Astrobiology is a rapidly evolving field of study. One major development has been a wealth of Exoplanet observations that inform the probability of forming earth-like planets in a habitable zone, while another has been the potential for life to occur well outside of traditional habitable zones under the surfaces of ice-covered moons, such as Europa and Enceladus.
The dynamics of bodies in evolving planetary systems result in planet growth, the delivery of water and organics to favourable environments and planetary migration, moon formation and planetary destruction, all of which have significant consequences for the development and sustainability of life. Formation of the organic constituents of biological systems in pre-solar clouds, in the proto-solar nebula or in planetary environments are essential steps on the path to life where significant new knowledge has emerged over the past decade.
The evolution of more complex life, and the emergence of intelligence, may require environmental extremes such as those resulting from asteroidal and cometary impacts, as well as from more prolonged events such as ice ages or massive, global-scale volcanism.
Astrobiology 2020 will trace the pathway to life on Earth and beyond from the simple chemistry established in astrophysical environments, through the formation of planetary systems, to beyond the beginnings of life as informed by studies of the very earliest terrestrial fossil record, taking into account the latest advances in all of these areas.
Scientific sessions and session chairs / keynote speakers
Chemistry in Molecular Clouds and in Proto-Planetary Nebulae
Maria Drozdovskaya (Switzerland)
Are the basic building blocks of Life established in the cores of Giant Molecular Clouds before a star begins to form? What chemical processes occur during cloud collapse? How does the chemical composition of a stellar nebula evolve during planet formation and as a function of the mass of the central star? Is the chemistry in each forming stellar system unique or do the same basic chemical processes play out in every stellar system in our galaxy? These are some of the basic questions that will be addressed during this session from the perspective of observations, laboratory experiments and/or modelling.
Formation and Evolution of Planetary Systems: Our Earth in the Exoplanetary Context
Daniel Apai (US)
Planetary systems are observed to span an extremely wide range of morphologies compared to our own Solar System. Jupiter-scale planets orbit central stars in days at distances measured in stellar radii. Earth-scale planets orbit millisecond pulsars. Multiple Earth-scale planets orbit within the Habitable Zones of their central stars. Almost all stars have planets. This session will focus on understanding the processes that produce planets and build the wide variety of planetary systems observed today in order to put the one planet, Earth, known to harbor Life into context. Contributions to understand these processes and their outcomes are welcome.
Impacts and their role in the evolution of life
Philippe Claeys (Belgium)
Earth has been subjected to asteroid and cometary impacts throughout its history, as have all bodies in our Solar System. If an impact does not destroy the target, then how do the multiple environmental stresses effect extant Life? This session will examine the terrestrial record to understand the magnitude of the stresses induced by impacts and the response of the terrestrial ecosystem to such stresses. We welcome contributions to address the many questions in this area such as; what are the characteristics of robust lifeforms? How do ecosystems respond after massive extinction events? Are extreme stresses required to force the evolution of more advanced lifeforms?
Early Earth (interactions between the lithosphere, atmosphere, ocean & microbial world)
Axel Hofmann, Nic Beukes (South Africa), Jana Meixnerova (USA)
The Earth surface has seen tremendous changes through time. Cooling of the Earth interior, secular changes in tectonic processes and the composition of the lithosphere, the evolution of the atmosphere and hydrosphere, and the appearance and radiation of life all left their imprint in the geological record. This session invites contributions that address the co-evolution of life with Earth’s surface environments over geologic time.
It investigates the geochemical, mineralogical, environmental and biological evolution of the Earth’s surface and immediate subsurface from its oldest volcanic and sedimentary record.
When (and How) Does Life Arise?
Kamilla Muchowska (France)
Before we can address the question of the Origin of Life, we must first agree on what distinguishes life from sets of repeated chemical reactions. The most primitive of today’s terrestrial lifeforms are extremely sophisticated compared to the original organisms that must have depended upon environmental factors to perform some of their most basic metabolic functions. Are there multiple pathways to life or only one? Contributions are solicited to define the most basic functions of life, where (and when) conditions that support such functions exist in nascent planetary environments, and how might some set of chemical reactions incorporate natural environmental processes to become living organisms.
Early Traces of Life; Co-evolution of Earth and Life during the Archaean
Emmanuelle Javaux (Belgium)
This session will examine the earliest fossil record to explore the relationships between life and the local environment. Changes in salinity, temperature, pH and solar insolation, among many other factors drive life to evolve or push it to extinction. The Archaean saw the development of multicellular lifeforms from single celled organisms, including a wide range of biological innovations that preceded and enabled this development. Contributions that address the relation of new biological innovations that enabled the development of more complex lifeforms to the changing environmental conditions throughout the Archaean or that examine the effects of life on the Archaean environment are welcome.
Extremophiles and Extreme Environments
Donald Cowan (South Africa), Ricardo Amils (Spain)
The session on Extremophiles and Extreme Environments aims to bring together a diversity of research on the diversity, functionality, adaptation and survival of microorganisms in a range of extreme environments, including those dominated by high and low temperatures, extremes of pH and salinity, extreme oligotrophy, high pressure and high radiation fluxes.
Such studies all contribute to defining the 'biological envelope', a critical parameter in the potential identification of habitable planets in the Solar System and the Universe.
Exoplanets and the Habitable Zone: What Makes a Planet Habitable?
Michel Mayor (Switzerland)
The Habitable Zone was initially defined as the range of planetary orbits where liquid water is stable on planetary surfaces. The parameters of the Habitable Zone depends on the type of the central star and the atmospheres of the planets. Habitable Zones for binary and triple star systems can be much more complex but are still defined as a function of the temperature of the planetary surface controlled by exposure to stellar radiation and thermal blanketing by greenhouse gases. Recent models have led to suggestions that this definition should be broadened to include the potential for life to exist within ice-covered moons heated by internal gravitational energy dissipation. Observations over the last several decades have demonstrated a remarkable diversity of planetary systems, including observations of earth-sized planets within the traditional Habitable Zone as well as moons orbiting Jupiter-scale planets. Contributions to understanding the range and extent of habitable environments are encouraged.
The Search for and Evolution of Life in Our Solar System and Beyond
Kevin Hand (USA), Fabian Klenner (Germany)
Earth is the only planet where life is known to exist and often serves as a model to evaluate where life might exist elsewhere. While we once believed that sunlight was essential for life, we have discovered chemotropic life in Earth’s deep oceans and in hydrothermal systems under continental landmasses. This has broadened the search for life from planets in the Habitable Zone to a more diverse array of environments. The first investigations to search for life on Mars were based on models of terrestrial metabolisms that may not have been appropriate for the chemical composition of Martian soils. Modern searches for life beyond Earth not only target possible hydrothermal ecosystems on Mars, but also look to subsurface oceans on the moons of giant planets such as Europa and Enceladus. Discovery of life in any or all of these environments would significantly expand understanding of the potential for life elsewhere in the universe by offering data to determine if life originated and evolved independently in each environment or shares a common biochemistry radiating from a single origin.