From Panspermia to bioastronomy, the evolution of the hypothesis of universal life

Abstract

During the 19th and early 20th centuries, ideas related to the possible origin in space of bioorganic molecules, or seeds, or even germs and organisms (and how they reached the Earth) included the Panspermia theory. Based on the idea of the eternity of life proposed by eminent physicists - such as Arrhenius and Kelvin - 'Panspermia' is mainly divided into two branches: lithopanspermia (transport of germs inside stones travelling in space) and radiopanspermia (transport of spores by radiative pressure of stellar light). We point out some arguments to help to understand whether 'Panspermia' could exist nowadays as the same theory defined one century ago. And we wonder about the kind of evolution 'Panspermia' could have undergone during only a few decades. This possible evolution of the 'Panspermia' concept takes place in the framework of the emergence of a new field, Bioastronomy. We present how this discipline has emerged during a few decades a how it has evolved. We consider its relationship with the progression of other scientific fields, and finally we examine how it is now included in different projects of space agencies. Bioastronomy researches having become more and more robust during the last few years, we emphasize several questions about new ideas and their consequences for the current hypothesis of 'Panspermia' and of universal life.