2. Homework 7 will be posted shortly

3. YU55 If it had struck land, it might have caused a magnitude seven earthquake and left a city-sized crater. If it has struck the ocean, it would have raised a large tsunami.

5. Jupiter’s Galilean Satellite’s

6. Orbital resonances among Galilean Satellite’s

7. Io’s Volcanoes The most volcanically active world in the solar system. Io

8. Europa: An ice-covered world

9. Europa: Heated by tidal friction

10. Europa –Tidal heating, –Tidal heating, similar to IO but weaker water ice crust –Young cracked water ice crust perhaps only a few kilometers thick warm ocean of salty liquid water –Thought to have a warm ocean of salty liquid water below its crust. –life?

11. – Icebergs

12. ice cliffs

13. Grooves & channels

14. Glaciers?

15. Earth: arctic ocean

18. Europa’s interior warmed by tidal heating. Internal structure derived from measurements taken by spacecraft in the Jovian system. Salty - Europa has a magnetic field

19. Sub-CrustOcean.. Life in the Ocean?.. Hydrogen-Carbon compounds likely: Amino acids First New Ocean Since Balboa

20. .... Conditions are consistent with the presence of volcanic vents (black smokers) at bottoms of ocean. Life could have developed there. Life in the Ocean?

21. Life in the Ocean?

22. Complex life? Probably requires oxygen High energy particles from Jupiter H O H Collisions disassociate water H H O Hydrogen lost to space, oxygen absorbed by ice On timescale of several million years, oxygen moves through ice to ocean

23. Missions to Europa http://www.jpl.nasa.gov/europaorbiter/

24. Ganymede

25. Ice-covered moon

26. Craters and pressure ridges

27. Ganymede Largest moon in the solar system Clear evidence of geological activity Tidal heating expected - but is it enough?

28. Ganymede Wrinkles due to tectonic movement in ice crust in (distant) past - possible water deep below?

30. Model of Ganymede's interior: cold rigid ice crust outer warm ice mantle inner silicate mantle metallic core.

31. Ganymede Cratering –Dark areas: cratering upon cratering  several byr old –Bright areas: far fewer craters and grooves –Explanation: “lava” (i.e., water) eruptions followed by freezing Ocean? –Magnetic field  convecting core –Part of magnetic field varies with Jupiter’s rotation  electrically conducting interior (brine?) –Salts found on the surface Heat source –Less tidal heating than Europa (larger distance from Jupiter) –Large mass  more radioactivity –Much less heat than in Europa  thick crust (>150 km?)  Much harder to prove the existence of life, never mind finding it

32. Callisto

33. “Classic” cratered iceball. No tidal heating - no orbital resonances. But it has magnetic field! This is not understood.

34. Callisto Scarp close up Possible water deep?

35. Callisto Cratering –Heavily cratered everywhere  no water gushing to the surface Gravity –Undifferentiated: mix of ice and rock throughout Induced magnetic field –Exists  underground ocean? Not clear. Heat source? –Does not participate in the tidal resonance –Radioactive decay: only possibility for heating of interior

37. Given our discussion of tidal synchronization of the rotation and orbital periods, what might this say about planets and stars? (red)nothing (yellow)planets close to stars will have synchronized rotations (green)planets far from stars will have synchronized rotations (blue)it will depend upon the composition of the planet

38. Given our discussion of tidal synchronization of the rotation and orbital periods, what might this say about planets and stars? (red)nothing (yellow)planets close to stars will have synchronized rotations

39. Life beneath the surface of Europa would most likely obtain energy from (red)the Sun (yellow)Jupiter (blue)radioactivity (green)tidal heating

40. Life beneath the surface of Europa would most likely obtain energy from (re)the Sun (yellow)Jupiter (blue)radioactivity (green)tidal heating

41. Life in the subsurface ocean of Europa will most likely consist of (red) creatures similar to seals and penguins which enter the ocean through holes in the icy crust (yellow) plants on the ocean floor (green) simple single-celled organisms (blue)fish and other complex aquatic organisms

42. Life in the subsurface ocean of Europa will most likely consist of (red) creatures similar to seals and penguins which enter the ocean through holes in the icy crust (yellow) plants on the ocean floor (green) simple single-celled organisms (blue)fish and other complex aquatic organisms

43. Life on Galilean Moons? IoIo EuropaEuropa GanymedeGanymede CallistoCallisto X Very active volcanically. Hostile environment Subsurface saline ocean, hydrothermal vents? ? Subsurface saline ocean? hydrothermal vents? ? Subsurface saline ocean? ??