Life in the Universe

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Life in the Universe

• Paul J. Thomas
• Department of Physics and Astronomy
• UW-Eau Claire

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Frank Drake

• President of the SETI Institute.
• Led Project OZMA (1960), the first radio search
  for extraterrestrial intelligence.
• Emeritus Professor of Astronomy and Astrophysics
  at the University of California.

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The Drake Equation

• N R ? fp ? ne ? fl ? fi ? fc ? L
• An equation to estimate N, the number of
  communicable civilizations in the galaxy

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R - rate of star formation

• Approximately 1 star/year for the galaxy
• Fairly well constrained by observations for star
  formation regions

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fp - stars with planets

• Planetary formation is probably a standard part
  of star formation.
• Protoplanetary disks (proplyds) are common in the
  Orion nebula.
• Disks have been detected around several nearby
  stars.

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A Golden Age of Exoplanet Discoveries

• 1600 Giordano Bruno burned at the stake for
  claiming "Innumerable suns exist innumerable
  earths revolve around these suns in a manner
  similar to the way the seven planets revolve
  around our sun.Living beings inhabit these
  worlds."

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A Golden Age of Exoplanet Discoveries

• 1952 Otto Struve describes techniques for
  exoplanet discoveries and suggests Hot Jupiters
  might be easiest to discover.
• 1987 Bradford Smith and Richard Terrile discover
  a dust disk around Beta Pictoris.

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A Golden Age of Exoplanet Discoveries

• 1995 Mayor and Queloz detect a Hot Jupiter
  around 51 Pegasi using radial velocity technique.
• a0.05 AU
• P4.23 d
• M sin i0.44 MJ
• T1300 K (estimated)
• Over the next few years, Marcy and Butler detect
  dozens more

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A Golden Age of Exoplanet Discoveries

• As of January 2008
• 271 planets are known outside our solar system
• 14 doubles
• 9 triples
• 1 atmosphere detected

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Multiple Planet Systems
b. 0.72 MJ/sin i, 4.62 d c. 1.98 MJ/sin i, 242
d d. 4.11 MJ/sin i, 1269 d
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Terrestrial Planet Finder

• Detect one photon in 109!
• Several concepts currently in study. Leading
  concepts
• Nulling interferometry
• Coronagraph.
• Probably will require 10-20 m space telescope.

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The Holy Grail
Earth as seen from Voyager 1 at 40 AU (1990)
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ne - Earth-like planets

• How many Earth-like environments are there in
  our solar system?
• Earth
• Ancient Venus?
• Ancient Mars?
• Europa?
• Titan?

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Discovery of methane on Mars

• In 2009, Mike Mumma (NASA Goddard) and coworkers
  announced the spectroscopic discovery of methane
  in Marss atmosphere.
• In the absence of an ozone layer, methane is soon
  broken down to CO2 and H2O by solar UV.
• What is making it?

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Aside Its not only Earths we should be looking
for!
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Conamara Chaos
10 km
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fl - planets with life

• Heavy Bombardment ended 3.8 Gya.
• Earliest microfossils date from 3.8 Gya.
• Organic molecules are common in interstellar
  space, meteorites and comets, and could be
  delivered to the surfaces of planets by impact.
• Organic molecules can also be made in atmospheres
  (Miller-Urey experiment).

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The Early Terrestrial Environment

• Complex terrestrial organisms 3.5 Gya.
• Probable biologically mediated C12/C13
  fractionation 3.8 Gya.
• Heavy Bombardment ended 3.8 Gya.

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Organic Molecules

• Molecules containing carbon.
• Common in interstellar clouds, comets, asteroids.
• Building blocks of living things
• HCN ? DNA bases
• amino acids ? proteins.
• Can be synthesized without life!

