Ponca City, We Love You writes "Space.com reports that over the weekend, a giant booster – a Delta 4 Heavy rocket — carrying a secret new spy satellite for the US National Reconnaissance Office roared into space to deliver into orbit what one reconnaissance official has touted as 'the largest satellite in the world.' The Delta 4 Heavy rocket is the biggest unmanned rocket currently in service and has 2 million pounds of thrust, capable of launching payloads of up to 24 tons to low-Earth orbit and 11 tons toward the geosynchronous orbits used by communications satellites. The mammoth vehicle is created by taking three Common Booster Cores — the liquid hydrogen-fueled motor that forms a Delta 4-Medium's first stage — and strapping them together to form a triple-barrel rocket, and then adding an upper stage. The exact purpose of the new spy satellite NROL-32 is secret, but is widely believed to be an essential eavesdropping spacecraft that requires the powerful lift provided by the Delta 4-Heavy to reach its listening post. 'I believe the payload is the fifth in the series of what we call Mentor spacecraft, a.k.a. Advanced Orion, which gather signals intelligence from inclined geosynchronous orbits,' says Ted Molczan, a respected sky-watcher who keeps tabs on orbiting spacecraft. Earlier models of the series included an unfurling dish structure about 255 feet in diameter with a total spacecraft mass of about 5,953.5 pounds, costing about $750 million and designed to monitor specific points or objects of interest such as ballistic missile flight test telemetry."