IEEE International Milestone in
Shirley Bay, Ottawa
May 13, 1993
|The Alouette/ISIS tracking antenna|
"Ladies and gentlemen, before beginning, I would like to say a few words on behalf of all those, in government and industry, who worked on the Alouette and ISIS program. I amnot sure that I can really adequately express how deeply we appreciate the honour and recognition which this ceremony represents. The program, and people who worked on it have received many awards over the years. However, this international recognition from the IEEE is especially gratifying. At the beginning we certainly had nothing like this in mind and I only wish that some of those early pioneers who contributed so much to the program, and who have now passed away, could be with us today. In particular, I think of Frank Davies (Chief Superintendent of the Defence Research Telecommunications Establishment, Ottawa), John Chapman, Eldon Warren, Bert Walker, and David Florida.
Let me now turn to my address. It will not be a detailed technical presentation but more of a personal perspective from someone who was there from the beginning. We had setbacks. In real life, successful programs are rarely the tidy affairs they seem when written up in scholarly journals.
I will begin with the Defence Research Telecommunications Establishment (DRTE), Ottawa. This is where the program was conceived and where the first two satellites were designed and built. DRTE had its origins in ionospheric sounding activities carried out by the Canadian Armed Forces and NRC during WW II. Before the satellite era radio propagation via the ionosphere was the main method of long distance communications, other than via landlines and underwater cables. Subsequently DRTE became a leader in the field of ionospheric research and by the late 1950s had become one of the foremost research establishments on the continent, with Radiophysics and Electronics laboratories that were on a par with any in the world.
With the launching of Sputnik in October 1957 it was realised at DRTE and elsewhere that a satellite-borne radar would provide a very powerful means of exploring the ionosphere from above (topside sounding), and that this could have important implications for long distance radio communications. Also, Bert Walker of the Canadian Joint Staff in Washington reported early in 1958 that the Naval Research Laboratory would welcome proposals from Canada for experiments in satellites and suggested that DRTE should respond.
|The antenna construction site|
At a meeting in October 1958, called by H.G. Booker of Cornell University to discuss ionospheric experiments in satellites, a number of groups in the USA and two in Canada, including DRTE, indicated their interest in topside soundings. This meeting resulted in DRTE submitting a proposal, to build a topside sounder satellite, to the newly created NASA in late 1958. Not a simple sounder operating on a few frequencies but a swept-frequency one that duplicated in a satellite the ionospheric sounders then used on the ground. The proposal was accepted and Canada's satellite program was born; without it seems much formality. Sputnik and the cold war produced a sense of urgency.
It was to be a cooperative undertaking between Canada and the U.S. with each country paying its own costs in the project. Canada subsequently undertook to provide a prototype and two flight spacecraft, and three ground stations including a master ground station and data processing centre in Ottawa. Canada also undertook to operate four ground stations for at least a year and exchange copies of all ionograms with cooperating agencies. The U.K. joined the program later and provided four telemetry stations.
The United States agreed to provide the launch vehicle, launch facilities, and a world-wide network of ground stations. The principal objectives of the program were to:
(1) develop a Canadian space capability;
(2) acquire new data for the engineering of high frequency radio communication links;
(3) acquire a better understanding of the properties of the ionosphere for scattering and deflection of radar beams.
NASA officials were nevertheless, sceptical (as indeed were some Canadians). They were convinced that it was too difficult to build the first Space-Based Radar (and a swept frequency one as well) at that time. The Central Radio and Propagation Laboratory (CRPL) at Boulder, Colorado agreed with the NASA view that the proposal was too ambitious, so their report recommended a fixed-frequency experiment as a first generation topside sounder and that DRTE "be encouraged to develop its swept-frequency system as a second generation experiment".
|The erecting of the antenna|
The rest is history; the CRPL/NASA fixed frequency satellite (S-48) suffered delays, the Canadian satellite (S-27) kept more or less on schedule; S-48 suffered more delays; S-27 was launched on 29 September 1962, to become Alouette I, the first satellite to be designed and built by a nation other than the United States or the Soviet Union. S-48 was eventually launched in August 1964, NASA later admitted publicly that they and CRPL were so convinced that it could not possibly function for more than an hour or two, if at all, that they had made no plans to use data from it. In fact Alouette I, constructed at a time when most satellites had a useful lifespan of a few months, continued to function and provided a wealth of data for ten years before it was turned off from the ground.
