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Ground Tracks

We now know something about what the shuttle's orbit looks like in space. However, what we really want to know is the location of the shuttle with respect to the surface of the Earth. The shuttle's ground track is the path on the surface of the Earth that lies directly below its orbit. A ground track map shows the locations on the surface of the Earth that the shuttle flies over as it travels repeatedly around its orbital path. Utilizing the shuttle's ground track maps is essential for targeting and image selection in KidSat.

All ground track drawings use the latitude-longitude coordinate system. Any point along the ground track is then described by two values: the latitude, which measures how far North or South a point lies from the equator, and the longitude, which measures how far East or West a point lies from the Prime Meridian.

Ground Tracks for a Non-Rotating Earth

The first step in understanding what ground tracks look like is visualizing the ground track the shuttle would have if it were orbiting around a non-rotating Earth. The figure below on the left shows the trace of points on the surface of a non-rotating Earth directly under a circular orbit with an inclination of approximately 50 degrees. On a globe, the ground track looks like an inclined circular path, called a great circle, whose plane slices through the center of the Earth.

Ground Track on a Globe
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Ground Track on a Flat Map
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