Astrobiology and Habitability

course ID





14 Weeks

Semester DD


Course details
• What is astrobiology? What is life? Dissipative structures. Thermodynamics and gravity in the expanding universe. 
• Matter and life. Types of bonding. Equations of state and phase diagrams.
• The essential elements of life (CHONPS). The role of carbon. The role of water. Alternative biochemistries.
• From molecules to cells. Membranes. Information storage (RNA and DNA). Movement and replication.
• The role of energy. ATP, respiration, fermentation. Chemoautotrophs. Photosynthesis.
Thermodynamics of energy and life.
• The tree of life. Natural selection. How would alien life look like?
• The physical limits of life. Extremophiles.
• Formation of the elements of life in the universe. Basics of star and planet formation.
• Basics of astrochemistry. Different environments: diffuse interstellar clouds, molecular clouds, protoplanetary discs. How are organic compounds formed? Comets. Chirality.
• The early Earth. Formation and differentiation. Formation of the Moon. Early crust and atmosphere. The faint young Sun paradox. The late heavy bombardment.
• The origin of life. Viable hypotheses. The RNA world. Where did life appear? The lithopanspermia mechanism.
• Early life on Earth. When did life appear? Isotopic evidence. Does the early appearance of life on Earth suggest that it is common in the universe?
• The geological history of Earth. Plate tectonics and rock cycles. Coevolution of life and the environment. The Precambrian and the Phanerozoic.
• The rise of oxygen in the early Earth. The great oxidation event and its possible causes. Snowball Earth and glaciations. Oxygen and the rise of land life.
• Mass extinctions. The five major events and their possible causes. The effect of high-energy astrophysical events. Impacts and extinctions. The KT event. The Torino and Palermo scale.
• Planetary habitability. Definition of habitability. The circumstellar habitable zone. Temperature and the greenhouse effect. The role of a large moon. The role of the magnetic field. Uninhabited habitats. Is there a super-habitability? Anthropic biases.
• Habitability of rocky planets in the solar system: Venus and Mars.
• The search for life on Mars. The Viking program. Martian meteorites. Transfer of biological material between Mars and Earth. Planetary protection. Future astrobiological missions.
• Icy worlds. The moons of giant planets: Europa and Enceladus. Titan and alternative biochemistries. Subsurface exolife.
• Exoplanets. Climatic models, atmospheric balance and habitability. The role of the host star in habitability. More on the circumstellar habitable zone. The frequency of habitable planets in the galaxy. The galactic habitable zone.
• The search for life on exoplanets. Detecting life: biosignature gases, surface biosignatures. Earth as an exoplanet. False positives. Future missions.
• The colonization of space. Human environments outside Earth. Present and future space stations and habitats. Terraforming. The hazards of space. The physical constraints to interplanetary and interstellar travel. The future of humanity.
• The search for extraterrestrial intelligence (SETI) and technosignatures. The Drake equation and its limits. Communication and language. The Kardashev classification. The Fermi paradox and its implications.

The course aims to provide a preparation on current specialized research topics in astrobiology, with a strong emphasis on interdisciplinarity. The educational objectives include the knowledge of the astrophysical and biological factors connected to habitability (ie the propensity for the appearance and survival of living organisms) both at a planetary level and, more generally, in the cosmic environment.

Students must have an in-depth understanding of the current state of research in astrobiology, and of the related problems, both at a theoretical and observational level. They must have developed the ability to investigate research topics independently, particularly on technical articles published in international journals. The verification of knowledge and comprehension skills is carried out through an oral exam that includes the presentation of a current research topic (starting from a technical article) as well as answers to questions on the topics of the course.

Students must be able to identify the key points of the main problems of astrobiological interest, being able to place them in the context of current knowledge and to create connections between the disciplines involved.