Planetary Geology pdf - NASA

3. a. Which of GanymedeÕs two principal terrain types is older? How can you tell?
b. What is the age of the ejecta for the crater marked ÒAÓ relative to the bright and dark terrain? How
can you tell?
4. Many researchers believe that the bright terrain of Ganymede was shaped by both volcanism and tectonism.
What is some evidence that this is true?
5. All the craters you can see in Figure 13.1a probably formed by the impacts of comets or asteroids. Many
show small central pits, created as a result of impact into an icy target.
Four craters that show unusual morphologies are indicated in Figure 13.1b with the letters A through D.
Describe the shapes and characteristics of these interesting craters. Include the dimensions of each crater using the
scale bar, and also describe the characteristics that make it peculiar compared to most other craters on Ganymede.
A:
B:
C:
D:
II. Enceladus
6. Enceladus orbits the planet __________ and has a radius of only _______ km. Its density of ______ g/cm3 means that it is composed of __________ _____________________. Its albedo of __________ is
__________ than the albedo of any other satellite.
Now make a geological sketch map of Enceladus. Use as a guide the map of Ganymede in Figure 13.1. Tape
a piece of acetate over the photograph of Enceladus, Figure 13.2. Trace the outline of the satellite. You will find
that it is simple to trace the satellite's limb, but the terminator is not as clearly defined. Next, outline the most
prominent craters on the satellite, you will have to decide which craters should be included.
7. Locate and describe two unusual looking craters.
Grooves on Enceladus are probably tectonic features; next map their locations. This symbol ( ) is one
way of mapping a groove. Draw a thin line along each groove you see, and place a dot near the center
of each line to indicate it is a groove.
8. Where do grooves (and the ridges between them) occur on Enceladus?
Exercise Thirteen:
The Geology of Outer Planet Satellites
157
EG-1998-03-109-HQ Activities in Planetary Geology for the Physical and Earth Sciences