It was not possible for the MSFN’s ground-based tracking stations to provide continuous communications coverage for a spacecraft in low Earth orbit.
This map below – taken from an Apollo 14 groundtrack map – illustrates the problem. The tracking limits for a vehicle in a 100 nautical mile orbit are here shown for Carnarvon, Honeysuckle Creek, Guam and Hawaii (the effects of local topography, as well as the antenna ‘keyholes’ – directions where mechanical constraints meant they could not point – may be readily seen).
This detail from the Apollo 14 Groundtrack Map shows the need for ARIA. For the full map, see the MSFN section.
The MSFN’s 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.
ARIA at Patrick AFB, Florida, 1969. Photo: Bob Burns.
Douglas Aircraft, at Tulsa, Oklahoma performed the airframe modifications, and Bendix Field Engineering Corporation performed the electronic design and installation.
Four aircraft were also modified to use an ALOTS pod (Airborne Lightweight Optical Tracking System). The pod was mounted on a C-135 cargo door and could be fitted to the aircraft when needed.
Goddard paid for the overall modification of the first eight aircraft at an approximate cost of $60 million.
The ARIA fleet was co-ordinated from the Aircraft Operations Control Center (AOCC – otherwise known as ARIA Control), in the NW corner of Patrick Air Force Base.
ARIA Control – otherwise known as the Aircraft Operations Control Center (AOCC) – Building 629 at Patrick Air Force Base, Florida, 1969.
Note the NASA C-121 Super Constellation parked on the ramp behind the building.
Photo: Bob Burns.
Here’s the former ARIA Control as it looked in April 2011. The building has been extended on the right hand side.
Photo: Colin Mackellar.
Stan Anderson, ARIA Control, writes:
A very early photo of the ARIA AOCC.
Right now Front Left to Right: Major Irv Schubert, Major Ed Knox, Captain Pete Kendrick, Unknown, Unknown, Sgt Tillman.
Back Row, Far Right, is Sgt. Stan Anderson.
In Australia, ARIAs were stationed at Townsville, Darwin and Perth for various Apollo missions.
The Network communicated with the ARIA fleet via HF radio. The aircraft used a trailing wire HF antenna – as seen in the diagram below. Australia’s Overseas Telecommunications Commission provided extensive support for ARIA through its HF antenna farms at Doonside (transmitters) and Bringelly (receivers) on the western fringe of Sydney – and OTC’s terminal in the inner eastern Sydney suburb of Paddington. (This is also where Sydney Video was located.)
A similar communications centre at Guam also supported ARIA, however, all the switching of various circuits to the Cape was done in Hawaii. (More details coming soon.)
The ARIA console at the OTC Paddington terminal in Sydney.
Top: J.N. Hodgson, foreground: A.H. Griffiths, right: B.W. Collett.
Dom Mancini writes,
To hear some comms through ARIA, click here to hear Apollo 11 Capcom Bruce McCandless speaking with Buzz Aldrin through ARIA 3 on Apollo 11’s first revolution after launch.
Illustration from NASA publication SP-87.
This cutaway diagram shows the 7 foot dish in the nose of the ARIA.
The ARIAs home base was Patrick Air Force Base, Florida, until November 1975, when the Air Force moved this operation to Wright-Patterson Air Force Base at Dayton, Ohio.
After Apollo, the Air Force renamed them Advance Range Instrumentation Aircraft.
If you worked on ARIA during Apollo and would like to contribute photos, information or stories, I would be delighted to add them to this section. (Send me an e-mail.)
For a dedicated tribute to ARIA, see also Randy Loseys www.flyaria.com