Astrobiology: the consideration of life in the Universe elsewhere than in the earth.

1. ASTROBIOLOGY: “ A Science Looking For a Subject ” (G. G. Simpson, evolutionary biologist) Lapo Bettarini

3. … JUST A BIT OF HISTORY - 1 1941: L. J. Lafleur , “ Astrobiology ”, leaflet 143, Astronomical Society of the Pacific “ Astrobiology: the consideration of life in the Universe elsewhere than in the earth ” 1949: G.A. Tikhov , ” Astrobotany ”, Kazakhstan SSR Acad. Of Science Press, Alma Ata, Kazakhstan (in russian) 1953: G.A. Tikhov , “ Astrobiology ”, Molodaya Gvardia Press, Moscow (in russian) 1953: H. Struhold , “ The green and the red planet: a physiological study of the possibility of life on Mars ”, Univ. of New Mexico Press, Albuquerque 1956: F.A. Pereira , “ Introducao a Astrobiologia ”, Sociedade Interplanetaria Brasilera, Sao Paulo, Brazil

4. Biogenic-looking features in ALH84001 Martian meteorite. Image credit: NASA … JUST A BIT OF HISTORY - 2 1975-6 : first 3 biological experiments on Mars made by means of Viking 1 and Viking 2 …inconclusive… 1996 : liquid water interior of Europa ( Galielo Orbiter ) 1996 : INDICATORS OF PRIOR LIFE ON MARS 1996 : first astrobiology scientific conference 1998 : NASA Astrobiology Institute and the Nasa Astrobiology Roadmap

6. SO, FIRST OF ALL…WHAT’S LIFE ? No generally accepted definitions (robust counter-examples): List of failed attempts (C. Sagan 1970) METABOLIC definitions imply the growth and the reproduction through chemical reactions….for example… FIRE !!!! THERMODYNAMIC definitions imply the creation and the support of a local order…for example… CRYSTALS !!!! (that may also reproduce) LEONARDO DA VINCI’s DILEMMA: What’s WATER ? We need a theory of the NATURE of the living systems

9. A stabilizing feed back driven by plate tectonics on Earth has allowed CO 2 and H 2 0 on Earth to maintain greenhouse heating in just the range to permit surface oceans to exist through geological time. Carbon dioxide levels in the atmosphere are mantained within the range yielding surface temperatures that allow liquid water via a negative feedback involving CO2 removal by rainfall, precipitation as carbonates, and resupply to the atmosphere due to volcanism subsequent carbonate subduction Venus, too close to the Sun, lost its H 2 0 owing to a moist or even runaway greenhouse Mars, too small to maintain substantial geological activity over the age of the solar system, saw its CO 2 atmosphere collapse

14. 850 well-observed stars analysis: strong correlation between <[Fe/H]> and Doppler-detected extrasolar planets (Fischer & Valenti 2005): Planet formation, thus system habitability, should increase with decreasing galactic radius, but supernovae may have a severe effect on habitable planet (Lineweaver, Fenner & Gibson 2004):

15. Galaxy Image credit: Nasa/Ipac 7 kpc 9 kpc Coupling the accumulation of metals in the Milky Way Galaxy with sterilizing supernovae explosions and taking 4 ± 1 Gyr timescale for the evolution of complex life

16. ORIGIN OF LIFE Determining that an environment is habitable for modern microorganisms doesn’t mean that the origin of life could have occurred in that environment BOTTOM-UP APPROACH (BUILDING LIFE) “ Primordial soup” (miller & Urey 1953) or “warm pond” (darwin 1871) PREBIOTICALLY SIMPLE MOLECULES ( CH 4 , NH 3 ) + Energy ( spark discharge, UV irradiation, immpact shock ) = AMINO ACIDS or NUCLEIC ACID BASES COMPARTMENTALIZATION: endogenous and/or exogenous sources (Deamer 1997)

23. Search for and monitor transients “around” 10 5 stars for 4 years: frequency of Earth-size worlds as well as the semimajor axes of these planets’ orbits (it covers a wide range of planet sizes, orbital distances and stellar types) LaUNCH: Winter 2008 - Spring 2009 (Earth-trailing heliocentric orbit, T ~ 372.5; “worst case” drift ~ 0.5 AU) http://kepler.nasa.gov

25. LaUNCH: 2015 (L2 orbit, 1.5 milion km from the Earth) Darwin will use a flotilla of three space telescopes, each at least 3 metres in diameter, and a fourth spacecraft to server as communications hub. The telescopes will operate together to scan the nearby Universe, looking for signs of life on Earth-like planets http://sci.esa.int/science-e/www/area/index.cfm?fareaid=28

26. AND HERE? LISTEN TO GIACOMO Micrometeoroid: 10 micron < size < 1 mm At the South Pole it is observed a largest number of these objects: variations of their properties different from what expected Love & Brownlee 1993 Early MicroMeteorite Accretion (EMMA) scenario (Maurette et al 2000): micrometeorites played an important role in atmospheric and oceanic formation and in the appearence of life on Earth. They are rich of carbon compounds… Niche for life (reactors)

27. A last question: intelligence in the universe Drake equation (drake, 1961): Fermi problem: “though the answer may be difficult to guess a priori, by breaking the calculation down into a product of numbers whose order of magnitude may be estimated, one can make a credible estimate…but L ? Anthropic argument: comparison between the lifetime of a main-sequence star like our Sun and the timescale for biological evolution (carter 1983) Enrico Fermi asked: “Don’t you ever wonder where everybody is?” Several solutions, but no certainties…

28. SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE SETI Institute (1984) The mission of the SETI Institute is to explore, understand and explain the origin, nature and prevalence of life in the universe ( LITU ). The SETI Institute is a private, nonprofit organization (externally funded with outside grants, often by NASA and NSF) dedicated to scientific research, education and public outreach. Project Phoenix: scanning of billions of microwave frequencies with narrow bandwidths while allowing for frequency drift and rigorously excluding terrestrial interference: SO FAR (over a decade): 460 days of observing times ~ 10 3 sun-like stars IN THE FUTURE (over a decade): 10 5 - 10 6 stars (Allen Telescope Array)