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NASA To Cryogenically Freeze Satellite Mirrors
coondoggie writes "NASA said it will soon move some of the larger (46 lb) mirror segments of its future James Webb Space Telescope into a cryogenic test facility that will freeze the mirrors to -414 degrees Fahrenheit (~25 K). Specifically, NASA will freeze six of the 18 Webb telescope mirror segments at the X-ray and Cryogenic Facility, or XRCF, at NASA's Marshall Space Flight Center in Huntsville, Alabama, in a test to ensure the critical mirrors can withstand the extreme space environments. All 18 segments will eventually be tested at the site. The test chamber takes approximately five days to cool a mirror segment to cryogenic temperatures."
First! ...In line to be frozen at the moment of my death.
Talk about getting a cold look....
--- Asking inconvenient questions for over 30 years...
that they don't get their imperial units mixed up with metric units, and freeze the thing to -414C instead.
http://www.youtube.com/watch?v=VNaDZIrxh-0
At least nobody can complain they aren't doing some thorough testing on this project.
So are these going to be zero-point mirrors?
If the only way you can accept an assertion is by faith, then you are conceding that it can't be taken on its own merits
Does any one know if they are using Ne?
"The test chamber takes approximately five days to cool a mirror segment to cryogenic temperatures."
My ex could do it in about one and a half seconds with a single glare. Of course, then she'd have to bask on a rock for a couple of hours to recover.
I've calculated my velocity with such exquisite precision that I have no idea where I am.
As this summary has been tagged with 'science' I'd expect scientific terms to be used.
Are these mirrors actually liquid at room temperature, or perhaps the submitter meant 'cool' rather than 'freeze'?
Physics is one of many fields where the more you study the closer you come to reality: you use more primitive models when you begin your study and each year after that you learn that the model you learned last is an approximation of something else. Perhaps it's a fitting way to learn, given that it's how the field develops, or perhaps it isn't, but please don't tell people to STFU because they're wrong; what they know may be a far better approximation of the truth than what most people know, and we want people with a less thorough background to feel comfortable talking in their communities about what they've learned, even if it's a model a professor short-on-time gave them to understand a concept. A pound of honey, as they say--if we insult everyone who doesn't know everything about physics but decides to talk about it, soon almost nobody will talk about physics. And not many people talk about it today.
Unfortunately the article gets the technical aspects wrong.
NASA is not "freezing" the mirror segments to make sure they "survive" space.
The JWST will operate at a cryogenic temperature in space. The mirrors are measured at cryovac to guide the manufacturing process so they will have the correct optical prescription at the telescope's operational temperature.
Similarly, we're testing support optics, for the pre-launch JWST testing, at cryo. We'll have the first of a one set down to temp in short order.
ShoutingMan.com
It'll be interesting to thaw these mirrors 50 or 100 years into the future and see what they have to say about the past. Maybe then we'll have the technology to their cracks and heal them. Wait, what we were talking about again?