What is the principle behind across-track scanning?

The principle behind across-track scanning involves the use of a rotating mirror that sweeps back and forth across the swath being imaged. This technique allows the sensor onboard a satellite to capture data over a wide area while the satellite moves along its orbit. By employing a rotating mirror, the sensor can cover different sections of the ground as it passes overhead, facilitating the collection of imagery from various angles and improving the ability to create a continuous image of the Earth's surface.

This method contrasts with other approaches, such as utilizing a linear array to gather data solely along the satellite's path, which would limit the breadth of the imagery. Additionally, across-track scanning does not specifically focus on employing multiple wavelength sensors, which would instead relate to spectral data collection rather than the scanning mechanism itself. Lastly, a fixed position imaging strategy would imply that the sensor does not move to capture data across a wider area, which contradicts the dynamic nature of across-track scanning. Overall, the rotating mirror system is key to enabling comprehensive and versatile data collection in this scanning method.