| Session Details | |
| Section | PS - Planetary Sciences |
| Session Title | Quest for Habitable Worlds |
| Main Convener | Dr. Rajmal Jain (Physical Research Laboratory, India) |
| Co-convener(s) | Dr. Louise Prockter (The Johns Hopkins University Applied Physics Laboratory, United States) Dr. Yasuhito Sekine (The University of Tokyo, Japan) Dr. Steven Vance (Jet Propulsion Laboratory, United States) Prof. Akihiko Yamagishi (Tokyo University of Pharmacy and Life Science, Japan) |
| Session Description | Since the first discovery of a planet orbiting a Sun-type star was announced in 1995 more than 300 planets outside our solar system (exoplanets) are now known. The presence of most of these exoplanets has been inferred either through detecting their parent star's 'wobble', which is caused by the gravitational tug of the planet, or through measuring a dip in the host star's light as the planet passes in front of it (transits). The focus of exoplanet research is now shifting towards finding planets that are the most promising candidates for supporting life, and searching for indicators of biological processes (biomarkers) in their visible and infrared spectra. Habitability can be defined as the set of the necessary conditions for an active life to exist, even if it does not exist. In astronomy, a habitable zone (HZ) is the zone defined around a sun/star, where the temperature conditions allow liquid water to exist on its surface. This habitability concept can be considered from different scientific perspectives and on different spatial and time scales. Characterizing habitability at these various scales requires interdisciplinary research. In this session we have chosen to develop the geophysical, geological and biological aspects and to insist on the need to integrate them, with a particular focus on our neighboring planets, Mars and Venus. Important geodynamic processes may affect the habitability conditions of a planet. The dynamic processes, e.g., internal dynamo, magnetic field, atmosphere, plate tectonics, mantle convection, volcanism, thermo-tectonic evolution, meteorite impacts, and erosion, modify the planetary surface, the possibility to have liquid water, the thermal state, the energy budget, and the availability of nutrients. They thus play a role in the persistence of life on a planet. The concept of habitability is very Earth-centric, as we have only one biological planet to study. However, life elsewhere would most probably be based on organic chemistry and leave traces of its past or recent presence and metabolism by modifying microscopically or macroscopically the physico-chemical characteristics of its environment. The extent to which these modifications occur will determine our ability to detect them in astrobiological exploration. In this view we wish to discuss and review the characteristics of habitable conditions to widen the habitability zone. |