Frequency and timing requirements for space exploration

The role of time and frequency standards in space missions is briefly discussed. The present status of the frequency and timing capability in the NASA deep space network (DSN) is presented, together with a review of the anticipated future requirements. Based on the future needs, areas for future development in frequency and timing technology are identified. The frequency and timing capability presently existing in the DSN meets the requirements of missions through 1995. The Cassini mission planned for 1996 launch represents the first DSN mission requiring the stability of new standards, the superconducting cavity stabilized oscillator (SCMO) and the mercury ion standard.<>