ABSTRACT
This chapter discusses several time transfer scenarios involving planetary orbiters, landers, and deep-space probes on science and exploration missions. The first scenario is not really a space mission at all since it describes time transfer between national laboratories on Earth via a geosynchronous satellite. The second scenario describes time transfer from Earth to Earth orbiters like the Space Shuttle. The third scenario involves time transfer to the Moon and satellites of the Moon. The fourth scenario involves time transfer for Mars orbiters, landers, and aero-probes. The fifth scenario involves navigation and time transfer from Earth to deep-space vehicles. The chapter describes a method for time transfer from Earth to a satellite in low-Earth orbit or medium-Earth orbit. The pulse-per-second signal is used as a precision time tag for transmissions of one station to the other, while the 5-MHz signal is multiplied to 25 MHz and used to drive the analog-to-digital and digital-to-analog converters and timing signals used in the modem.
