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What is astrobiology?
The main theme of this lecture is a new discipline called astrobiology. Astrobiology is the study of the origins, evolution, distribution and future of life in the universe. It requires fundamental concepts of life and habitable environments that will help us to recognize biospheres that might be quite different from our own.Astrobiology addresses three basic questions that have asked in various ways for generations:
- How does life begin and evolve?
- Does life exist elsewhere in the universe?
- What is the future of life on Earth and beyond?
The 7 scientific goals of astrobiology
At the end of 2003, NASA identified 7 broad scientific goals in astrobiology. See the figure captions for concrete objectives. For more details, credits and copyrights, see http://astrobiology.arc.nasa.gov/roadmap/index.html.Goal 1: Understand the nature and distribution of habitable environments in the Universe.
Determine the potential for habitable planets beyond the Solar System, and characterize those that are observable.
Models of formation and evolution of habitable planets. Indirect and direct astronomical observations of extrasolar habitable planets.
Goal 2: Explore for past or present habitable environments, prebiotic chemistry and signs of life elsewhere in our Solar System.
Determine any chemical precursors of life and any ancient habitable climates in the Solar System, and characterize any extinct life, potential habitats, and any extant life on Mars and in the outer Solar System.
Mars exploration. Outer Solar System exploration.
Goal 3: Understand how life emerges from cosmic and planetary precursors.
Perform observational, experimental and theoretical investigations to understand the general physical and chemical principles underlying the origins of life.
Sources of prebiotic materials and catalysts. Origins and evolution of functional biomolecules. Origins of energy transduction. Origins of cellularity and proto-biological systems.
Goal 4: Understand how past life on Earth interacted with its changing planetary and Solar System environment.
Investigate the historical relationship between Earth and its biota by integrating evidence from both the geologic and biomolecular records of ancient life and its environments.
Earth's early biosphere. Foundations of complex life. Effects of extraterrestrial events upon the biosphere.
Goal 5: Understand the evolutionary mechanisms and environmental limits of life.
Determine the molecular, genetic, and biochemical mechanisms that control and limit evolution, metabolic diversity, and acclimatization of life.
Environment-dependent, molecular evolution in microorganisms. Co-evolution of microbial communities. Biochemical adaptation to extreme environments.
Goal 6: Understand the principles that will shape the future of life, both on Earth and beyond.
Elucidate the drivers and effects of ecosystem change as a basis for projecting likely future changes on time scales ranging from decades to millions of years, and explore the potential for microbial life to adapt and evolve in environments beyond its planet of origin.
Environmental changes and the cycling of elements by the biota, communities, and ecosystems. Adaptation and evolution of life beyond Earth.
Goal 7: Determine how to recognize signatures of life on other worlds and on early Earth.
Identify biosignatures that can reveal and characterize past or present life in ancient samples from Earth, extraterrestrial samples measured in situ, samples returned to Earth, remotely measured planetary atmospheres and surfaces, and other cosmic phenomena.
Biosignatures to be sought in Solar System materials. Biosignatures to be sought in nearby planetary systems