Transcript Leo_Presentation_Combined_2

Steven Prinsen
Dan Cipera
Mat Remillard
Mark Johnson
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What Is Life?
The Search Within Our Solar System
Searching Beyond the Solar System
Probability of Life
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Broad definition
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“The period between birth and death”
“The sum of all activities of a plant or an animal”
“Activities”
Respiration
• Reproduction
• Nutrition
• Excretion
• Locomotion
• Growth
• Reaction to stimuli
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Quartz
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Lifelike
 Growth
 Nutrition
 Reproduce?
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Not Lifelike
 Movement
 Excretions
 External Stimuli
www.howstuffworks.com/quartz-watch.htm
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Fire
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Lifelike
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Respiration
Growth
Movement
Reproduction
Eats
Excretes
Reacts to stimuli
Not Lifelike
• Evolving
• Adaption to change
www.funsci.com/fun3_en/fire/fire.htm
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Life
Growth
 Reproduce
 Adapt
 Evolve
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http://www.hickerphoto.com/rain-forest-streams-9157-pictures.htm
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95% of Life
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Last 5%
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Calcium, Phosphorus, Chlorine, Sulfur, Potassium,
Sodium, Magnesium, Iodine, Iron, and trace
elements
Most abundant universal elements
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Hydrogen, Oxygen, Carbon, Nitrogen
Hydrogen, Oxygen, Carbon, Nitrogen
Helium, Neon
Most abundant earth elements
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Silicon, Iron, Magnesium, Oxygen
The Search For Life In The Universe, Goldsmith and Owen
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Carbon
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Monomers
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Complex molecules
Nitrogen and Oxygen
Small molecules
Compose polymers
Amino Acids, sugars, fatty acids, nucleotides
Polymers
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More complex molecules
Proteins
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Laevorotatory (L) vs Dextrorotatory (D)
 Non living material is 50/50
 L configuration
 Amino Acids
 D configuration
 Sugars, DNA, RNA
 Increases efficiency
Amino Acids
 20 used
Astrobiology, November 10, 2008.
 100 per protein
 20100 possible combinations
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Meteorites
L-amino acids 16% excess
Astrobiology, November 10, 2008.
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Nucleotides
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Four types
 A, T, G, C
Specify Amino Acids
 16 combinations
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Sets of Three
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64 combinations
Redundancies
Prevents mistakes
http://yihongs-research.blogspot.com/2008/09/new-generationbusiness-demands-new-dna.html
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Molecular level
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DNA Mutation
• Gamma Rays
• Cosmic Rays
• Mutagens
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Changes reproductive efficiency
Energy
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From the Sun
Photosynthesis
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Sunlight
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Steady energy
 Key to survival
 3.5 billion years
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Photosynthesis
 Ensures a chance to survive
http://photo.net/photodb/photo?photo_id=3666216
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Formed by accretion
 Hydrogen
 Reducing
 Methane
 Ammonia
 Water Vapor
Resembles Jupiter and Saturn
 Left quickly
 Volatile elements joined earth last
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 H, C, N, O
 Life elements
 Comets
http://www.williamsclass.com/EighthScience
Work/Atmosphere/EarthsAtmosphere.htm
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Hydrogen bound to Oxygen
UV breaks up
 Photodissociation
 Made new compounds
Chem Reactions with crust
Mildly Reducing
 CO
 CO2
 N2
 H2O
 H, H2
Mars, Venus
Astrobiology, Monica Grady
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Water doesn’t imply life
May be able to detect atmosphere data
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Transiting planets
Nonequilibrium reaction byproducts
 Free Oxygen
 Photosynthesis
Terrestrial
Similarities
M
≈ 1 Earth Mass
Iron Core -> Magnetic Field
Orbit
The
and Rotation
4 Most Vital Elements for Life
Carbon,
Liquid
Hydrogen, Oxygen, Nitrogen
Water!
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Europa
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Galileo Missions
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Slightly smaller than our
moon
Silicate Rock – Iron Core
Atmosphere of Oxygen
Smooth, icy surface
Oceans Underneath?
Extremophiles?
