Episode 2: International Satellites for Ionospheric Studies

The year is 1969, and Defence Research and Development Canada has been recognized on the international stage thanks to the resounding success of the Alouette topside ionospheric satellite missions. Universities in Canada and the United States wanted to build off of that research with newly developed experiments, and they looked to Canada to deliver.

On the coattails of the success of Alouette 1 and Alouette 2, a pair of satellites named the "International Satellites for Ionospheric Studies" were the third and fourth in a series of Canadian satellites launched to study the ionosphere. There were technically three satellites in the ISIS joint program with the United States. The success of Alouette 1 piqued the United States' interest and became more involved in Alouette 2, prompting a rename to ISIS-X. The project team reconsidered name change, and the satellite remained Alouette 2 due to the mission profile and hardware similarities to Alouette 1. In this video, we'll be focusing on the two formally named ISIS satellites. I go into depth on the Alouette missions in Episode 1. Check that out with the link in the top right!

RCA Victor Company Limited of Montreal, you know, the company that notably brought us the phonograph, vacuum tubes, and the videodisc was contracted to do the bulk of the work on both ISIS satellites. De Havilland Aircraft of Canada in Toronto and SPAR Aerospace did still see some subcontracted work out of this. SPAR saw their first significant contract outcome to be as providers of ISIS 2's mechanical structure and sounder antennas. Through this work, these companies became substantial participants in the Canadian Space Program in the future.

The DRTE gradually reduced their involvement in the design and construction of the satellites throughout the program until the industry accepted complete responsibility for meeting performance expectations for ISIS 2. A fundamental condition set by the Canadian government that came with the approval of the ISIS plan was that industry should be brought into the program to the greatest extent with the goal that by the end of the program, there should exist a skilled industry in Canada for spacecraft development. Overall management of the mission remained at DRTE.

Measurements were taken over an entire 11-year solar cycle and helped determine how the ionosphere reacts to changes in the Sun's radiation. Both Canadian and American universities and government laboratories contributed to the instruments that were on board. The results streaming down from Alouette 1 and 2 made it clear that merely understanding the distribution of electrons in the ionosphere was not sufficient in understanding the ionosphere. Information like ion mass and temperatures were required to interpret the ionosphere's behaviour.

The ISIS satellites hosted far more complex - for the time - navigational equipment and a tape recorder to record experiments when the spacecraft was out of communications range. This was a massive improvement over the Alouette satellites. It allowed for data collected by the experiments to be played back as the spacecraft passed over Canada. Lower priority experiments were not recorded, but the data was still beamed to the same stations Alouette was heard from in Hawaii, Singapore, India, the UK, Norway, New Zealand, and Central Africa.

ISIS featured both swept and fixed frequency sounders. These allowed researchers to understand how the ionosphere reacted with various frequencies. They also featured a full set of experiments designed to measure ion mass and temperature directly. Active spin maintenance also helped keep the satellites oriented for optimal performance. RCA also included a clock to act as a master timekeeper to keep the various experiments synchronized as required. These improvements contributed to overall near-perfect orbits and mission performance.

ISIS 1, article 1969-009A, was launched at 10:46 PM Pacific Standard Time on Thursday, January 30th, 1969, on a Delta 100 rocket from Space Launch Complex 2E at Vandenberg Air Force Base in California. It was delivered to a very eccentric orbit of 578 kilometres and 3526 kilometres at an inclination of 82 degrees, much like Alouette 2. ISIS 1 weighed 241 kilograms or 531 pounds at launch and played host to ten experiments.

ISIS program manager Dr. C. David Florida died suddenly just before the launch of ISIS 2 in 1971. A plaque was mounted onto ISIS 2 commemorating his contributions to the project. The satellite testing facility at the Communications Research Centre Canada in Ottawa, Ontario, was named the David Florida Laboratory when it opened in September 1972. This laboratory is today operated by the Canadian Space Agency. It is regularly rented out to Canadian and foreign aerospace and telecommunications companies and organizations for qualifying space-bound equipment like satellites or components made to be placed on satellites or the International Space Station. Today the facility features clean rooms, electrodynamic shakers, anechoic chambers, space simulation chambers, and in-house mechanical, electrical, and electronics shops.

