Mapping Unknown Surfaces
We always want to know what the surface of a planet is like. Sometimes we can't see it, like in the case of Venus. There, a thick
cloud layer covers the surface of the planet. Other times, we can see the surface and we take a picture of it. But these images are two dimensional. We have no definite information on depth. To find out the high and low points of a planet's surface,
scientists use radar to map the landscape. A spacecraft orbiting the planet beams radar down to the surface and then measures how long it takes for the reflection to come back. A shorter time means a higher surface; a longer time means a lower surface. In this way, we can create a three-dimensional picture of the landscape. Using this information, we can create flyovers of the planet.
In this activity, we have a hidden landscape. Groups must take radar measurements and determine if there is a safe landing spot
for their spacecraft. A safe location would be one that is 4 x 4 holes, with no more than centimeter change in landscape measurements.
Preparation
1. Make unknown landscape boxes, one for every 3 to 4 students.
2. Use a box with a lid, like a shoebox.
3. Create an uneven landscape, including craters, mountains, and valleys, using modeling clay, Pla-Doh, stucco, rocks, or other
materials.
4. Use an awl to punch holes in the box top, about 1-2 centimeters apart, in a grid pattern.
5. Label the grid: letters across the top, numbers down the side.
6. On several thin, wooden skewers, measure out and draw in centimeter markings.
Materials
For each group:
- one unknown landscape box
- skewer with centimeter marks on it
- worksheet/grid with the same letter/number grid written in as on the box top.
- pencil
Procedure
1. Insert skewer down a hole until it can t go any further.
2. Read the measurement for how far down the skewer went.
3. Write each measurement on the worksheet in the box that corresponds to the hole you measured.
4. After you take measurements for all the holes, examine your data. Is there a square area that is 4 x 4 holes where all the
measurements are the same or differ by no more than centimeter? That means the measurements can all be 5's and 5's, or all 7's.
5. Is there a safe landing spot for your spacecraft on this landscape?
Next Step...
Once your measurements are all taken, draw lines connecting equal measurements to create a topographic map of your surface.
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