satellites must be dormant during launch.) A brief system check-out is then performed. A ground command is then issued to activate a pyrotechnic device to release the rectenna from its ASAP interface. The rectenna occupies one ASAP position and the tether mechanism is located on an adjacent position, with the tether cable running between them. Springs provide the initial impetus to start the tether deployment mechanism, and either gravity gradient or centripetal acceleration ensures continued deployment of the tether. Ideally, it would be desirable if the tether mechanism had the capability to stop the tether deployment at various intervals in order for transmission tests to be conducted over different distances (e.g. every 100 meters or so). Such a capability is not a priority requirement, however. Once the tether is deployed, the rectenna is inflated. The rectenna is essentially a pressurised torus structure that supports a diaphragm on which are etched microstrip elements for rectifying the microwave transmission. Pressurisation requires an inflation device, on which is also located a simple transmitter to relay measurement from the rectenna directly to the service module located on the ASAP. The tether is attached to the rectenna via three cables - somewhat like a parachute - in order to ensure it is properly oriented with respect to the ASAP. The estimated diameter of the rectenna is about 12.5 meters. This large size enables a much more significant transmission distance (on the order of several hundred meters) to be contemplated than for the single position ASAP demonstrator discussed in the Eurospace Interim Report. The service module which contains the on-board computer electronics, data storage system, and TT&C receiver, transmitter and omnidirectional antenna is located on the ASAP ring. (Figure 5.1-4) In addition, an option for a small CCD camera is included within the service module to observe rectenna deployment and inflation. The solid state data storage system would collect information relayed from the rectenna during power-beaming experiments and then down-load this data near perigee.
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