ISIS 2, or article 1971-024A, was launched at 6:57 PM Pacific Daylight Time on Thursday, April 1st, 1971 aboard another Delta 100 rocket and it certainly wasn't an act of April Fools! The satellite was placed into a nearly circular orbit at 1358 kilometres and 1458 kilometres in a polar orbit of 88 degrees. It weighed 23 kilograms or 51 pounds heavier than ISIS 1 at 264 kilograms or 582 pounds at launch due to two additional experiments on board.

These new experiments were designed to study atmospheric optical emissions, otherwise known as the Aurora Borealis. These significant contributions were produced by an Auroral Scanning Photometer provided by the University of Calgary and an Atomic Oxygen Red Line Photometer provided by York University in Toronto, Ontario.

The revolutionary Auroral Scanning Photometer used the slowly rotating spacecraft to systematically scan across the Earth while the dark side of the Earth was visible. It was tuned to be sensitive to the visible green light at 557.7-nanometers and 391.4-nanometer wavelength light, just nearing ultraviolet. The Red Line Photometer experiment was effectively a colour camera that used the perceived brightness of the light being emitted by the Aurora Borealis. A single orbit of the satellite was capable of surveying the entire polar region. This was incredibly historical as these were the first images of Aurora from above.

There was a third and final satellite planned for the ISIS campaign; however, in 1969, the Canadian government changed its focus towards developing communications satellites and, as a result, was cancelled.

Due to budget restrictions in part thanks to DRTE's change in focus, ISIS 2 had a very similar design to ISIS 1. Slight changes to the frequency sounders were made to increase frequency accuracy and overall output power. ISIS 2 also included a feature called Automatic Ionogram Transmission that allowed automatic operation of the sounder once every three minutes. This allowed small institutions to acquire low-cost ionograms to study. The VLF (Very Low Frequency) experiment was increased to include antenna impedance measurements on the sounder's short dipole antennas. On both satellites, these were 73 and 18.7 meters long. These are significantly different in length than the Alouette missions but were built of the same construction.

NASA support of the ISIS project was terminated on October 1st, 1979. However, a significant amount of experimental data was acquired after this date by the Canadian project team. Both satellites were terminated on March 9th, 1984 until Radio Research Laboratories in Tokyo, Japan, requested and received permission to reactivate the satellites. The regular operation was then started from Kashima, Japan, in early August 1984 until it was again deactivated on January 24th, 1990. The same data restoration effort we mentioned in Episode 1 also included the ISIS project data and saved a large amount of high-resolution before the telemetry tapes were discarded.

You can find more information on the ISIS/Alouette Topside Sounder Data Restoration Project in the link in the description. (https://nssdc.gsfc.nasa.gov/space/isis/isis-status.html)

The ISIS satellites achieved their mission goals with a very high rate of success, and over 1200 scientific papers were created in response to the data that was collected over a staggering 21-year period. Scientists learned about the physical processes that occur in the upper atmosphere and the ionosphere, including densities, temperatures, magnetic field strengths, and structure. We became experts in imaging in space and measuring solar particles and plasma.

Stay tuned for the rest of Season 1, where we'll continue our conversation on some of the other satellites Canada has contributed and what that's meant for innovation in Canada and abroad! Follow Canadian Space on Twitter and at cdnspace.ca. There you'll find transcripts of our episodes and additional resources to continue your own exploration into Canadian space! If you like what we're doing here and want to contribute financially, head on over to our Patreon page at patreon.com/cdnspace. Thanks for watching, stay safe, and be well.

References:
https://en.wikipedia.org/wiki/ISIS_(satellite)
https://en.wikipedia.org/wiki/Delta_(rocket_family)
https://photoreportages.ca/node/22329
https://www.asc-csa.gc.ca/eng/satellites/isis.asp
https://www.friendsofcrc.ca/Projects/ISIS/isis.html
https://ui.adsabs.harvard.edu/abs/1991CaJPh..69..938G/abstract
https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1969-009A
https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1971-024A
https://en.wikipedia.org/wiki/DavidFloridaLaboratory
https://www.ncbi.nlm.nih.gov/pubmed/20125605
https://www.osapublishing.org/ao/abstract.cfm?uri=ao-12-8-1753
https://en.wikipedia.org/wiki/Light
https://link.springer.com/chapter/10.1007/978-3-319-20756-8_4