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

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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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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”

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Books” (1712)

-Sir Richard Blackmore, “The Creation: a Philosophical Poem in Seven

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

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Lagrange points

Space Probes

Three main types

Probes that land on a planet

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Mars rovers, etc.

Probes that orbit around a planet

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Pioneer Venus 1

Probes that operate in free space

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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

Flagship probes: Voyager 1 & 2

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

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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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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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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

Collected atmospheric data

GC/MS, Aerosol collectors, Surface composition analyzers

Postulated

“shoreline” landing

Huygens 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 Cassini


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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

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Neptune, discovered in 1846

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