Amsatuk Colloquium Highlights

The 6th Annual AMSAT-UK Colloquium was held at the University of Surrey in the United Kingdom on July 25-28. Approximately 150 people were present from 21 countries. The list of lecturers looked more like a who's who of the amateur satellite world. Unfortunately the British cosmonaut, Helen Sharman, was unable to be present, but hopes to come next year.

The main topics were about future satellites, but the 42 different presentations also gave much more information, reports, knowledge and wisdom to all present. Some typical subjects were WARC-92 preparations and CCIR participation; selecting orbits for radio amateur missions; telemetry, past, present and future; VITA operations using UO-3; a low-cost receiver for UO-11 and DOVE; digital satellites and equipment required to use them; AO-13 management, past and future; portable antenna systems for use with UO-3 and PACSAT; and the UO-22 CCD camera. The following is a summary of some of the presentations.

Phase 3D

The European Space Agency has confirmed a launch slot on the second ARIANE-5 flight timed for October 1995. The primary payload is the "cluster" spacecraft. Phase 3D will look like a doughnut of nonuniform thickness, 10.5 feet in diameter and about 2.1 feet tall weighing 880-1100 pounds and will also have two deployable "wings" carrying extra solar panels. The power budget is about 200 watts. The inside of the "hole" will be a launch adaptor to carry the main pay-load. I hope to upload a sketch (in GIF format) to UO-14 soon. Because a 10-foot spacecraft is too big for doors, elevators, etc, Phase 3D will probably be made in separate pieces and the blocks finally assembled at the launch site.

Launched into a standard geostationary transfer orbit, the aim is for the first motor firing to occur at perigee and raise apogee to about 31070 miles. Subsequent firing(s) will be made at apogee to raise the perigee and make a plane change to 60-63 degrees inclination. Energy required for this is actually less than that needed for AO-13.

The intention is to fine tune the orbital period to exactly 16 hours in order to give regular and repeatable access times with consecutive apogees occurring and repeating, over Europe, North America and the Far East. Target times for access are local time synchronous at 0500-0800 and 1800-2400 hours.

The spacecraft will carry gain-agile antennas, possibly 13 dB at 70 cm and 20 dB at 24 cm for narrower beamwidth at apogee and then widening out at lower altitudes. Digital communications links will be similar to existing RUDAK experiments. Analog links will be equipped with the LEILA concept to kill alligators. An excessively strong uplink signal will first be overlaid with a tone and then, if you do not decrease power, it will be notched out. LEILA can handle several signals simultaneously.

The concept of transponder "mode" may be abandoned. Instead Phase 3D could have communications links connected at baseband like a matrix. See Figure 1.

A camera experiment, SCOPE, is likely from Japan. This will have at least two lenses (24 and 90 degree fields) and return color images of the Earth. If possible there will be a third lens to return sky, planet and star images. Resolution of all of these is expected to be about 750 by 580 pixels.

Another possible experiment comes from AMSAT South Africa. This will provide educational broadcasts of up to 15 minutes of digitized speech on 29 MHz using Compatible Amplitude Modulation (SSB and carrier). These transmissions are expected to occur at perigee and are targeted at schools and other educational establishments.

Finally, the doughnut has a hole in the middle. Can we mount something inside this area? It is possible that this void may have an extra AMSAT-DL payload, a spacecraft to send to Mars. The possibility of accurate

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