9/30/03Prof. Lynn Cominsky1 Class web site: lynnc/courses/a305 Office: Darwin 329A and NASA E/PO...

9/30/03 Prof. Lynn Cominsky 1

Class web site: Class web site: http://http://glastglast

.sonoma.edu/~lynnc/courses/a305.sonoma.edu/~lynnc/courses/a305

Office: Darwin 329A and NASA E/POOffice: Darwin 329A and NASA E/PO

(707) 664-2655(707) 664-2655

Best way to reach me: Best way to reach me: [email protected]@charmian.sonoma.edu

Astronomy 305/Frontiers in Astronomy 305/Frontiers in AstronomyAstronomy


Astrobiology Questions (3 Astrobiology Questions (3 weeks)weeks)

Is there life elsewhere in our Solar Is there life elsewhere in our Solar system? (Group 5)system? (Group 5)

Are Earth-like planets common? Are Earth-like planets common? (Group 6) (Group 6)

Are we alone? (Group 7)Are we alone? (Group 7)


Is there life elsewhere in the Is there life elsewhere in the solar system? What is life? solar system? What is life? Activity #1Activity #1 In groups of 3-4 students, develop a common In groups of 3-4 students, develop a common

set of characteristics that can identify lifeset of characteristics that can identify life Write these characteristics down on your Write these characteristics down on your

worksheetsworksheets Test your definition by asking 5-10 questions Test your definition by asking 5-10 questions

– one group thinks of something that is alive – one group thinks of something that is alive or not, and a second group asks them or not, and a second group asks them questions about the characteristics to see if questions about the characteristics to see if they can correctly determine the answerthey can correctly determine the answer

NOTE: you cannot ask “Is it alive?”NOTE: you cannot ask “Is it alive?”


Group 5Group 5


What is Life?What is Life?

Some good criteria:Some good criteria: Has heritable traits that can be transferredHas heritable traits that can be transferred Able to have a population that evolves and Able to have a population that evolves and

adapts to the external environmentadapts to the external environment Uses energy to maintain an internal stateUses energy to maintain an internal state

Some pretty good criteria:Some pretty good criteria: Has a complex internal structure (icicles?)Has a complex internal structure (icicles?) Has cell membranes or walls that create an Has cell membranes or walls that create an

internal environment (viruses?)internal environment (viruses?) Able to extract energy from the environment Able to extract energy from the environment

(fire?)(fire?)


What is Life?What is Life? Some not-so-good criteria:Some not-so-good criteria:

Moves independently (plants?)Moves independently (plants?) Takes in nutrients (fire?)Takes in nutrients (fire?) Gives off energy (fire?)Gives off energy (fire?) Produces waste products (fire, icicles?)Produces waste products (fire, icicles?)

Also on Earth, all life:Also on Earth, all life: Has Carbon-based chemistryHas Carbon-based chemistry Requires liquid waterRequires liquid water

LIVING MATTER EVADES THE DECAY TO EQUILIBRIUM

- Erwin Schrodinger (famous physicist)


What is life? Activity #2What is life? Activity #2 Examine the three jars – you can smell and Examine the three jars – you can smell and

touch the contents, but do not taste themtouch the contents, but do not taste them Now add hot water to cover the contentsNow add hot water to cover the contents Record your observations on the worksheetRecord your observations on the worksheet Use your list of characteristics to determine if Use your list of characteristics to determine if

there is anything alive in jars 1, 2 or 3there is anything alive in jars 1, 2 or 3 How can you distinguish between a living and How can you distinguish between a living and

non-living chemical change?non-living chemical change? Refine your definition of life based on these Refine your definition of life based on these

activities and write it on your worksheetactivities and write it on your worksheet


Schrodinger on What is Life?:Schrodinger on What is Life?: What is the characteristic feature of life? What is the characteristic feature of life?

