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On the abundance of extraterrestrial life after the Kepler mission

  • Amri Wandel (a1)

The data recently accumulated by the Kepler mission have demonstrated that small planets are quite common and that a significant fraction of all stars may have an Earth-like planet within their habitable zone. These results are combined with a Drake-equation formalism to derive the space density of biotic planets as a function of the relatively modest uncertainty in the astronomical data and of the (yet unknown) probability for the evolution of biotic life, F b. I suggest that F b may be estimated by future spectral observations of exoplanet biomarkers. If F b is in the range 0.001–1, then a biotic planet may be expected within 10–100 light years from Earth. Extending the biotic results to advanced life I derive expressions for the distance to putative civilizations in terms of two additional Drake parameters – the probability for evolution of a civilization, F c, and its average longevity. For instance, assuming optimistic probability values (F b~F c~1) and a broadcasting longevity of a few thousand years, the likely distance to the nearest civilizations detectable by searching for intelligent electromagnetic signals is of the order of a few thousand light years. The probability of detecting intelligent signals with present and future radio telescopes is calculated as a function of the Drake parameters. Finally, I describe how the detection of intelligent signals would constrain the Drake parameters.

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International Journal of Astrobiology
  • ISSN: 1473-5504
  • EISSN: 1475-3006
  • URL: /core/journals/international-journal-of-astrobiology
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