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The previous project described mapping the global wind patterns using wind streaks. At a more abstract level, that project involved mapping a directional field on a global scale. (Its a directional field because we're not measuring the magnitudes of elements in a vector field, just their direction.) Naturally, there is more than one directional field on Mars that can be investigated. You don't have to search Mars too hard to find evidence of past water. You can even find many features that look like rivers. Where do these rivers empty out? On Earth, rivers tend to combine and eventually empty out in an ocean. Does this happen on Mars? Did it have oceans? Can anything be learned by following the rivers up-stream? On Earth where rivers tend be fed by rainfall the just keep branching into small and smaller streams. Does this happen on Mars? Besides rain, where else might surface water come from? Create a map view of a region of Mars showing only elevation data. The lowest terrain is in red, the highest in blue. Some of these red features could be rivers. By studying the imagery closely you discover how likely it is they were formed by a flowing liquid. Remember that water flows down hill. But what is downhill today might not have been downhill a billion or more years ago when the river formed. Planets change, a low region can be uplifed or a high region can sink down. Water isn't the only thing that can flow. Lava can pour out of the ground and flow down downhill. Some planets support other liquids such as methane. Dust in the air behaves similarly to debris in water and can cause similar features. As is always the case, identifying features can be a little tricky. |
