Astronomers get different information by searching the heavens at different wavelength bands, from gamma rays right up through the infrared and radio bands. This image of the Orion Nebula combines infrared and visible-light data from both the Hubble Space Telescope and the Spitzer Space Telescope.
Powerful new space telescopes in the works
Last Updated Sept. 6, 2007
The Hubble Space Telescope, certainly the most famous telescope of our generation, is starting to show its age.
After more than 15 years in space, parts have stopped working and it's sorely in need of a facelift. In the wake of the Columbia space shuttle disaster, the last servicing mission was cancelled and Hubble was sentenced to a slow death until an outcry from the scientific community persuaded NASA to reschedule that last servicing mission and keep Hubble working until about 2013.
The configuration of the Square Kilometer Array will include a compact core with about 50 per cent of the collecting surfaces within an area of 5 kilometres, an extended array with stations located up to 150 km from the core, and the rest of the collecting area in various distant stations out to at least 3,000 km. - SKA Project Office/XILOSTUDIOS
Hubble is certainly impressive — a telescope the size of a school bus that can see the universe above the distortion of the Earth's atmosphere — yet future telescopes, including Hubble's successor, involve even larger and more complex instruments. One of them, called the Square Kilometer Array, is a series of radio telescopes that could potentially stretch across a whole continent.
"It's what we call a world radio telescope, because it has participation from across the world," says Peter Dewdney, director of the Dominion Radio Astrophysical Observatory near Penticton, B.C. "It's an inevitable process of the maturation of astronomy, having to use more and more expensive and complex telescopes to answer the scientific questions that are out there."
Hubble's not so similar successor
There are definite advantages to sending a telescope into space. For Hubble, which looked at the universe in everything from the visible spectrum to infrared to ultra-violet light, most of that advantage came from being above the Earth's atmosphere, which either distorts or blocks light.
A technician examines a fully functional, one-sixth scale model of the James Webb Space Telescope mirror built for testing purposes. - NASA
The James Webb Space Telescope, considered Hubble's successor and set for launch in 2013, will only look at infrared light. Infrared astronomy is particularly good at seeing processes that went on in the early universe. With the universe expanding, distant objects are moving away at very high speeds and this causes the light to shift to the red part of the spectrum.
While Hubble just needed to orbit the Earth at an altitude of about 600 kilometres, the James Webb will need to be about a million kilometres farther away to collect its images. Infrared light is best collected and studied in conditions that are very dark and very cold. This is why the James Webb will be sent 1.5 million kilometres away from the Earth into what is called a Lagrange point, where the gravitational pull of the Earth and the sun are balanced.
Canada will be contributing one of the four instruments to the James Webb, an international collaboration among NASA, the European Space Agency and the Canadian Space Agency. This instrument actually has two completely separate parts: The Fine Guidance Sensor and Tuneable Filter Imager. The former is a two-camera system that tracks certain stars with great accuracy in order to keep the telescope pointed in the right direction, while the later allows scientists to filter incoming light from brighter objects, such as a star, in order to see fainter objects that are near them, such as a planet.
A full-scale model of the James Webb Space Telescope, shown at the meeting of the American Astronomical Society in Seattle in January 2007. The JWST's sunshield measures about 22 metres by 12 metres.
"James Webb is designed from a scientific point of view to take on where Hubble leaves off," said Dr. Mark Clampin, observatory project scientist for the telescope.
"Hubble has been able to see galaxies up to about a billion years after the big bang. James Webb will push back even further, to about 400 million years after the big bang," he says. Even alone in space, the James Webb needs to be shielded from the energy of the sun. NASA has designed a unique light shield the size of a tennis court that will keep the telescope at -220 degrees C.
The size of the telescope posed some tricky issues for its makers. About twice as big as Hubble, the James Webb must be folded up for its ride into space aboard a rocket. "The whole telescope is like an origami problem," Clampin said.
Promise of unexpected discoveries
While the new telescope is sure to expand scientific frontiers, researchers are also looking forward to the unexpected. Clampin, who also worked on Hubble, said that of its top 10 cited discoveries, half of Hubble's findings were things its designers hadn't imagined. He expects the same from the James Webb.
"But I think for the public, it's the images that have really had an impact and elevated the consciousness of Hubble's mission," Clampin said.
The James Webb will take equally amazing pictures, it's just that they will be infrared pictures, he said. "Sure, we may not see the famous eagle nebula like Hubble did, but we can see inside the nebula and that will certainly capture the public's imagination as well."
