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Space Sci Rev DOI 10.1007/s11214-007-9281-4

Summary: Space Sci Rev
DOI 10.1007/s11214-007-9281-4
Earthshine Observation of Vegetation and Implication
for Life Detection on Other Planets
A Review of 20012006 Works
Luc Arnold
Received: 23 February 2007 / Accepted: 19 September 2007
Springer Science+Business Media B.V. 2007
Abstract The detection of exolife is one of the goals of very ambitious future space mis-
sions that aim to take direct images of Earth-like planets. While associations of simple mole-
cules present in the planet's atmosphere (O2, O3, CO2, etc.) have been identified as possible
global biomarkers, this paper reviews the detectability of a signature of life from the planet's
surface, i.e. the green vegetation. The vegetation reflectance has indeed a specific spectrum,
with a sharp edge around 700 nm, known as the "Vegetation Red Edge" (VRE). Moreover,
vegetation covers a large surface of emerged lands, from tropical evergreen forest to shrub
tundra. Thus, considering vegetation as a potential global biomarker is relevant.
Earthshine allows us to observe the Earth as a distant planet, i.e. without spatial reso-
lution. Since 2001, Earthshine observations have been used by several authors to test and
quantify the detectability of the VRE in the Earth spectrum. The vegetation spectral signa-
ture is detected as a small "positive shift" of a few percentage points above the continuum,


Source: Arnold, Luc - Observatoire de Haute-Provence


Collections: Physics