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The Search for exoplanets and Extraterrestrial Life

The Search for exoplanets and Extraterrestrial Life. http:// www.jpl.nasa.gov/news/news.cfm?release =2011-373 Kepler mission Are we alone? http://www.jpl.nasa.gov/videos/phoenix/phx20070724/phx-20070723-1280.m4v How did life start on Earth?

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The Search for exoplanets and Extraterrestrial Life

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  1. The Search for exoplanets and Extraterrestrial Life • http://www.jpl.nasa.gov/news/news.cfm?release=2011-373 • Kepler mission • Are we alone? http://www.jpl.nasa.gov/videos/phoenix/phx20070724/phx-20070723-1280.m4v • How did life start on Earth? • Where can we find potentially life supporting conditions in our solar system? • SETI • Video • Habitable zone

  2. Kepler mission • Kepler mission is looking for earth like planets. http://www.youtube.com/watch?v=q1qqJ3AwaBk CURRENT PLANET COUNT: 687 stars with planets: 474 Earthlike planets: 0 ? As of 12/5/11 http://planetquest.jpl.nasa.gov/missions/missions_chart6.html

  3. http://www.youtube.com/watch?v=q1qqJ3AwaBk • What is habitable zone? • What is the primary science goal of Kepler mission? • How is that goal achieved? • How big is Kepler’s field of view? • How does Kepler see? (What is Kepler’s sensors?) • In What direction (constellation) do Kepler look at? • What is photometry?

  4. NASA's Kepler Confirms Its First Planet In Habitable Zone

  5. Are we alone? Planet Quest : NASA JPL http://planetquest.jpl.nasa.gov/science

  6. How did life start on earth? • An Updated Miller-Urey Experiment • exposed a mixture of gaseous hydrogen, ammonia, methane and water to an electrical arc for a week. At the end of the experiment, the reaction chamber was coated with a reddish-brown rich in amino acids and other compounds essential to life. • Chemosynthesis : evolved here & panspermia: evolved elsewhere

  7. Extremophiles • thermophiles: exist in hot environments Thermusaquaticus, discovered in hot springs in Yellowstone National Park (70+oC). Pyrolobusfumarii, grows on the walls of black smokers (113oC). • acidophiles: exist in acidic environments Sulfolobusacidocaldarius inhabits hot (85C) and sulphurous thermal springs (in Yellowstone national park) • psychrophiles: exist in cold environments Polaromonasvacuolata, which lives in antarctic sea ice. Ice worms fround at sea floor @ 0oC. • halophiles: exist in salty environments These cyanobacteria survive until @ Shark bay, which is far too salty for any predators to exist in it.

  8. The Search for Life on Mars • It appears that Mars at some point in its history was very much wetter and warmer than it is today • Scientists have been looking for life there • The Viking landers (1970’s) tested for the presence of microbes, but returned inconclusive results • We are still looking! average distance of 1.52 AU from the Sun rotation period = 24 hours 37 minutes orbital period is 687 days. rotation axis is tilted at 25 degrees: seasons Mars's radius ~ half of Earth's, mass is only 10% low surface gravity = 0.38 Earth gravities. Remember Phoenix Lander?

  9. Environment • CO2 thin atmosphere • Erosion due to flash floods • Erosion due to sustained water flow, • Features around the boundaries of the northern lowlands which may be the shores of an early liquid-water ocean or group of lakes. This would explain why the lowlands appear so smooth. • Signatures of minerals which can only form in the presence of liquid water, such as sedimentary deposits of crystalline haematite(iron ore). evidence for ancient Martian life: * tiny, elongated tubular structures around 100 nanometres long, which resemble fossilized microbial life. * pure crystals of iron sulphide and magnetite, which are rarely found together, but can be formed by certain types of bacteria. * polycyclic aromatic hydrocarbons (PAHs), organic molecules which result from the decay of microorganisms.

  10. Europa of Jupiter http://www.jpl.nasa.gov/video/index.cfm?all_videos&id=649 orbits Jupiter: every3.5 days @ d= 670,000km density of about 60%: mostly rocky materials radius of 1,500km: surface gravity=0.14 Earth’s. Europa's frozen surface with ocean of liquid water (tidal heating) Europa most likely has organic compounds containing oxygen, carbon, sulphur, hydrogen and nitrogen. Potential life near geothermal underwater vents investigation of Europa shall include: cryobot, to melt through the surface ice, and a hydrobot, to explore the underlying ocean and look for signs of life.

  11. Possible Europa Life Cracks with freshly frozen water and long faults make it clear that Europa's ice is no more than 100 miles thick. The ocean below surges up through cracks with tidal frequency, water that is likely at 32° Fahrenheit — just at freezing — a tolerable temperature for life.

  12. Titan of Saturn http://saturn.jpl.nasa.gov/multimedia/flash/Titan/index.html - Titan is the largest of Saturn's satellites significant atmosphere (nitrogen, ammonia, methane and hydrocarbons such as ethane and propane. similar to smog on earth!) - Orbit Saturn every 20.3 days @ d=1.2 million km - mixture of ices (methane & ethane) and rocky compounds, diameter ~5,000 km, (larger than Mercury) - Surface temperatures ~ -180C The present-day prospects for life on Titan are poor, due to the low temperatures. Titan’s atmosphere and surface are rich in the prebiotic compounds which eventually produced life on Earth.

  13. SETI • SETI: Search for Extra-Terrestrial Intelligence • Listens for electromagnetic evidence of intelligence elsewhere in the universe • To date, evidence has been sparse.

  14. This graph shows the background noise level from the sky at various radio and microwave frequencies. The so-called water hole is a range of radio frequencies from about 103 to 104 megahertz (MHz) 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 communication. Within the water hole itself, the principal source of noise is the afterglow of the Big Bang, called the cosmic microwave background. To put this graph in perspective, a frequency of 100 MHz corresponds to “100” on a FM radio, and 103 MHz is a frequency used for various types of radar. Water hole Since 1995 the SETI Institute in California has been carrying out Project Phoenix. When complete, this project will have surveyed a thousand Sunlike stars within 200 light-years at millions of radio frequencies. At Harvard University, BETA (the Billion-channel ExtraTerrestrial Assay) is scanning the sky at even more individual frequencies within the water hole.

  15. Drake equation N = R*fpneflfifcL • N = number of technologically advanced civilizations in the Galaxy whose messages we might be able to detect • R* = the rate at which solar-type stars form in the Galaxy(=1) • fp = the fraction of stars that have planets (=1) • ne = the number of planets per solar system that are Earthlike (that is, suitable for life) (~0.25) • fl = the fraction of those Earthlike planets on which life actually arises (=1) • fi = the fraction of those life-forms that evolve into intelligent species (=1) • fc = the fraction of those species that develop adequate technology and then choose to send messages out into space (=1) • L = the lifetime of a technologically advanced civilization (=200 years?)

  16. The Drake Equation : Putting it all together * R* is well-known * fp is reasonably well-known * ne is uncertain * fl is highly uncertain * fi is extremely uncertain * fc is extremely uncertain * L is extremely uncertain Based on the above estimates of each term in the Drake Equation, the expected number N of civilizations in the Galaxy which are currently producing electromagnetic signals is 50. Taking the radius of the galactic disk as 15 kiloparsecs, and assuming that stars are spread evenly throughout this disk, then on average we can expect to find one communicating civilization in each 14 square kiloparsecs of the disk (i.e., in each 120 by 120 parsec region, or about 400 light year).

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