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.
