RHYOLITE, also known as AQUACADE, was the code name for a series of National Reconnaissance Office-operated satellites that collected signals intelligence for the United States. While NRO launched and operated the satellites, the primary organization concerned with reducing the data they collected was the National Security Agency.
Their primary receiving station was at Pine Gap, Australia, and its principal target was Soviet missile telemetry, with a secondary communications intelligence capability. They operated in geosynchronous orbit.
Details of the program were revealed to Soviet intelligence by Christopher Boyce, an administrative employee of TRW Systems, and Dalton Lee, a friend of Boyce.