Satellite communication makes the establishment of communication channels between two or more sources and receivers at different locations on the planet, with little to no reliance on local ground infrastructures, possible.
By transmitting the signal to and between satellites orbiting Earth, one can exchange information with a receiver beyond the curvature of the Earth. For this reason, communication satellites generally function as part of satellites constellations made of a several satellites – up to several thousand – depending on orbits and power capabilities.
These communication constellations operate at very specific electromagnetic frequencies to avoid interferences between each other, and with other signals on Earth. This also ensures good signal performance despite the attenuation due to the long distance between antennas and the absorption by the atmosphere.
Historically, most communications satellites were deployed in geostationary orbit (GEO) – about 36,000 km away from Earth – in order to have a fixed position relative to ground antennas. More and more, communications satellites are being deployed in low earth orbit (LEO) – less than 2,000 km away from Earth – as part of much larger constellations made of smaller satellites.
Communication satellites are important space-based capabilities for climate action.
First, they are key for emergency response: as extreme weather events become more intense and more frequent, the ability to communicate with any affected area where ground communication infrastructures may be damaged or overloaded, becomes extremely important.
Beyond satellite telephones, satellite internet allows for access to much more information, logistics, imagery and resources to address a crisis locally. Additionally, communication satellites are used to gather data from a multitude of environmental sensors such as weather stations in very remote areas (oceans, poles, etc.) to monitor climate change and improve current models.