NSCI 314LIFE IN THE COSMOS10 - SEARCHING FOR LIFE IN OUR SOLAR SYSTEM: THE OUTER PLANETS AND THEIR MOONSDr. Karen KolehmainenDepartment of Physics CSUSBhttp://physics.csusb.edu/~karen/JUPITERDIAMETER: 11 X EARTHMASS: 318 X EARTH = MORE THAN REST OF SOLAR SYSTEM (EXCLUDING THE SUN) COMBINEDDENSITY: 1.3 gm/cm³SUNLIGHT: 4% OF EARTHTEMP: 125 K (–150oC OR –235oF) AT CLOUD TOPS, BUT WARMER DEEP IN ATMOSPHEREATMOSPHERE: 86% H, 14% He, TRACES of CH4, NH3,H2O, HIGH WINDS & STORMSSURFACE: ONLY ATMOSPHERE IS VISIBLESTRUCTURE: SMALL ROCKY CORE, COVERED BY A LAYER OF METALLIC HYDROGEN, THEN A LAYER OF LIQUID HYDROGEN, THEN THE ATMOSPHERESATURNDIAMETER: 9.5 X EARTHMASS: 95 X EARTHDENSITY: 0.7 gm/cm³SUNLIGHT: 1% OF EARTHTEMP: 90 K (-185 oC or –300 oF) AT CLOUD TOPS, WARMER DEEPER DOWNATMOSPHERE: 86% H, 14% He, TRACES of CH4, NH3, H2O, HIGH WINDS & STORMSSURFACE: ONLY ATMOSPHERE IS VISIBLE STRUCTURE: SMALL ROCKY CORE, COVERED BY LAYERS OF METALLIC HYDROGEN AND LIQUID HYDROGEN, THEN ATMOSPHERERINGS: LARGEST RING SYSTEM OF ANY PLANET, COMPOSED MOSTLY OF CHUNKS OF WATER ICEURANUS DIAMETER: 4 X EARTHMASS: 15 X EARTHDENSITY: 1.2 gm/cm³SUNLIGHT: 0.3% OF EARTHTEMP: 64 K (-210 oC OR –345 oF) AT CLOUD TOPS, WARMER DEEPER DOWNATMOSPHERE: 84% H, 14% He, 2-3% CH4 (NH3 & H2O FROZEN), BLUE COLORS DUE TO METHANESURFACE: ONLY ATMOSPHERE VISIBLESTRUCTURE: SMALL ROCKY CORE, COVERED BY LAYER OF WATER, METHANE, AND AMMONIA, THEN ATMOSPHERENEPTUNEDIAMETER: 3.9 X EARTHMASS: 17 X EARTHDENSITY: 1.7 gm/cm³SUNLIGHT: 0.1% OF EARTHTEMP: 50 K(-220 oC OR –370 oF) AT CLOUD TOPS, WARMER DEEPER DOWNATMOSPHERE: 84% H, 14% He, 2-3% CH4 (NH3 & H2O FROZEN), BLUE COLORS DUE TO METHANESURFACE: ONLY ATMOSPHERE VISIBLESTRUCTURE: SMALL ROCKY CORE, COVERED BY LAYER OF WATER, METHANE, AND AMMONIA, THEN ATMOSPHERELIFE ON THE OUTER PLANETS?DEEP ENOUGH DOWN IN THE ATMOSPHERE, IT IS WARM ENOUGH FOR LIQUID WATER DROPS.SIMPLE ORGANIC MOLECULES HAVE BEEN FOUND IN THE ATMOSPHERES. SUGGESTION: PERHAPS BLIMP-LIKE LIFE FORMS COULD FLOAT OR FLY IN THE ATMOSPHERE.IF THESE EXIST, JUPITER IS THE MOST LIKELY SITE. IT IS THE WARMEST OF THE OUTER PLANETS, AND THEREFORE HAS THE MOST ACTIVE CHEMISTRY.PROBLEM: STRONG CIRCULATION PATTERNS IN THE ATMOSPHERE MIGHT PREVENT COMPLEX ORGANIC MOLECULES FROM FORMING, SO HOW COULD LIFE GET STARTED?MOONS OF OUTER PLANETSMIXTURE OF ICE AND ROCKLOTS OF THEMEACH PLANET WITH ITS MOONS RESEMBLES A MINIATURE SOLAR SYSTEMSMALL MOONS ARE IRREGULARLY SHAPED, WITH NO ATMOSPHERES, NOT GOOD CANDIDATES FOR LIFELARGER ONES ARE SPHERICAL, SOME HAVE ATMOSPHERES OR ARE INTERESTING IN OTHER WAYSCHARACTERISTICS OF LARGE MOONSPlanet NameDensity (g/cm3)Mass (Moon=1)Diameter(Moon=1)EarthJupiterJupiterJupiterJupiterSaturnNeptuneMoonIoEuropaGanymedeCallistoTitanTriton(Pluto)3.33.53.01.91.91.92.12.111.20.72.01.51.80.30.1711.10.91.51.41.50.80.65TIDAL FORCES AND MOONSTHE SIDE OF THE MOON CLOSEST TO ITS PLANET EXPERIENCES A STRONGER GRAVITATIONAL PULL FROM THE PLANET THAN DOES THE SIDE OF THE MOON FARTHEST FROM THE PLANET. THIS PULLED THE MOON INTO AN ELONGATED SHAPE.AS THE MOON ROTATED ON ITS OWN AXIS, ITS SHAPE KEPT CHANGING