Low-noise microwave receiving systems in a worldwide network of large antennas

The Deep-Space Network (DSN) consists of a world-wide network of 25- and 64-m antennas spaced approximately 120° around the world. The DSN is a precision communications system designed to communicate with and control unmanned spacecraft traveling at interplanetary ranges. The ever increasing complexity and distances of spacecraft missions require that the network capability be kept at the state of the art of telecommunications. To meet this objective, a continuing development program on large antennas, low-noise maser, phase-locked receiving systems, and high-power transmitters has been underway for some years. Recent developments in the performance and evaluation of the antennas and maser receivers are discussed, and developments which have contributed to radio science projects, such as planetary radar astronomy, very long baseline interferometry, pulsar, and other astronomical observations are described. It is also shown how these radio science measurements have been used to evaluate the performance of the antenna-receiver systems.