Spotlight shines on JWST after 'near-death experience'
BY STEPHEN CLARK
Posted: January 12, 2012
AUSTIN, Texas -- Entering the new year with solidified political support and renewed scientific potential, some work on the James Webb Space Telescope will be accelerated this year to keep the $8.8 billion observatory on track for launch in late 2018.
Over the next three years, workers will assemble the observatory's telescope element, a complex system composed of 18 hexagonal primary mirror segments stretching 21.3 feet across, seven times bigger than the Hubble Space Telescope. The primary mirror, along with secondary, tertiary and fine steering mirrors, will be mounted to a support structure with deployable wings and booms that must function perfectly in space.
Four scientific instruments built in the United States, Europe and Canada will be housed inside a chassis called the Integrated Science Instrument Module, or ISIM.
The first payload, the Mid-Infrared Instrument, will be shipped from the United Kingdom to the Goddard Space Flight Center in Maryland around April, according to Eric Smith, the observatory's deputy program director at NASA Headquarters.
MIRI will look at stellar debris disks, extrasolar planets and distant galaxies.
Canada's Fine Guidance Sensor, which will allow the telescope to point precisely and study forming planets and stellar gas clouds, is undergoing cryogenic vacuum testing and should be delivered to Goddard later this year, said Matt Greenhouse, project scientist for JWST's instrument payloads.
NIRCam, JWST's primary deep-field infrared camera, is under construction at the Lockheed Martin Advanced Technology Center in California. It should begin environmental testing in March before arriving at Goddard in the second half of 2012, Greenhouse said.
The near-infrared spectrometer, built by EADS Astrium in Europe, will be transported to the United States in February 2013, officials said.
Each component, including the instruments and mirrors, is going through cryogenic testing individually, but the first time the telescope's optics will be collectively strained to their operating temperature -- an unimaginably crisp minus 387 degrees Fahrenheit -- will be in 2015 inside a massive cooling chamber at the Johnson Space Center in Houston.
The Texas test facility was used to check the performance of Apollo lunar landers.
According to Scott Willoughby of Northrop Grumman Corp., the mission's primary industrial contractor, the test in Houstin will be the "real verification" of the telescope's functionality.
JWST has already cost more than $3 billion, and a significant chunk of the money went toward developing basic technologies to enable the revolutionary telescope. Some limited technological research may still be necessary in the coming years.
"It's not complete, but it's well along the way," Willoughby, Northrop Grumman's vice president for JWST, said in an interview with Spaceflight Now. "All the major technologies have been through. We've proven out the technology to build the mirrors and things like microshutters."
Microshutters are tiny cells that measure 100 by 200 microns, or about the width of three to six human hairs. They will open and close in space to allow JWST to take spectra observations of more than 100 cosmic targets at once with the NIRSpec instrument.
"[Technology development] is not done until you run the last test, but components, technologies, parts, materials are well over 90 percent complete," Willoughby said.
The prioritized tasks this year include finishing up assembly of the telescope's support structure and outfitting an expansive cryogenic test chamber at the Johnson Space Center in Houston. The Texas test facility will simulate the telescope's super-cold operating conditions during a major check-up in 2015.
"The outcome of JWST being funded, and supported by the administration and funded by Congress, was not accidental," said John Grunsfeld, NASA's associate administrator for science. "It was real drama. I know it was for me."
"Folks have referred to this as a near-death experience," Willoughby said.
The political battle came after an independent review panel blasted the telescope program's management and budgeting practices. NASA resolved to come up with a new, more credible plan to continue the program through launch.
"I think it's fair to say that a year ago, when we entered into this replan activity, there was doubt on the side of the administration and Congress that JWST could be brought under control," Smith said.
"It was the task of the project and the industrial partners to come up with a plan that was executable and believable, with a story behind that told folks it was different this time," Smith said. "Over the past year, that plan was put in place."
The replan set a launch readiness date for October 2018 and estimated the program's total cost at $8.8 billion. Before the review panel its report in 2010, NASA was publicizing a launch in June 2014 at a cost of $5.1 billion.
"It does put a spotlight on the project," Grunsfeld said.
The telescope's backplane, a graphite composite structure being constructed by ATK in Utah, is pacing the program's development schedule, according to Willoughby.
"The mirrors are done, so the next thing that needs to come in is the structure," Willoughby said. "That was one of the things that we had stretched out over the past couple of years as the budgets were going to be much lower. 2012 was going to be a much lower year than the $530 million."
"All indications that will perform at [cryogenic temperatures] the way it's supposed to," Smith said. "I'm feeling confident about the image quality and the sensitivity from the telescope."
With additional money this year, Smith said the construction of the backplane structure was moved forward by more than six months. The assembly so far is beating that schedule by two months, Willoughby said.
The center section of the backplane, which will support 12 of 18 primary mirror segments, should be complete this summer. Foldable wings for the other six mirror segments will be finished in 2013.
"The proof is in the pudding this summer if things are still on track," Smith said.
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