Related papers: The Imprecise Search for Habitability
The existence of intelligent extraterrestrial life forms among the thousands of billions of galaxies that dance in the Universe is beyond doubt. Meeting with one of them is only a matter of time. SETI (Search for Extraterrestrial…
Surprisingly, the question "Is there Life in the Universe outside Earth?" has been raised, in rational terms, almost only in the western literature throughout the ages. In a first part I justify this statement. Then I try to develop an…
We use a probability theory framework to discuss the search for biosignatures. This perspective allows us to analyse the potential for different biosignatures to provide convincing evidence of extraterrestrial life and to formalise…
We have found many Earth-sized worlds but we have no way of determining if their surfaces are Earth-like. This makes it impossible to quantitatively compare habitability, and pretending we can risks damaging the field.
In their recent comment, Cockell et al. argue that the habitability of an environment is fundamentally a binary property; that is to say, an environment can either support the metabolic processes of a given organism or not. The habitability…
Context. Astrobiological evolution of the Milky Way (or the shape of its "astrobiological landscape") has emerged as one of the key research topics in recent years. In order to build precise, quantitative models of the Galactic…
In this paper we discuss and illustrate the hypothesis that life substantially alters the state of a planetary environment and therefore, modifies the limits of the HZ as estimated for an uninhabited planet. This hypothesis lead to the…
When we try to search for extraterrestrial life and intelligence, we have to follow some guidelines. The first step is to clarify what is to be meant by "Life" and "intelligence", i.e. an attempt to define these words. The word "definition"…
Earth is the only planet known to harbor life and, as a result, the search for habitable and inhabited planets beyond the Solar System commonly focuses on analogs to our planet. However, Earth's atmosphere and surface environment have…
As the only known habitable (and inhabited) planet in the universe, Earth informs our search for life elsewhere. Future telescopes like the Habitable Worlds Observatory (HWO) will soon look for life on rocky worlds around Sun-like stars, so…
A habitable zone of a star is defined as a range of orbits within which a rocky planet can support liquid water on its surface. The most intriguing question driving the search for habitable planets is whether they host life. But is the age…
The Habitable Worlds Observatory (HWO) aims to telescopically constrain the frequency and abundance of biospheres in the solar neighborhood. Origin-of-life theories vary in their predictions for the environmental requirements and the…
One of the major goals for astronomy in the next decades is the remote search for biosignatures (i.e.\ the spectroscopic evidence of biological activity) in exoplanets. Here, we adopt a Bayesian statistical framework to discuss the…
The search for a second instance of life is one of the greatest problems of modern science. Outside of creating an artificial origin of life on Earth, the primary targets for the search for life are planets inside or outside the solar…
Since the launch of Kepler and Hubble more than a decade ago, we have come a long way in the quest to find a potentially habitable exoplanet. To date, we have already discovered more than 4000 exoplanets most of which are not suitable for…
Future telescopes will survey temperate, terrestrial exoplanets to estimate the frequency of habitable ($\eta_{\text{Hab}}$) or inhabited ($\eta_{\text{Life}}$) planets. This study aims to determine the minimum number of planets ($N$)…
The concept of the Circumstellar Habitable Zone has served the scientific community well for some decades. It slips easily off the tongue, and it would be hard to replace. Recently, however, several workers have postulated types of…
The field of astrobiology has made huge strides in understanding the habitable zones around stars (Stellar Habitable Zones) where life can begin, sustain its existence and evolve into complex forms. A few studies have extended this idea by…
In this paper we discuss how we can read a planets spectrum to assess its habitability and search for the signatures of a biosphere. After a decade rich in giant exoplanet detections, observation techniques have now reached the ability to…
The discovery of a biosphere on another planet would transform how we view ourselves, and our planet Earth, in relation to the rest of the cosmos. We now know Earth is one planet among eight circling our sun; our sun is part of a swirling…