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G. Tinetti (JPL/USC), V. S. Meadows (JPL/Caltech), D. Crisp (JPL), W. Fong (Caltech), H. Snively (UCSC), T. Velusamy (JPL)
The principal goal of the NASA Terrestrial Planet Finder (TPF) mission is to detect and characterize extrasolar terrestrial planets. However, the first generation of instruments for studying extrasolar planets are expected to provide only disk-averaged spectra with modest spectral resolution and signal to noise. As a part of the NASA Astrobiology Institute's Virtual Planetary Laboratory (VPL, V. Meadows, PI) we are exploring what can be learned about a planet's surface and atmospheric properties from disk-averaged spectra at a number of spectral resolutions at visible and IR wavelengths. We are using a spectrum resolving (line-by-line) atmospheric/surface radiative transfer model (SMART, D. Crisp) and atmospheric and surface data for Earth, Mars, Venus and Titan to generate a database of spatially resolved synthetic spectra for a range of illumination conditions (phase angles) and viewing geometries. These results are then processed with a model that resamples the spatially resolved spectra to create a synthetic, disk-averaged view of the planet from a specific viewing geometry. To validate these methods, we have compared observational data with our synthetic spectra of Mars and Earth. We will present a complete study of Mars, and the first results for Earth, including disk-averaged synthetic spectra, images and the spectral variability at visible and mid-IR wavelengths as a function of viewing angle. We have also simulated an increasingly frozen Mars, and have studied the detectability of CO2 ice in the disk averaged spectrum, using a TPF instrument simulator. We have determined that surface CO2 ice can be spectrally identified in a TPF mid-IR spectrum of a disk-averaged Mars, even at low resolution, if the ice cap extends down to at least 50 degrees latitude from the pole.
This work is supported by the NASA Astrobiology Institute.
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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, 35 #4
© 2003. The American Astronomical Soceity.