Satellitles

1. Satellitles Io, Europa and Titan Anuradhi Gallage Thakshajini Kulahan

2. Discovery • Io and Europa were first observed by Galileo Galilei on January 7, 1610 using a 20x-power, refracting telescope at the University of Padua. • Differentiated as two moons the next night • Titan was discovered on March 25, 1655, by the Dutch astronomer/physicist Christiaan Huygens

3. Io • A bit larger than Earth's Moon, Io is the third largest of Jupiter's moons, and the fifth one in distance from the planet. • The information we have about the moon is from Pioneer spacecraft, Voyager spacecraft and Galileo spacecraft • On the outside Io looks like a giant pizza covered with melted cheese and splotches of tomato and ripe olives • Io geologically active

4. Surface of Io • Surface active with volcanoes • Io was observed to be covered with irregular shaped pits and calderas(>200 with 20km ) of all sizes. • Many of them also exhibited lava flows and also presented large diffuse red deposits around the volcanic vents • Plumes were also discovered on the surface • plumes not short-lived and heights implied velocities of 100-500 m per second.

5. Surface of Io • Plumes on Io more like hot geysers. • first discovered plume was named Pele, behind the legendary Hawaiian volcano goddess. • The colour on the surface of Io is believed to be from silicate lava topped by a cooler solidified crust. These thin veneers of sulphur-bearing compounds and sulphur dioxide frost provide the observed colouration. • Lack of crater impacts suggests that Io is geologically young and surface is renewing

6. Io has tall mountains with an average height of 6 km • the largest of these features displayed temperatures of 300K to 600K • Other places 110K to 120 K • Plateaus are also observed

7. Atmosphere of Io • volcanic activity gases emitted form a thin patchy atmosphere around Io with a global frost of sulphur dioxide. • The atmosphere has significant variations in density and temperature with time of day, latitude, volcanic activity, and surface frost abundance.

8. Atmosphere of Io • Gas in Io's atmosphere is stripped by Jupiter's magnetosphere, escaping to either the neutral cloud that surrounds Io, or the Io plasma torus • The maximum atmospheric pressure on Io ranges from 3.3 × 10−5 to 3 × 10−4 Pascal (Pa)

9. Europa • It is the sixth moon of Jupiter and the smallest of the Galilean satellites. • One of the places where possibility of extraterrestrial life is under debate.

10. Surface of Europa • Less impact craters, geologically young • Europa smoothest surface-icy surface • possible liquid water beneath Europa’s surface • mix of bright plains, mottled terrains and disrupted regions • Galileo colour data collected indicates salt deposit like the magnesium sulphate compound

11. Bright plains with ridges and grooves • Mottled terrain darker zones • Triple band (now diminishing) could be explained with cryovolcanism • Craters present • 30 km wide crater called Manann’an in Europa’s trailing hemisphere • circular and elliptical lenticulae present-domes, some are pits and some are smooth, dark spots.

12. Atmosphere of Europa • Europa has atmosphere of molecular oxygen-not biological origin • Solar ultraviolet radiation and charged particles collide with surface-split out oxygen • presence of a tenuous ionosphere around Europa created by solar radiation and energetic particles from Jupiter's magnetosphere

13. As observed by Galileo and Cassini spacecrafts the molecular hydrogen that escapes Europa's gravity, along with atomic and molecular oxygen, forms a torus (ring) of gas in the vicinity of Europa's orbit around Jupiter. • “Neutral clouds” similar to Io but larger content

14. Titan • Largest moon of Saturn • Only natural satellite with dense atmosphere • Only place other than Earth where surface liquid has been found

15. Surface of Titan • Haze covering surface, preventing clear study • The Cassini–Huygens spacecraft –Saturn mission 2004 • Surface geologically young • Surface temperature is about 94 K • Possibility of seas, lakes and even ponds of liquid hydrocarbons (ethane) over a “bedrock” of liquid ice. • On Jan 15,2005 Hugini Probes landed on Titan’s surface • Titan's south pole has Ontario Lacus discovered through Cassini mission

16. In 2012, Cassini's radar detected in Titan's northern polar region a river more than 400 kilometres. • Xanadu, a large, reflective equatorial area about the size of Australia present. The region is filled with hills and cut by valleys and chasms.Also has highest craters. • Impact crater called Menrva was observed with a 440 km wide two-ring impact basin • Sinlap and Ksa are other smaller craters observed

17. A mountain range measuring 150 km long, 30 km wide and 1.5 km high was also discovered by Cassini in 2006. This range lies in the southern hemisphere and is thought to be composed of icy material and covered in methane snow. • Presence of Cryovalcanism is under debate as new geological structures are studied.

18. Titan’s Atmosphere • Atmosphere denser than Earth • Dominant gas is nitrogen,98% • Methane as predicted before Voyager I’s arrival is also present in smaller quantity. • nitrogen and methane molecules are being broken apart by suns UV photons and by the bombardment of electrons from Saturn’s magnetosphere aided in formation of acetylene, propane and hydrogen cyanide in trace amounts

19. Titans atmosphere rotates faster than its surface as observed by Cassini • Titan has 1.5 times Earth's atmospheric pressure. • Possibly a secondary atmosphere that's come from outgassing from the interior.

20. Tidal Heating and Surface Water

21. Tidal Force and Tidal Bulge

22. Tidal Heating • When a major satellite is orbiting a giant planet, the magnitude of the tidal attraction between them can distort the shape of satellite. • When a satellite is in an elliptical orbit, both the continual variation in the heights and the oscillation in the locations of the bulges deform the satellite's interior. This process generates the tidal heating.

23. Io • Io is the most volcanic body in the solar system • The energy to power all volcanism comes from tidal heating

24. Io’s elliptical orbit and tidal bulge

25. Surface or Ground Water on Io

26. Europa • The similar but weaker tidal heating process • Europa has less fractured ice surface than the other icy planets

28. Titan • Tidal heating is smaller than Europa • In 1998, the European Space Agency's Infrared Space Observatory (ISO) detected water vapor in the atmosphere of Titan.

29. Titan’s Interior

30. Possibility of liquid water on Titan scientists say it is possible that an impact pool created by a comet or asteroid could maintain liquid water for as long as 1,000 years. (http://www.pbs.org/lifebeyondearth/alone/titan.html) Wait till 2030 !!!

31. References Beatty,J.K. & Peterson, C.C. & Chaikin, A. (1999). The New Solar System. Cambridge, UK: Cambridge University Press. Sotin , C., W. Head III, J., & Tobie, G. (2002). Europa: Tidal heating of upwelling thermal plumes and the origin. GEOPHYSICAL RESEARCH LETTERS, 29(8), doi: 10.1029/2001GL013844 http://labspace.open.ac.uk/mod/resource/view.php?id=343740 http://exoplanet.as.arizona.edu/~lclose/teaching/a202/lect17.html http://www.solar-system-school.de/lectures/planetary_interiors_surfaces/grieger.pdf http://en.wikipedia.org/wiki/Io_%28moon%29 http://en.wikipedia.org/wiki/Europa_%28moon%29 http://en.wikipedia.org/wiki/Titan_%28moon%29