TO KEEP THE BULGES ON A LINE FACING THE PLANET. THIS CAUSED FRICTION INSIDE THE MOON, WHICH SLOWED ITS ROTATION.JUST LIKE WITH THE EARTH’S MOON, THIS HAS LOCKED THE MOON INTO “SYNCHRONOUS ROTATION” WITH THE PLANET. ONE SIDE OF THE MOON ALWAYS FACES TOWARDS THE PLANET, AND THE OTHER SIDE FACES AWAY FROM THE PLANET.TIDAL FORCES AND MOONSAS THE ORIGINAL ROTATION OF THE MOON WAS SLOWING (BEFORE IT WAS LOCKED INTO SYNCHRONOUS ROTATION), INTERNAL FRICTION HEATED THE MOON ENOUGH TO MELT IT, LEADING TO A DIFFERENTIATED (LAYERED) STRUCTURE.TIDAL FORCES ALSO AFFECTED ORBITS OF MOONS AROUND THEIR PLANETS, LOCKING THEM INTO “RESONANCES.”–EXAMPLE: MOON FARTHER OUT ORBITS IN TWICE THE TIME OF ONE CLOSER IN. ORBITS ARE ELLIPTICAL (NOT CIRCULAR), SO SHAPE OF MOON VARIES SLIGHTLY THROUGHOUT ITS ORBIT AROUND ITS PLANET.–MORE ELONGATED WHEN CLOSER TO PLANET–MORE SPHERICAL WHEN FARTHER AWAY–THIS LEADS TO CONTINUING INTERNAL FRICTION, HEATING THE INTERIOR OF THE MOON.TIDAL EFFECTS ON MOONSAS A RESULT, THE INTERIORS OF THE LARGE MOONS OF THE OUTER PLANETS ARE WARMER THAN WE WOULD EXPECT BASED ON THEIR DISTANCE FROM THE SUN AND THEIR SIZES (SMALL, SO LOST HEAT RAPIDLY).THE LARGER THE MOON AND THE CLOSER IT IS TO ITS PLANET, THE GREATER THE AMOUNT OF TIDAL HEATING.THIS EFFECT MAKES SOME MOONS WARM ENOUGH TO BE POSSIBLE CANDIDATES FOR LIFE!MAJOR MOONS OF JUPITER (IN ORDER OUT FROM JUPITER, THEREFORE HOTTEST TO COLDEST)IOEUROPAGANYMEDECALLISTOIOCLOSEST MOON TO JUPITER, SO TIDAL EFFECTS ARE LARGESTHIGHEST DENSITY - ROCKIER THAN OTHER MOONS, TEMPERATURE IS TOO HIGH FOR ICE HOT ENOUGH TO BE COMPLETELY MOLTEN INSIDELOTS OF SULFUR ON SURFACEMANY ACTIVE VOLCANOES ERUPTING CONSTANTLYMORE VOLCANOES THAN ANY OTHER OBJECT IN THE SOLAR SYSTEMNOT A GOOD PROSPECT FOR LIFE: NO WATER, LITTLE OR NO ATMOSPHERE, AND LARGE TEMPERATURE EXTREMESEUROPANEXT LARGE MOON OUT FROM JUPITER WARM INTERIOR, NOT AS HOT AS IOCOMPOSITION:–ROCKY AND/OR METALLIC CORE –SURROUNDED BY LIQUID WATER OCEAN(?) 50 TO 150 KM DEEP–COVERED BY CRUST OF CRACKED ICE 20 TO 25 KM THICK–NO ATMOSPHERE, BUT ICE CRUST PREVENTS WATER FROM BOILING INTO SPACE FEW CRATERSEVIDENCE FOR OCEAN ON EUROPAFEW IMPACT CRATERS–IMPACT BREAKS THROUGH ICE, WATER FROM BELOW FILLS IN CRATER AND FREEZESCHAOTIC TERRAIN–PATCHWORK RIDGED PATTERN OF ICEBERGS FROZEN IN PLACESTAINS ON CRUST INDICATE UPWELLING OF WATER CONTAINING DISSOLVED (ORGANIC?) MATERIALSMAGNETIC FIELD–IMPLIES PRESENCE OF ELECTRICALLY CONDUCTING LIQUID MATERIAL (SALT WATER)LIFE ON EUROPA?NO ATMOSPHERE, BUT ICE PREVENTS WATER FROM BOILING AND PROVIDES UV PROTECTION ENERGY SOURCE:–HYDROTHERMAL VENTS?–UNDERSEA VOLCANOES?–RADIOACTIVE DECAY IN INTERIOR OF MOON?–PHOTOSYNTHESIS COULD OCCUR IN POCKETS OF WATER DIRECTLY UNDER THINNER ICE? (BUT NOT MUCH SUNLIGHT)–HIGH ENERGY ELECTRICALLY CHARGED PARTICLES ARE ACCELERATED BY JUPITER'S MAGNETIC FIELD AND HIT ICE AT HIGH SPEEDS–UV PHOTONS FROM SUN HIT ICELIFE ON EUROPA?PROBABLY NO COMPLEX LIFE, BUT MAYBE SIMPLE LIFE FORMS–PROBABLY NOT ENOUGH ENERGY TO SUPPORT LARGE AND COMPLEX ECOSYSTEMSPACECRAFT MISSION PLANNED, FUNDING CUT–WILL DRILL THROUGH ICE AND