When is a piece of matter said to be alive? When is a piece of matter said to be alive? When it goes on 'doing something', When it goes on 'doing something', moving, exchanging material with its moving, exchanging material with its environment, and so forth, and that for a environment, and so forth, and that for a much longer period than we would expect much longer period than we would expect an inanimate piece of matter to 'keep an inanimate piece of matter to 'keep going' under similar circumstances. When going' under similar circumstances. When a system that is not alive is isolated or a system that is not alive is isolated or placed in a uniform environment, all placed in a uniform environment, all motion usually comes to a standstill very motion usually comes to a standstill very soon as a result of various kinds of friction; soon as a result of various kinds of friction;


Schrodinger on What is Life? Schrodinger on What is Life? (cont’d)(cont’d) differences of electric or chemical differences of electric or chemical

potential are equalized, substances potential are equalized, substances which tend to form a chemical which tend to form a chemical compound do so, temperature becomes compound do so, temperature becomes uniform by heat conduction. After that uniform by heat conduction. After that the whole system fades away into a the whole system fades away into a dead, inert lump of matter. A dead, inert lump of matter. A permanent state is reached, in which no permanent state is reached, in which no observable events occur. The physicist observable events occur. The physicist calls this the state of thermodynamical calls this the state of thermodynamical equilibrium, or of 'maximum entropy'.equilibrium, or of 'maximum entropy'.


Solar SystemSolar System

diameter ~5.9 x 109 km



Relative sizes and order of planetsSun Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto


Planet Distance Orbital Period Diameter Mass Moons

(103 km) (days) ( km) (kg)

Mercury 57910 87.97 4,880 3.30e23 0

Venus 108200 224.70 12,104 4.869e24 0

Earth 149600 365.26 12,756 5.9736e24 1

Mars 227940 686.98 6,794 6.4219e23 2

Jupiter 778330 4332.71 142,984 1.900e27 61

Saturn 1429400 10759.50 120,536 5.68e26 31

Uranus 2870990 30685 51,118 8.683e25 21

Neptune 4504300 60190 49,532 1.0247e26 11

Pluto 5913520 90800 2274 1.27e22 1



Solar System habitability Solar System habitability factorsfactors

• Temperature range (–15o C to +115o C on Earth)

• Protection (look what happened to the dinosaurs!)

• Light (or other source of heat or energy)

• Liquid water (geothermal or atmospheric cycles)

• Nutrients (chemicals, vitamins, minerals, fertilizers)

• Energy source (light, food, carbohydrates, fats, sugars)


MercuryMercury Highly eccentric orbit (used to test GR)Highly eccentric orbit (used to test GR) Rotates 3 times in every 2 yearsRotates 3 times in every 2 years Great temperature variations on surfaceGreat temperature variations on surface -183-183ooC (dark side) – 252C (dark side) – 252ooC (sun side)C (sun side) Very thin atmosphereVery thin atmosphere Low magnetic fieldLow magnetic field No waterNo water Many cratersMany craters


VenusVenus Brightest object in sky Brightest object in sky

(except Sun and Moon)(except Sun and Moon) 1 day on Venus = 1 day on Venus =

243 days on Earth243 days on Earth Greenhouse effect raises Greenhouse effect raises

surface temperature to surface temperature to 464464ooC (hotter than Mercury)C (hotter than Mercury)

Thick carbon dioxide Thick carbon dioxide atmosphere with sulfuric atmosphere with sulfuric acid cloudsacid clouds

No surface water, few No surface water, few craterscraters

Lava flows from volcanoesLava flows from volcanoes

Magellan Radar image


EarthEarth

71% of the surface is covered with liquid 71% of the surface is covered with liquid waterwater

Atmosphere of 77% nitrogen, 21% oxygenAtmosphere of 77% nitrogen, 21% oxygen Greenhouse effect from small amount of Greenhouse effect from small amount of

carbon dioxide raises the surface carbon dioxide raises the surface temperature to 14temperature to 14ooCC Active surface due to Active surface due to plate tectonics plate tectonics earthquakes and earthquakes and volcanoesvolcanoes Mantle and crust Mantle and crust mostly silicon mostly silicon compounds compounds Few cratersFew craters


Earth’s Moon (Luna)Earth’s Moon (Luna) Lunar Prospector missionLunar Prospector missiondiscovered ice at both discovered ice at both

polespoles No atmosphereNo atmosphere -153-153ooC to 107C to 107ooCC Receives same amount of Receives same amount of

sunlight as Earth, has sunlight as Earth, has same chemical makeupsame chemical makeup


MarsMars Being explored by Global Surveyor and 2001 Being explored by Global Surveyor and 2001

Mars OdysseyMars Odyssey Average temperature –63Average temperature –63ooCC Varied terrain, mountains, canyons and cratersVaried terrain, mountains, canyons and craters Erosion indicates water used to be presentErosion indicates water used to be present Similar to Earth chemicallySimilar to Earth chemically No active volcanoesNo active volcanoes Very thin COVery thin CO22 atmosphere atmosphere Little oxygenLittle oxygen Iron and sulfur coreIron and sulfur core


MarsMars

Permanent Permanent COCO22 ice caps ice caps with some with some water icewater ice

Weak Weak sunlightsunlight

Large dust Large dust stormsstorms

Panoramic view from Pathfinder


Life on Mars?Life on Mars?

