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The James Webb Space Telescope Has Emerged From the Freezer (arstechnica.com)
The James Webb Space Telescope has emerged from a large vacuum chamber that was home to temperatures of just 20 degrees Celsius above absolute zero. Scientists have reviewed the data and given the instrument a clean bill of health. "We now have verified that NASA and its partners have an outstanding telescope and set of science instruments," said Bill Ochs, the Webb telescope project manager at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "We are marching toward launch." Ars Technica reports: The $10 billion telescope underwent tests inside Chamber A at Johnson Space Center, which was built in 1965 to conduct thermal-vacuum testing on the Apollo command and service modules. Beginning in mid-July, after the telescope was cooled down to a temperature range of 20 to 40 Kelvin, engineers tested the alignment of Webb's 18 primary mirror segments to ensure they would act as a single, 6.5-meter telescope. (They did). Later, they assessed the fine guidance system of the telescope by simulating the light of a distant star. The Webb telescope was able to detect the light, and all of the optical systems were able to process it. Then, the telescope was able to track the "star" and its movement, giving scientists confidence that the Webb instrument will work once in space. Webb still has a ways to go before it launches. Now that project scientists know that the optic portion of the instrument can withstand the vacuum of space, and the low temperatures at the Earth-Sun L2 point it will orbit in deep space, they must perform additional testing before a probable launch next year.
Why doesn't Slashdot delete spam like the parent comment? Slashdot has deleted plenty of comments, so I'd really like to know why the GNAA spam gets a free pass.
To put nitpicking to the highest degree, there is not even such a thing as a 'degree' of 'K'.
Actually, the standards bodies do specify not to use "Degrees Kelvin" and instead use just "Kelvins"
However, I'd argue that was a poor choice, because there are other uses of the term Kelvins in physics, notably in noise measurements, and using degrees Kelvin makes it unambiguous.
Excuse the Unicode crap in my posts. That's an apostrophe, and slashdot is busted.
L2 is in the earth's shadow. It will orbit around L2 in such a way that it is never in the earth's shadow but also so that it's sun shield will block light from the earth, the moon and the sun. It will also be about 6 times further from the earth than the moon.
“The James Webb Space Telescope has emerged from the freezer” is one of the worst secret recognition codes I’ve heard in a long time. People are going to notice that one!
#DeleteChrome
It was out of the freezer before Christmas. My wife works at JSC and we waited in line for 4 hours to see it back on Dec. 20.
... to its final orbit (and been commissioned and been tested and is sending back science data). And then Iâ(TM)ll worry that itâ(TM)s running out of its consumables too quickly or its gyroscopes are failing at a higher than predicted rate.
These multi-billion dollar space science projects always put me on edge, especially one like this which is so far from earth that there are no easy repair scenarios such as the one that saved Hubble. Too bad that it wonâ(TM)t be unfolded and tested in LEO (so that it would have at least the possibility of being fixed). Of course then it would probably then need an ion drive in order to (very slowly) get it to L2 because the delicate unfolded mirrors couldnâ(TM)t possibly maintain their precision with a chemical rocket.
Anyway, hereâ(TM)s hoping that Elon can bring the cost of space flight down by a factor of ten or more so a repair mission to L2 wouldnâ(TM)t be prohibitively expensive. Also if getting things to orbit werenâ(TM)t so expensive maybe a much bigger telescope (possible because it would just entail more mirror modules right?) could be sent because they wouldnâ(TM)t have to worry about shaving every gram off. The reduced constraints on weight might also allow for a more robust safer and cheaper design.
So everything will be helped out a lot by cheaper access to space! (Captain Obvious)
No, it's "degrees Celsius", "degrees Fahrenheit" and "Kelvin". If you look at the symbols, you'll see a little superscript circle in front of C and F but not in front of K. The degrees symbol is part of the unit, it's not "degrees times Celsius/Fahrenheit", there's no relation to angles.
(I wish Slashdot could display a simple "degrees" character so I wouldn't have to resort to descriptions like "little superscript circle", but who am I kidding, of course it cannot, in 2018...)
... And then it will be blown to smithereens by a faulty launch vehicle.
What? Never heard of angular temperature? 90 degrees Kelvin is either right or hot, while 0 degrees Kelvin is cold ahead.
45 5F E1 04 22 CA 29 C4 93 3F 95 05 2B 79 2A B2
These multi-billion dollar space science projects always put me on edge, especially one like this which is so far from earth that there are no easy repair scenarios such as the one that saved Hubble.
If we never go beyond repair range it's going to take an awfully long time to do anything useful in space. Gotta take some risks sooner or later.
Anyway, hereâ(TM)s hoping that Elon can bring the cost of space flight down by a factor of ten or more so a repair mission to L2 wouldnâ(TM)t be prohibitively expensive.
I think a better idea is to learn to make things that don't need repair missions. Harder task to be sure but necessary if we really want to explore our solar system in a serious way.
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Try Alt + 248 if on a Windows PC.
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Try Alt + 248 if on a Windows PC.
Yeah, nevermind...
What? Never heard of angular temperature? 90 degrees Kelvin is either right or hot, while 0 degrees Kelvin is cold ahead.
This comes from the measurement of water faucets in degrees/degree, the amount of water temperature change per degree of rotation. Residential faucets are typically in the range of 0.25 to 1 degrees/degree. Hotel faucets are are in the range of 5 to 30 degrees/degree to ensure that the water goes from freezing to scalding quickly to invigorate their guests and to reduce time in the shower, saving water.
The James Webb Space Telescope has emerged from a large vacuum chamber that was home to temperatures of just 20 degrees Celsius above absolute zero. Scientists have reviewed the data and given the instrument a clean bill of health.
I guess 20 Kelvin was too "scientific" to be used instead of "20C above absolute zero".
Elok
How do they test it for surviving the 9G ascent?
So trolling with idiot goddamned smartquotes is a thing now?
And I take it the canonical retort is "stop posting from your iphone".
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
You crazy. But this is slashdot and so it's easy to pass for normal here.
I suggest you spend next Christmas in Uruguay or Australia.
Unicodes completely broken on Slashdot. God knows if I post from my iphone , the iphones "helpful" smart quotes feature interacts with slashdot to turn a humble ' into a splatter of unicode mess
Excuse the Unicode crap in my posts. That's an apostrophe, and slashdot is busted.
Yeah, clearly I'm an idiot and I've never actually tried to do something I just figured was built in at this point..
My bad.
Unfortunately, Slashcode is a terrifying mess of Perl and unfresh hell. It's an ancient codebase that probably can't be saved.
Excuse the Unicode crap in my posts. That's an apostrophe, and slashdot is busted.
Everything is eventually going to run out of propulsion gas for maneuvering, no matter how big you make the tank.
What is your point exactly? Should we have not sent the Voyager probes because they can't maneuver anymore? Missions don't have to last forever and it's certainly possible to design robotic refueling missions for those where refueling is appropriate. What we shouldn't do is design spacecraft such that they need unnecessary amounts of servicing. Hubble is a great spacecraft but it required more servicing than it really should have. Limiting ourselves only to missions where servicing is comparatively easy is going to slow us down quite a lot.
I'm not saying it's never appropriate to design a mission where servicing the spacecraft is necessary. But I think it is something to be avoided whenever possible. Any mission beyond low Earth orbit is going to be a problem to service so we might as well learn how to do high reliability as soon as possible.