Transcript Neptune, discovered in 1846

There Goes The Neighborhood:
Our Understanding of Life in the
Solar System as Gathered by
Space Probes
I.A. Townsend
Spring 2011
Part I: What We Believed
Space: The Final Frontier. . .
http://www.courier-journal.com/blogs/bruggers/uploaded_images/space2-735342.jpg
But Are We Alone?
Early Understandings
Ancient societies: Muddled with religion
Celestial bodies inhabited by Gods
Talmud, Bible, Koran etc. all very vague on
concept of other worlds
Aristotle and Ptolemy
Proponents of geocentric universe

This makes other worlds unlikely!

Ancient Greek thinking basically fell in line with this
New Outlooks
• 16th Century:
Copernican
heliocentric model
• 1608: First refracting
telescope
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http://physicsworld.com/blog/galileo_04.jpg
Astronomy Explodes!
Objects formerly
undetected are now
visible
More planets than
expected discovered in
solar system
Moons, Rings, Asteroids,
etc.
Neptune, discovered in 1846
http://upload.wikimedia.org/wikipedia/commons/0/06/Neptune.jpg
Period of Speculation
Many astronomers optimistic about intelligent
life
“Cosmic Pluralism” championed by Kant and
Franklin
Inspires art and literature postulation
“We may pronounce each orb sustains a race /
Of living things adapted to the place”
-Sir Richard Blackmore, “The Creation: a Philosophical Poem in Seven

Books” (1712)
Life on Mars?
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Canal Network
Late 19th Century:
Canals Discovered on
Mars
Lakes also appear to
exist
An intelligent society
could exist / have
existed
http://www.spacestationinfo.com/images/canals-mars.gif
Science, What A Buzzkill
1894: William Wallace Campbell
spectroscopicallly analyzes Mars
No substantial evidence of water or oxygen
Canal building beings probably can’t survive
By 1909, telescopes have improved enough to
rule out canals too
Merely optical illusions
Early 20th Century
“UFO” sightings popular
Alien based religions pop
up (e.g. Scientology)
Belief that celestial
bodies could be
populated still strong
http://www.prlog.org/10265449-dianetics-the-modern-science-of-mental-health.jpg
Part II: Age of Exploration
Space Age
1957: Sputnik 1
launched
US Government and
Citizens Panic
NASA formed and first
US satellite in 1958
http://upload.wikimedia.org/wikipedia/commons/b/b0/Sputnik_1.jpg
Space Probes
Robotic spacecraft that leaves the gravity well of
earth
Once out of well: heliocentric orbit
Different approaches to guided movement
Fuel burning
Gravitational slingshot
Interplanetary transport network

Lagrange points
Space Probes
Three main types
Probes that land on a planet

Mars rovers, etc.
Probes that orbit around a planet

Pioneer Venus 1
Probes that operate in free space

Pioneers 10 & 11, Voyagers 1&2, etc.
First Encounters
1960’s: Many probes
designed to study nearby
planets
Both U.S. and Soviet
missions
Invaluable information
gathered by both orbiters
and landers
Venera 7, 1970
http://upload.wikimedia.org/wikipedia/commons/5/58/Venera_7_capsule.jpg
Outer Solar System
Early atmospheric and surface data confirms life
highly unlikely on Mercury, Venus or Mars
Only hope: Outer solar system objects
First probes: Pioneer 10 & 11
First clear view of Jupiter and Saturn
Used to find safe passage through region
Open many more questions for future
exploration
Voyager Program
Launched in 1977
Two identical craft
“Grand Tour”
Powered by PuO2
Thermal energy
Mission: Study outer
planets, satellites, and
eventually heliopause
http://en.wikipedia.org/wiki/File:Voyager.jpg
http://en.wikipedia.org/wiki/File:Voyager_Program_-_spacecraft_diagram.png
Key Instrumentation
Magnetometers
Cosmic Ray Detectors
IR/UV Spectrometers
Photopolarimeter
Digital tape recorder
(62.5 MB data storage)
http://rst.gsfc.nasa.gov/Sect19/Sect19_14.html
Primary Mission
Close visits of Jupiter, Saturn, Uranus, and
Neptune
Pluto optional, not taken
Data gathered on planet composition, observed
weather phenomena, satellites, etc.
Greatly expands our understanding of these
planets
Primary Mission Flight Path
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Interstellar Mission
Mission extension funded after 12 year primary
mission complete
Characterize solar influence on far reaches of
solar system
Find the heliopause boundary

