Is the exoplanet Kepler-452 b, located at fourteen hundred light years from Earth -potentially habitable? At what other places of the Universe can the phenomenon of life have taken place? All these questions on life research inside and outside the Solar System are the thread of the journey in the book "(In)habitabilidad planetaria. Fundamentos de astrobiogeología" (Ed. Marcombo). Andrea Butturini, lecturer from the Department of Evolutionary Biology, Ecology and Environmental Sciences of the Faculty of Biology of the University of Barcelona, is the coordinator of the book and Daniel García-Castellanos, researcher at ICTJA-CSIC, is one of the co-authors of the book.
Other participants in this book, which reminds us the importance of taking the phenomenon of life into the view of the science of the Universe, are the experts Carme Jordi, from the Faculty of Physics and the Institute of Cosmos Sciences of the UB (ICCUB) and the Institute of Space Studies of Catalonia (IEEC), Jordi Urmeneta, from the Faculty of Biology and the Biodiversity Research Institute (IRBio) of the UB; and Ignasi Ribas, from IEEC and the Institute of Space Sciences (ICE-CSIC).
Between the Earth and the stars: searching for alien life
The discovery of other lives far from the planet Earth would be a total scientific and intellectual revolution in our perception of nature and the Universe. “Life could have taken place in other places and times, but what we know about is that it took place and evolved here, in our planet Earth”, notes the emeritus professor of the UB Ricard Guerrero, in the prologue of the book. “And it did so because there was cooperation between the first inhabitants, instead of competition”, he adds.
With a multidisciplinary perspective, the book highlights the values of the astrobiogeology as a meeting point for several disciplines that take part in the debate on accepted paradigms and the most speculative speech. “It is a research field with an enormous growth. It is obvious that its development depends on technology and investments that only a few entities and countries can make, and which usually make consortiums to optimize resources”, says Andrea Butturini, lecturer at the Department of Evolutionary Biology, Ecology and Environmental Sciences of the UB.
“The most crucial aspect of astrobiogeology –he continues–, is that it feeds from the interaction between physics, chemistry, geology and biology, a mix that is promoting the development of scientific works in which many researchers are involved, not necessarily linked to the research institutes in Space Sciences. This scientific literature has a speculative component –which is very attractive from an academic and didactic perspective–, which would be great to introduce in the university studies and promote the union of all these disciplines”.
Butturini had the idea to write the book after verifying the interest the general public had for astrobiology. Butturini recalls the success of a workshop devoted to the astrobiology which was held in the Faculty of Biology in 2015: "There were more than 300 attendants. I had never seen such a crowded auditorium. Years later, there are students who ask me if we would repeat it someday".
Are we alone in the Universe?: a revolution in how we see the Universe
According to Ignasi Ribas, director of the Institute of Space Studies of Catalonia (IEEC) and researcher at the Institute of Space Sciences (ICE-CSIC), “setting the context in which the life takes place in the Universe represents one of the biggest challenges of science for the next decades. In order to reach this objective, it is essential to have a multidisciplinlary approach since the many intervening factors cover knowledge areas that are traditionally separated from each other”.
The researcher also notes that “this approach combining astrophysics, biology, and geology –all them to the extreme–, will have to allow us to respond to one of the big questions, not only in science but in humanity: are we alone in the Universe? The transcendence of its answer will involve a new revolution”.
Through this journey along the human knowledge in the Cosmos, “we look for the signals of life existence left by an exoplanet in its atmosphere. In order to find the chemical composition and thermal structure of the atmospheres we use the spectroscopy, and we take measurements in the moment when the planet passes in front of the star”, notes Professor Carme Jordi, from the Department of Quantum Physics and Astrophysics of the Faculty of Physics of the UB.
“The study of the exoplanet atmospheres is one of the scientific objectives of the future space telescope from the NASA and the European Space Agency, James Web, using infrared-spectroscopy. The next ESA ARIEL mission is the first to be exclusively dedicated to the same aim, and covering a wide range of exoplanets, in this case to be studied with optical ear infrared-spectroscopy”, adds Carme Jordi, also member of ICCUB, IEEC and the scientific team of the ESA Gaia Mission.
"Life has been a crucial element in shaping the geochemistry of the Earth, because it allowed high O2 levels, without which many of the minerals that are present in the Earth's crust would not have been that plentiful"
Geology of the Earth and exoplanets
In order to study and model the geological processes that occurs beyond the Earth, "we apply everything we've learnt about our planet", notes Daniel García-Castellanos. The exploration and the discovery of new planets in other solar systems are an excellent opportunity to contrast what we think we know about the Earth, whose processes repeat frequently. Moreover, simulating these processes we're able to predict better the sceneries of a future mission to a planet or a moon of our Solar System".
The Earth is the most and better known case of planetary geodynamics. As the discoveries of exoplanets grows exponentially and the exploration of the planets of the Solar System progresses, two exciting opportunities appear: first, we are able to better estimate the sceneries that a future exploration will possibly find. Second, we have the opportunity to test in other planetary environments the models that have been building over the last centuries about Earth's evolution.", said García-Castellanos.
The erosion caused by the liquid water was essential in regulating the terrestrial climate so there could be life. “Does this mean there cannot be life without a water cycle similar to ours? We also know that the terrestrial magnetic field stopped the volatile loss of our atmosphere, including water. Could we predict, with what we learnt about the Earth, whether a faraway exoplanet has its well-developed magnetic field, before visiting it?”
García-Castellanos highlights the potential relevance that life may have had on the geodynamical evolution of a planet, signaling the Earth as a case of study. "Life has been a crucial element in shaping the geochemistry of the Earth, because it allowed high O2 levels, without which many of the minerals that are present in the Earth's crust would not have been that plentiful", said García-Castellanos.
Living matter: behind the hints of extreme life in the Cosmos
The study of microorganisms that live in extreme environments changed the way of considering the possibility of life presence in other places in space. The books sheds light on the research of life in Cosmos and it offers alternative situations on the potential alien biospheres.
“It has been found that life is tenacious and that it appears wherever it is possible in our planet, even in places where, due to the apparently inhospitable conditions, it seemed impossible. This led us to think there could be many extra-terrestrial environments where life could have taken place”, notes Jordi Urmeneta, lecturer at the Department of Genetics, Microbiology and Statistics of the Faculty of Biology and the Biodiversity Research Instiute (IRBio) of the UB.
As a direct invitation to speculative thinking, the book leaves room for doubt in a context in which the object of study in astrobiogeology -alien life- is absent. “Perhaps the day we detect its existence, astrobiogeologu will step into a more orthodox phase, and the speculative side will lose its relevance”, note the authors.
Butturini, A., García-Castellanos, D., Jordi, C., Ribas, I., Urmeneta, J. (2020). (In)Habitabilidad planetaria. Fundamentos de astrogeobiología. Marcombo, Barcelona. 314 p. ISBN: 9788426728340
This text has been adapted from the materials provided by Universitat de Barcelona