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A thin layer of gold on each of the James Webb Space Telescope’s 18 mirror segments reflects mostly infrared light. (Drew Noel/NASA)

Infrared Dawn: The Next Space Telescope Will Be Hubble x 100

The James Webb Space Telescope will see out to the universe’s edge.

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On a rainy Monday morning in early 2014, Senator Barbara Mikulski of Maryland joined NASA Administrator Charles Bolden on a stage at NASA’s Goddard Spaceflight Center in Greenbelt, Maryland, to congratulate the team building the James Webb Space Telescope on having cleared a hurdle familiar to anyone who’s just arrived home with a box of furniture from IKEA: making sure all the major parts are there.

All four of the scientific instruments NASA’s new flagship observatory will carry—built by the European Space Agency, the Canadian Space Agency, the University of Arizona, Lockheed Martin, and NASA—had arrived. Ball Aerospace had delivered all 18 hexagonal segments of the observatory’s honeycomb-like, 6.5-meter primary mirror, designed to look into a past 13 billion years distant. From an observation platform, you could see one of the mirrors on display in the Spacecraft Systems Development and Integration Facility, the largest clean room in the world. Others sat in their custom shipping crates, each one like a stove-top popcorn tin the size of a large kiddie pool.

Two decades after astronomers first convened to discuss what sort of space-based observatory should succeed the Hubble Space Telescope, Hubble’s three-times-as-large, 100-times-as-powerful replacement, whose fabrication was overseen by primary contractor Northrop Grumman, finally seemed to be coming together. “Going from Hubble to the James Webb Space Telescope is like going from a biplane to the jet engine,” said Mikulski, who has long been the project’s strongest legislative advocate—and who four years earlier had called for an independent panel to uncover the causes of its delays and ballooning expense.

That panel published its findings in October 2010, concluding that NASA had, in essence, requested an indie-movie budget to make a high-tech blockbuster. It praised the quality of NASA’s technical innovations while criticizing its management. NASA responded with a dramatic “re-plan,” establishing a schedule that now has Webb slated for launch in October 2018, at a grand total of $8.8 billion—more than eight times the amount NASA estimated when work began nearly a generation ago.

In 2015, the mirrors will be mounted to the backplane. (Northrop Grumman)
Mirror segments are prepped for testing at Webb’s 50-degree-Kelvin operating temperature. (Emmet Givens/NASA MFSC)
NASA has been exhibiting a full-scale model of the telescope all over the world, including in Orlando, Florida ( Dr. Mark Clampin/NASA Goddard)
At NASA’s Goddard center the segments sit packed, ready to ship. (Ball Aerospace)
CalTech’s Richard Ellis is eager for Webb to probe even further back than his Hubble Ultra Deep Field survey did in 2012. (Courtesy Richard Ellis)
Since Bill Ochs came on board as mission manager in 2010, the project has stayed on schedule. (Reprinted with permission of the Baltimore Sun Media Group. All rights reserved.)
Engineers work on Webb’s sunshield. (Northrop Grumman Aerospace Systems)

Bill Ochs, who came on as project manager late in 2010 to implement the re-plan, says that the Webb has stayed essentially on schedule—though now an especially tight one—during his watch. “Instruments are typically one of your high-risk items,” Ochs explains in his office at Goddard, where a shoe-size model of the telescope sits on a side table next to miniatures of other satellites he’s worked on in the last 30 years. “So to have them delivered here almost five years prior to launch is just outstanding.”

Or almost four years after the launch date anticipated by the decadal survey of 2000, in which astronomers named the Webb telescope their top priority. At least the launch has finally seemed to stop doing what the objects Webb was built to observe are doing—receding ever farther into the cosmic distance.

In 2002, the space telescope was officially named after James Webb, a Marine Corps pilot who served as the space agency’s administrator from 1961 to 1968, overseeing the Mercury, Gemini, and Apollo programs. “There’s no other project on the table even 20 years out that can do what [Webb] should be able to do,” says James Dunlop, a professor of extragalactic astronomy at the University of Edinburgh, Scotland. “Sometimes people want to can these projects because in the meantime some new, cheaper technology breakthrough is made that renders the facility obsolete before it’s even flown. There’s no danger of that happening with James Webb.”

No one disputes that the Webb will be an extraordinary machine, one that will allow astronomers to look farther back in time than they’ve ever been able to see, to the earliest galaxies that formed after the Big Bang. The gold coating on its mirror segments, totalling about a golf ball’s worth and spread in a thin layer across the surface of each segment, will absorb light on the blue end of the spectrum, allowing the observatory to see a bandwidth between 0.6 to 28 microns, firmly in the infrared and stretching just slightly into the visible spectrum.

Scientists have known since Hubble was launched that its successor would need powerful infrared capabilities. Advances in knowledge made during the Webb telescope’s long gestation—the discoveries of thousands of extrasolar planets, for example—have served only to underscore the scientific need for a cold, infrared-optimized observatory in space.

For viewing faint, distant stars and galaxies, infrared is where the action is, because the expansion of the universe extends the wavelength of light over time. This phenomenon, known as redshift, gradually stretches visible light waves outside that part of the spectrum, beyond where Hubble (which has some infrared capabilities but captures mostly visible and ultraviolet light) and even the infrared Spitzer Space Telescope can register. Like Webb, Spitzer is a cryogenic telescope with a beryllium mirror, but less than one meter in diameter—“a tiny little tiny can,” as Dunlop puts it. “At the relevant wavelengths, [Webb] has a collecting area 100 times greater than the best facility we have,” he says. “It’s an order-of-magnitude jump in what we can do.”

Simon J. Lilly, a professor at ETH Zurich, a university in Switzerland, who was part of the committee that in the mid-1990s advised NASA on what was then called the Next Generation Space Telescope, is just as enthusiastic. “The current frontier for reliable detection is not much beyond redshifts of seven,” he says, using the redshift formula in which the higher the number, the more distant and earlier in time the object. “The very first objects, I think, are probably actually beyond reach even of [the Webb]. But I’m optimistic that we might get back out to redshifts of 15—substantially beyond where we have any information today.”

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