EARLY HISTORY OF RADAR AURORA, IONOSPHERIC PLASMA, AND METEOR RESEARCH AT THE RADIO & EE DIVISION OF NRC

A.G. McNamara

See also the discussion on NRC in the transcript

My introduction to 'space science' was brief but fascinating. It was the summer of 1949 and I was finishing my Masters thesis on the energy calilbration of the betatron at Saskatoon. One evening, word went around that Peter Forsyth had got the newly acquired 106 MHz radar operational and was receiving auroral echoes. I dashed to the back of the Physics building and into his crowded van. Huge echoes were lighting up the radar screen. What an interesting phenomenon for research!

Soon after, I headed of to the University of Michigan for Ph.D. studies. After 2 years,I had completed the course requirements and was trying to find an interesting dissertation project. During that time I renewed acquaintance with Cec Costain who was on a post-doctoral fellowship after graduating from Cambridge. I left U. of Michigan in 1951 to join the Radio and EE Division of NRC where a Section under Dr. D.W.R. McKinley was doing radar development and research on radar echoes from meteors. Don McKinley at the NRC and Peter Millman at the Dominion Observatory had joined forces in 1947 to combine their researches on meteors using radar, photographic, spectroscopic and visual techniques. Their work in that field was some of the foremost in the world.

Cec Costain also joined the NRC in 1952 in the Physics Division with Dr. Herzberg. One day in the summer of 1952 he called excitedly to tell me of a wonderful opportunity to complete my Ph.D. with a thesis in a field which I would enjoy. He had heard that Peter Forsyth was leaving the Saskatoon auroral radar project to go to D.R.B., and Dr. Currie was looking for someone to carry on the auroral radar research. I jumped at the opportunity for the research and to work with Dr. Currie, a wonderful person and mentor, and renowned for auroral research done at Saskatoon.

After graduation in 1954 I returned to NRC. The Radio and EE Division had just built a new building and was re-oganizing its research along more civilian lines. Don McKinley, now an Assistant Director , invited his collaborator in meteor studies, Peter Millman, to head a newly formed Upper Atmosphere Research Section, to be primaritly focussed on meteors and aurora. (Soon after, Radio Astronomy also grew strongly within the Division, gaining impetous from the pioneering work of Art Covington. Jack Locke transferred from the Dominion Observatory to head Radio Astronomy at NRC).

Between 1954 and 1968 the Upper Atmosphere Resaerch Section grew with the acquisition of scientists who either were or became prominent in their research fields. Don McDiarmid became my associate in auroral radar work, and other Section members were Bruce McIntosh and Romeo Wlochowicz doing meteor research. Later, Alister Jones and Dick Gattinger came from the University of Sakatchewan, Ian Halliday from the Dominion Obsevatory, and Fokke Creutzberg and Frank Harris from the Churchill Research Range. In 1971 Peter Millman retired from NRC.

Around 1962, NRC formally undertook financial and technical suppport of a new Canadian rocket program to support all rocket space science in the Universities and Government labs. Under the direction of Don McKinley, the entire staff of the Space Electronics Section of REED was assigned to the engineering and building of the payload structures for incorporation in Black Brant rockets built under contract by Bristol Aerospace. These payloads would carry experiments designed and built by any Canadian group. The Upper Atmosphere Research Section of REED and the Cosmic Ray Section of Physics Division entered this mode of space research in a major way. UAR's experiments were focussed on auroral plama probes and photometers, and on micrometeoid detection. The first rockets in this new program were instrumented by the two NRC Sections and by the Physics Department of the University pf Saskatchewan. The first two rockets of the new program were launched successfully into aurora in the winter of 1962/63 from the CRR.

After several years of in-house payload fabrication, REED transferred the payload engineering and and launch checkout capabiliies to Bristol Aerospace Ltd., and soon after, the Space Engineering Division (SED) of the University of Sakatchewan was established by Prof. Alex Kavadas to also do contract work for NRC on both rocket and balloon payloads and launches.

In the early-mid 1970's the NRC formed the Herzberg Institue of Astrophysics with Jack Locke as Director. The new Institute incorporated a number of Sections from different Divisions, and in many cases the Section names were changed to better represent their evolving activities. The Radio Astronomy Section and the Upper Atmosphere Section ( Planetary Sciences) came from the REE Division; the Cosmic Ray Section (Solar-Terrestrial Physics) and Spectroscopy from the Physics Division; the Dominion Astronomical Observatory at Victoria and the Dominion Radio Astronony Observatory at Penticton were also included. The Ottawa-based Sections were all consolidated physically at the NRC Sussex Drive buiilding.

It should be noted that the various manifestations of the Space Research Facilities Branch/Canada Centre for Space Science/Canadian Space Agency' Space Science Program were also located at Sussex Drive thereby facilitating the interaction of program management and scientists.


In addition to the following, see also related material in the transcript of the workshop.

PERSONAL REMINISCENCES OF AURORAL RADAR AND SPACE RESEARCH IN THE EARLY YEARS

A.G. McNamara

My Ph.D. research at the U. of S. Physics Department , 1952-1954, followed the pioneering work of Peter Forsyth. I used the same 56/106 MHz dual frequency radar equipment but added some new equipment for specific objectives. Additional 56 MHz antennas at different heights were used for lobe switching to effect a direct determination of reflection height. The value 107 km was obtained. Cross-polarized antennas were used to study the polarization of 56 MHz echoes. (Some years later, excellent studies of the complete polarization characterics of echoes were made by Alex Kavadas and by George Sofko at Saskatioon).

