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In this section we're going to take a look at some of the easier features to identify. Lets start with a feature at latitude = 24 and longitude = -96. There we find the following:
We're trying to determine the type of the large feature in the center of the screen. My first step is generally to create an elevation cross section. You might be tempted to judge if something is a hill or a hole based just on its appearance but looks can be deceiving.
Using the mouse, I created the white reference line and PEP drew its elevation cross section in red. So, we have a big round feature that sticks up and has a hole in its middle. There really isn't much else it can be besides a volcano. Sometimes classifying an object is just that simple.
Next, turn to latitude = 2, longitude = -47. There we find:
What are the light features to the southwest of the round craters? They are wind streaks. This means Mars has both wind and some material small enough to be blown around. That isn't going to be the case on other planets. By identifying wind streaks all over Mars you can map the global wind patterns.
Next, we're off to latitude = 4, longitude = -44. There we find:
What is this long, meandering feature making a vertical cut through the landscape? Note that from the elevation cross section we know it is depression/low feature. This feature is a river channel. It was carved by a flowing liquid that etched away material to create the channel. If you look closely and zoom in you can even find a couple small rivers that flowed into the large one. Any flowing liquid can potentially etch a channel: water, lava, liquid methane, etc.
From the above features you might get the impression planetary exploration is pretty easy. That isn't true. Scientists can spend many years working very hard trying to uncover the history of a planet. Many aspects of Mars are still not understood. Still, identifying some features, like the ones above, is pretty straightforward. Just as you can probably tell a reptile from a mammal, you can also accurately identify many geologic features and determine the geologic processes that created them. Just as you would have trouble classifying the platypus, you'll find many features on Mars you won't be able to explain. When that happens you can do a little research and learn some more planetary geology, ask for an image to be posted on the planetarydata.blogspot.com to get other people's opinion or simply move on to another area of Mars.
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