““Face on Mars”Face on Mars”

1976 Viking ViewMars Global Surveyor Image April 2001


Life on Mars? Martian MeteoriteLife on Mars? Martian Meteorite Found in Antarctica in 1984 but origin is MarsFound in Antarctica in 1984 but origin is Mars Left Mars 16 million years ago, arrived in Left Mars 16 million years ago, arrived in

Antarctica 13,000 years agoAntarctica 13,000 years ago Evidence of water infiltration while on Mars Evidence of water infiltration while on Mars Carbonite mineral globules contain shapes that Carbonite mineral globules contain shapes that

could be dead, fossilized bacteria and their could be dead, fossilized bacteria and their byproductsbyproducts

Meteorite Carbonate Globules

Fossilized Shapes


MeteoritesMeteorites

Most meteorites are chunks of Most meteorites are chunks of asteroids, the Moon or Mars; some are asteroids, the Moon or Mars; some are from cometsfrom comets

>50 billion meteorites have traveled >50 billion meteorites have traveled between Earth and Mars since the birth between Earth and Mars since the birth of the solar systemof the solar system

Panspermia = Life comes from spacePanspermia = Life comes from space Some think meteorites could have Some think meteorites could have

carried life from Mars to Earth or vice carried life from Mars to Earth or vice versaversa

meteor


JupiterJupiter

Giant gas planet: 75% hydrogen, 25% Giant gas planet: 75% hydrogen, 25% heliumhelium

Four largest moons known since 1610 Four largest moons known since 1610 (Galileo):(Galileo): Io, Europa Ganymede and Callisto

Spacecraft exploration since 1973, Spacecraft exploration since 1973, Galileo is still in orbit around JupiterGalileo is still in orbit around Jupiter

Liquid metallic hydrogen mantleLiquid metallic hydrogen mantle Possible hot, rocky corePossible hot, rocky core High velocity winds High velocity winds

driven by internal heatdriven by internal heat


JupiterJupiter

Great Red Spot is lightning storm, with Great Red Spot is lightning storm, with higher pressurehigher pressure

Temperature from –200Temperature from –200ooC at cloud tops C at cloud tops to thousands of degrees in interiorto thousands of degrees in interior

Huge magnetic fieldHuge magnetic field


Jupiter’s Moon: IoJupiter’s Moon: Io

• Youngest surface in Solar System

• Many active volcanoes, sulfur

• Temperature –150oC to 1250oC

• No known water

• Sulfur crust

• No atmosphere

Prometheus volcano

Prometheus erupting


Jupiter’s Moon: EuropaJupiter’s Moon: Europa

• Thin outer layer of water ice (1-10 km thick)

• Possible liquid water ocean underneath the surface

•No atmosphere

• Volcanic activity under ocean?

•Sulfur dust from Io’s eruptions on surface


Jupiter’s Moon: GanymedeJupiter’s Moon: Ganymede

• Rock and water ice on surface

• No atmosphere

• Average noon temperature –121oC on equator


Jupiter’s Moon: CallistoJupiter’s Moon: Callisto

• Ice-rock mix throughout

• Possible salt water underneath the surface

•No atmosphere

•Average temperature –108oC on equator


SaturnSaturn Giant gas planet: 75% hydrogen, 25% heliumGiant gas planet: 75% hydrogen, 25% helium Oblate, flattened appearance, with bright ringsOblate, flattened appearance, with bright rings Three spacecraft visits since 1979, Cassini is Three spacecraft visits since 1979, Cassini is

on its way, will arrive in 2004on its way, will arrive in 2004 Least dense planet, density is less than waterLeast dense planet, density is less than water Hot rocky core, liquid hydrogenHot rocky core, liquid hydrogen Bands less visible thanBands less visible thanJupiter; also has spotsJupiter; also has spots Very thin ringsVery thin rings Rings mostly water iceRings mostly water ice Strong magnetic fieldStrong magnetic field


