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Stargazing is as old as the human race, but the practice of astronomy changed forever when Galileo, in 1609, became the first to turn a telescope toward the heavens.

Although his instrument was extremely primitive, he was still able to discern that four satellites orbit Jupiter and that, like the moon, Venus experiences phases. These and other observations helped to verify the Copernican view of the solar system - with the sun at its centre.

That work landed Galileo in hot water with the Vatican, hell-bent on upholding the ancient belief that all celestial bodies revolve around the Earth. But today all is forgiven as special events across Canada and around the world kick off the 400th anniversary of Galileo's monumental achievement in what the United Nations Educational, Scientific and Cultural Organization and the UN General Assembly have declared as the International Year of Astronomy.

Meanwhile, scientists and technicians are busy creating a telescope that Galileo could have never envisioned even in his wildest dreams - one so powerful that it can see almost to the dawn of the time.

The $3.5-billion James Webb Space Telescope, named after a key figure in the Apollo moon program, is being designed to see the first stars that formed in the universe; peer into cosmic dust clouds to observe the creation of planets; and gain new insights into the mysterious dark matter that is driving the movement of the galaxies.

At a cost of $130-million, the Canadian Space Agency is contributing two key pieces of hardware - a tunable filter imager, which can take pictures in specific wavelengths of light, and the all-important fine guidance sensor camera, which will keep the U.S. telescope on target as it takes pictures of the sky. The guide camera works by selecting a relatively bright star and keeping precise track of it. The 18 hexagonal panels that make up the main mirror have individual motors that can be adjusted multiple times per second, enabling the telescope to maintain a sharp focus.

The Webb is expected to far surpass the discoveries made by the famed Hubble telescope, which has provided breathtaking snapshots of the universe. But, after 18 years in Earth's orbit, its intricate instruments are breaking down. One last repair trip is slated for May, but even that will extend the life of the telescope only by a couple of years. The Webb is set to launch in 2013.

"It's guaranteed that we will find things we never dreamed of. And some of them will change our thinking of the universe forever," says John Hutchings, the scientist in charge of Canada's contribution to the telescope.

According to current estimates, our universe began 13.7 billion years ago in a cataclysmic event known as the Big Bang. From an infinitely small, hot, dense point, the universe sprang into being and has been expanding ever since.

It took several hundred million years for the first stars to emerge from the soup of primordial matter. Before the nuclear furnaces of these stars ignited, the universe was in the grips of a "dark age" - without a spark of light.

The Hubble has provided images of galaxies dating back to about one billion years after the Big Bang, but the Webb's ability to peer farther into space will allow scientists to observe the universe at an even earlier stage of formation. That's because looking deeper into space also means you're looking further back in time.

The new telescope's massive light-gathering mirror (6.6 metres in diameter, compared with the Hubble's 2.4-metre mirror) will allow it to see objects 10 to 100 times farther away than the Hubble can see.

What's more, the Webb's instruments are designed to analyze light in the infrared portion of the electromagnetic spectrum. The Hubble, by contrast, takes pictures only in the part of the spectrum visible to the human eye.

The reason for focusing on the infrared is linked to the ongoing expansion of the universe. As galaxies, with their millions of stars, fly farther and farther apart, the wavelengths of light travelling between them stretch out - a phenomenon known as redshift because visible light gets "shifted" into the infrared part of the spectrum. As the pace of separation was faster when the universe was younger, it's virtually impossible to see the first stars without viewing them in the infrared.

Because a solid glass mirror of the required size couldn't fit into the nose cone of a rocket, the Webb's mirror will be made of the lightweight metal beryllium. Divided into 18 hexagonal segments that fold into a compact package for launch, the segments will unfurl in space to form a smooth reflective surface.

The sensitive infrared instruments are also designed to operate at super-cold temperatures. "Infrared is essentially heat radiation," explained John Decker, the deputy program manager of the Webb at the U.S. National Aeronautics and Space Administration's Goddard Institute in Greenbelt, Md. That means infrared heat from nearby bodies in space - the sun, Earth and moon - or from the telescope itself could swamp the faint signals coming from distant space.

Positioned 1.5 million kilometres from Earth - four times farther out than the moon (the Hubble is just 600 kilometres above the planet) - the Webb will be equipped with a multilayered sun shield the size of a tennis court.

"It's like a giant beach umbrella," Mr. Decker says.

