From The Space Review:
In any given year, companies worldwide launch about two dozen commercial communications satellites. These spacecraft, some weighing more than 6,000 kilograms, are distributed across geosynchronous orbit, providing a wide range of services, from relaying television programming to broadcasters and individual customers to providing critical links for credit card and banking systems.
These spacecraft, though, have the capability to perform another role as well. Many spacecraft have, or can make room for in the design process, additional payload capacity in the form of mass, volume, and power. This capacity can be used to host additional, primarily government, payloads, such as communications transponders, Earth observation cameras, or technology demonstrations. These “hosted payloads,” as they’re called, can provide the government with capabilities at a fraction of the cost of a dedicated satellite, and also provide satellite operators with an ancillary source of revenue.
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