June 30, 2003, the eyes of the international scientific community were
riveted on the Plesetsk Cosmodrome in northern Russia, watching the
launch of MOST, the new microsatellite of the Canadian Space Agency
The flight of the MOST satellite (MOST stands for
Microvariability and Oscillations of Stars) was a key step in the
ambitious project being carried out with the participation of Steve
Torchinsky, a scientist with the CSA's Space Astronomy Program.
was conceived primarily to measure changes in the luminosity of stars,"
says Mr Torchinsky. How will a satellite the size of a suitcase manage
to do that? With the help of an ingenious telescope it is equipped
with. The optical concept used by the instrument makes it possible to
optimize diffusion over a greater number of detectors, making MOST
capable of detecting even the tiniest variations in luminosity.
instrument is so powerful that, if humans were capable of doing the
same thing, a person standing one kilometre away from a streetlamp
would be able to notice an increase in luminosity after moving only
half a millimetre closer to the light source!
MOST in Action
astounding capabilities of MOST will be used to measure the vibrations,
or oscillations, of stars. "The Sun, a star that we know well, does not
always shine the same way," explains Mr Torchinsky. "Changes in
luminosity happen regularly. It is like a bell that rings and emits
acoustic vibrations. The larger the bell, the lower its tone. In the
same way, the bigger the star, the longer the vibration. MOST therefore
makes it possible to study the fundamental vibrations of stars and
their harmonics - their various frequencies - and compare them to those
of the Sun."
The study of asteroseismology therefore
provides us with data - such as the density of the star and the
pressure of its surface layers - which we can use, along with the
star's temperature and mass, to determine that star's age.
MOST, we will finally be able to determine the dynamic composition of
stars," says Mr Torchinsky. "In addition to seeing what is found on the
surface, we will also be able to discover what is hidden inside the
stars, and thus be able to understand their innermost nature."
On the Trail of New Planets
1995, astronomers discoveredthe existence of a planet orbiting a star
other than the Sun. Today, we believe that the galaxy could contain
billions of these extrasolar planets but, to date, we have been able to
detect only about a hundred of them. This was done indirectly, by
observing their gravitational effect on neighbouring stars. However,
thanks to the sensitivity of MOST, we will now be able to directly
detect the light reflected by an extrasolar planet.
sees the light reflected on planets and notes minuscule variations in
luminosity," says Mr Torchinsky. "This is a different system of
observation, which will provide us with data we never had access to
before, since no other telescope - not even Hubble - is capable of
collecting this type of information."
A Very Busy Schedule
MOST has just been launched, it already has its work cut out for it.
Its schedule for the next two years is busy indeed. "The use of MOST
has been planned for the next two years," says Mr Torchinsky. "The
satellite's activities were determined based on scientific priorities
and the visibility of the stars. Consequently, we will give priority to
stars that resemble the Sun and to some extrasolar planets."
its third year of operation, MOST, whose operational life is estimated
at two years but which is expected to continue functioning optimally
for five years, could be made available to groups of scientists other
than the original research team.
"The satellite could
even be used for educational purposes by enabling schools to propose
experiments that take advantage of the unique capabilities of MOST,"
emphasizes Mr Torchinsky. "There are so many things to study!"
For the Advancement of Science
the end of the day, the entire international scientific community could
benefit from the valuable data acquired by MOST. "Obviously, as is the
custom, the scientific team responsible for the project will be the
first to look at the results. However, those results will be published
in scientific journals as and when they are acquired," affirms Mr
Torchinsky. "The data will therefore be made public internationally and
will add to the sum of human knowledge."
experiment will also be used as a cornerstone for a series of similar
future experiments, including the European Space Agency's COROT
project. MOST is expected to remain a focal point not only for this
reason, but also because its attitude control system - a major
technological innovation - is generating a great deal of interest.
system is exceptional!" says Mr Torchinsky. "Although it is miniature,
its pointing remains very accurate. There is no other system like it
and, if we prove that the technology does indeed work, demand for it is
sure to be great."
Despite his enthusiasm for
technological progress, Mr Torchinsky believes that we should focus on
the project's initial intent: "For me, the scientific aspect of
projects is the most important. We conduct experiments to enrich our
fundamental knowledge. This should be the goal that guides how we
choose the subjects we study. Technology will follow."
One thing is certain: with its immense potential, we are sure to hear more about MOST in the years to come!