USA-171

USA-171 is an American SIGINT reconnaissance satellite which is operated by the National Reconnaissance Office. Launched in September 2003, it is the secret Orion satellite.

Overview

This is the last Orion satellite launch on Titan IV rocket and last launch of Titan IV B/Centaur-T Version and last Titan IV launch with extremely long metallic fairing and future Orion mission will launch on the Delta IV Heavy rocket.
Orion also known as Mentor is a SIGINT/ELINT satellite build to replace Magnum satellite and the COMINT capability also made Orion a replacement for the Mercury satellite. It is called that the satellite has a reflector of a diameter as big as ~100m