On the abundance of extraterrestrial life after the Kepler mission

TL;DR

This paper uses Kepler data and Drake equation formalism to estimate the abundance and detectability of extraterrestrial life and civilizations within our galaxy, highlighting the potential for future spectral observations and SETI efforts.

Contribution

It introduces a method to estimate the distance to extraterrestrial biotic and intelligent civilizations based on Kepler data and Drake parameters, incorporating spectral observations and SETI detection probabilities.

Findings

Biotic planets may be within 10-100 light years if Fb is between 0.001 and 1.

Likely distance to detectable civilizations is a few thousand light years under optimistic assumptions.

Detection probability depends on Drake parameters and can constrain their values.

Abstract

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, Fb. I suggest that Fb may be estimated by future spectral observations of exoplanet biomarkers. If Fb 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, Fc, and its average longevity. For instance, assuming optimistic probability values (Fb Fc 1) and a broadcasting longevity of a few thousand years, the likely distance to the nearest civilizations detectable by SETI 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.