1. 1 Astrobiology: The Semester in Review ASTR 390 with Dr. Harold Geller

2. 2 A Universe of Life zSearching for life everywhere zPlanets, stars, galaxies, Big Bang yConception of size and distance zStars and the origins of chemicals zFormation of planets zDefining astrobiology – the science

3. 3 iClicker Question The nebular condensation model of the formation of the solar system suggests that __________ should condense closest to the Sun. AJovian planets Bmetals and metal oxides Csilicates Dices of water, methane, and ammonia Elow density materials

4. 4 The Science of Life in the Universe zAncient cosmologies zScience as a way of knowing zCopernicus, Galileo, Kepler, Newton zPseudoscience and nonsense

5. 5 The Nature of Life zWhat is it? zCells zMetabolism zDNA zExtremophiles

6. 6 iClicker Question Life on Earth is based on Asilicon chemistry. Bhelium chemistry. Ccarbon chemistry. Doxygen chemistry. Enitrogen chemistry.

7. 7 The chemical building blocks of life are found throughout space zAll life on Earth, and presumably on other worlds, depends on organic (carbon-based) molecules zThese molecules occur naturally throughout interstellar space zOrganic molecules needed for life to originate were possibly brought to the young Earth by comets or asteroids, as well as being formed on Earth

8. 8 The Geological History of the Earth zGeologic Timescale zPlate Tectonics zSolid Earth zGreenhouse Effect zRelative/Absolute Dating

9. 9 iClicker Question The greenhouse effect occurs because Acarbon dioxide is transparent to visible light and opaque to infrared radiation. Bcarbon dioxide is transparent to infrared radiation and opaque to ultraviolet radiation. Cozone is transparent to ultraviolet radiation and opaque to infrared radiation. Dmethane is transparent to infrared radiation and opaque to visible light. Ethe sun emits more infrared radiation than ultraviolet radiation.

10. 10 The Origin and Evolution of Life on Earth zOrigin of Life zProkaryotes zEukaryotes zOxygen in Air zImpacts & Extinctions zHuman Evolution

11. 11 zAnother likely source for organic molecules is chemical reactions in the Earth’s primitive atmosphere zSimilar processes may occur on other worlds

12. 12 Searching for Life in the Solar System zEnvironmental Needs zIn the Solar System

13. 13 Mars zScience Fiction zSearch for Life zMartian Meteorites zExploration

14. 14 NASA rovers that reached Mars in 2004 landed at locations that may once have been covered in water zThe unsuccessful Beagle 2 mission to Mars was to carry out a different set of biological experiments on samples taken from the interiors of rocks

15. 15 The Viking Lander spacecraft searched for microorganisms on the Martian surface, but found no conclusive sign of their presence

16. 16 A so-called “Face” on Mars

17. 17

18. 18 Meteorites from Mars have been scrutinized for life-forms zAn ancient Martian rock that came to Earth as a meteorite was examined for evidence that microorganisms once existed on Mars zThis has not been corroborated

19. 19 Life on Jovian Moons zEuropa zTitan zOthers

20. 20 Europa and Mars best potential for life to have evolved zBesides 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 zMars once had liquid water on its surface, though it has none today zLife may have originated on Mars during the liquid water era zEuropa appears to have extensive liquid water beneath its icy surface yFuture missions may search for the presence of life

21. 21 The Nature and Evolution of Habitability zHabitability Zone yPast, Present, Future

22. 22 The Search for Habitable Worlds zPlanet Formation zExtrasolar Planets yDetection zEarth-like Planets?

23. 23 Infrared telescopes in space began searching for Earthlike planets zA new generation of orbiting telescopes may be able to detect terrestrial planets around nearby stars zIf such planets are found, their infrared spectra may reveal the presence or absence of life

24. 24 The Search for Extraterrestrial Intelligence zSETI zDrake Equation

25. 25 The Drake equation helps scientists estimate how many civilizations may inhabit our Galaxy

26. 26 iClicker Question The Drake equation allows us to estimate Athe number of intelligent civilizations in our galaxy. Bthe number of stars in our galaxy. Cthe number of people on the Earth. Dthe lifespan of a civilization. Ethe lifespan of a species.

27. 27 Interstellar Travel zHow realistic? yEngineering yLimited by c zRelativity and time dilation zWormholes and hyperspace?

28. 28 iClicker Question What limitation(s) make it close to impossible to travel, round trip, between stars? I.Fuel requirements II.The tremendous distances between stars III.The finite speed at which objects can travel AI BI and II CIII DII and III EI, II and III

29. 29 The Fermi Paradox zWhere are the aliens? zGalactic colonization zResolving the paradox

30. 30 Contact – Implications of the Search and Discovery zCan we make contact yWhich kind 1 st, 2 nd, 3 rd zContact implications

31. 31 Radio searches for alien civilizations are under way zNo signs of intelligent life have yet been detected ysearches are continuing and using increasingly sophisticated techniques zThe so-called water hole is a range of radio frequencies in which there is little noise and little absorption by the Earth’s atmosphere yscientists suggest that this noise-free region would be well suited for interstellar communication

32. 32 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?

33. 33 Astrobiology in One Sentence zThe 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