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MOST: Canada's astronomical contribution

What you need to know

From the small, polished lenses of Galileo’s invention to mountaintop observatories and huge radio telescope dishes, for centuries, astronomers have used telescopes in the search for our origins. But all Earth-based telescopes are subject to two limiting factors: distortion caused by the atmosphere, and the night–day cycle that restricts observing time. Science answered a pressing need with the launch of the Hubble Space Telescope in 1990. The size of a large school bus, Hubble has produced spectacular results, but is fast approaching the end of its lifetime. It was a Canadian space telescope that broke the size barrier.

Huge innovation in a small package

Launched into its 820-km high orbit in June 2003, Canada’s little space telescope MOST measures changes in the brightness of the light emitted by nearby stars. These oscillations in brightness tell us about a star’s structure and chemical composition and allow scientists to more accurately determine its age and the age of the universe.

MOST, named for “microvariability and oscillations of stars,” is the smallest space telescope ever built: 65 cm long, 63 cm wide, and 30 cm deep, and only 60 kg. Its mirror lens is the size of a dinner plate.

Of the many technical issues to overcome, perhaps the most important challenge was how to point such a tiny instrument accurately at one star for several weeks to detect minute changes in brightness. The technology breakthrough came from Dynacon Enterprises Ltd. in Toronto. They devised a novel system of miniature reaction wheels and gyroscopes that fix MOST’s gaze on a star for up to seven weeks.

Revisiting theories about certain stars

After only one year in operation, the MOST science team, led by Dr. Jaymie Matthews of the University of British Columbia, made a major discovery. Procyon, a well-known star, was expected to show readily detectable variations in brightness. But it showed no oscillation during 32 consecutive days of constant observation, and double-checking confirmed the initial observations.

For astronomers, this astounding result is like detecting no heartbeat on a live, healthy person. MOST is expected to provide exciting observations of the universe and expand our knowledge of its origins for several years to come.