The Jupiter Outposts was a series of unmanned sensor satellites that were deployed in a network around the planet Jupiter in the Sol system. Their purpose was to serve as an early warning system if any danger threatened Earth which became the capital for the United Federation of Planets. The monitoring of the information transmitted from the satellites was examined at Jupiter Station.
In 2367, it was Jupiter Outpost 92 which warned of the Borg invasion of the Sol system though the network did not detect the Breen raid against Earth in 2371 during the time of the Dominion War. As a result of this later failure, Starfleet Command debated whether to scrap the network as it was considered a relic of older technology. (Decipher RPG module: Worlds)