The Search for Extraterrestrial Life 1 Guiding Questions 1 What role could comets and meteorites have played in the origin of life on Earth 2 Have spacecraft found any evidence for life elsewhere in our solar system 3 Do meteorites from Mars give conclusive proof that life originated there 4 How likely is it that other civilizations exist in our Galaxy 5 How do astronomers search for evidence of civilizations on planets orbiting other stars 6 Will it ever be possible to see Earthlike planets orbiting other stars 2 A Universe of Life Searching for life everywhere Planets stars galaxies Big Bang Conception of size and distance Stars and the origins of chemicals Formation of planets Defining astrobiology the science 3 The Science of Life in the Universe Ancient cosmologies Science as a way of knowing Copernicus Galileo Kepler Newton Pseudoscience and nonsense 4 The Nature of Life What is it Cells Metabolism DNA Extremophiles 5 The chemical building blocks of life are found throughout space All life on Earth and presumably on other worlds depends on organic carbon based molecules These molecules occur naturally throughout interstellar space Organic molecules needed for life to originate were possibly brought to the young Earth by comets or asteroids as well as being formed on Earth 6 The Geological History of the Earth Geologic Timescale Plate Tectonics Solid Earth Greenhouse Effect Relative Absolute Dating 7 The Origin and Evolution of Life on Earth Origin of Life Prokaryotes Eukaryotes Oxygen in Air Impacts Extinctions Human Evolution 8 Another likely source for organic molecules is chemical reactions in the Earth s primitive atmosphere Similar processes may occur on other worlds 9 Searching for Life in the Solar System Environmental Needs In the Solar System 10 Mars Science Fiction Search for Life Martian Meteorites Exploration 11 NASA rovers that reached Mars in 2004 landed at locations that may once have been covered in water The unsuccessful Beagle 2 mission to Mars was to carry out a different set of biological experiments on 12 samples taken from the interiors of rocks The Viking Lander spacecraft searched for microorganisms on the Martian surface but found no conclusive sign of their presence 13 A so called Face on Mars 14 15 Meteorites from Mars have been scrutinized for life forms An ancient Martian rock that came to Earth as a meteorite was examined for evidence that microorganisms once existed on Mars This has not been corroborated 16 Life on Jovian Moons Europa Titan Others 17 Europa and Mars best potential for life to have evolved Besides Earth only two worlds in our solar system the planet Mars and Jupiter s satellite Europa may have had the right conditions for the origin of life Mars once had liquid water on its surface though it has none today Life may have originated on Mars during the liquid water era Europa appears to have extensive liquid water beneath its icy surface Future missions may search for the presence of life 18 The Nature and Evolution of Habitability Habitability Zone Past Present Future 19 The Search for Habitable Worlds Planet Formation Extrasolar Planets Detection Earth like Planets 20 Infrared telescopes in space began searching for Earthlike planets A new generation of orbiting telescopes may be able to detect terrestrial planets around nearby stars If such planets are found their infrared spectra may 21 reveal the presence or absence of life The Search for Extraterrestrial Intelligence SETI Drake Equation 22 The Drake equation helps scientists estimate how many civilizations may inhabit our Galaxy 23 Interstellar Travel How realistic Engineering Limited by c Relativity and time dilation Wormholes and hyperspace 24 The Fermi Paradox Where are the aliens Galactic colonization Resolving the paradox 25 Contact Implications of the Search and Discovery Can we make contact Which kind 1st 2nd 3rd Contact implications 26 Radio searches for alien civilizations are under way No signs of intelligent life have yet been detected searches are continuing and using increasingly sophisticated techniques The so called water hole is a range of radio frequencies in which there is little noise and little absorption by the Earth s atmosphere scientists suggest that this noise free region would be well suited for interstellar communication 27 If an alien civilization were someday to find this message which of the features on the plaque do you think would be easily understandable to them 28 Astrobiology in One Sentence The universe is unimaginably large and alive you are not at the center of the universe and the way to know the universe is through science Dr Harold Geller HAVE A GREAT SUMMER 29