Saturn’s moon TitanSaturn’s moon Titan

Average surface temperature –179Average surface temperature –179ooCC Water icebergs in an ocean of methane?Water icebergs in an ocean of methane? 95% nitrogen, 5% methane atmosphere95% nitrogen, 5% methane atmosphere Pressure about 1.5 timesPressure about 1.5 times

Earth’s atmosphereEarth’s atmosphere No water in atmosphereNo water in atmosphere Dim sunlightDim sunlight Will be visited by HuygensWill be visited by Huygens

probe dropped from Cassiniprobe dropped from Cassini


UranusUranus

Gas giant, mostly hydrogen atmosphereGas giant, mostly hydrogen atmosphere Looks blue due to methane in atmosphere Looks blue due to methane in atmosphere Discovered by Herschel in 1781Discovered by Herschel in 1781 Visited by Voyager 2 in 1986Visited by Voyager 2 in 1986 Uranus’ pole points toward SunUranus’ pole points toward Sun Rock and ice, only 15% hydrogenRock and ice, only 15% hydrogen No rocky core evidentNo rocky core evident Clouds and color changesClouds and color changes 11 known rings11 known rings Extremely tilted magnetic fieldExtremely tilted magnetic field 20+ moons, 5 are rather large20+ moons, 5 are rather large

HST image of Uranus and its rings


NeptuneNeptune Discovered in 1846 after being predicted from Discovered in 1846 after being predicted from

perturbations in Uranus’ orbitperturbations in Uranus’ orbit Visited by Voyager 2 in 1989Visited by Voyager 2 in 1989 Composition similar to UranusComposition similar to Uranus Internal heat sourceInternal heat source Strong winds and stormsStrong winds and storms Great dark spot in 1989, Great dark spot in 1989, not seen by HST in 1994not seen by HST in 1994 3 Dark rings seen by Voyager 23 Dark rings seen by Voyager 2 Tilted magnetic fieldTilted magnetic field 8 known moons, Triton is large8 known moons, Triton is large

HST image of Neptune


PlutoPluto

Smallest planet and furthest from Sun (usually)Smallest planet and furthest from Sun (usually) Smaller than 7 moons in our solar systemSmaller than 7 moons in our solar system Discovered in 1930 by Clyde TombaughDiscovered in 1930 by Clyde Tombaugh Orbit crosses inside NeptuneOrbit crosses inside Neptune No spacecraft observationsNo spacecraft observations Is Pluto really a planet?Is Pluto really a planet?

YES: It has a moon named CharonYES: It has a moon named Charon NO: It resembles asteroids NO: It resembles asteroids NO: It has an elliptical orbitNO: It has an elliptical orbit

Rock and ice, little atmosphereRock and ice, little atmosphere

Pluto and Charon


CrateringCratering

Mercury and the Moon show the Mercury and the Moon show the results of bombardment during results of bombardment during early formation of solar systemearly formation of solar system

Mercury

Moon


Earth’s SurfaceEarth’s Surface

Q: Why does the Earth’s surface Q: Why does the Earth’s surface show little evidence of cratering?show little evidence of cratering?

Bombardment of Earth was similar Bombardment of Earth was similar to that of the Moon, Venus, Mars to that of the Moon, Venus, Mars and Mercuryand Mercury

A: Earth’s surface is actively A: Earth’s surface is actively reforming due to volcanic activity, reforming due to volcanic activity, erosion from water, plate erosion from water, plate tectonics,etc.tectonics,etc.


Volcanic ActivityVolcanic Activity

Io Jupiter’s Moon) shows volcanic Io Jupiter’s Moon) shows volcanic activityactivity

Venus also has lava flowsVenus also has lava flowsPrometheus

volcano on Io

Magellan Radar image of Venus


Erosion and WaterErosion and Water

Erosion (most likely due to liquid Erosion (most likely due to liquid water) also seems to have affected water) also seems to have affected Mars, which also has mountains Mars, which also has mountains and cratersand craters

Moon has frozen water at poles but Moon has frozen water at poles but no signs of erosionno signs of erosion

Mars


Where is the Water?Where is the Water?

