As NASA prepares for the launch of the last Hubble Space Telescope servicing mission next week, astronomers are already anticipating the construction and 2013 launch of the beloved observatory's successor.
In the coming weeks, engineers will wrap up testing the segments of the primary mirror on the James Webb Space Telescope, NASA's newest space-bound observatory. Like astronomer Allan Sandage, it will pick up where Hubble left off -- by studying the redshifted galaxies speeding away from us, in an attempt to understand the nature of the accelerating universe and its origins.
"We generally refer to the James Webb Space Telescope as a successor for Hubble. It's not really a replacement for Hubble; it's intended to take the next, deeper look into the universe," said John Decker, deputy project manager for the James Webb project, based at Goddard Space Flight Center in Greenbelt, Md.But like any proud parent, Decker had to do a little bragging: "The images that we will see will be very much like the Hubble images, only better," he said.
The scope was conceived, designed and executed with an aim at ingenuity. Among JWST's engineering feats are the space umbrella that will unfurl to keep the scope cool once it reaches its outpost a million miles from Earth, and the design of its primary mirror, which will contain 18 segments that come together somewhat like the eye of a fly.
When the pieces are put together, Webb's primary mirror will be 6.5 meters wide, about three times the size of Hubble's. If engineers used Hubble-esque materials to make JWST, the scope would weigh 10 times what Hubble does -- way too much to get off the ground.
"It would be like trying to launch Palo Alto into space. You wouldn't want to do that," said Scott Texter, telescope manager for Northrop Grumman, which is NASA's main contractor on JWST.
So how to make a lighter, yet light-receptive mirror? Scientists turned to beryllium, a space-worthy material that's as hard to find on Earth as it is in the heavens.single page
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