Final answer:
Active remote sensing involves using instruments that send out signals and then analyse the reflected radiation to study the earth's surface. This is useful for mapping, planning, and disaster evaluation, although designing systems to capture this data can be challenging.
Step-by-step explanation:
Active remote sensing involves the use of instruments that emit their own signals or radiation, which then bounce back from the earth's surface to be captured and analysed by sensors. This technology is incredibly useful for geographers in understanding landscape changes caused by both natural processes and human activities. The data acquired from active remote sensing is integral in cartography, land use planning, and can be critical for disaster response, such as evaluating tornado damage.
One of the challenges in designing systems for active remote sensing is the creation of mirrors to reflect high-energy radiation like X-rays and gamma rays. Additionally, systems like telescopes, spectrometers, and cooled detectors play a crucial role in capturing and recording a variety of wavelengths, which are essential for thorough environmental analysis. Instruments placed on satellites, such as GPS satellites and other active space observatories, circumvent atmospheric interference like water vapor which can affect the quality of data.