Suitcase satellite set to pinpoint stars' age UBC Reports
April 16, 1998

Suitcase satellite set to pinpoint stars' age

by Stephen Forgacs
Staff writer

Using a satellite the size of a suitcase, a UBC researcher hopes to provide clues to one of astronomy's most fundamental questions: How old is the universe?

"This project should appeal to the basic Canadian admiration for the underdog," says Jaymie Matthews, an assistant professor in the Dept. of Physics and Astronomy and principal investigator of the Microvariability and Oscillations of STars (MOST) project. MOST will be Canada's first space telescope.

"With a relatively small amount of money and a very small satellite, we're going to address a large and fundamental question about the history of our universe. And we will do this using a telescope no bigger than those used by backyard stargazers," he says.

The $11-million project is a joint effort involving UBC, Dynacon Enterprises Ltd. and the University of Toronto Institute for Aerospace Studies (UTIAS). MOST is a mission proposed under the Small Payloads Program, sponsored by the Canadian Space Agency's Space Science Branch. Project approval from the CSA is contingent on approval of all funding contributions.

Once launched in 2000 or 2001, Matthews' satellite will be pointed at one stellar target after another for six or seven weeks each to collect information on the "ringing" of stars.

This ringing, or oscillating, is caused by sound waves bouncing around inside the star. The waves paths' are modified by the temperature and composition of gases through which they travel.

The telescope will measure the resulting vibrations, which cause the brightness of the star to vary.

The project involves use of a technique called asteroseismology, which exploits the subtle surface oscillations of stars to probe their internal structures and measure their ages.

Matthews likens detecting the oscillations to trying to listen to a sound that is 30 decibels below what the human ear can detect, while sitting next to a steadily beating bass drum.

The small telescope, with a collecting mirror about 15 centimetres across and housed in a casing the size of a suitcase, will hitchhike into space with another, bigger satellite.

Once free of the launch vehicle and primary payload, the 50-kilogram microsatellite will turn its telescopic eye toward any one of a number of stellar targets before relaying its data on the star's oscillations to Earth.

"While modest in size, the MOST instrument will be able to accomplish what no other telescope on Earth or in space, including the Hubble Space Telescope, can -- the detection and characterization of rapid oscillations in stars like our Sun," Matthews says.

The stars are expected to ring in pitches or periods near five to 10 minutes. Each star will vibrate in a symphony of many such periods. To distinguish the closely spaced tones and then extract the desired information about the interior of the star, each star must be monitored for weeks with almost no interruptions.

Armed with these data, the team of MOST astronomers led by Matthews hopes to measure the ages of some of the oldest stars in our galaxy, setting a meaningful limit on the age of the universe itself.

Efforts to measure the tiny oscillations of other Sun-like stars using a series of land-based telescopes are problematic because of atmospheric noise, which makes stars appear to twinkle from Earth.

The MOST project also represents a major breakthrough in the way microsatellites are used for space science, Matthews says. Because of their small size, microsatellites have traditionally been quite difficult to point accurately, making it useless to put a telescope aboard one.

UBC, with the technical support of CRESTech, an Ontario Centre of Excellence, has designed a simple, inexpensive yet highly precise telescope that can operate effectively from a microsatellite platform. Dynacon, with UTIAS, has in turn designed a microsatellite platform that can be pointed with great precision. Precision control of the microsatellite platform will open up new opportunities for low-cost space astronomy and Earth-observation missions, says Matthews.

Four small, spinning, gyroscope-like wheels are used to position and reposition the microsatellite from Earth. These "reaction wheels" are the only moving parts in the satellite and, when made to spin in varying directions by the Earth-based controller, cause the satellite to change orientation.

The microsatellite, travelling at a speed of 27,000 kilometres per hour, will orbit the Earth once every 100 minutes at an altitude of 800 kilometres.

Powered by solar panels, it is expected to function from five to 10 years before radiation damage to its electronic components renders it inoperable.

The microsatellite will also host its own hitchhiker, a transceiver installed on behalf of AMSAT, the Radio Amateur Satellite Corp., which is also a partner in the MOST project.

AMSAT is a non-profit organization that invented microsatellite technology and is playing a major role in the development of the satellite housing design. The transceiver will serve as a backup communication system for the satellite while also allowing North American amateur radio operators to communicate with operators in Europe.