Europa Lecture 15 Post Midterm No copyright infringement is intended by the creation or use of these notes Jovian planets gas giant planets Jupiter Saturn Uranus Neptune o Jovian planets have retained most of their atmosphere b c of their high escape velocity result of coldness slower atom velocity and mass of planet gravitational pull o Mostly H and He Moons of Jovian Planets o Large D 1500km active and ongoing geology o Medium D 300km inactive but evidence of past geological activity o Small non spherical inactive Europa is a large satellite of Jupiter o Slightly smaller than our moon o Many large and medium moons formed in a disk like planets Galileo discovered Galilean moons moons of Jupiter o Io active volcanoes b c of tidal heating o Europa subsurface oceans o Ganymede large scale tectonism o Callisto craters o They all have synchronous rotation Spin period orbital period Always same face toward Jupiter Tides o Tides are gravitational forces that distort the shape of an object ex Sun and Moon exert tides on Earth Moon pulls Earth and Water causing bulges in Earth s shell flexible Solid parts of earth distorts as well Earth distorts the moon also Tidal force slows down Earth rotation and causes moon to recede Earth rotation causes bulge to be ahead of tidal line Moons gravitation pull tries to pull bulges back to tidal line Bulge pulls moon ahead causing it to increase orbit between Earth and Moon slow Earth rotation distance o Tides important in controlling spin and internal heating of solar system bodies o Tidal Heating Io most volcanically active Ball of orange sulfur b c of volcanic activity Mountains that aren t volcanoes Long lava flows No crater b c constant resurfacing Eccentric elliptic orbit one side closer to Jupiter than the other different tidal deformation Io continually flexes o Flexing heat generation melting of rocks rocks erupt on surface volcanic activity o Eccentricity not 0 b c of resonance with outer moons orbit completely in sync in sync force 1 2 4 resonance Io Europa Ganymede The two are directly opposite to Io causing an amplification of force Io closer to Jupiter on one side and closer to moons on the other Eccentric Volcanic activity Europa o Ice covered moon o Low topography flat o Crust broken up into moving plates Plates open close as tides stretch planet Water sloshes back and forth underneath and facilitates motion of o Salty deposits well up in between plates evidence of subsurface ocean o Evidence for subsurface ocean Density 3000 kg m3 implies a mix of ice and rock 3 times of plates water Tidal heating calculations warm enough Chaotic terrain sloshing of water split plates Few craters implies young surface age Induced magnetic field that seems to provide evidence to respond to waves UCLA Spin measurements and thickness of shell show that it s tilted too much to be solid body UCLA o Astrobiological Potential Subsurface ocean Thin possibly icy shell with cracks that link ocean to surface Tidal heating Oxidants Hydrothermal vents o The moon is geologically dead Why do smaller moons have complex geological activity Ice can melt and deform at lower temperatures than rock To have geological activity you have to be able to deform and cause friction via movement heat and cause splits in surface Three ingredients necessary for life o Water solvent to facilitate chemical reactions o Chemistry build organic molecules o Energy disequilibrium to drive metabolism