How to map a Mars river delta

The JPL mapping specialists first laid a grid of 1.2 by 1.2 kilometer (0.75 by 0.75 mile) blocks over the landing zone and surrounding region, giving us distinct blocks—which we call quads—to map.

Spanning the quads are 7 distinct geographic regions—different surface types like delta, crater floor, and crater rim—each of which was assigned 2 or 3 mapping leads. The leads coordinated mapping of the individual quads in their areas and also coordinated with one another to ensure consistency and continuity across the entire grid.

Each quad received an informal name to make it easier to keep track of them. The Perseverance rover science team is an international conglomerate of scientists and engineers, so we chose a naming theme of parks and preserves from around the world. During the actual mission, this will also help us choose informal names for rocks and features the rover studies.

To map each quad, we started with a base map of high-resolution images from Mars orbiters and added to that topography and slope maps showing changes in elevation as well as false-color maps showing differences in surface mineralogy.

By using these different data sets, we were able to identify and distinguish different rock types, such as delta sediments versus the crater floor, and surface types, such as fractures versus dunes. We charted hills, river channels, impact craters, and fractures caused by tectonism. All those subtle differences within each quad amount to a lot of drawing lines and shapes on a map!

Here’s an example of how one quad came together over time: