The fourth and final orbiter, Atlantis, entered service in October 1985 on a mission cloaked in military secrecy. Little was announced beyond the fact of the flight; the crew of five, commanded by Karol Bobko, deployed a classified Defense Department payload widely believed to be a pair of military communications satellites lofted to a high orbit.
Atlantis flew a short, quiet mission and returned to Edwards after about four days. Its debut completed the operational fleet — four winged orbiters that would carry the entire programme, for better and worse, through the decades ahead. Within months the optimism of that autumn would be shattered, and Atlantis's early career, like the fleet's, would be reshaped by the accident to come.
Atlantis made its first flight in October 1985 under an almost complete news blackout. The mission was dedicated to the Department of Defense, and NASA published the launch window, the landing time and little else; the payload is generally understood to have been a pair of military communications satellites released to geostationary transfer orbit.
Classified flights were run differently in every respect. Air-to-ground voice was encrypted, the press was excluded from the usual briefings, launch times were announced only within a broad window, and crews were instructed not to describe what they had done afterwards — an arrangement that sat awkwardly on an agency whose charter committed it to the widest practicable dissemination of information.
The fourth orbiter arrived at a moment of enormous confidence. Atlantis was completed under budget and ahead of schedule, the fleet had flown nine times that year, and the manifest for 1986 promised fifteen more. Three months after this flight Challenger was lost, the military moved its payloads back to expendable rockets, and the Shuttle never again flew at anything like the rate its design had promised.