Text books on space technology and the in-orbit radiation environment were non-existent and the open literature and internal NASA reports were sparse. The young Canadian engineering team, at one point referred to as the "farm team", had no prior experience in the design of space systems and hardware but was highly skilled in the emerging area of solid state electronics. It also had the great advantage of being in day-to-day contact with world class scientists in the Radio Physics Laboratory. Finally there was the excellent support received from the emerging Canadian space industry and the close working relationships and trust that developed with our NASA, CRPL and AIL (Airborne Instrument Laboratories) colleagues. AIL built the U.S. topside sounder. Indeed we dealt with our U.S. colleagues as if we were all part of one big family.
To continue, little of the technology developed for ground-based sounders was directly applicable. Aside from the use of vacuum tube systems with their associated reliability problems and weight, size and power consumption, these sounders typically used large separate antennas for reception and transmission which were physically separated from one another in order to minimise RF interference between their transmitters and receivers.
Initially it was thought that these problems might best be solved using a swept-frequency CW radar instead of a more conventional pulse system and a good deal of time was wasted on this approach. The development of a vacuum tube transmitter was then undertaken but abandoned when a parallel development showed the required performance could be obtained using transistors.
There were stormy scenes on the subject of transmitter power. Caution said keep it low for reasons of cost, reliability and power consumption. The bolder approach eventually prevailed and a transmitter power ten times greater than the calculated minimum needed was finally chosen. This was a milestone decision since it greatly eased the antenna design and the mass production of high quality ionograms.
Cosmic noise was the subject of more scenes because of its impact on the transmitter power required for the sounder. Two attempts were made to measure cosmic noise in Javelin rockets from Wallops Island in 1959. They failed. In 1960 a 3.8 MHz cosmic noise receiver was designed and flown on a U.S. navy TRANSIT navigation satellite providing the first measurements of cosmic noise to be made above the ionosphere.
|The erected Alouette/ISIS tracking antenna|
One of the most difficult problems was the design of the sounder antenna system which had to cover a 1-10 MHz frequency range. Four STEM (Storable Tubular Extendible Member) devices formed two long sounding dipoles (150 feet and 75 feet tip-to-tip). A test flight on a Javelin rocket from Wallops Island was carried out to test the extension of a pair of STEMs in space. It was a partial success, one STEM did not fully extend. The STEM has since become an important, multi-purpose space mechanism and has been used on many space vehicles, including manned space flight projects. It was developed by Spar Aerospace from an NRC design for an extendible mast antenna for use in WW II.
The design of the telemetry system was unexpectedly difficult. The sounder antennas generated multiple nulls in the radiation pattern of the telemetry antenna. Because the satellite was spinning, these nulls would have produced regular drop-outs in telemetry which in turn would have hampered data analysis and severely reduced the value of the ionograms. The effect of the nulls was largely eliminated through a novel design of the telemetry and command antenna system in the satellite and by diversity reception and combining on the ground.
Nine months before launch we had no telemetry transmitter to send the ionospheric data to the ground. A U.S. company said the specifications, due to the sounder, were too difficult to meet. When John Stewart at RCA Victor, Montreal (now Spar) heard of our problem, over breakfast at a conference we were both at in Philadelphia, he said he thought his team could do it. He was told to go ahead, forget about costs and contractual details, and get us an engineering model within two months. He succeeded, the subsequent flight models operated flawlessly, and the design became the standard for subsequent Canadian and U.S. ionospheric sounder satellites.
The approach taken on reliability was novel and controversial. Little reliance was placed on statistical reliability calculations. Instead we insisted on a thorough understanding of semiconductor devices and circuit operation and worked closely with manufacturers to ensure that only semiconductors with median parameter values were procured. Circuits capable of operating under much greater than expected temperature and power supply variations were developed to counter expected and unexpected modes of degradation and failure. The consequences of radiation damage to semiconductor components were minimised by designing for far larger variations in transistor parameters than was the accepted practice at the time. This was an early example of what is now known as Robust Design. At the time critics said we would end up damaging components and degrading reliability. Similarly on the mechanical side, deployable items were designed to be fully tested under 1g conditions on the ground, although critics claimed this was overdesign.
