NASA To Cryogenically Freeze Satellite Mirrors 47
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."
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First! ...In line to be frozen at the moment of my death.
You want to die by freezing? Doesn't sound very nice to me.
Re:Cryo! (Score:5, Informative)
May want to look into it more then. Freezing to death is one of the more pleasant ways to go. It does suck for a bit as you start getting too cold, but then after a while you start to feel warm again. At this point you start to feel rather detached and dreamy. Most people that have been brought back from cold water drownings or hypothermia report the same things. Having nearly frozen to death on a hike I can confirm just how pleasant it was, up to the point that it finally sank into my head I was freezing to death and managed to get to warmth. Now, I'm not recommending it to folks, even if I do know a few that would benefit from it... But, as far as death goes, it is one of the more comfortable ones.
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That's one thing I don't understand about the expensive drugs they use to execute people. They've been said to be quite painful when they don't work right.
Junkies kill themselves with heroine all the time. $40 of heroine all at once will knock your ass out and stop your heart, essentially painlessly.
Aside from heroine, I can think of quite a few cheaper ways to painlessly kill a person. Carbon monoxide overdose is another way. You basically fall asleep and your brain dies from lack of oxygen. This is super
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Carbon monoxide overdose is another way. You basically fall asleep and your brain dies from lack of oxygen. This is super cheap.
I didn't quite like the smell of the smoke that comes with it. It took me three whole bags of charcoal to kill myself, but I guess it was all worth it.
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Gaffa tape a hand grenade to their face an the won't feel a thing. Since such soultions are obvious I think the underlying argument is about the death penalty itself rather than the form of execution. It's a political argument and as such if you move the legal boundries even in very small ways
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I agree with Albert Pierrepoint [wikipedia.org] who after hanging around 400 people (including a friend) came to the conclusion that capital punishment is not justice, it's formalised revenge.
Just to be clear: Are you saying that it isn't just to formally revenge the victim? (Of course given that the real murderer is executed, that he got a fair trial, that the murder wasn't an accident etc) If you are saying that: what do you believe is just in a murder case?
Re:Cryo! (Score:5, Insightful)
The answer depends on how you define [wikipedia.org] Justice [wikipedia.org], I would define the implementation of justice as an act that restores, or adequately compensates for, what the victim has lost. Some deeds simply can't be undone or justly compensated for. Other than the poetic kind (and using my #def) there is no possible justice for the murder victim, although blood money may compensate the relatives for the loss of the victims material input, it does nothing for the victim.
The overused Gahndi quote sums it up best "an eye for an eye makes the whole world blind". The victim and the murderer are both dead and (unless you believe in hell), are no longer suffering. The outcome for those still alive after the execution is a doubling of the number of families that are suffering a loss.
Since murder can't be undone the question then becomes one of can we do anything to the murderer to deter other would-be murderers, such as publicly hang, draw and quater him [wikipedia.org] followed by prominently displaying the butchered corpse at various public places? It's a logical idea that appeals to our base emotions but real world experience says it doesn't work as a deterent even for less passionate crimes such as drug smuggling.
"Of course given that the real murderer is executed, that he got a fair trial, that the murder wasn't an accident etc"
In the same manner that you can defeat terrorists without using their methods, you can punish murderers without killing them. Personally I think the state should set the example of - we only kill in self defence or defence of the innocent in mortal danger, but it's "you're country - you're rules".
None of the above means I think that murders don't deserve a bullet to the head but what we are given is the track record of the state/church/lynch-mob, It says that there is a very significant risk of inadvertently commiting the irreversible act you're trying to deter. IMHO and the opinion of the clear majority of nation states [amnesty.org], it's an unacceptable risk.
I don't see the US joining the rest of the world in this "enlightened" view of capital punishment any time soon. A poll of SCOTUS a few years ago found that a majority of the SC Judges thought that shooting an unarmed fleeing thief was justifyable.
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Wow... (Score:2)
Lets just hope (Score:5, Funny)
that they don't get their imperial units mixed up with metric units, and freeze the thing to -414C instead.
