Title: Detecting bio-signatures of the Earth, as if it was an Exoplanet: Building a snapshot full-stokes spectropolarimeter to search for life on Earth

Speaker: Willeke Mulder, Leiden Observatory

Are we alone? The search for life outside Earth is a driving force for (exo)planetary research. Numerical simulations confirm the possibility of being able to distinguish between different surface types as well as molecules in atmospheres, by looking at the reflected flux from their host stars. Linear spectropolarimetry proves to be an even more effective tool to identify structures of different surfaces. In  addition to this, homochirality is the one unambiguous bio-signature of life on Earth that can be identified by measuring the fraction of reflected circular polarized light. To  detect extraterrestrial life, either on solar-system planets and/or moons or on exoplanets, we need highly dedicated instruments as well as data analysis algorithms. Spectropolarimeters help us to understand the sensitivity that is required to identify bio-signatures. In this colloquim, I will introduce you to the search of bio-signatures  on our own Earth, as a testbed to search for life elsewhere. I will go through the measurement  concepts of existing spectropolarimeters, present results from our succesfull field campaign in Switzerland, and end of with a concept space-based instrument designed to measure polarization signals, in the visible spectrum, from the Earth as if it were an exoplanet.