New telescopes: Keeping it visible
An artist's rendering of the Thirty Meter Telescope. The project is a collaboration between the University of California, the Associated Universities for Research in Astronomy, the Association of Canadian Universities for Research in Astronomy, and Caltech. - Thirty-Meter Telescope Project
Jaymie Matthews, an astronomer at the University of British Columbia, remembers when Hubble was about to be built. Many people predicted the death of ground-based telescopes and the beginning of a new era of astronomy centred on space-based ones. While space-based telescopes have certainly done a lot for astronomy in recent years, Matthews said, the ground based-telescope is far from dead. In fact, one of them, the Thirty Meter Telescope, is set to fill in part of the gap for observing objects using visible light that will be left by the James Webb.
"The key is that the technology has advanced very rapidly in terms of instrumentation and optics in the last few years," said David Halliday, one of the scientists working on the Thirty Meter Telescope. "There are features you can add to ground-based telescopes that make them much better, such as adaptive optics which can remove the problems of the atmosphere. The idea has been around for a long time but the problem has always been computing power."
The Thirty Meter Telescope will have about 300 segments of glass that make up its primary mirror. Using a laser to create an artificial star, the segmented mirrors can then be adjusted, or adapted, to take out the atmospheric fluctuations and get a clear picture.
The 10-metre large Keck telescopes in Hawaii, which were until a few years ago the largest telescopes in the world, use the same principle but with only 36 segments. And, Halliday added, "as you get bigger, the challenges get bigger as well."
Having just finished the design phase of the Thirty Meter Telescope, one of those challenges was how to house such a large structure. This is what occupied Empire Dynamic Structures Ltd., a Vancouver-area based company where Halliday is a vice-president. The current plan looks like a 36-metre onion, he said, like a giant sphere but with its bottom cut off.
Let's not forget the little guy
The briefcase sized Microvariability and Oscillations of Stars (MOST) space telescope, Canada's first and the world's smallest, was nicknamed the Humble Space Telescope because it cost only a fraction of its larger cousin yet could do things even the Hubble could not.
While the Hubble is "the Swiss army knife of space telescopes," said Jaymie Matthews, MOST's principal investigator, the MOST is a tool that does just one thing - measuring how a star's brightness changes over time - better than any other telescope can.
Entering the fourth year of what had been planned as a one-year mission, MOST is still running strong and Matthews thinks his satellite has shown you can do big science on a small budget. The Canadian Space Agency is thinking of building more microsatellites, including one that will detect a class of Earth-threatening asteroids.
While they might not inspire as much awe, Matthews points out that it was smaller telescopes that have made some of the biggest recent discoveries, including dark energy and extra-solar planets.
The Thirty Meter Telescope won't be completed until about 2015 when it will become the biggest optical telescope in the world. However, that title may only last a few years: A proposed European telescope could measure 42 metres and be completed in 2017.
A Canadian-American project, the Thirty Meter Telescope will help answer questions about everything from the birth and growth of the universe to questions about dark matter, and will even help with the search for planets outside our solar system. While the new telescopes won't see any farther into the universe's past than the Hubble could, Halliday said it will see what we already see, but clearer.
And if you think that's big
While the Thirty Meter Telescope will be the world's largest optical telescope, it's still small compared with radio telescopes that are already hundreds of metres wide. With radio telescopes, you can also put several together to get an even better signal — which is what the Square Kilometer Array (SKA) hopes to do.
The idea is to build a network of radio dishes with an accumulated collecting area of one square kilometre, but using telescopes spanning thousands of kilometres that are all linked. Currently, the most capable such array is the Very Large Array in New Mexico that spans only several dozen kilometres, with a collecting area 750 times smaller than the SKA.
Still in the planning stages, Dewdney of the Dominion Radio Astrophysical Observatory calls the SKA "a gleam in the eye of the world's radio astronomers as essentially the next generation of radio telescopes." Eighteen counties have so far signed on to the project, and there are two possible sites: Australia, where the telescope would span most of the continent, or South Africa, where the telescope would stretch as far as Kenya and Ghana.
The project is scheduled for completion in 2020, and right now a lot of work is going into researching technologies. Dewdney and colleagues are currently helping to build pathfinder projects in each of the locations to test the technology.
The MOST telescope enters a thermal vacuum chamber as part of its pre-launch test at the David Florida Laboratories near Ottawa. - Canadian Space Agency/Dynacon
Canadian scientists are considered particular specialists for something called correlators and they are currently building one for the Very Large Array in New Mexico. These devices help filter out 99.9 per cent of the useless information that a single radio telescope sees, while keeping the small bit of information that correlates to what other telescopes in the same array also see.
From a scientific prospective, radio waves are really good for looking at the coldest and darkest material in the universe, Dewdney said, adding that "we expect radio telescopes to see back farther towards the big bang than other types of telescopes." But even with that advantage, he points out, "some things are only understood when all the information from all the telescopes are put together. The Square Kilometer Array won't necessarily solve cosmic riddles itself, for that you need all the different kinds of telescopes."
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