozen Mars, an increasingly cloudy/forested/oceanic/tilted/eccentric-orbit Earth-like planet, and to determine the detectability of biosignatures (e.g. red-edge signal). The Earth-model was validated against disk-averaged observations of the Earth by the Mars Global Surveyor-TES and Earth-shine spectra; the Mars-model was validated against spectra recorded by Mariner 9-IRIS.
If you would like more information about this abstract, please follow the link to http://spider.ipac.caltech.edu/staff/tinetti/mypage.html. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.
The author(s) of this abstract have provided an email address for comments about the abstract: tinetti@ipac.caltech.edu
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.