The MOST Humble Space Telescope

Space telescopes usually thought of as huge machines. The famous Hubble Space Telescope, for example, is 13.2 meters (43.5 ft) long and 4.2 meters (14 ft) in diameter. Though not all are so large; 800 kilometers above the Earth there is a satellite that is just 65 centimeters (about 25 inches) long – not larger than a large suitcase – proving that, when it comes to science, “size doesn’t matter”.

This astonishing device is called MOST (which stands for Microvariability and Oscillations of Stars). Although being very small compared to its peers, this satellite is helping scientists answer intriguing questions about stars, planets and even the Universe itself.

The MOST Space Telescope Credit: Canadian Space Agency

Staring at the Stars

Launched on June 30th 2003, MOST is the first space telescope to be entirely designed and built in Canada. As its name suggests, it is designed to take precise measurements of variations in intensity (the brightness) of stars in order to determinate their composition and age. The larger space telescopes cannot afford the time required for this task as to measure these oscillations, is necessary to keep the lens pointed at a single target in the sky for weeks at a time, and they can’t do so because of the high demand for their time.

Usually, astronomers use expensive ground-based telescopes to measure these stellar pulsations. However, this isn’t the best way to do so, since the readings are distorted by the Earth’s atmosphere. Moreover, the day-night cycle makes impossible to scientists to observe a star for 24 hours a day. Though with its orbit above the Earth’s atmosphere MOST can avoid both problems; and is able to look at any part of the sky continuously for up to seven weeks with a minimum of distortion.

The Secret life of Stars

The technology of this incredible telescope is helping astronomers figure out some very interesting things about stars, things well beyond our expectations. One of these discoveries was made as soon as the satellite became operational.

In 2004, the MOST team reported that Procyon (the brightest star in the constellation Canis Minor) shows no pulsations at all, contradicting more than 20 years of observations. Later, in 2006, the scientists realized that they were dealing with an unknown class of stars, the “slowly pulsating B supergiants”.

Furthermore, MOST has also been used to study exoplanets in alien star systems. Indeed, this is the only telescope – in space and on Earth – able to detect the light reflected by a planet orbiting around another star. Although not designed for this purpose, MOST is giving us a hint of what the atmosphere of those planets look like. It does this by detecting subtle variations in the light from either the planet or the star itself. MOST can see changes down to levels of one part to a million – or one ten thousandth of a percent!