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Earth as an extrasolar planet: Earth model validation using EPOXI earth observations
Tyler D Robinson1, Victoria S Meadows, David Crisp
1University of Washington Astronomy Department , Seattle, USA.
Astrobiology
|June 3, 2011
Summary
This study validates an Earth spectral model using EPOXI mission data, improving simulations for detecting exoplanet characteristics. The enhanced model accurately reproduces Earth's lightcurves and spectra, aiding in the search for habitable exoplanets.
Area of Science:
- Planetary science and astrobiology.
- Remote sensing and radiative transfer modeling.
Background:
- Understanding exoplanet characteristics relies on validating Earth-based models.
- The Virtual Planetary Laboratory (VPL) spectral Earth model requires refinement.
Purpose of the Study:
- To validate and improve the VPL's 3D spectral Earth model using EPOXI mission data.
- To enhance simulations of Earth's observable properties for exoplanet studies.
Main Methods:
- Reused EPOXI spacecraft data for Earth observations (visible photometry, NIR spectroscopy).
- Upgraded the VPL spectral Earth model with ocean reflectance and atmospheric effects (Rayleigh scattering, gas absorption).
- Generated synthetic spectra and images, optimizing model parameters against observational data.
Main Results:
- The validated model achieved <3% RMS error for lightcurves and ~10% residuals for absolute brightness (visible/NIR).
- Model validation extended to mid-infrared using AIRS data, yielding ~7% residuals and <1K brightness temperature errors.
- Minimum spatial resolution of ~100 pixels and four cloud categories were necessary for acceptable fits.
Conclusions:
- The validated forward model accurately simulates Earth's time-dependent brightness and spectral properties (UV to FIR).
- This model is crucial for understanding remotely detectable extrasolar planet characteristics and assessing habitability.
- The study provides a robust tool for simulating Earth as an exoplanet analog.
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