Satellite Technology

- Overview

Services that satellites can provide for disaster risk management and emergency response include weather forecasting, remote sensing, geolocation, navigation, television and telecommunications. Instruments on satellites orbiting the Earth are designed to cover specific wavelengths of the electromagnetic spectrum for image capture, atmospheric sounding, satellite communications, geolocation and navigation. 

Depending on the type of application or onboard instrumentation, satellites orbit the Earth in different orbits: A satellite in a geostationary orbit circles the Earth synchronously with the Earth's rotation above the equator (0° latitude). Its apparently fixed position at an altitude of more than 36,000 km above the equator makes it suitable for communications and regional climate observations in this particular region, with high temporal resolution but low spatial resolution. 

Earth observation satellites and those used for meteorological purposes are located in low Earth orbit, usually at an altitude of about 500-800 km, near polar inclinations. Due to their orbits, these satellites provide global coverage with relatively low temporal resolution, but moderate to very high spatial resolution. Because of the high cost of space transportation, constellations of communications or navigation satellites are also placed in low-Earth orbit. 

Earth observation satellites use optical or radar sensors to capture images of the Earth: Optical sensors used for Earth observation are designed to provide images in either panchromatic spectral format or multi-spectral format. Panchromatic refers to a black-and-white image reflected from the Earth's surface exposed to all visible light. Multispectral images typically include four bands of the electromagnetic spectrum: blue, green, red, and near-infrared.

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