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that they don't get their imperial units mixed up with metric units, and freeze the thing to -414C instead.
Thinking about those lasers which are used to cool small particles to near zero temperatures. Can the photons from those lasers be considered to have a negative temperature, because of the energy they remove from the particles being cooled?
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Can the photons from those lasers be considered to have a negative temperature, because of the energy they remove from the particles being cooled?
Maybe [wikipedia.org].
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So, when people speak of the temperature of the cosmic microwave background, [nasa.gov] they're just confused?
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I wouldn't think so. At least not any more then a speaker can be considered to create negative sound when it is used for phase cancellation in noise canceling headphones. Or that one truck can be said to have a negative velocity when it impacts an other truck heading in the other direction and they both stop dead. But then this is just my personal opinion YMMV.
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Thinking about those lasers which are used to cool small particles to near zero temperatures. Can the photons from those lasers be considered to have a negative temperature, because of the energy they remove from the particles being cooled?
Not really... negative temperature can be a 'meaningful' concept in some scenarios, but it's not necessary to invoke it here. Temperature is a property of an object such that two objects in contact (or exchanging radiation, etc) with different temperatures will exchange energy (heat) so as to try and 'meet each other in the middle', i.e., hot one loses energy to the colder one until the the temperatures become equal. Basically the character of laser beams is that they are not-very-thermal-at-all, so you c
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I'd say the Nobel prizes in physics they'd get from it would more than make up for their little "accident". The odds are about as good as accidentally making FTL travel though.
My Governor Approves (Score:2)
http://www.youtube.com/watch?v=VNaDZIrxh-0 [youtube.com]
At least nobody can complain they aren't doing some thorough testing on this project.
Re:It seems off... (Score:4, Informative)
It says ~25K not -25k. The tilde (~) usually means approximately [wikipedia.org] in written English.
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It's possible they meant it as a logical tilde, and it could be a temperature other than 25K.
that will freeze the mirrors to -414 degrees Fahrenheit (not 25 K).
(((-414 - 32) * 5) / 9) + 273 = 25.2
Shucks. They probably meant your thing.
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not to be a pedantic fuck, but the conversion from C to K is 273.15 which changes your answer to 25.372
sorry, I just couldn't resist
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yup: http://en.wikipedia.org/wiki/Temperature_conversion
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Well, at the time they came up with 0-k, they thought so as well, as that is the point that atomic motion stopped. Then they went and discovered that while atomic motion stopped at that temp, sub atomic motion did not. They went on further to discover that they could 'cool' things further and reduce/stop some of the sub-atomic motion. I think they have given up on a true absolute-zero at this point, and simply use it as an arbitrary point where one is needed. Until they can find the smallest bit that makes
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Bravo. I was going to wait until you got modded informative but it's midnight and I'm going to sleep.
Re:It seems off... (Score:5, Informative)
Well, at the time they came up with 0-k, they thought so as well, as that is the point that atomic motion stopped. Then they went and discovered that while atomic motion stopped at that temp, sub atomic motion did not. They went on further to discover that they could 'cool' things further and reduce/stop some of the sub-atomic motion. I think they have given up on a true absolute-zero at this point, and simply use it as an arbitrary point where one is needed.
This is really wrong. Temperature has a precise mathematical definition (relation between system energy and entropy), which is universal. Applied to most systems, this yields the concept of temperature familiar from everyday life. Indeed, some systems are such that they can be manipulated to a state of `negative temperature', in the formal mathematical sense. However it is definitely not the case that the concept of absolute zero is tied to the motion of atoms in particular, or that it is merely 'a reference point' that has later been surpassed.
(I kinda hope you're just trolling, otherwise please just STFU when you don't know WTF you're talking about. )
Physics is Complicated... (Score:1, Insightful)
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 pe
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Not sure, but their competitors will use Meh...
More Money Wasted (Score:3, Funny)
"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.
Freeze - really? (Score:1)
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'?
Getting it right (Score:3, Informative)
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.
To thaw in the future? (Score:2)