Outer limit of solar magnetic fields and wind
Measure interstellar fields, particles, and waves
unaffected by solar winds
Interstellar Mission Flight Path
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http://rst.gsfc.nasa.gov/Sect19/Sect19_14.html
Future
Voyager 1: Currently 17,428,000,000+ km out
Will not be overtaken by any current human
object
Currently in heliosheath, will reach interstellar
medium by 2015
Instruments are systematically shutting down to
extend useful lifetime to 2020
Golden Record
Society’s message to extraterrestrials
Mounted on the side of both Voyagers
Contains greetings from earth in 55 languages
Music and sounds
115 analog images
How could the record be played?
Instructions on cover
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http://voyager.jpl.nasa.gov/spacecraft/images/VoyagerCover.jpg_2big.gif
Most Important Discoveries
Atmospheric composition of all four gas giants
22 satellites undetected from earth
Active volcanism (IO)
Probable liquid water existence (Europa)
Large scale storms on Neptune (Dark Spot)
Peculiar Magnetospheres (Uranus, Neptune)
Heliopause, Solar System asymmetry
Cassini-Huygens
Launched in 1997
Designed specifically to
orbit and study Saturn
Modern
instrumentation
Hugens probe: first
landing accomplished
in outer solar system
http://lasp.colorado.edu/cassini/images/cassini_config_large.jpg
Huygens
Collected
atmospheric data
GC/MS, Aerosol
collectors, Surface
composition
analyzers
Postulated
“shoreline” landing
http://upload.wikimedia.org/wikipedia/commons/b/bc/Huygens_on_Titan.jpg
Gathered Data
Hydrocarbon lakes not as
common as thought
Titanian haze made up of
complex organic molecules,
methane
“Sand” made of ice grains,
possibly water ice
Atmosphere: Mostly N2,
remainder CH4 + hydrocarbons
http://upload.wikimedia.org/wikipedia/commons/b/bc/Huygens_surface_color.jpg
What we learned
Most important: Europa’s probable ocean
Strong life potential
Active volcanoes on IO
Intense storms on Jupiter and Neptune
Winds >1000 km/hr
Detailed composition of Titan’s atmosphere
Hydrocarbon lakes, Complex Molecule Haze
Future Work
Solar system probes confirm that neighbors of
any sort are improbable at best
To find any life in solar system, we will need
more invasive tactics
Life forms might need to deviate entirely from
our biological understandings
Philosophical Implications
We have sent human artifacts millions of miles
into space
Voyager 1 might approach other solar systems in
40,000 years
Maybe we won’t have to find intelligent life,
they will come to us
At the very least, we might confuse some aliens
long after extinction
http://upload.wikimedia.org/wikipedia/commons/5/58/Venera_7_capsule.jpg
Conclusion: Pale Blue Dot
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Pictures from Voyager
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Pictures from Voyager
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Pictures from Voyager
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Pictures from Voyager
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Pictures from Voyager
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Pictures from Voyager
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Pictures from Voyager
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Pictures from Voyager
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Pictures from Voyager
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http://voyager.jpl.nasa.gov/image/images/neptune/darkspot.gif
Pictures from Cassini
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Pictures from Cassini
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Pictures from Cassini
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http://upload.wikimedia.org/wikipedia/commons/5/59/Enceladus_backdropped_by_ring_shadows_on_Saturn.jpg
Sources
http://www.exploratorium.edu/origins/arecibo/ideas/index.html
http://saturn.jpl.nasa.gov/
http://lifeng.lamost.org/courses/astrotoday/CHAISSON/AT306/HTML/AT30606.HTM
http://library.thinkquest.org/03oct/02144/text/mars/probes.htm
http://messenger.jhuapl.edu/the_mission/index.html
http://www.nasa.gov/mission_pages/voyager/voyagerf-20070820.html
http://www.nasa.gov/mission_pages/cassini/main/index.html
http://rst.gsfc.nasa.gov/Sect19/Sect19_14.html
http://en.wikipedia.org (Multiple Pages)