This document discusses remote sensing platforms and sensors. It describes the different types of orbits used for satellites, including low earth orbit, medium earth orbit, high earth orbit, and geostationary orbit. It also discusses the types of platforms that can be used, including ground-based, airborne, and spaceborne platforms like satellites, rockets, and space shuttles. Finally, it outlines the characteristics of different sensors, such as spatial, spectral, radiometric, and temporal resolution.