Question

In active remote sensing of Earth objects from a satellite-borne sensor, the source of the energy used for sensing, lies at the _____________

• A. satellite
• B. Sun
• C. object being sensed on Earth
• D. ground station

Hint:

Active = sensor emits (source on the platform). Passive = sensor listens (source external, typically the Sun or thermal Earth).

Answer 1

The Correct Option is A

Active sensors (e.g., SAR, LiDAR, radar altimeters) transmit their own electromagnetic energy and measure the backscattered signal. When the sensor is satellite-borne, the transmitter—and therefore the energy source—resides on the satellite. Passive sensors, in contrast, rely on external sources such as the Sun or Earth’s thermal emission.