Europa Kaitlyn Young

Discovery January 8, 1610 by Galileo Galilei Sixth closest moon to Jupiter Smallest of the four Galilean moons, sixth largest moon in Solar System

General Information Orbit Size: 671,000 km Mean Orbit Velocity: 49,476.1 km/h Orbit Eccentricity: 0.0094 Density: 3.013 g/cm3 Surface Gravity: 1.315 m/s2 Escape velocity: 2026 m/s Rotational Period: 3.5 Earth Days

Surface Water ice with linear fractures Not very cratered 40-90 million years old

Surface Clay-like material found – phyllosilicates Organic material from comet or asteroid Asteroid (1,100m) or Comet (5,600m) diameter Galileo Orbiter

Surface Strange pits and domes – convecting due to heat below surface “Chaos terrain” – mysterious reddish brown material

Surface “Chaos terrain” – places where surface has collapsed above lakes within the ice Conamara Chaos – ice particles, mineral contaminants spread by water vapor

Lineaments Four classes by age (Galileo observations) Cracks Ridges Triple Bands Ancient Bands

LIneaments Record of stresses due to tides Point in different directions but the same part of ice shell always faces Jupiter Hypothesis: frozen outer shell rotates faster than moon orbits Jupiter

Lineaments 1. Rotation of ice shell (250,000 years) 2. Tilted axis, changing pole orientation 3. Cracks laid out in random directions

Surface Galileo Mission Lenticulae Warm ice moving upward, colder ice sinks downward

Magnetic Field Galileo spacecraft Magnetic-field lines from Jupiter bent around Europa Implies special magnetic field created inside Europa Hypothesis: global ocean of salt water creating magnetic field

FLybys Pioneer 10 & 11 – 1970s Voyager 1 -1979 Voyager 2 – 1980 Galileo – 1995 (12) Cassini - 2001

Voyager missions Voyager 1 – linear fractures due to tectonic processes Voyager 2 – fractures lack topological relief Tidal heating  survival of oceanic organisms

core Thin ice model vs thick ice model Iron core, rocky mantle like Earth

Evidence for an Ocean Est 50 km ocean Magnetic field Few impact craters Linear surface features fit pattern of fractures if there was an ocean Tidal heating

Plumes? Hubble Space Telescope (2012) Ultraviolet Imaging Spectrograph (UVIS) Cassini (2014)

Life? Tidal heating  energy for oceanic organisms Plumes Ocean believed to have direct contact with rocky interior (similar to Earth’s sea floor) Minimum requirements: liquid water, essential chemical elements, source of energy

Future Missions Instruments ICEMAG – Interior Characterization of Europa using Magnetometry MISE – Mapping Imaging Spectrometer for Europa (probe) REASON – Radar for Europa Assessment and Sounding: Ocean to Near-surface Need to withstand 5.40Sv of radiation

Future Missions ($80M) Europa Multiple-Flyby Mission – explore for habitability, select future lander sites – orbit Jupiter Ice-penetrating radar, short-waved IR spectrometer, topographical imager, ion- & neutral-mass spectrometer Europa Orbiter – characterize extent of ocean Radio subsystem, laser altimeter, magnetometer, mapping camera, Langmuir probe European Space Agency – Jupiter Icy Moon Explorer (JUICE) Flybys of Europa, but focused on Ganymede

Bibliography http://solarsystem.nasa.gov/planets/europa/indepth http://www.jpl.nasa.gov/news/news.php?feature=3982 http://www.jpl.nasa.gov/spaceimages/index.php?search=europa&category=#submit http://solarsystem.nasa.gov/planets/europa/facts https://solarsystem.nasa.gov/europa/overview.cfm http://www.nasa.gov/content/goddard/long-stressed-europa-likely-off-kilter-at-one-time http://www.planetary.brown.edu/pdfs/2208.pdf http://science.nasa.gov/missions/galileo/ http://solarsystem.nasa.gov/europa/newsdisplay.cfm?Subsite_News_ID=37213&SiteID=4