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Peter Calamai
Science Reporter
Toronto, January 12, 2006 - Canada's bargain-basement "Humble" space telescope has launched a search for Earth-sized planets around distant stars, a feat none of the much bigger and costlier telescopes in space or on the ground can match.
Its initial survey came up empty, chief scientist Jaymie Matthews announced yesterday at the annual scientific conference of the American Astronomical Society in Washington.
Yet the University of British Columbia astronomy professor isn't downcast.
"We're the first people who can look for planets about the same size as the Earth and we're the only ones who can tell you what's not there," Matthews joked in an interview.
U of T spacecraft, a bargin at $10M
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The $10 million telescope spacecraft was assembled at the University of Toronto's Institute for Aerospace Studies, which also provides mission control.
An American researcher says the Canadian telescope is blazing the Earth-search trail since NASA won't launch the first dedicated planet-hunting satellite, called Kepler, before 2008.
"The search for other worlds like home is on now," said Dimitar Sasselov of the Harvard-Smithsonian Center for Astrophysics, who works with Matthews.
The Washington meeting heard that the Canadian telescope last year "staked out" a star 160 light years away that was already known to possess a Jupiter-sized planet, one of 120 so-called "exoplanets" discovered in recent years. Astronomers suspected a smaller Earth-sized planet might also be orbiting close to the same star.
"The Jupiter planet is too big for its mass, so some people thought the gases were being puffed up by tides caused by the pull of another nearby planet. We were able to rule that out," Matthews said.
The 45-day astronomical stakeout found no Earth-sized planet in the five possible "resonance" orbits calculated by experts, all closer to the star than Mercury is to our sun.
Matthews says the Canadian telescope will make another intensive search for an Earth-sized planet this fall when the star, known prosaically as HD209458a, heaves back into view in the constellation Pegasus. The magnitude 7.8 star is visible with binoculars but not the unaided eye.
"We're going to sweep outwards from the star and get to the Goldilocks zone where it's not too hot or too cold," he said.
In an interview from Washington, Matthews said the telescope has already spent a month trained on a second star where another giant exoplanet has been detected.
"It's completely different than anything we've seen before and we're still trying to sort it out," the astronomer said.
Most exoplanets discovered so far are massive gas giants orbiting close to their parent stars and therefore dubbed "hot Jupiters." The exoplanets are detected by the minute distortions that their gravity causes in light from the parent star.
Launched from Russia in the summer of 2003, the Canadian-designed MOST telescope is sometimes jokingly called "Humble."
The suitcase-sized spacecraft cost a mere $10 million, compared with more than $2 billion for NASA's Hubble, which is as large as a tractor-trailer.
But unlike Hubble, the Canadian spacecraft can keep its modest 15-centimetre telescope centred on the same star for as long as two months even while orbiting the Earth every 100 minutes at a height of 820 kilometres. Its "hunting ground" amounts to about one-eighth of the cosmos.
This super-precise aiming lets MOST, or the Microvariability and Oscillations of Stars, detect changes in a star's brightness as small as one part in one million, a kind of super-sensitive light meter no other telescope comes anywhere near.
Timing the regular faint dips in brightness as the "hot Jupiter" crosses in front of the star lets the MOST team detect any subtle gravitational tugs from other smaller planets hidden in the system.
"We can use those transits as a clock and we're the only people who can record the ticking," said Matthews.
Chief contractor for the MOST spacecraft was Dynacon Inc., a Toronto high-tech company specializing in automation and robotics. The Canadian Space Agency is financing the project.
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