Passings: William (Bill) Gault was a project scientist at York University

William Gault worked as a project scientist at York University from 1970 until 2003. He was a close colleague of Professor Emeritus Gordon Shepherd, who sent this tribute to YFile about his friend and collaborator, who died of cancer on Nov. 19.

Bill Gault

William (Bill) Andrew Gault was born in Ottawa on May 25, 1939 and received his BSc from Carleton University in 1961. On a trip across Canada in 1962, he stopped off to visit the University of Saskatchewan and stayed on as a PhD student. His first supervisor was Donald M. Hunten, who later moved to the University of Arizona, becoming a world leader in planetary science. Bill continued with Howard Rundle as supervisor and in 1967 completed a thesis titled “A Study of the Twilight Airglow Emissions of Sodium, Lithium, And Potassium.” He then moved to the Service d’ Aeronomie in France for three years, further studying potassium in the high atmosphere. His return to Canada in 1970 coincided with the creation of what is now the Canada Centre for Remote Sensing, a newly recognized area of Earth observations, taking a position in the Centre for Research in Earth Science & Engineering (CRESS) at York University.

Under a contract from this new agency, he developed instruments that could be used for the remote sensing of land surfaces and oceans. When the contract ended, he continued with the development of new instruments for the observation of the aurora and airglow, which occupied him to the end of his career. The first was a basic scanning Michelson interferometer, used for the observation in 1977 of the spectrum of the daytime (in winter darkness) aurora at Cape Parry, Nunavut, the first such observation, in support of a campaign of two rockets. This campaign was so successful that a second was carried out in 1981, in collaboration with NASA and involving five rocket launches. This allowed for more ambitious ground-based optical instrumentation, so Bill designed a system based on the Fabry-Perot interferometer, which had better suppression of the scattered sunlight, obtaining unique results. He also built a new Michelson interferometer for incorporation on one of the rockets. It was destroyed when the rocket went off course, but the experience was still valuable.

It was by now established that the Michelson interferometer could be used for the measurement of winds in the upper atmosphere, and an opportunity to exploit this from space, by flying an instrument on the newly developed space shuttle appeared when in 1979 NASA accepted a proposal from Canada. WAMDII, the Wide Angle Michelson Doppler Imaging Interferometer, exploited the concept of field-widening that allowed the observation of winds at the low light levels of airglow. A demonstration model was built by SED Systems in Saskatoon, supported by Bill; it performed incredibly well in the laboratory and in field tests.

However, this opportunity was replaced by another in 1984, to measure winds from the newly approved NASA Upper Atmosphere Research Satellite (UARS). This would require a still more sophisticated instrument, called WINDII (WIND Imaging Interferometer), as a Canada-France collaboration. Thus WAMDII was terminated, but by then it had proven the concept. WINDII was developed by (then) Canadian Astronautics Limited in Ottawa, with Bill ensuring that the requirements of the WINDII team would be met by the instrument; in this, he acted as “instrument scientist” on behalf of the Science Team. He retained this position for the duration of WINDII, launched in 1991 and operated in space until 2003. Throughout, Bill ensured that WINDII delivered the required data and he led the “validation” of the results obtained through comparison with simultaneous co-located observations made with ground-based instruments worldwide.

With the WINDII experience, Bill designed a ground-based wind instrument called ERWIN (E Region WINd interferometer), which measured ground-based winds from Resolute in Nunavut for a number of years and later from Eureka, one of the most Northern points in Canada. It was operated remotely from Toronto, so in a sense was not so different from a satellite mission. He was also involved in other possible missions for winds lower in the atmosphere than for WINDII, which meant extending the wavelength observed into the infrared. However, none of these ended with a mission. Bill retired in 2003, having left his mark on the upper atmospheric community in terms of sophisticated measurements of winds and other parameters of the upper atmosphere.

Bill was an inherently quiet and honest person who would undertake tasks on his own, then offering thorough and ingenious solutions. In the WINDII Science Team, he established a unique position through his knowledge, personality and integrity, and when differences of opinion appeared, he was often the one able to suggest the accepted solution. He was regarded as a friend to all.

Early on the morning of Nov. 19, after a long bout with cancer, Bill passed away peacefully, leaving behind his wife, Danielle; son, Ian; daughters, Stephanie Schaller and Kathleen Baggio; grandchildren; great-grandchildren; and other family members. The family will remember his patience, kindness and empathy.

In leaving the science community in 2018, he has also left his mark with the many colleagues he acquired along the way with his insights and his quiet, thoughtful and caring manner.

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