Webb Space Telescope

[aostling]

I got up early today, and witnessed the perfect launch of the James Webb Space Telescope. I'll be checking the progress of its voyage to the L2 insertion point, here:

https://webb.nasa.gov/content/webbLa...ereIsWebb.html

The JWST will be able to answer questions we don't even know how to ask yet.

[Joel]

One astronomer said that if it were on the earth, it could see something as small as a bumblebee on the moon.

[JRouche]

Dont getme going on this. Because I am torn.

I heard they spent 6 billion dollars on this telescope.

I said to my wife, hey Bronwyn, dont you think 6B would feed the world. She never answers me. Nurse, be careful if you find one. hahaaaa. Love my wife, Bronwyn.

I think 6 billion dollars could feed many people. And the sci guy says but?? Naw. 6 Billion dollrs for one scope doing one thing? No. JR

[Joel]

How useful it is to 'feed the world' for but a few days? If it were of any sort of long term value, any country or philanthropist would throw that small amount of cash at the problem (and they do, in addressing various aspects), but obviously, it is all much more complicated than that.
Research often pays massive dividends. Also, technology allows one man to feed very many. And the scope isn't doing 'one' thing (there is a lot of useful information in light). And while the exact tangible benefits that are gained from large technical projects such as this are somewhat unknowable, this where technology comes from, and what has allowed us the leisure and enormous comforts we so enjoy.
And a bunch more, but this is a major digression of an already OT post.

[The Metal Butcher]

Dont getme going on this. Because I am torn.

I heard they spent 6 billion dollars on this telescope.

I said to my wife, hey Bronwyn, dont you think 6B would feed the world. She never answers me. Nurse, be careful if you find one. hahaaaa. Love my wife, Bronwyn.

I think 6 billion dollars could feed many people. And the sci guy says but?? Naw. 6 Billion dollrs for one scope doing one thing? No. JR

Because that 6B keeps fella like me at work.

[old mart]

6 billion and more will be spent on arms to kill people every year, at least the telescope won't be doing that.

[lakeside53]

Hey, this 10B (NOT 6) may be a first step in us getting out of here so we can mess up another planet or two 😊

[wdtom]

I am all for it. The only problem I see is we don't have the capability to go to where they are going to park it and fix it.

[aostling]

The only problem I see is we don't have the capability to go to where they are going to park it and fix it.

The telescope will not actually be parked at the L2 point, it will go into a "halo orbit" of that empty point in space. This is nicely illustrated here:

https://en.wikipedia.org/wiki/James_...elescope#Orbit

[Rich Carlstedt]

.................I think 6 billion dollars could feed many people. And the sci guy says but?? Naw. 6 Billion dollrs for one scope doing one thing? No. JR

can you imagine ? Queen Isabella gave old Chris 6 Billion to build 3 boats Nina,Pinta,and Santa Maria ( they sound like girls names !) ---and he expects to use it to sail off the edge of the world.
A lot of peasants could be fed for that ..can you imagine ?
Rich

A basic instinct in man is to
"Go where no one has gone before"

[darryl]

I got up early to watch the launch. I've been kind of following the development of the JWST for the last 20 years or so. The part that impresses me is the accuracy of the reflecting surface over the whole area of the combined segments. No small feat. The launch appeared to be perfect, and the degree of deployment to this point seems to be perfect as well. High hopes for that telescope.

This will give us yet another chance to look back towards earth and think 'man, look at that planet- it's got all the things we need to survive there, and without protective suits to boot.' 'Let's wreck it'. Perhaps this further look back in time and deeper into the universe will give us enough fresh perspective to consider how valuable our current home really is- and give us a renewed interest in preserving it.

[mikey553]

https://webb.nasa.gov/content/webbLa...bbMediaKit.pdf
The above link gives some details about this project. I am mostly interested in the primary mirror. It consists of 18 hex segments 4.3 feet in size each. Tiny electrical motors keep the segments in perfect alignment to each other. The material for the segments is beryllium, which is very light and strong. It is gold plated on the mirror side.

Years ago I have made (but did not finish) a 6" mirror for the telescope-reflector. As machining board members we should appreciate the tolerances on the mirror surface shape. According to an excellent telescope making book I have the deviation of the surface should not exceed 1/8 of the wave length of light. For the yellow-green light the wave length is .00055 mm, so the tolerance is .00007 mm. Webb telescope is made to observe red and infra-red spectrum of light, so the tolerance is slightly bigger. Anyway just imagine the level of accuracy they need to maintain for the whole structure to achieve a good image quality. I am not sure how NASA aligns all 18 segments with this kind of accuracy, but individual segments were most likely checked by optical means. The same book describes some good old ways to do that without any expensive equipment. That does not mean the mirror manufacturer counted pennies for the inspection tools.

[aostling]

https://webb.nasa.gov/content/webbLa...bbMediaKit.pdf

. . . The above link gives some details about this project.

Mikey, thanks for the informative link.

I am wondering about the shape of the concave primary mirror. Spherical seems most likely as it would be easier to grind and measure. If so, is the convex secondary mirror aspherical to minimize aberrations?

[epicfail48]

Dont getme going on this. Because I am torn.

I heard they spent 6 billion dollars on this telescope.

I said to my wife, hey Bronwyn, dont you think 6B would feed the world. She never answers me. Nurse, be careful if you find one. hahaaaa. Love my wife, Bronwyn.

I think 6 billion dollars could feed many people. And the sci guy says but?? Naw. 6 Billion dollrs for one scope doing one thing? No. JR

Boy, wait till you see the defense budget...

[macona]

One astronomer said that if it were on the earth, it could see something as small as a bumblebee on the moon.

No, not even close. The size of a mirror needed to have that kind of resolving power would be massive. What makes this telescope special is it can see in the infrared which allows us to see though a lot of the "dirt" between us and the rest of the galaxy, and there is a lot.