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HOW DO WE SEARCH FOR LIFE IN THE UNIVERSE?. The Search for Life. Robotic Emissaries. Remote Detection. Robotic Emissaries. Pioneer 10 & 11 (1972/3) Voyager 1 & 2 (1977). Traveling 23,000 – 39,000 mi/hr Essentially no onboard guidance system
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The Search for Life • Robotic Emissaries • Remote Detection
Robotic Emissaries • Pioneer 10 & 11 (1972/3) • Voyager 1 & 2 (1977) • Traveling 23,000 – 39,000 mi/hr • Essentially no onboard guidance system • Random encounter with a stellar system in 1019 years
Martian Meteorites • Crystals of iron pyrite • Nodules of carbonate • PAH’s (organic material) • Fossil bacteria?
Life on Mars? • History of water • History of thicker atmosphere • Probable Earth-like geologic history
Viking Biology Experiments • No organic compounds found in soil • Atmosphere: very small amounts of methane and nitrogen • Biological experiments based on Earth-like life (is this realistic?) • Three biological experiments performed on Martian soil
Viking Biology Experiments GEX: Gas Exchange – “feed” the soil • Gas chromatograph measured composition of gasses in chamber before/after feeding LR: Labeled Release – look for respiration • Look for radioactive carbon in gaseous form. PR: Pyrolitic Release – “Roast” the soil • look for radioactive carbon in atmosphere.
Viking Biological ExperimentsResults: • All 3 gave positive results! • BUT! All positive results can be produced by non-biological chemical reactions.
Europa OceanExplorer (2008?) • Arrive 2012
The Search for Life:Remote Detection If it existed we currently couldn’t detect it Why? • We can detect the presence of extrasolar planets • We cannot image the planets themselves • Light from host star is too overwhelming
What technology is necessary? • Interferometry for high resolution • Space based or ground based • Nulling technology to reduce glare of host star
What Do We Look For? • Image extrasolar planets (if not planets maybe their moons) • Look for chemical signatures for life • Make detailed images of extrasolar planets
Planetary Imaging Interferometric Projects (ground based): • Palomar Testbed Interferometer • Keck Interferometric Array • CHARA (Mt. Wilson) • Others…
Space Interferometry Mission(SIM, NASA) • Lower mass limit of 5 earth masses detection out to 10 parsecs (33 LY) • Lower mass limit of 1 earth mass detection out to 16 LY
Terrestrial Planet Finder (TPF, NASA) Detection of 1 earth-mass planets out to a distance of 50 light years
Planetary Imager (PI, NASA) • 6000 km baseline • 8-m telescopes
Last Week: • Chapter 16: 401 – 409 • Questions: 5, 6, 7 This Week: • Chapter 14: 335 – 357 • Questions: 1-7, 11