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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."
that they don't get their imperial units mixed up with metric units, and freeze the thing to -414C instead.
It says ~25K not -25k. The tilde (~) usually means approximately in written English.
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.
When you're afraid to download music illegally in your own home, then the terrorists have won!
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.
Question reality.
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 up what we call reality and see what temp it stops at, we'll never know the true absolute-zero, and I think scientists are finally getting tired enough of looking like fools for shouting to the world they have found it, then some one else getting even farther a few years later. Took a while, but pattern recognition seems to be setting in. There is little that scientists seem to love more then showing up each other, and making a claim of finding an absolute anything that can not be passed or gotten around is a bit like visiting a wolf pen while wrapped in fresh raw steak.
Question reality.
>i>"Some states probably spend millions of dollars keeping staff, equipment, materials, procedures, etc. on hand and updated and still they end up in court because lethal injection doesn't always work right."
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 then it's a "win".
I grew up in Australia, I was 8 when they hung Ronald Ryan but still recall that adults were making a big deal about it. Sure some people deserve stringing up but it leaves no room for error and we all know the legal system is anything but error free. I agree with Albert Pierrepoint who after hanging around 400 people (including a friend) came to the conclusion that capital punishment is not justice, it's formalised revenge. The only "just" way for the death penalty to actually be "just" is on the spot during the act, eg: the Somali pirates that were taken out by snipers.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
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. )
"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.
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
"Are you saying that it isn't just to formally revenge the victim?"
The answer depends on how you define Justice, 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 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, 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.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.