Here we advocate an observational strategy to help prioritize exoplanet observations. It starts with more easily obtained observational data, and ranks exoplanets for more difficult follow-up observations based on the likelihood of avoiding planets for which oxygen is a false positives or even an inconclusive signature of life. We find that for oxygen to be a robust biosignature, both land and surface water must be present. Landless exoplanets have much slower biogeochemical cycles, so while oxygenic photosynthesizing life could exist on such planets, it could not produce oxygen at a rate competitive with abiotic rates such as photolysis. These habitable planets, whose life would not be detectable, should be avoided.
@article{arxiv.1801.06935,
title = {A procedure for observing rocky exoplanets to maximize the likelihood that atmospheric oxygen will be a biosignature},
author = {Steven J. Desch and Stephen Kane and Carey M. Lisse and Cayman T. Unterborn and Hilairy E. Hartnett and Sang-Heon Shim},
journal= {arXiv preprint arXiv:1801.06935},
year = {2018}
}
Comments
6 pages, 1 figure, white paper submitted in response to the solicitation of feedback for the "Astrobiology Science Strategy for the Search for Life in the Universe" by the National Academy of Sciences