Planetary Geology Lecture - Jovian satellites

4 major moons: Io Europa Ganymede Callisto

Decrease in density in Jovian major moons as move outwards - why?


Io

1,821 km radius, mean density of 3.5 gm/cc

Spouting volcanoes and few impact craters.

Ejection velocities of >3000 km/hour, a boiling cauldron!

Calderas, with long, narrow and sinuous dark flows. Variety of volcanic construct morphologies.

Sulfur rich outer layer, not silicate melts.

Phase relationships of sulfur and sulfur compounds important for understanding the volcanism.

Etched terrane - some unusual process of erosion (sublimation?).

Where is the heat/energy from that drives such abundant activity?


Europa

1,565 km radius, 2.99 gm/cc mean density.

Rare craters, young surface.

Different coloration of surfaces (fractures often darker) - why?

Triple bands and some local grooved terrain.

Many generations of fractures, and often irregular or semipolygonal pattern.

Distinctive arcuate and scalloped ridges.

Subcrustal water and prospects for life?


Ganymede

2,634 km radius, 1.940 gm/cc mean density

Darker, older, smoother cratered terrane preserved. Recent craters have distinct white ejecta.

Palimpsests: circular color patch = ghost craters?

Abundant linear or grooved terrain - active tectonic history.

Most of the tectonic fun over with (as suggested by crater density)?


Callisto

2,403 km radius, 1.851 gm cc mean density

Heavily cratered with distinct white ejecta rays.

Valhalla: the requisite late mega-impact, multi-ringed.

Overall darker surface even though least dense and therefore most icy of Jovian satellites. Carbon compounds?

Possible impact melts forming transient seas?

Why the difference between Ganymede and Callisto even though fairly similar in many other regards?


Instead of a discussion question, for next time you will be assigned an image to interpret and report on.

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