Are we alone? Is our Earth, the tiny blue star in this infinite Universe the only harbor for life? This oldest philosophical question frequently appears in scientific fictions and now becomes a science. Astrobiology concerns the study of the origin, evolution and destiny of life in the Universe. The emergence of this science is the natural outcome of the great advances in astronomy, biology and geology. The development of molecular biology has revealed the unitary origin and DNA-coding of all life on Earth, despite the great diversity after a long Darwinian evolution. Geologists dated the origin of life back to almost 3.8 billion years ago. Planetary explorations in our solar system have indicated abundant life materials being stored in the planetesimal zone and beyond. Furthermore, the detection of exoplanets has practically extended life exploration to the deep Universe. The astrobiological studies can be classified into cosmic, planetary, ecosystematic scales on a space dimension and, stellar and interstellar evolution, chemical evolution of prelife on Earth and modern ecosystem on a time dimension. Stellar nucleosynthesis and the evolution of galactic chemistry tell us about the formation of life-essential elements such as H, C-O-N-S-P and Fe-peaked transition metals. So, believe it or not, the elements in our body are much older than Earth! The breakthrough in exoplanet detection is a great step in searching a second life and scientists began to develop techniques to examine the atmosphere composition of Earth-like exoplanets. Based on our understanding of life origin on Earth, a body of liquid water, enough carbon and a silicate crust on a planet with a right distance to its sun are enough premises to make a planet habitable. When those conditions are met, life may start in hundred million years or even shorter time. We understand now that life deeply changes the surface spheres of Earth and our current atmosphere is pretty much the result of biological respiration. We also wonder that the great events happened on Earth, such as the appearance of free oxygen, the starting of plate tectonics, the appearance of ice ages, planet-wide formation of banded iron may have either stimulated the evolution of life, or on the contrary, resulted in mass extinction. Now we are on a fast lane going forward but have a quite unpredictable future. How long can our Gaia last? Can our offspring find another oasis in the Universe? Astrobiology cannot answer these questions but will give you a way to think about them.
The synopsis of series lectures:
1. Introduction of Astrobiology.
2. Origin and chemical evolution of life on Earth.
3. Nucleosynthesis of life essential elements in the interior of star.
4. Habitable zones in the galaxy and planetary system.
5. Detection of exoplanet.
6. Building a habitable planet.
7. Life on Mars.
8. Titan: it low temperature organic chemistry and significance in the origin of life.
9. Interstellar organic molecules.
10. Discussion: cosmic preparation of the origin of life.
11. Geomicrobiology: in introduction.
12. Biomineralization.
13. A concise history of life on Earth.
14. Evolution of ocean, atmosphere and continent during the Archaean eon.
15. Global carbon cycles.
16. Iron-reducing bacteria: its mineral physiology.
17. Hyperthermophiles: applied to the early evolution of life.
18. Cryobiosphere: its application to the evolution and preservation of life.
19. Subsurface biosphere.
20. International plans for exploration of extraterrestrial life.
21. Discussion: geological preparation of the origin of life.



Yi-Liang Li