Outer planets proximity link protocol

A directional X-band proximity link protocol derived from the Consultative Committee for Space Data Systems (CCSDS) Proximity-1 protocol that accommodates link dynamics and end-to-end file transfer considerations is presented. This implementation is targeted for the NASA Europa Multiple Flyby (aka Clipper) and Lander Missions currently under study, and is intended to be extensible for other outer planetary missions. A variant of the Proximity-1 protocol has been successfully used at Mars for UHF communications between Mars rovers and relay spacecraft. Mission designs currently under study for the Europa Multiple Flyby and Europa Lander missions include ranges that do not support high data rate, omni-directional UHF relay links. Directional X-band links are an attractive alternative given the presence of X-band telecommunications systems on many outer planetary spacecraft such as Europa Multiple Flyby and the Europa Lander's Carrier spacecraft. Relay link concepts of operations and implementation of hardware, firmware and software in the Johns Hopkins University Applied Physics Laboratory (JHU/APL) Frontier Radio are discussed. The proposed tailoring of Proximity-1 for these Europa missions will be described for the Physical layer and Coding & Synchronization sub layer (C&S). An analysis of the interfaces between the protocol and the spacecraft command and data handling system is described. After the Europa Lander has completed its primary mission, the Europa Multiple Flyby and Lander Carrier spacecraft could potentially both serve as long-term relay assets for future Jovian missions.