The EPOXI View of Earth

The EPOXI View of Earth Nick Cowan (University of Washington) KITP (May 18, 2010)

“Habitable” Planets Nick Cowan's Talk at ESMSSP

Looking for Water } Daily Variability • Water in atmosphere? • H2O vapor • Variable cloud cover • Water on surface? • Color of oceans • Glint of oceans • Polarization from oceans Long-Exposure Spectroscopy } Yearly Variability Nick Cowan's Talk at ESMSSP

NWO, THEIA, TPF/Darwin, etc.(n+1 decades from now) Long-Exposure Spectroscopy Time-Resolved Photometry (Simulated image from Oakley & Cash 2009) Nick Cowan's Talk at ESMSSP

Orbital & Rotational Variability flux Oakley & Cash (2009) time • Will not know A0 (degenerate with Rp) • Will measure A(t)/A0 and A()/A0 Nick Cowan's Talk at ESMSSP

EPOXI (PI: A'Hearn)~Deep Impact Part II EPOCh (PI: Deming) • Observe known exoplanets • Observe Earth as an exoplanet Nick Cowan's Talk at ESMSSP

EPOXI Light Curves Nick Cowan's Talk at ESMSSP

EPOXI Light Curves Cowan et al. (2009) Nick Cowan's Talk at ESMSSP

Backward Modeling v.s. Forward Modeling Simple Model Data Starved Assumptions Data Parameters Sophisticated Simulation Data Rich Nick Cowan's Talk at ESMSSP

Forward (Predictive) Modeling Nick Cowan's Talk at ESMSSP

RMSE = 1.9% Data RMSE = 2.3% Model time March 19th, 2008 (Robinson et al. 2010) RMSE = 2.0% RMSE = 1.6%

RMSE = 1.9% Data RMSE = 2.3% Model time March 19th, 2008 RMSE = 2.0% RMSE = 1.6%

RMSE = 2.8% Data RMSE = 3.5% Model time June 5th, 2008 (Robinson et al. 2010) RMSE = 3.7% RMSE = 3.7%

RMSE = 2.8% Data RMSE = 3.5% Model time June 5th, 2008 RMSE = 3.7% RMSE = 3.7%

Backward (Interpretive) Modeling Nick Cowan's Talk at ESMSSP

Time-Averaged Spectrum 1) Clouds are plentiful and bright Can we learn about planetary surface despite them? Cowan et al. (2009) Nick Cowan's Talk at ESMSSP

Principal Component Analysis C2 C1 <C> Fb Fa Nick Cowan's Talk at ESMSSP

Eigencolors Cowan et al. (2009) Nick Cowan's Talk at ESMSSP

Earth from Above Cowan et al. (in prep) Nick Cowan's Talk at ESMSSP

Northern Eigencolors Cowan et al. (in prep) Nick Cowan's Talk at ESMSSP

Earth from Below Cowan et al. (in prep) Nick Cowan's Talk at ESMSSP

Southern Eigencolors Cowan et al. (in prep) Nick Cowan's Talk at ESMSSP

Reflected Light Diffuse (Lambert) Reflection Specular (Shiny) Reflection Nick Cowan's Talk at ESMSSP

Specular Reflection (it’s small) Williams & Gaidos (2008) Nick Cowan's Talk at ESMSSP

Equatorial Map Cowan et al. (2009) Nick Cowan's Talk at ESMSSP

A Different Kind of Map Simulated white light curve of Earth with real cloud cover 2) Can’t recover major landforms Oakley & Cash (2009) Nick Cowan's Talk at ESMSSP

Conclusion Time-Resolved, Multi-Band PhotometryComplements Time-Averaged Spectroscopy From VPL Nick Cowan's Talk at ESMSSP

The EPOXI View of Earth