demonstration can attract f unding both for itself and for future experiments in the same area. For instance, on the single watt level, a transponder could send out a “beep” or Morse-code signal saying something like “power received” strongly enough for amateur radio operators to pick up. On the next higher power level, a light bulb could serve as a flash bright enough to illuminate a logo (“Eat at Joe’s,” for instance) printed on the receiver long enough for a photograph to be taken. At the kilowatt level, a light could be set to flash on and off (in Morse code, perhaps) and could even be visible from Earth with a small telescope. The determining factor for all of these possibilities is, of course, the area of the microwave collector. The equipment necessary for monitoring the received power levels and frequency dispersion and transmitting the data back to Earth can easily be made compact and lightweight, so it does not impose any real restrictions. For reception on the order of a single watt, the rectenna area need only be about 4 m2. Such a rectenna could be easily deployed from a small package using existing, well- tested technology. To get the larger receiver area necessary for demonstrations on the 100 watt scale, more innovative types of deployable structures would have to be used. Reception on the kilowatt scale with a collector deployed from a microsatellite is probably not feasible in the near term. Vehicle Configuration The choice of an ASAP platform puts rather stringent restrictions on the size, shape, and mass of the receiving satellite. The ASAP ring lies on top of the Ariane H10 upper stage, and is capable of carrying up to six separate payloads of up to 50 kg each. Each of these positions can accommodate a payload with dimensions equal to a 45 cm cube, though exceptions are sometimes made allowing the payload’s height to be up to 60 cm or so depending on the nature of the mission’s main payload. Individual payloads on the ring can be connected to each other by wires. [9] Working within the above constraints, a two-section spacecraft is envisioned. One position on the ASAP platform would be taken up by the main satellite equipment, including sensors, data-handling equipment, a transponder for data transmission, an independent power supply, and whatever else is necessary for the demonstration chosen. The other position would be connected to the main satellite bus by wires strung along the ASAP ring, and would be used to house an inflatable reflector. When deployed, the spacecraft would look something like the one shown in Figure 6. The inflatable reflector would be transparent on one side with a reflective parabolic inner surface. Connected by wires to the main bus about 12.5 m away, the satellite would be gravity-gradient stabilized and would always point toward Earth. Oscillations could be damped out using small RCS thrusters. Microwaves transmitted from Arecibo would be collected by the reflector and focused on a small rectenna on the surface of the main spacecraft. There are several advantages which come from the use of such an inflatable reflector to collect the beamed power. The main three are in mass, volume, and area. Using an inflatable rigidifiable antenna allows one to get the largest surface area
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