A BRIEF HISTORY OF THE PHASE 3-D SATELLITE PROGRAM Development of the Phase 3 series of Amateur Radio relay satellites was initiated in 1975 to provide a capability for longer range, more reliable communications than had been possible with the preceding series of low altitude Amateur Radio satellites that were initiated with the launch of OSCAR 1 in December, 1961. The name OSCAR is short for Orbital Satellite Carrying Amateur Radio. The Phase 3 series of satellites were designed to fly in highly elliptical "Molniya" orbits pioneered by the Soviet Union, carrying multiple transponders and operating in frequency bands allocated to the Amateur Radio Service. While many of the worldwide, non-profit Radio Amateur Satellite Corporation (AMSAT) groups were involved in these projects, the most involved were Germany's AMSAT-DL, and North America's AMSAT-NA organizations. Three 150 kg class spacecraft of similar design were developed and launched between 1980 and 1988. Unfortunately, the first, Phase 3-A, was lost due to a booster failure. Recovering from this setback, the second and third spacecraft were successfully launched to become AMSAT-OSCAR 10 and AMSAT-OSCAR 13 upon reaching orbit. They both continue to operate successfully in providing communications relay capability, although attitude control of AO-10 has been lost due to radiation damage to its onboard computer. Following the launch of AO-13, two design studies were initiated to define follow-on missions. AMSAT-DL chose to study a continuation of the Phase 3 series using a larger, more capable Phase 3-D spacecraft launched into an improved elliptical orbit. The orbit would be carefully selected to be easier understood by most Amateur Radio Operators, allowing them both increased access time and more convenient availability than orbits afforded by the current Phase 3 spacecraft. At the same time, AMSAT-NA began study of a Phase 4 satellite that would operate in a geostationary orbit. The Phase 4 spacecraft would have provided a platform for vastly improved communications for those Amateurs within range, but the concept would have required multiple satellites to provide worldwide coverage. Both studies assumed similar three-axis stabilized, 500 kg class spacecraft carrying more and higher power transponders, operating across a wider range of frequencies as well as modulation techniques, than the current Phase 3 satellites. When it became clear that funding for the Phase 4 program would have had to come almost exclusively from the Amateur Radio community in North and South America for a single satellite, and would have required a much larger outlay of resources from the worldwide Amateur Radio community for a multiple satellite system, the decision was made, albeit reluctantly, to shelve the Phase 4 concept in favor of teaming with AMSAT-DL on the Phase 3-D program. An added decision driver for this course of action was the fact that AMSAT-DL had been successful in securing a flight opportunity on one of the two test flights of the new Ariane 5 launch vehicle under development with the European Space Agency (ESA). First flight of the Ariane 5 is planned for the 1995/6 time period. This timing could not have been better, as orbital instabilities will now make certain the atmospheric reentry of AO-13 in late 1996. Without a replacement, the Amateur Radio community would be left without a high altitude satellite for the first time in more than a decade. Today, the International Phase 3-D Project Team also includes AMSAT groups from Great Britain, Japan, Finland, South Africa, Russia, Belgium, Czech Republic, Slovenia and Hungary in addition to the groups from AMSAT-NA and AMSAT-DL. Recent advances in propulsion, materials, electronics, antennas, structures, orbital stability and control as well as computational finite element structural and thermal analyses have shown that construction and launch of a Phase 3-D-like vehicle is now well within the technical expertise of the AMSAT community. Further, this project can be accomplished while still supporting all the stringent launch requirements of ESA for the Ariane 5. Ongoing tests of structural materials, electronic components, stability and control mechanisms as well as development of high-strength, lightweight, high- temperature materials and the availability of powerful personal computers for design, integration and testing of such a vehicle have advanced progress toward this goal. AMSAT-NA's specific contributions to the Phase 3-D effort involves the design and fabrication of the spacecraft's structure, including part of the supporting cylinder used to carry the spacecraft on the Ariane 5 vehicle during launch. In addition, AMSAT-NA will serve as the lead organization to design and procure the solar panels and power systems, as well as design and fabricate the spacecraft's antennas and the GPS experiment. In addition, AMSAT-NA will assist with design and fabrication of the spacecraft's propulsion systems, and may possibly serve as host for the spacecraft's final integration effort prior to launch. While its primary focus will be on improved worldwide satellite communications, the Phase 3-D project will also have a positive influence on the very future of Amateur Radio. Whenever the topic of Amateur Radio is discussed at international meetings, it's frequently the Amateur Radio space communications program that captures the attention and imagination of national officials. It's often the Amateur Radio community's continued willingness to support projects like Phase 3-D...projects that continue to expand the state of the art in communications...that garner praise by these officials and help justify the Amateur's continued access and use of valuable radio spectrum. In addition, as the leading showcase of expertise and talent for the Amateur Radio community, the Phase 3-D effort epitomizes perhaps the most unique managerial and technical approach to research and development of a space vehicle ever realized. There is nothing else quite like the Phase 3-D program anywhere in the world. The managerial and technical challenges and resulting "lessons learned" from an international team of volunteers working largely on their own time, in their own homes, and at their own pace, will be significant. This experience will be invaluable in providing corporate, government and private institutions with information on alternative ways to promote significantly lower cost access to space while still maintaining technical excellence in a non-profit environment. During the current phase of the program, designers have matured key structural and electronic designs including new structural materials, various command, control and attitude systems, transponder and antenna configurations as well as thermal control systems. Baseline program master schedules are in place and are being used to status the program. An engineering model of the spaceframe has been fabricated and is now being evaluated. A flight model structure is being fabricated, and planning has commenced for final integration of the spacecraft. While the vast majority of design, development and fabrication costs will be donated by private individuals and institutions, active fund raising efforts are underway by AMSAT and other Amateur Radio organizations worldwide to secure the approximate $4 Million out-of-pocket development and launch resources needed to make the Phase 3-D program a reality. (Current as of February, 1994) For more information contact: Keith C. Baker, KB1SF 1324 Fairgrounds Road Xenia, Ohio 45385-9514 USA "kb1sf@amsat.org"