The Search for Extraterrestrial LifeGuiding QuestionsA Universe of LifeThe Science of Life in the UniverseThe Nature of LifeThe chemical building blocks of life are found throughout spaceThe Origin and Evolution of Life on EarthSearching for Life in the Solar SystemThe Geological History of the EarthMarsBoth of the NASA rovers that reached Mars in 2004 landed at locations that may once have been covered in water The Viking Lander spacecraft searched for microorganisms on the Martian surface, but found no conclusive sign of their presencA “Face” on Mars Meteorites from Mars have been scrutinized for life-formsLife on Jovian MoonsEuropa and Mars have the potential for life to have evolved The Nature and Evolution of HabitabilityThe Search for Habitable WorldsInfrared telescopes in space will soon begin searching for Earthlike planetsThe Search for Extraterrestrial IntelligenceThe Drake equation helps scientists estimate how many civilizations may inhabit our GalaxyInterstellar TravelThe Fermi ParadoxContact – Implications of the Search and DiscoveryRadio searches for alien civilizations are under wayIf an alien civilization were someday to find this message, which of the features on the plaque do you think would be easily uUniverse in a NutshellThe Search for Extraterrestrial LifeGuiding Questions1. 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?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 scienceThe Science of Life in the Universe• Ancient cosmologies• Science as a way of knowing• Copernicus, Galileo, Kepler, Newton• Pseudoscience and nonsenseThe Nature of Life• What is it?• Cells• Metabolism•DNA• ExtremophilesThe chemical building blocks of life are foundthroughout space• All life on Earth, and presumably on other worlds, depends on organic (carbon-based) molecules• These molecules occur naturally throughout interstellar space• The organic molecules needed for life to originate were probably brought to the young Earth by comets or meteorites• Another likely source for organic molecules is chemical reactions in the Earth’s primitive atmosphere• Similar processes may occur on other worldsThe Origin and Evolution of Life on Earth• Origin of Life• Prokaryotes• Eukaryotes• Oxygen in Air• Impacts & Extinctions• Human EvolutionSearching for Life in the Solar System• Environmental Needs•In the Solar SystemThe Geological History of the Earth• Geologic Timescale• Plate Tectonics• Solid Earth• Greenhouse Effect• Relative/Absolute DatingMars• Science Fiction• Search for Life• Martian Meteorites• ExplorationBoth of the NASA rovers that reached Mars in 2004 landed at locations that may once have beencovered in water• The unsuccessful Beagle 2 mission to Mars was to carry out a different set of biological experiments on samples taken from the interiors of rocks• These experiments may be attempted again on a future missionThe Viking Lander spacecraft searched for microorganisms on the Martian surface, but found no conclusive sign of their presenceA “Face” on MarsMeteorites from Mars have been scrutinized for life-forms• An ancient Martian rock that came to Earth as a meteorite shows circumstantial evidence that microorganisms once existed on Mars• Additional rock samples are needed to provide corroborationLife on Jovian Moons• Europa• Titan•OthersEuropa and Mars have the 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 thereThe Nature and Evolution of Habitability• Habitability Zone– Past, Present, FutureThe Search for Habitable Worlds• Planet Formation• Extrasolar Planets– Detection• Earth-like Planets?Infrared telescopes in space will soon beginsearching 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 reveal the presence or absence of lifeThe Search for Extraterrestrial Intelligence• SETI• Drake EquationThe Drake equation helps scientists estimate howmany civilizations may inhabit our GalaxyInterstellar Travel• How realistic?– Engineering– Limited by c• Relativity and time dilation• Wormholes and hyperspace?The Fermi Paradox• Where are the aliens?• Galactic colonization• Resolving the paradoxContact – Implications of the Search and Discovery• Can we make contact– Which kind 1st, 2nd, 3rd• Contact implicationsRadio searches for alien civilizations are under way• No signs of intelligent life have yet been detected, but 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• Some scientists suggest that this noise-free region would be well suited for interstellar communicationIf an alien civilization were someday tofind this message, which of the features on the plaque do you think would be easily understandable to them?Universe in a Nutshell• The universe is unimaginably large and alive.• You are not at the center of the universe.• The way to know the universe is through science.» Dr. Harold GellerHAVE A GREAT HOLIDAY