A TEST FOR THE DETECTABILITY OF VEGETATION ON EXTRASOLAR PLANETS: OBSERVING THE TERRESTRIAL VEGETATION IN THE EARTHSHINE SPECTRUM

摘要

The search for life on extrasolar planets can be made either indirectly by the detection of by-products of biological activity, such as oxygen and methane, or directly by "vegetation-like" spectral features. They should both be associated with detection of water, assumed to be a prerequisit for the development of life. After a review of the compared advantages and disadvantages of both approaches (artefacts, universality, etc), we focus on a test of the detectability of vegetation on Earth seen as a single dot: the detection of vegetation in the spectrum of the global Earth on the lunar surface, or Earthshine. We review the first results obtained by different groups, new ongoing observations and future plans.