Astronaut Robert Thirsk, the first Canadian to live on the International Space Station (ISS), visited the University of Toronto on October 27th.
His visit was an opportunity to review the results of an experiment Thirsk conducted while aboard the ISS, which was designed by Professor Masahiro Kawaji (ChemE).
Thirsk spent 188 days aboard the ISS between May and December of 2009. While aboard, he was responsible for the maintenance and repair of the ISS, in addition to conducting experiments on behalf of Canadian and international researchers.
U of T’s contribution to Dr. Thirsk’s mission was the Marangoni Experiment in Space (MEIS-2), which sought to understand how a zero-gravity environment impacts upon the physical processes underlying crystal formation.
If you have ever noticed “the tears” that form when you swirl a glass of wine, you’ve noticed the Marangoni effect. When a liquid with a high surface tension pulls more strongly on the surrounding liquid than one with a low surface tension, the presence of a gradient in surface tension will naturally cause the liquid to flow away from regions of low surface tension. Because alcohol has a lower surface tension than water, that can cause the tears to appear along the side of the wine glass.
However, this effect also has a significant impact on the manufacturing of semiconductor crystals, which are widely used in electronics. Creating a liquid bridge is one way to produce semiconductor crystals, but the Marangoni effect causes convection that needs to be better understood. Gravity has made obtaining precise data on the Marangoni effect difficult on earth, so outer space provides a perfect environment to conduct this research.
The results of the experiment are still being analyzed. Professor Kawaji explained that over three terabytes of data was collected over the course of the experiment. This information will help to better understand the transition from steady to oscillatory Marangoni flow, as well as the effects of g-jitter (random vibrations) on the liquid bridge. That knowledge, in turn, can be used to develop higher quality and more efficiently produced semiconductor crystals.
While on campus, Dr. Thirsk also met with Professor Peter Lewis, U of T’s Associate Vice-President of Research, and Professor Stewart Aitchison (ECE) Vice-Dean, Research, for the Faculty of Applied Science & Engineering, to express his thanks to the University.
“We were very proud of our association with the University of Toronto and the contribution Dr. Kawaji made to our mission through the MEIS-2,” Dr. Thirsk said.
He presented U of T with a mission patch that was flown in space, as well as a personalized collage of his time in space to Professor Kawaji. He also participated in an information session for graduate students, where he detailed his experience aboard the ISS.
“I woke up every morning feeling tired,” Dr. Thirsk noted, “but then I would remember I was in space and thought ‘that’s pretty cool’ and got on with my day.”
Dr. Thirsk, who holds the Canadian record for the most time spent in space, announced that he was retiring from space travel on October 25th.