The major component of the thesis was the use of a new 90.7 MHz long-pulse coherent radar (transmitter and receiver provided by D.R.B.) to provide a Doppler capabililty. To achieve this I had to design a signal processing system to extract the spectrum. Note that this was before the era of digital data, video tape recorders, computers and the FFT (1965) ! Analog circuitry was used to separate the upper and lower sidebands, and to direct these to twin banks of 5 narrow band audio filters, spaced 25 HZ apart, from 0 to 250 Hz. Each of these 10 signals was fed to its dedicated milliammeter. The milliammeters were photgraphed with a single frame 16 mm camera at any desired rate up to once per second. After developing the film, the meters were read with the aid of a microscope, and the spectra plotted, -400 m/s to +400 m/s. The spectra showed all the characteristics of modern digital Doppler radar spectra -- broad and narrow shifts, positive and negative, from 0 to >= 400 m/s, and often rapid variability. At that time, the theories of ionspheric small scale plasma wave instabilities were virtually unknown; it was not until the theoretical papers of Farley and of Buneman in 1963 that a more rational explanation of radar echoes was obtained.

The IGY of 1957/58 required major efforts in the Arctic from the newly formed Upper Atmosphere Research Section. An automatic 35 mm all-sky camera was designed and deployed at 9 stations extending in latitude from Victoria to Alert. A 48 MHz auroral radar was designed for continuous automatic operation and recording of backscatter and were installed at Ottawa, Saskatoon, Baker Lake and Resolute. The beams were stepped through 360 degrees synchronously under precision time control so that overlapping beams would be viewed simultaneously. This would permit studies of the aspect sensitivity. It is interesting that prior to installing the IGY network some U.S. radar researchers yold us that we were wasting our time and money locating radars at Baker Lake and Resolute since strong aspect sensitivity would preclude obtaining any echoes at all! In fact, echoes were easily obtained at all stations, with the two high latitude stations registering south as the dominant echo direction. Analysis of all the Saskatoon-Baker Lake simultaneous data by Don McDiarmid and Al McNamara (1967) showd that the averaage aspect sensitivity at 48 MHz was only 1 db per degree over aspect angles from 5 to 20 degrees.

One surprise was that the Resolute radar recorded virtually all of its echoes around local noon, not at night time. It was only years later with the advent of satellite imagery and better magnetospheric theory that it was apparent they were associated with the dayside auroral cleft region.

Following the IGY, the radars were all fitted with 360 degree rotating antennas, for transmittig and receiving. These were operated continuously at Ottawa, Saskatoon and Courchill, and for shorter perids of time at Thompson and Great Whale River.

In the late 1980s/early 1990s, Goerge Sofko and Jim Koehler of the U.of S. ran a number of bistatic c.w. radar campaigns in western Sakatchewan and northern U.S. The Planetary Sciences Section co-operated by providing installation assistance and operations personnel in several campaigns. The interactions of our radar groups were very pleasant and beneficial.

With the inception of the NRC-sponsored rocket program in 1962, I have flown plasma probes on the rockets primarily for the purposes of clarifying the mechanisms of auroral radar processes, and of measuring ionospheric events. The probes were usually of the spherical Langmuir type, yielding total electron densities and electron temperatures as functions of height and location. In addition, the probes had the capability of responding to the small and very rapid fractional fluctuations in electron density, dN/N, which were expected to be radar scatterers of VHF and UHF. The first rockets of the NRC program were flown in the winter of 1962/63 at Churchill. The program continued at Churchill until 1984.

Total electron densities inside visual auroral forms were measured as great as 10**6 per cc. (corresponding to a critical reflection frequency of 10 MHZ). Very small-scale density variations (dN) capable of radar scattering were recorded on many flights, providing the first in situ confirmation of structures capable of VHF/UHF radar scattering. The altiude profiles of the small scale structures could extend from about 95 km to 125 km, with the peak most frequently occurring around 107 km (confirming earlier radar measurements of reflection height). R.m.s. values of the fluctuations at the peak commonly reached 5% or more. Frequency spectra of the dN fluctuations showed a quasi-exponential decrease and sometimes extended to greater than 2000Hz. Exact conversion of the frequency spectra to scale size is complicated by the horizontal velocity component of the vehicle and the (unknown) comparable velocity and direction of the (assumed) propagating plasma waves. However, using some reasonable assumptions indicated that the scale sizes go down at least to 10cm, and these are capable of scattering to 1000 MHz or higher.

An interesting co-operation in the 1960s was an attempt to launch one of the plasma probe rockets into an aurora seen on the PARL radar. At Prince Albert, Al Seaman programmed the PARL radar to generate a crude array (~8x8 ?) of latitudes and longitudes centered on Churchill as the radar scanned. Each box of the array held a single digit representing average echo strength. The array of data was transmitted by the PARL radar via telphone line to a Telex machine at the launch control site. Unfortunately the relatively long azimuth scan and signal integration times of the radar and the slow Telex display, coupled with the exceedingly transient nature of the echoes, prevented their use as launch criteria.

The Herzberg Institute's Planetary Sciences Section had a major involvement with several components of the CANOPUS network for auroral studies. One component, the BARS 48 MHz radar system, engineered by contract to Canadian Astronautics Limited, were installed at Red Lake, ON and Nipawin, SA, with a common radar observing area centered on Churchill. They were fully digital radar systems, controlled remotely from Ottawa, and transmitted their data continuously via ANIK satellite to the CANOPUS data center in Ottawa.