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Titan
Cassini-Huygens
Mission
50% Larger than our moon
Surface of water ice and organic
compounds
Thick Atmosphere of Nitrogen
Liquid Hydrocarbon Lakes
(Ethane and Methane)
But... -290 F (-179C)
Mariner
Probes
No Plate Tectonics
No Global Magnetic Field
Atmospheric Pressure roughly
1% of Earth's
No liquid water on surface
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… No multicellular organisms
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Viking Landers
Search for bacteria-like
organisms
Soil showed C02
production when
interacted with water
No organic molecules
detected
Phoenix Lander (May 25 2008)
Water-ice in Martian
subsurface
Small concentrations of salts
Mars Reconnaissance Orbiter
(November 20, 2008)
Vast glaciers of ice
Evidence of a previously
“wet” Mars
Planned Missions
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Mars Science Laboratory
(2009)
Maven (2013)
Other Proposals
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Mars Sample Return
Astrobiology Field Lab
Deep-Drill Lander
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Idea is to Identify
“Earth-like”
planets- rocky
worlds similar to
our own
Very difficultmost exoplanets
we’ve found thus
far are gas giants
the size of Jupiter
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Planet’s gravity affects it’s
parent star- causes slight
variations in star’s radial
velocity
These variations are detectable
by measuring Doppler shifts (i.e.
a spectrograph measuring
Doppler shifts in spectral lines
from a star)
Current instruments can detect
~1 m/sec shift; problem is,
Earth-size planets induce ~0.1
m/sec shift
Also, can only tell mass- not
diameter/ composition/
atmosphere/ etc.
HARPS 3.6 m telescope
(www.eso.org)
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As planet transits in front
of sun, dip in luminosity is
recorded
Technique can be used to
determine diameter and
mass, thus giving a density
Orbit must lie in correct
plane
Period must be sufficiently
short, or telescope must
observe star continuously
for a longer time
www.space.com
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Best way to determine a
planet’s chemical make-up
(analyzing spectral lines)
Fomalhault b was first
exoplanet to be directly
imaged visually - HST
Problem: for most stars,
luminosity from star far
outshines reflection from
planet
Also, Earth’s atmosphere
both narrows observable
frequency ranges and
causes blurring/seeing of
visible light
Fomalhault b
www.spacetelescope.org
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Space-based telescopes (Hubble, Kepler, TPF)
negate the atmosphere problem
The light problem is much trickier (for
example, at 10 pc, angular separation for 1 A.U.
is 100 marcseconds)
To block out the light from the star, a
coronagraph is needed
Possible designs for the
Terrestrial Planet Finder
satellites
planetquest.jpl.nasa.gov
Kepler Space Telescope
www.seti-inst.edu
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Ratio of Sun’s Luminosity to light reflected from Earth
-Lsun= 4e33 erg/sec
-1 AU= 1.5e13 cm
-Earth’s radius= 6.4e8 cm
-Earth’s Albedo= 0.367
Flux from the sun to Earth:
Fsun
L
4 1033
6
2
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1.4
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10
erg/sec/cm
4ππ 2 4ππ(1. 1013 ) 2
“Luminosity” of Earth
LEarth   (rE2 )( Fsun )
 0.367(3.14)(6.4 108 ) 2 (1.4 106 )  6.6 1023 erg / sec
Ratio
LEarth 6.6  10 23
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LSun
4  10 33
1.7  1010
(About 1 in 20
Billion)
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Occulter: part of a
coronagraph that
physically blocks light
from a star
Problems: lower
resolution, diffraction
effects still obscure planet
New Worlds Mission- use
a distant occulter to block
star’s light
Geometry of occulter can
be modified to “smooth
out” diffraction rings
Occulter can also be
“apodized”- modified to
help offset diffraction
effects
New Worlds Mission Concept
www.planetquest.jpl.nasa.gov
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Chemical Composition- Water, Oxygen,
Ozone, CO2
Can determine through spectral analysis
“Red Edge”- Chlorophyll in plants reflects in
infrared
Changes in reflectivity
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If a star passes in front of a
background star, the gravity
of the foreground star causes
microlensing
The presence of a planet
orbiting the foreground star
affects the observable
microlensing
This effect can be observed
even with planets at Earth’s
scale
Correct alignment is very
rare, and only observable for
a few days/weeks
An equation postulated by Dr. Frank D. Drake in 1961.
