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Originally Posted by TrevorW
A million miles from Earth, I wonder who's going to fix it
a) if it doesn't work as they expect or
b) when something breaks down as it inevitably will
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Good questions. And I think that probably has something to do with the small mission time this telescope will have. Apparently it's only meant to run for 5 years, 10 years at most. There was talk of attaching a "grappling hook" to it so future space missions could possibly work on it, but I haven't heard whether that will go ahead or not.
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Originally Posted by renormalised
Plans to, but whether it does or not is another matter. Look at the TPF, it's nothing more than a pipe dream now. They've had their budget slashed again, so they're trying to do too much with even less money than they had last year. This is where things could get dangerous, with corners being cut in order to save dollars.
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Man, what is with all this cynicism on this board.
It's no pipe dream, parts and being built and tested as we speak. And it's not just NASA involved in this, there are 15 countries involved in it's development including the European Space Agency (it will be launched on the Ariane 5) and the Canadian Space Ageny (who are providing sensors). I don't see it falling anytime soon, and from what I've read the budget is still on target.
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Originally Posted by multiweb
 ... I'm no rocket scientist but a big mirror like that, modular or not, in the open with no protection what so ever... Is it meant to last very long once deployed?  HST had a compact design in a tube with a closing flap. |
Good question. I managed to find some information below.
http://www.jwst.nasa.gov/faq.html
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16. The primary mirror on Webb will be made of beryllium. What is beryllium?
Beryllium (atomic symbol: Be) is a gray, brittle metal with an atomic number of 4. Beryllium has a high strength per unit weight. It tarnishes only slightly in air. The addition of beryllium to some alloys often results in products that have high heat resistance, improved corrosion resistance, greater hardness, greater insulating properties, and better casting qualities. Many parts of supersonic aircraft are made of beryllium alloys because of their lightness, stiffness, and dimensional stability. Other applications make use of the nonmagnetic and nonsparking qualities of beryllium and the ability of the metal to conduct electricity. Beryllium is toxic and no attempts should be made to work with it before becoming familiar with proper safeguards. The specific advantages to Webb are beryllium's light weight, stiffness and its stability at very cold temperatures.
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18. Will micrometeoroids damage the beryllium mirror?
We tested beryllium discs for micrometeoroids using test facilities in the US and showed the micrometeoroids have negligible effects on the beryllium. Cryogenic beryllium mirrors have been flown in space exposed to micrometeoroids without problems. The Spitzer Space Telescope, launched in 2003, has a beryllium primary mirror. All of Webb's systems are designed to survive micrometeoroid impacts.
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There's more information on the Webb Telescope on Wiki:
http://en.wikipedia.org/wiki/James_Webb_Space_Telescope
Seriously this is better than nothing. Let's try and think a little more positive.