The power supply was designed for what appeared at the time to be a very pessimistic figure of 40% degradation for solar cell charging currents, after one year in orbit. This paid off even before launch because it allowed the Alouette design to survive an unexpected artificial radiation belt created by a hydrogen bomb test at high altitude over Johnston Island in the Pacific in July, 1962.
With the assistance of the Defence Research Chemical Laboratory, Ottawa (now DREO) a major effort was made to improve the reliability of commercially available Ni Cd batteries. This resulted in some important differences between the Alouette and ISIS batteries and those used in U.S. spacecraft. The resulting batteries functioned for ten years in Alouette I and II and twenty years in ISIS-I and -II and were superior to those used in any other space program of the period. Particular attention was paid to the design of dc-dc converters. Other problems included the design of a novel transmit- switch and the elimination of electromagnetic interference in VLF and HF receivers.
The electrical and mechanical design and most of the environmental testing was done in Canada. The Canadian Armament Research and Development Establishment, Valcartier provided the thermal-vacuum test facilities.
The De Havilland Special Products Division, later to become Spar Aerospace Ltd, in addition to providing the STEM antennas, manufactured the satellite structure, and performed spin and centrifuge testing. Sinclair Radio designed the telemetry and command antenna subsystem in the spacecraft.
Within a few weeks of the launch of Alouette-I, it was clear that the satellite would provide the comprehensive and detailed data on ionospheric structure that was its primary mission.
This posed the problem of whether there should be an ongoing satellite program and, if so, what form it should take. Most of the skills and expertise responsible for the success of the satellite were in a government establishment, and not in industry. If Canada was to reap the full benefits of space technology it needed a strong domestic space industry. John Chapman took the lead in negotiating with NASA a follow-up program of scientific satellites, and took action to ensure that an increasing proportion of the design and construction work would be carried out in Canadian industry. This led to the International Satellites for Ionospheric Studies (ISIS) programme in which Canada and the U.S. shared the major costs for the construction and launching of four more satellites; three Canadian and one U.S. The U.K. and seven other countries actively participated through the provision of telemetry facilities and scientific analysis effort. The three Canadian satellites were Alouette-II - a refurbished Alouette-I flight spare spacecraft launched in 1965 along with a U.S. probe satellite, and two observatory satellites ISIS-I and ISIS-II launched in 1969 and 1971 respectively. The two observatory satellites were heavier and more complex than the Alouettes, and were prime contracted and built in Canadian industry. They carried tape recorders, probe and particle experiments from the U.S. and the U.K., and in the case of ISIS-II, two optical experiments. The principal experiment in each was still the ionospheric sounder which was essentially an upgraded version of the Alouette-I system plus a fixed frequency sounder.
A DRTE proposal for a further satellite in the series, ISIS-C, with 375m tip-to-tip antennas, was approved by NASA. It was an ambitious program to explore the magnetosphere but was withdrawn following the government's decision in 1968 to redirect Canada's space program from scientific to communications and remote sensing applications of space technology.
The Alouette/ISIS program has been an immense scientific and technological success with over 1200 papers and scientific reports published. Alouette II operated for nearly ten years before being turned off. Operation of the ionospheric sounders and VLF receivers in ISIS-I and -II operated for twenty years in orbit. In July, 1984, ISIS-I and ISIS-II were loaned to Japan's Communications Research Laboratory where they were operated for another five years for research purposes. They were turned off in 1990 with the ionospheric sounders and VLF experiments still fully operational. It was the gradual deterioration of battery capacity however that finally made impractical the continued operation of these satellites.
The success of Alouette-I led not only to the follow-on international program but more importantly to the establishment of the Canadian space industry which in 1990 had annual sales of approximately $350 million and 4000 employees, exports amounting to 45% of sales, and an annual growth rate which has been more than 10% annually for many years. If we include the services industry (Telesat, Teleglobe and Cancom) the annual space sales total is over $1 billion.
Finally, the fact that Alouette and its three successors performed so well and much beyond expectations gave Canada an international reputation for excellence in satellite design and engineering.
The Alouette/ISIS program produced a mountain of some 50,000 analogue tapes of topside sounder data. Is anyone going to digitise and preserve these for the archives or they simply going to be thrown out? A question for the CSA and perhaps DOC to ponder and on that note I will conclude my talk. Thank you."