The Drake equation in it’s original form:
Dr. Frank Drake
N*= Total stars in galaxy
fs = sun-like stars (fraction)
fp = stars with planets (fraction) fi = planets with life (fraction)
ne = life supportable planets
fc = planets with intelligence (fraction)
fl = life time of communicative civilization (fraction)
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Galaxy Factors
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Solar System Factors
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“Earth” Factors
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Wild Cards
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Galaxy Factors
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Type of galaxy
 Enough heavy elements
 Not small, irregular or elliptical
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Position in galaxy
 Not positioned in the halo, edge, or center
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Solar System Factors
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Stable planetary mass
 Giant planets allow for orbital stability
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Jupiter-like neighbor
 Absorbs comets and asteroids
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A Mars
 Possible life source
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Large Moon
 Stabilizes tilt
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Right Mass of star
 Right amount of ultraviolet released
 Long enough lifetime
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“Earth” Factors
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Distance from star
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 Sufficient amount
 Habitat for complex life
 Liquid water near surface
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 Enough heat for plate
tectonics
 Able to support
atmosphere and ocean
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 Right composition and
Planetary mass
 Solid/molten core
pressure
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Carbon amount
 Enough for life but not enough
for runaway greenhouse effect
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Oxygen Evolution
 Development of
Tilt
 Mild seasons
Atmospheric properties
 Adequate temperature
 No tidal lock
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Oceans’ size
photosynthesis
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Biological evolution
 Complex plants and animals
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“Earth” Factors
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Giant impacts
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Plate tectonics
 Few giant impacts
 Land mass creation
 No major sterilizing
 Biotic diversity
impacts
 Silicate thermostat
 Magnetic field
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Wild Cards
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Inertial interchange
event
Snowball Earth
Cambrian explosion
An equation suggested by Professor Peter Ward and Professor
Donald Brownlee from their book “Rare Earth”:
N*= Total stars in galaxy
fc = planets with complex life (fraction)
fp = stars with planets (fraction)
fi = planets with life (fraction)
fpm = metal-rich planets (fraction) fm= planets with large moon (fraction)
ne = life supportable planets
fj = Jupiter-sized planets (fraction)
ng = stars in habitable zone
fme = low number of mass destruction events (fraction)
fl = life time of complex life (fraction)
Drake Equation with Dr. Drake’s current estimation of intelligent life in our galaxy:
Rare Earth Equation with our estimation of intelligent life in our galaxy:
The Point:
If any of these many variables approach zero, the total will be near zero!
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“I'll tell you one thing about the universe,
though. The universe is a pretty big place. It's
bigger than anything anyone has ever dreamed
of before. So if it's just us... seems like an awful
waste of space”.
-Ellie Arroway, Contact
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“…And pray that there's intelligent life
somewhere up in space, -'Cause there's buggerall down here on Earth”.
-Monty Python and the Meaning of Life
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What Is Life?
The Search Within Our Solar System
Searching Beyond the Solar System
Probability of Life
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Astrobiology, Monica Grady, The Natural History Museum, London,
2001
The Search For Life In The Universe, 2nd Edition, Goldsmith and
Owen, Addison-Wesley Publishing Company, 1992
A Race To Find Alien Planets, Carlisle, Sky & Telescope, January 2009,
p28.
Circular Polarization and the Origin of Biomolecular Homochirality,
Bailey, Bioastronomy, 1999
On the Origins of Biological Homochirality, Sandra Pizzarello,
Astrobiology, November 10, 2008.
www.nasa.gov
Rare Earth, Ward, Brownlee, Springer Science, 2000
Titan: Earth in Deep Freeze, Barnes, Sky & Telescope, December 2008
Are We Alone, Imaging Extrasolar Earthlike Planets from Space,
Presentation by Prof. N. Jeremy Kasdin
David J. Des Marais et al. “The NASA Astrobiology Roadmap.” 9 Oct
2008. 19 Oct 2008