Speaker
Description
The search for signs of life on other worlds is an exciting and now key component of exoplanet science. In the exoplanet context, biosignatures are potentially-detectable impacts of life on a global planetary environment. Biosignatures may include identified and sought after molecules in a planetary atmosphere, reflectivity signals on its surface, or the characteristic variation of these or other characteristics as a function of time. Biosignatures may also be “agnostic”, meaning that they are not associated with a known or postulated metabolism, thereby allowing us to search for unknown forms of life. Agnostic biosignatures consist of anomalous patterns or molecules that are unlikely to be generated by abiotic planetary processess. All biosignatures, and particularly agnostic biosignatures, must be interpreted in the context of their planetary environment. This context can provide additional information to help rule out biosignature “false positives” where instead of being generated by life, a sought after environmental characteristic is instead generated by abiotic processes like volcanism and photochemistry. In the near-term, the search for life on exoplanets will focus exclusively on M dwarf exoplanets, which, due to the coevolution with their star, may undergo a very different evolutionary path than our own Earth. These searches will be undertaken using low-medium resolution transmission spectroscopy with JWST, and high-resolution transmission and reflected light spectroscopy with ground-based telescopes. In the longer term, a large-aperture space-based telescope will use direct imaging techniques to obtain reflected light from planets orbiting a broader swath of host stars, including the more “Sun-like” FGK dwarfs. This will expand our search for life in the universe to planetary systems that are more analogous to our own. In this talk I will introduce the field of biosignatures, and describe the potential capabilities for biosignature searches using high-resolution spectroscopy with ground-based telescopes, placing these opportunities in the context of what might be possible with space-based telescopes over the next two decades.
