Terrestrial Planet Optical Phase Curves. I. Direct Measurements of the Earth
Roderick De Cock (Student TU Delft)
Timothy A. Livengood (JPL, University of Maryland)
D. Stam (Astrodynamics & Space Missions)
Carey M. Lisse (Johns Hopkins University)
Tilak Hewagama (JPL)
L. Drake Deming (University of Maryland, Virtual Planetary Laboratory)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
NASA's EPOXI mission used the Deep Impact spacecraft to observe the disk-integrated Earth as an analog to terrestial exoplanets' appearance. The mission took five 24 hr observations in 2008-2009 at various phase angles (57. 7-86. 4) and ranges (0.11-0.34 au), of which three equatorial (E1, E4, E5) and two polar (P1, North and P2, South). The visible data taken by the HRIV instrument ranges from 0.3 to 1.0 μm, taken trough seven spectral filters that have spectral widths of about 100 nm, and which are centered about 100 nm apart, from 350 to 950 nm. The disk-integrated, 24 hr averaged signal is used in a phase angle analysis. A Lambertian-reflecting, spherical planet model is used to estimate geometric albedo for every observation and wavelength. The geometric albedos range from 0.143 (E1, 950 nm) to 0.353 (P2, 350 nm) and show wavelength dependence. The equatorial observations have similar values, while the polar observations have higher values due to the ice in view. Therefore, equatorial observations can be predicted for other phase angles, but (Earth-like) polar views (with ice) would be underestimated.
help_outline