Building James Webb: the biggest, boldest, riskiest space telescope

Daniel Clery in Science:

GREENBELT, MARYLAND—For months, inside the towering Building 29 here at Goddard Space Flight Center, the four scientific instruments at the heart of the James Webb Space Telescope (JWST, or Webb) have been sealed in what looks like a house-sized pressure cooker. A rhythmic chirp-chirp-chirp sounds as vacuum pumps keep the interior at a spacelike ten-billionth of an atmosphere while helium cools it to –250°C. Inside, the instruments, bolted to the framework that will hold them in space, are bathed in infrared light—focused and diffuse, in laserlike needles and uniform beams—to test their response.

The pressure cooker is an apt metaphor for the whole project. Webb is the biggest, most complex, and most expensive science mission that NASA has ever attempted, and expectations among astronomers and the public are huge. Webb will have 100 times the sensitivity of the Hubble Space Telescope. It will be able to look into the universe’s infancy, when the very first galaxies were forming; study the birth of stars and their planetary systems; and analyze the atmospheres of exoplanets, perhaps even detecting signs of life. “If you put something this powerful into space, who knows what we can find? It’s going to be revolutionary because it’s so powerful,” says Matt Mountain, director of the Association of Universities for Research in Astronomy in Washington, D.C., and former JWST telescope scientist. Like that of Hubble, however, Webb’s construction has been plagued by redesigns, schedule slips, and cost overruns that have strained relationships with contractors, partners in Canada and Europe, and—most crucially—supporters in the U.S. Congress. Other missions had to be slowed or put on ice as Webb consumed available resources. A crisis in 2010 and 2011 almost saw it canceled, although lately the project has largely kept within its schedule and budget, now about $8 billion.

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