Tests under way on the sunshield for Webb telescope

Sep 19, 2011
The five-layer James Webb Space Telescope sunshield consists of thin membranes made from a polymer-based film and supporting equipment such as spreader bars, booms, cabling, and containment shells. Designed to block solar light and keep the Observatory operating at cryogenic temperatures. Credit: NASA/Northrop Grumman

NASA is testing an element of the sunshield that will protect the James Webb Space Telescope's mirrors and instruments during its mission to observe the most distant objects in the universe.

The sunshield will consist of five tennis court-sized layers to allow the Webb telescope to cool to its cryogenic operating temperature of minus 387.7 (40 Kelvin).

Testing began early this month at ManTech International Corp.'s Nexolve facility in Huntsville, Ala., using flight-like material for the sunshield, a full-scale test frame and hardware attachments. The test sunshield layer is made of Kapton, a very thin, high-performance plastic with a reflective metallic coating, similar to a Mylar balloon. Each sunshield layer is less than half the thickness of a sheet of paper. It is stitched together like a quilt from more than 52 individual pieces because manufacturers do not make Kapton sheets as big as a tennis court.

The tests are expected to be completed in two weeks.

This is a September 2009 artist conception of the James Webb Space Telescope, with the five-layer sunshield stretched out in space. Credit: NASA

"The conclusion of testing on this full size layer will be the final step of the sunshield's development program and provides the confidence and experience to manufacture the five flight layers," said Keith Parrish, Webb Sunshield manager at NASA's Goddard Space Flight Center in Greenbelt, Md.

During testing, engineers use a high-precision to measure the layer every few inches at room temperature and pressure, creating a 3D map of the material surface, which is curved in multiple directions. The map will be compared to computer models to see if the material behaved as predicted, and whether critical clearances with adjacent hardware are achieved.

The test will be done on all five layers to give engineers a precise idea of how the entire sunshield will behave once in orbit. Last year, a one-third-scale model of the sunshield was tested in a chamber that simulated the it will experience in space. The test confirmed the sunshield will allow the telescope to cool to its operating temperature.

After the full-size sunshield layers complete testing and model analysis, they will be sent to Northrop Grumman in Redondo Beach Calif., where engineers verify the process of how the layers will unfurl in space. There the layers will be folded, much like a parachute, so they can be safely stowed for launch.

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Decimatus
not rated yet Sep 19, 2011
I had wondered what the hell that thing was for.

I wonder how resistant the sheet is to tearing once a small piece of space junk puts a hole in it.
scidog
not rated yet Sep 20, 2011
too many stitches...i hope they looked at every one very-very close and by several people over time.
Gthedon
not rated yet Sep 20, 2011
Id thought we lost her ! After the funding setback I was upset, I have been looking forward to this telescope since I was a teenager it always fascinated me. I'm glad to see progress is still being made. I can't wait for all the secrets it unlocks abot the earliest points of our universe. And it also shows that americans can still build something revolutionary regarding space, you know because lately we've been slacking lol.
Royale
not rated yet Sep 20, 2011
Yea Gthedon, I just read on here that they were planning on canning the project. Hopefully it continues to live on!

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