Concluding Observations

Now that the discussion of the key features of the form and function of the DSN is concluded, it is well to note that the Network is also a business that exists, quite simply, to provide services to its customers. Customers of the DSN range from the currently operating and in-flight missions to those that are in their early planning stages. DSN customers also include both the flight missions (e.g., Voyager) and ground-based observations (e.g., those of the Goldstone Solar System Radar).

Interaction between the DSN and its customers begins early, as soon as mission concepts are defined and the potential support is identified. The ensemble of potential needs of all of these becomes the inspiration for many of the research and development efforts of the dedicated DSN Advanced Systems Program. As described earlier, products of the Advanced Systems Program range from theoretical concepts to physical models, and include demonstrations of devices and subsystems that could in the future become a part of the operating DSN and its technology base, which is applied as needed to benefit the DSN's customers.

Under appropriate circumstances, the engineering models produced by the Advanced Systems Program may be used to directly support a customer on a "best-effort" basis, but more often, they become the starting point for the design of equipment to be implemented in the Network. The implementors use the technological products of the Advanced Systems Program and other sources, as appropriate, to design subsystems in a form suitable to install in the Network for long-term effective support of the DSN's customers. The implementors typically work in close coordination with staff participating in the Advanced Systems Program; their products are the hardware and software of the operational DSN.

Although the configuration and capabilities of the operational DSN are kept relatively stable, they are not static. Both the Network and the planning for it evolve in response to the needs of its customers, whenever those needs arise. Customer requirements can be formally stated as the outcome of a long-recognized planning process, or appear in the form of a problem to be solved or an opportunity to enhance a customer's data return. Ready examples can be found in the support to Voyager and elsewhere. Early failures in the receivers on Voyager 2 necessitated precompensating the forward-link Doppler, which was accomplished by applying the programmable local oscillators developed and demonstrated under the Advanced Systems Program via Goldstone radar. And the extensive use of arraying, which was first demonstrated by the Advanced Systems Program in 1973, was initiated operationally with the Voyager's Saturn passage, and subsequently became the key to significant enhancement of the mission return from Uranus and Neptune.

In summary, the needs of the DSN's customers have been the driving force for all activities, including not only the active operational support, but also the early planning in concert with the mission planners, and supporting research and technology development efforts. A strong technology development program motivated by the needs of the Network's customers has been an essential element in providing effective support to the customer base. An effective and flexible, yet needs-driven implementation program is also essential to providing the quality of support that the DSN's customers can and do expect.