Europa (Jupiter’s Moon) Europa (Jupiter’s Moon) thin outer layer of water ice thin outer layer of water ice

(1-10 km thick)(1-10 km thick) possible liquid water ocean possible liquid water ocean

underneath the surfaceunderneath the surface Callisto (Jupiter’s Moon)Callisto (Jupiter’s Moon)

• Ice-rock mix throughoutIce-rock mix throughout

• Possible salt water Possible salt water underneath surfaceunderneath surface


Where is the Water?Where is the Water?

SaturnSaturn Rings are mostly water iceRings are mostly water ice Will be studied by Cassini Will be studied by Cassini

in 2004in 2004

Titan (Saturn’s Moon)Titan (Saturn’s Moon) Water icebergs in an Water icebergs in an

ocean of methane?ocean of methane? No water in atmosphereNo water in atmosphere Huygens probe will be Huygens probe will be

dropped from Cassinidropped from Cassini


Planetary MissionsPlanetary Missions

MESSENGERMESSENGER (ME (MErcury rcury SSurface, urface, SSpace pace ENENvironment, vironment, GEGEochemistry and ochemistry and RRanging), being built for launch April anging), being built for launch April 2004, arrives at Mercury in 20092004, arrives at Mercury in 2009

VenusVenus program – no current plans program – no current plans Galileo Galileo mission is now over. It flew by Io mission is now over. It flew by Io

on 1/17/02, and by Amalthea on on 1/17/02, and by Amalthea on 11/05/02. It is due to plunge into the 11/05/02. It is due to plunge into the Jovian atmosphere on September 21, Jovian atmosphere on September 21, 2003.2003.


Mars – 5 spacecraft on their way!Mars – 5 spacecraft on their way!

Pathfinder (1996)Pathfinder (1996) Global Surveyor (1999) then two Global Surveyor (1999) then two

disasters. disasters. Two NASA landers (Spirit and Two NASA landers (Spirit and

Opportunity) are on their way to Mars, Opportunity) are on their way to Mars, due to land on January 4 & 25, 2004. due to land on January 4 & 25, 2004.

Europeans: Mars Express orbiter and Europeans: Mars Express orbiter and Beagle 2 lander – due to arrive 12/26/03Beagle 2 lander – due to arrive 12/26/03

Japanese orbiter (launched in 1998) will Japanese orbiter (launched in 1998) will arrive at Mars in January 2004.arrive at Mars in January 2004.


Spirit and OpportunitySpirit and Opportunity

Launch movie Entry movie

Exploration movie


Europa orbiterEuropa orbiter – approved then – approved then eliminated in FY03 budget. Officially eliminated in FY03 budget. Officially “under study.”“under study.”

Cassini Cassini mission to Saturn arrives July mission to Saturn arrives July 2004. Will drop an ESA probe (Huygens) 2004. Will drop an ESA probe (Huygens) onto Titan, and flyby Titan and three onto Titan, and flyby Titan and three smaller moons.smaller moons.

Pluto/Kuiper ExpressPluto/Kuiper Express – Preliminary – Preliminary designs under consideration. Possible designs under consideration. Possible launch in 2006, to arrive 2015-2017.launch in 2006, to arrive 2015-2017.

Planetary MissionsPlanetary Missions


What makes a world habitable?What makes a world habitable? In groups of 3-4, take a set of cards that In groups of 3-4, take a set of cards that

summarize the properties of various solar summarize the properties of various solar system bodiessystem bodies TemperatureTemperature WaterWater AtmosphereAtmosphere EnergyEnergy NutrientsNutrients

Consider the following:Consider the following: What does life need?What does life need? What kinds of conditions might limit life?What kinds of conditions might limit life?

Select your top three candidates for lifeSelect your top three candidates for life


Web ResourcesWeb Resources

Nine Planets tourNine Planets tour http://www.seds.org/nineplanets/nineplahttp://www.seds.org/nineplanets/nineplanetsnets

Martian MeteoriteMartian Meteorite http://www.lpi.usra.edu/lpi/meteorites/mhttp://www.lpi.usra.edu/lpi/meteorites/mars_meteorite.htmlars_meteorite.html

Solar System missionsSolar System missions http://solarsystem.jpl.nasa.gov/missions/http://solarsystem.jpl.nasa.gov/missions/

Schrodinger:Schrodinger: http://dieoff.org/page150.htmhttp://dieoff.org/page150.htm

9/30/03Prof. Lynn Cominsky1 Class web site: lynnc/courses/a305 Office: Darwin 329A and NASA E/PO...

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