The telescope and its heat-sensitive instruments will remain in constant shade - with the sun, Earth and moon always on the opposite side of the massive unfolded solar shield. The temperature in the shade is expected to dip to minus-225 Celsius - perfect operating conditions for the Webb.

In a solar orbit that will follow the Earth in its annual path around the sun - a position in space known as a Lagrangian Point - the telescope will need minimal fuel-consuming course corrections because of the stabilizing gravitational forces of the Earth and sun.

But being so far away rules out the possibility of astronauts performing service and repair calls. No spacecraft currently exists that could make such a trip and return the human crew safely to Earth. That puts enormous pressure on the Webb scientists and engineers to get it right the first time around - including the Canadians behind the tunable filter imager and fine guidance sensor camera.

"It's a huge responsibility," says Dr. Hutchings, at the National Research Council's Herzberg Institute in Victoria. "If our guide camera doesn't work, the whole telescope is dead - it can't work."

Indeed, because it's so crucial to the success of the mission, there will be two identical guide cameras. "Should one fail, we can work completely off the other one," says Neil Rowlands, chief program scientist of COM DEV, which has the contract to supply Canada's high-tech space hardware.

Canadian astronomers will be guaranteed at least 5 per cent of the observing time on the telescope, which is also being financially supported by the European Space Agency.

"It may sound like a small amount of time, but this is a multibillion-dollar project and our contribution is actually less than 5 per cent of the total cost. So we are getting a good deal," Dr. Hutchings says. (On top of its initial cost, the Webb will need at least $1-billion to operate over the next 10 years.) Over the life of the telescope, which is expected to last more than a decade, "it amounts to hundreds of hours of observations - and that is precious stuff," he says.

Initially dubbed the "first light" telescope, the Webb might be able to see the first stars to burn in the universe. "We have some theories, but it really is an exploration of the unknown," says Isabelle Tremblay, a space systems engineer with the Canadian Space Agency. "The fact that Canada is part of this project is really important because it is going to help develop our scientific and engineering capacities for the future."

Paul Taylor is a Globe and Mail writer and editor.

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Starring ... Canada!

Canada is one of 140 countries participating in the International Year of Astronomy, launched by the International Astronomical Union and the United Nations Educational, Scientific and Cultural Organization. The official opening ceremony is in Paris on Thursday, but Canada's celebrations begin today, with events planned in Vancouver, Victoria, Sechelt, B.C., Edmonton, Calgary, Regina, Winnipeg, London, Kingston, Toronto, Ottawa and Halifax. Activities include astronomy talks, children's programs, planetarium shows and public telescope viewings of the full moon and other celestial sights.

Details on all IYA Canada events can be found at

http://www.astronomy2009.ca and http://www.astronomie2009.ca.

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The James Webb Space Telescope

DEPLOYMENT After the Webb is put into position, the solar panels will unfurl first, followed by the sun shield, instruments and primary and secondary mirrors.

ROCKET

The Arian 5 ECA is a heavy-lift launch vehicle that has been operating since 2002.

Payload. 16 tonnes capacity

Solid rocket boosters

Stage 2 HM7B rocket

Stage 1 Vulcain 2 engine

INSTRUMENTS

The telescope will look mostly at infrared light and study the 'redshift' of galaxies at the edge of the universe. It includes a fine guidance sensor camera, designed and built by the Canadian Space Agency.

Sun shield The shield will keep the instruments cool, increasing their sensitivity to infrared radiation.

Craft control systems

Solar panels

Primary mirror

Secondary mirror

MICRO SHUTTERS

Because the objects the Webb will be looking at are so far away and so faint, the telescope needs a way to block out the light of nearer bright objects. Tiny cells called micro shutters, about the width of three to six human hairs, will respond when a magnetic field is applied. Each cell can be controlled individually, allowing it to be opened or closed to view or block a portion of the sky.

ORBIT

The Webb will be stabilized by the gravitational forces of the sun and Earth at what is called a Lagrangian Point

Webb

Lagrangian Point 5

Lagrangian Point 2

Earth

Moon

Lagrangian Point 1

Sun

Lagrangian Point 4

Lagrangian Point 3

MIRROR COMPARISON

Hubble primary mirror

Webb primary mirror

Bigger is better The Webb's collecting area is seven times greater than the Hubble's.

French Guiana The launch date is set for June, 2013

NINIAN CARTER/THE GLOBE AND MAIL; SOURCES: CSA; NASA; ESA; ARIANESPACE