Planetary Geology pdf - NASA

Unit
Four
The three decades from the mid-1960s to the
mid-1990s have revolutionized our understanding
of the planets and their satellites.
During this period, spacecraft made an initial reconnaissance
of all of the planets except Pluto, returning
a wealth of information, much in the form of
images. The surfaces revealed in these images range
from the subtly familiar, such as the riverlike valleys
of Mars seen by the Viking Orbiters, to the wildly
exotic, like the ice cliffs of Miranda, a satellite of
Uranus.
What we understand of the histories of the planets
and their satellites is based on observations of
their surfaces. For example, Mars shows a myriad of
landforms that were shaped by running water in the
past, even though liquid water is not stable near the
surface of Mars today. Thus, planetary scientists
conclude that Mars had a wet early history, and that
Introduction to
Planetary Surfaces
113
its climate somehow evolved to make Mars the
frozen desert that it is today. Many of the icy satellites
of the outer solar system show evidence for
extensive flows of icy material, even though these
moons are frozen solid today. Thus, some energy
source increased the internal temperatures of these
satellites in the distant past.
This unit introduces students to the interpretation
of geologic landforms and processes on the
planets and satellites through five exercises. First,
the overall geology of the terrestrial planets is introduced.
Then, individual activities concentrate on
the geology of Mars and Venus. Next, students are
led through the outer solar system using some of the
spectacular images from the Voyager mission.
Finally, the types of landforms and processes introduced
in preceding activities are reviewed through
analysis of stereoscopic planetary images.
EG-1998-03-109-HQ Activities in Planetary Geology for the Physical and Earth Sciences