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Searching for Life

Searching for Life. FYOS. Biomarkers (=biosignatures). = feature whose presence or abundance can be attributed to life. Remote Detection of Life Sign. We will not be able to “resolve” the extrasolar planet Everything we learn about the planet will be obtained from disk-averaged data.

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Searching for Life

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  1. Searching for Life FYOS

  2. Biomarkers (=biosignatures) = feature whose presence or abundance can be attributed to life

  3. Remote Detection of Life Sign • We will not be able to “resolve” the extrasolar planet • Everything we learn about the planet will be obtained from disk-averaged data. • The signs of life must be a global phenomenon

  4. Viewing Angle Differences Phase and Seasonal Variations

  5. Vegetation signature

  6. Surface Biosignatures : Vegetation “Red-Edge” Vegetation Red-Edge

  7. ? VENUS X 0.60 CO2 CO2 EARTH-CIRRUS O2 H2O H2O O2 O3 H2O H2O MARS Iron oxides H2O ice EARTH-OCEAN Spectra of Terrestrial Planet in Solar System Terrestrial planets in our Solar System offer diverse spectra that will be a set of nice references to exoplanet!

  8. Earth’s changing appearance at IR Modern Earth 355ppm CO2

  9. Changing Biosignatures with time Proterozoic 0.1PAL O2 100ppm CH4 15% decrease in ozone column depth Mid-Proterozoic Earth-like atmospheres show strong signatures from both CH4 and O3 Segura, Krelove, Kasting, Sommerlatt,Meadows,Crisp,Cohen

  10. Changing Biosignatures with time Archean N2 99.8% 2000ppm CO2 1000ppm CH4 100ppm H2 Karecha, Kasting, Segura, Meadows, Crisp, Cohen

  11. Earth N2O AD Leo planet CH4 O3 + CH3Cl H2O CO2 Earth-like Planets Around M Stars Segura et al., Astrobiology, 2005.

  12. Can we detect Biosignatures with TPF-C?

  13. Terrestrial Planet Finders Terrestrial Planet Finder NASA Direct detection of planets Launch 2015? Darwin ESA

  14. TPF survey range radius of ~200 Ly 25,000 Ly

  15. Level of Technological Advancement • Nikolai Kardashev (1932 -- ) : based on the amount of usable energy at alien’s disposal. • Type I – planetary civilizations : use the resources of their home planet (us!) energy usage upto 1017 Watts • Type II – stellar civilizations : a civilization that is able to harness all of the power available from a single star energy usage up to 1026 Watts • Type III – Galactic civilizations : can employ the resources of the entire galaxy energy usage of 1037 Watts

  16. Detecting Type II civilizations • If we capture the energy released by the Sun for just 1 second… • enough energy for us to live next 1 million years! • Advanced civilization, in a full scale usage of their host star energy, could have built a thin-wall energy collecting sphere around their star Dyson sphere

  17. Dyson Sphere in the Startrek Seen from the USS Enterprise bridge

  18. Dyson Sphere in the Startrek The Enterprise in orbit around the Dyson sphere

  19. Variants of Dyson Sphere Dyson Ring Dyson Swarm

  20. Other Attempts (or suggestions) • Artifacts which can be detectable from a great distance… • Karl Gauss (1777-1855) suggested planting trees in Siberia in the form of a right triangle so that it can be recognized by peoples on the Moon… • Dig trenches in the Sahara in various geometric shapes and fill them with oil and lit.

  21. Alien Artifacts Instead of sending a signal, advanced aliens might have visitedEarthalready and buried their instruction somewhere in the Solar System! • Some believe that UFOs, crop circles, etc. are those… • 2001: A Space Odyssey : Advanced alien being buried their signaling device under the ground of the Moon.

  22. Best to places to hide • Lagrange Points

  23. Next Presentations (~ 5 min long) • Z. Rindik : “SETI Wow! signal”  Feb 29 On Mar 7 • C.Barmore & G. Chant : “SETI debate : Zuckerman” • S. Jordan & T. West : “SETI debate : Shostak”

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