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Astronomers working with the James Webb Space Telescope are praising the newly commissioned observatory’s performance and scientific potential after a public release of test images.

In one image showing a portion of the Large Magellanic Cloud – a satellite galaxy of the Milky Way that is located more than 150,000 light years away – the stars appear as crisp points compared with the fuzzy blobs that were previously visible using Webb’s predecessor, the Spitzer Space Telescope.

At a press briefing on Monday, scientists working with the telescope said the dramatic improvement in image quality is a sign that Webb’s 18 gold-plated mirror segments are operating as designed to provide the sharpest views ever obtained of the universe at infrared wavelengths.

In a side-by-side comparison, a distant field of stars appears far sharper in a test image (right) taken by the Mid-Infrared Instrument on the newly commissioned James Webb Space Telescope than the same region when it was previously observed (left) by the Spitzer Space Telescope, which launched in 2003.The Associated Press

“This is an extraordinary milestone for humanity,” said Michael McElwain, an observatory project scientist at the Goddard Space Flight Center in Greenbelt, Md. He added that Webb is on track to reveal “the first luminous objects in the universe,” as well as fulfill a host of other scientific objectives.

The telescope was built by NASA in partnership with the Canadian and European space agencies. After launching last December, it spent a month travelling to its operating position some 1.5 million kilometres from Earth. Since then, astronomers have been busy aligning the telescope’s components and checking its various instruments. A key part of the process involved using the telescope’s Canadian-built Fine Guidance Sensor to precisely lock its mirrors onto distant targets in the cosmos.

While the initial results suggest the telescope is performing even better than anticipated, such a positive assessment is never a foregone conclusion. It was during the commissioning phase that a debilitating flaw was discovered in the main mirror of the Hubble Space Telescope in 1990. The flaw impeded the telescope’s performance until astronauts could install corrective optics three years later.

Webb is located much too far from Earth for a rescue mission, so astronomers who are planning to work with it say they are relieved and excited to see that so far the US$10-billion telescope is operating as intended.

“I was absolutely thrilled,” said Els Peeters, an astronomer at Western University in London, Ont., who will be among the first to use the new telescope as part of a project to study hydrocarbon molecules in space. She said that the Large Magellanic Cloud image was taken at the same wavelength she uses for her work.

“I can’t wait to see the first science observations,” she added.

During the news briefing scientists said the telescope’s first science images are likely to be released sometime in July. While they would not reveal where they will point the telescope for what will likely be an iconic set of pictures, they said it would include targets that demonstrate that Webb can perform the science it was built for.

Unlike Hubble, Webb sees primarily in the infrared part of the spectrum, which is well suited for peering at the most distant galaxies in the universe and nearer targets including planets in orbit around other stars.

Klaus Pontoppidan, Webb project scientist at the Space Telescope Science Institute in Baltimore, said that while the human eye is not sensitive to infrared light, astronomers can make use of the multiple filters on Webb to translate the images into full-colour photos that have a similar aesthetic quality to those obtained using Hubble.

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