
James Webb Space Telescope - antr
http://www.jwst.nasa.gov/
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josePhoenix
Hey, my job's on HN! I work on JWST (simulation software, among other stuff)
and I think it's pretty cool too :)

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IndianAstronaut
Very cool. How much data is going to be arriving from JWST daily? Is it going
to be readily open to the public?

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privong
> Is it going to be readily open to the public?

The scientific data will be available to the public, sometimes after a
"proprietary" period (typically in the range 6–18 months) where the data is
only accessible to the team who successfully proposed to obtain that data.

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rootbear
My group at Goddard has done work on the JWST detectors. JWST is a big deal
here. It also scares the crap out of me, due to the gymnastics that are needed
to get it unfolded properly, in a location where repair is impossible. A lot
of people will be very, very happy when this thing is in orbit and working.

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toufka
What kind of detectors are you working with? Are they of a different kind or
just more powerful than what's already up there?

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rootbear
Sorry, I'm just the sysadmin here. A lot of the JWST work was done before I
got here, but we still help support them. I'm sure there is detailed
information on the web about the detectors in use on JWST.

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freshyill
As excellent has Hubble has been, the JWST is going to put it to shame. The
potential risk, however is that it won't be serviceable, as Hubble famously
needed to be very early in its life. If all goes as planned, we're all going
to have some really nice new desktop wallpapers in a few years. And, I
suppose, a better understanding of the universe will be a nice side benefit.

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sanxiyn
Interesting tidbit: JWST can't see blue. While Hubble could see entire visible
light spectrum, astronomically infrared is more interesting. So JWST can see
infrared, but not blue.

Astronomical images always have been heavily edited and it never was "what you
may see", but it is more so for JWST.

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sp332
It's not just that IR is "more interesting" (maybe it is), but it's much more
difficult to see through the atmosphere. It's obviously cheaper and easier to
build huge optical telescopes on the ground, but to see into the infrared, you
need to get above the atmosphere.

Edit: source
[http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutor...](http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/irwindows.html)

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spdustin
IR is _profoundly_ more interesting, precisely because it is able to penetrate
all sorts of media, most especially interstellar dust and gasses, allowing
JWST (and others) to see stars that can't be seen by their visible light.

Regarding our atmosphere filtering IR: do you feel the heat of the sun when it
shines on you? That's light. Infrared.

Edit: Additional point of fact: our atmosphere interferes with light by
scattering it away from its angle of incidence. Light with a longer wavelength
is able to get through without scattering (IR, red, orange, yellow, etc) light
with a shorter wavelength (blue) is more likely to collide with a molecule of
_something_ on the way in, and it gets bounced around so frantically that all
those blue light waves seem to kind of pile up and come from _everywhere_. No,
our atmosphere's light transmission woes are much more deleterious to the
smaller wavelengths of light than to IR.

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whalesalad
This fella is down at Northrop in Smell Segundo! My Dad always shoots me a
text whenever he's had a chance to look at it. He told me a neat story once
about the mirrors inside it... that when he stood in front of it, he felt
really strange. It's because the mirrors we are all accustomed to have so many
imperfections compared to the types used in this device. He wasn't used to
seeing such a perfect mirror image.

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Florin_Andrei
Not to diminish the achievements of the opticians working on the JWST, but you
can obtain the same level of perfection at home, using everyday tools.
However, you'll be working on a much smaller surface.

Make your own telescope mirror. To pass the tests, it must follow the ideal
surface with an error less than lambda/4, where lambda is the wavelength of
visible light. In practice, that's 0.1 microns or less. Also, the density of
scratches and pits must be very low (not detectable by usual means).

It's totally doable by hand, working in your garage, on a piece of glass the
size of a dinner plate. It just takes a very, very long time, at least on
first attempt. My first telescope took over a year (admittedly, I took too
many breaks, and then I did a lot of experiments with the techniques).

[http://florin.myip.org/blog/150-mm-f8-mirror-25-mm-pyrex-
pol...](http://florin.myip.org/blog/150-mm-f8-mirror-25-mm-pyrex-polishing-
and-figuring-log)

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bgtnhz
Telescope mirrors:

[https://www.flickr.com/photos/nasawebbtelescope/page9/](https://www.flickr.com/photos/nasawebbtelescope/page9/)

[https://www.flickr.com/photos/nasawebbtelescope/page11/](https://www.flickr.com/photos/nasawebbtelescope/page11/)

JWST vs Hubble:
[https://farm5.staticflickr.com/4076/4813007838_13c736d9ca_z....](https://farm5.staticflickr.com/4076/4813007838_13c736d9ca_z.jpg)

Mirror curvature( large jpg ):
[https://farm5.staticflickr.com/4114/4813106662_0d3eeddc27_o....](https://farm5.staticflickr.com/4114/4813106662_0d3eeddc27_o.jpg)

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ck2
Remember who runs congress now, prepare for it be canceled (again).

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antr
I saw this in Wikipedia:

"The JWST has a history of major cost overruns. In 2011, the United States
House of Representatives voted to terminate funding, after about $3 billion
had been spent and 75 percent of its hardware was in production. Funding was
restored in compromise legislation with the US Senate, and spending on the
program was capped at $8 billion. As of December 2014, the telescope remained
on schedule and within budget, but at risk of delays."

Source:
[https://en.wikipedia.org/wiki/James_Webb_Space_Telescope](https://en.wikipedia.org/wiki/James_Webb_Space_Telescope)

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java-man
Some things ARE expensive because they are difficult, require quality
components or processing. I would rather spend on difficult science than on
dumb bombs...

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martythemaniak
I'm glad to see some folks on here involved with the JWST, thanks for all your
efforts!

I have a question: is the big cost primarily due to the one-off nature of the
components, figuring things out for the first time etc? I ask because there's
some proposals (ExoEarth Mapper) for constructing a giant array of 20+ of
JWST-like telescopes in order to get pictures of earth-like planets.

So if one JWST costs $8Billion, how much would 25 cost?

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hulbert
Also check out:
[http://jwstsite.stsci.edu/webb_telescope/](http://jwstsite.stsci.edu/webb_telescope/)

STScI will be the Science and Operation Center for JWST.