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Organic Molecules found in Space

• Interstellar Clouds
• CH4
• H2CO
• HCN
• CH3COOH
• CH3C4H
• CH2CHCN

• Comets and Asteroids
• CH4
• HCN
• CH3OH
• H2CO
• CH3CN?
• amino acids

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Miller-Urey Experiment

• Miller, S., 1953, A Production of Amino Acids
  Under Possible Primitive Earth Conditions
  Science, 117, 528
• CH4, NH3 electric current in presence of H20 ?
  amino acids

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Cyanobacteria

• Aquatic, photosynthetic organisms (principally
  Microcoleus and Phormidium).
• Over time, evolved inside plant cells to form
  chloroplasts.
• Stromatolites are cyanobacteria colonies,
  originating 3.5 Gya.

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Shark Bay World Heritage Area
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Hamelin Pool

• One of three sites in the world where living
  stromatolites have been found.
• Survival is due to local hypersaline environment.
• Stromatolites build up by trapping of mineral
  particles by bacterial mucus (0.4 mm/y).
• Typical stromatolite is 1000 y old.

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Life Finder

• Formation Flyer telescope array in space.
• Will look for spectroscopic evidence of biogenic
  chemicals in extrasolar planets.

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fi - life with intelligence

• Origin of Life on Earth 3.8 Gya
• Multicellular life 1 Gya
• Complex organisms 550 Mya
• Mammals 200 Mya
• Australopithecus aferensis 4 Mya
• Homo sapiens 300,000 ya
• Agriculture 6,000 ya

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Dolphin Tool Use in Shark Bay
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Dolphin Language Analysis

• Dolphins exhibit whistle sequences 1600 ms in
  length, separated by 300 ms intervals.
• Over 100 have been identified.
• These are distinct from echo location and infant
  cry vocalizations.
• McCowan, Hanser and Doyle (1999).

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Dolphin Language Analysis

• Whistle sequences do not occur in random order.

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fc - communicability

• Radio signals with frequencies 1 MHz can escape
  to space.
• First signals strong enough to be detected over
  interstellar distances were probably WWII radar
  installations (now 50 ly away)
• Current signals include radar, FM, TV, microwave
  telephone, etc.
• At some frequencies the Earth is brighter than
  the Sun!

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L - lifetime

• Cuban Missile Crisis was 20 y after first
  interstellar-strength signals.
• Do inherited traits that lead to evolutionary
  dominance put civilizations at risk?
• Overpopulation.
• Territoriality.
• Pollution and destruction of natural resources.
• Organized warfare.
• Natural catastrophes?
• Comet/asteroid impact.
• Massive volcanism.
• Ice age.

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Estimates of N

• N R ? fp ? ne ? fl ? fi ? fc ? L
• N 1 ? 0.5 ? 2 ? 1 ? 1 ? 1 ? 109 y
• 109 civilizations
• 1 star in 100 has a communicable civilization
• Nearest could be 45 ly away

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Estimates of N

• N R ? fp ? ne ? fl ? fi ? fc ? L
• N 1 ? 0.5 ? 2 ? 1 ? 1 ? 1 ? 102 y
• 102 civilizations
• 1 star in 109 has a communicable civilization
• Nearest could be 3000 ly away

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Project Phoenix
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Project Phoenix

• Successor to cancelled NASA SETI program, funded
  entirely from private sources.
• Began in 1995 using the 65 m radio telescope in
  Parkes, Australia.
• 1000 sun-like stars within 200 ly, at frequencies
  of 1-3 GHz, 1Hz at a time.
• The search is for narrow-band artificial
  signals.

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Is the signal real?

• Narrow band?
• Detectable over several frequencies?
• Defense/civilian interference?
• Repeatable observation?
• FUDD - Follow Up Detection Device
• Tracks at sidereal rate?
• Modulation?

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Ohio State Wow Signal

• Ohio State University detected a very strong
  signal on August 5, 1977.
• It did track at a sidereal rate.
• It was never observed again.
• http//www.setileague.org/articles/calibwow.htm

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Ohio State Wow Signal
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Ohio State Wow signal

• Jerry Ehman, the volunteer who was present when
  the Wow signal was detected poses beside the
  Big Ear radio telescope