EDWARDS AIR FORCE BASE, Calif -- The sole remaining EC-135E Advanced Range Instrumentation Aircraft was flown to the Air Force Museum at Wright-Patterson AFB, Ohio. The aircraft was one of eight modified C‑135s developed by the National Aeronautics and Space Administration in the 1960s. Dubbed Apollo Range Instrumentation Aircraft, they originally tracked lunar missions, unmanned orbital, and ballistic re-entry programs. The Air Force Flight TC divested the ARIA program due to diminishing requirements for its unique mission capabilities.
The tracking ships were deployed to give coverage for key events (launch, TLI and re-entry), but these could not be quickly moved if, for example, launch holds or TLI burns on later revolutions were necessary. Something more mobile was needed. A 1965 paper by L C Shelton in NASA publication SP-87 (Proceedings of the Apollo Unified S-Band Conference, page 283ff.) points out that 20 to 30 extra ground and ship-based tracking stations would be required to maintain near-continuous coverage.
For this reason, eight Apollo Range Instrumented Aircraft – specially modified and instrumented EC-135N jet aircraft (a military version of the Boeing 707) – were developed to provide airborne voice relay and telemetry with the Apollo spacecraft during critical portions of the TLI and reentry phases of the lunar missions. Their job was to supplement the existing stations and to be able to rapidly move (within the constraints of airspeed and fuel usage) where they were needed. The ARIA were operated for NASA by the US Air Force Eastern Test Range out of Patrick Air Force Base, just south of the Kennedy Space Center in Florida. They were designed by the Goddard Space Flight Center – the nose section was modified to house a 7-foot diameter S-band tracking dish, and the interior was configured to contain all the necessary electronic support equipment.