The IAP Planet TOPERS field of research supports a broad community in an interdisciplinary approach to understand habitability. The Pole will focus its contribution on the full integration of these themes in the following Work Packages (WP) to better demonstrate how life can be sustained and to characterize the existence and persistence of life through the development of potential habitats.
The first work package studies key questions of the physics of the atmosphere and the interior interactions. It comprises the study of the thermal-chemical evolution of planetary interior relevant to atmospheric evolution and habitability. This includes the self-regulating (bio)geochemical cycles and models of mantle convection and tectonics in relation to magnetic field generation. The interactions between a solid and possibly partially liquid planet (existence of a liquid core) and its atmosphere encompass, in particular, the (partial) protection of the atmosphere from escape processes related to the existence of a magnetic field. The volatile exchange rates with the interior of the planet, and the dynamics of the interior are also of importance.
The second work package deals with the thermal-chemical evolution of planetary atmospheres (net loss, sources and chemical reactions) and its interaction with surface, hydrosphere, cryosphere, and space to determine the evolution of pressure, temperature and composition in time, and the existence or not of liquid water. This includes the greenhouse effect as well as the regulating role of a magnetosphere on atmospheric losses. The comets and asteroids volatile mass influx from space into the atmosphere will be dealt with as well.
The third work package is related to the identification and preservation of life tracers. Life leaves traces by modifying microscopically or macroscopically the physical-chemical characteristics of its environment. The extent to which these modifications occur and to which they are preserved will determine the ability to detect them. By characterizing chemical and morphological biosignatures on macro- to micro-scale, preservation and evolution of life in early Earth or analogue habitats will be studied, with the objective to constrain the probability of detecting life beyond Earth and the technology needed to detect such traces. The Earth biosphere has been interacting with the atmosphere and crust at a planetary scale probably soon after its origin, in the Archaean, and most significantly since the 2.5 Ga oxygenation, with profound implications for planetary and biosphere evolution.
The fourth work package will investigate the chronology of differentiation processes, the onset of plate tectonics and the recycling of the crust and implications for life sustainability. To that aim, samples from the worldwide meteorite collections will be analyzed with the objective of relating their age (to be determined) and their composition to planetary evolution. The role of asteroid and comet impacts in planetary evolution of the planets will be examined. In addition, the meteorites themselves document the early evolution of the Solar System and its solid bodies including their deep interiors.
The fifth work package consists in developing, in a holistic approach, an integrated model of planetary thermodynamic engine that includes mass, energy, and entropy balances into a “Global System dynamics”. The role of feedback cycles to stabilize habitable conditions will be examined. For instance the net loss or gain of volatiles in the atmosphere depends on the atmospheric pressure itself. Case studies and comparisons of evolution pathways, such as between Mars, Venus, and Earth will be considered. Ultimately, a roadmap for assessment of habitability on terrestrial bodies (terrestrial planets, asteroids, rocky and icy satellites, extrasolar terrestrial planets) will be provided.