Lunar Surface Suit Telemetry and Voice Communications

When an extra-vehicular suited astronaut steps onto the hostile environment of the lunar surface, he is essentially operating in his own personal spacecraft - the extra-vehicular suit system. The primary function of this system is of course, life support, but at least secondary in importance is the communications link with the lunar spacecraft and earth. Another function supplied by the system is suit telemetry to safeguard the astronaut's well being, as observed by monitors on earth. This includes the transmission of physiological data as well as suit environmental and performance data. The latter includes such things as suit pressure and the amount of oxygen remaining in the suit system. This paper describes the two functions of voice communications and suit telemetry. It includes functional requirements of the communication system which encompass range, relay links, and redundant modes. Design considerations are also briefly covered including past development work leading to the present prototype system. The paper also describes some of the hardware implementation problems including suit antenna considerations.