HOW DO WE SEARCH FOR LIFE IN THE UNIVERSE

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HOW DO WE SEARCH FORLIFE IN THE UNIVERSE?
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The Search for Life

• Robotic Emissaries

• Remote Detection

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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

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The Search for Life on Mars
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Giovanni Schiaparelli (1877)
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Percival Lowell (1894 1916)
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The Face on Mars
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Martian Meteorites

• Crystals of iron pyrite

• Nodules of carbonate

• PAHs (organic material)

• Fossil bacteria?

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Life on Mars?

• History of water

• History of thicker atmosphere

• Probable Earth-like geologic history

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Viking I II(1976)
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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

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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.

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Viking Biological ExperimentsResults

• All 3 gave positive results!
• BUT! All positive results can be produced by
  non-biological chemical reactions.

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Pathfinder(1997)
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Europa OceanExplorer (2008?)

• Arrive 2012

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The Search for LifeRemote Detection

• If it existed we currently couldnt detect it
• Why?
• We can detect the presence of extrasolar planets
• We cannot image the planets themselves
• Light from host star is too overwhelming

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What technology is necessary?

• Interferometry for high resolution
• Space based or ground based
• Nulling technology to reduce glare of host star

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Nulling Technology
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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

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Planetary Imaging

• Interferometric Projects (ground based)
• Palomar Testbed Interferometer
• Keck Interferometric Array
• CHARA (Mt. Wilson)
• Others

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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

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Terrestrial Planet Finder (TPF, NASA)

• Detection of 1 earth-mass planets out to a
  distance of 50 light years

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DARWIN (ESA)
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Planetary Imager (PI, NASA)

• 6000 km baseline
• 8-m telescopes

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• Last Week
• Chapter 16 401 409
• Questions 5, 6, 7
• This Week
• Chapter 14 335 357
• Questions 1-7, 11