The Webb Telescope

Of the 17 modes of operation of the Webb, only one remains to be completely readied for science. This is straight from NASA:

3. NIRCam coronagraphy. When a star has exoplanets or dust disks in orbit around it, the brightness from a star usually will outshine the light that is reflected or emitted by the much fainter objects around it. Coronagraphy uses a black disk in the instrument to block out the starlight in order to detect the light from its planets. Example target: the gas giant exoplanet HIP 65426 b.

@Liljo
Before anything else, I'd like to know exactly how much damage Webby suffered when that small asteroid violently smashed into it last month.

@bunnyknight said
@Liljo
Before anything else, I'd like to know exactly how much damage Webby suffered when that small asteroid violently smashed into it last month.

Couldn't tell you, but it seems there wouldn't be near the level of excitement for July 12, 9:30CST, if there was much damage. All the NASA chat is full systems go.

@Liljo
I wonder if those big support arms directly in front of the mirrors affects the resolution?

@sonhouse said
@Liljo
I wonder if those big support arms directly in front of the mirrors affects the resolution?

Those actually are used to mount the secondary mirror, which reflects light from the primary mirror assembly. This can be maneuvered to focus that light into the ISIM (Integrated Science Instrument Module). It is the ISIM that actually produces an image.

@Liljo
Newes teaser image from Webb:
https://phys.org/news/2022-07-nasa-james-webb-telescope-teaser.html

it is telling that the spikes from the close in stars have 6 spikes so that means those two big supports must not have much effect or they would have produced their own variety of spikes.
I guess the only way to eliminate those spikes from bright stars would be to have a separate craft held in place with magnetic forces or some such. It wouldn't matter much how you made supports for the secondary mirror; they would still produce those spikes.

The only other way to eliminate those kind of spike would be to use a refracting scope, like we have for amateur use but making something 30 feet across is very difficult indeed!

I do see work being done on making huge mirrors in space by blowing up big bubbles of polymer that get rigid under UV, the Israeli's are working on that tech.

That might make for scope with 100 METERS or more in diameter being built in space so you don't even have to launch folded up mirrors like Webb.

News at 11🙂

Here are a couple of the latest articles from NASA, including a very well written piece called:
Webb: The World Is About To Be New Again
https://blogs.nasa.gov/webb/2022/07/07/webb-the-world-is-about-to-be-new-again/

https://blogs.nasa.gov/webb/2022/07/06/webbs-fine-guidance-sensor-provides-a-preview/

A quote from the second article explains the stars' six spikes:
" Bright stars stand out with their six, long, sharply defined diffraction spikes – an effect due to Webb’s six-sided mirror segments. Beyond the stars, galaxies fill nearly the entire background."

@Liljo
I thought that might be the cause of the spikes but wasn't sure. I guess any gap in the mirrors will be seen in spikes like that, if it was four mirrors, four spikes. I wonder if that will ever affect looking at stuff right where a spike is?
It is pretty amazing they limit those spike to just 6, it could have been a lot worse.

This article reveals what NASA will show the world in a few days. These are the opening targets for Webb:

https://www.nasa.gov/feature/goddard/2022/nasa-shares-list-of-cosmic-targets-for-webb-telescope-s-first-images


Of these images, the one I most look forward to is Stephan's Quintet. Four galaxies locked in an Game of Gravity. A fifth galaxy seen in the same grouping is not currently physically associated with the four, but astronomers believe it will be at some distant point in the future.

@sonhouse said
@Liljo
Newes teaser image from Webb:
https://phys.org/news/2022-07-nasa-james-webb-telescope-teaser.html

it is telling that the spikes from the close in stars have 6 spikes so that means those two big supports must not have much effect or they would have produced their own variety of spikes.
I guess the only way to eliminate those spikes from bright stars would be to ...[text shortened]... r being built in space so you don't even have to launch folded up mirrors like Webb.

News at 11🙂

I once read a novel where one of the characters made a home-made space telescope with a gravity lens using pure gravitation force. His telescope had way better resolution than all the Earth-made telescopes put together.

@bunnyknight
The thing about gravity lenses is this: they are pretty terrible as a real telescope lens, only a small portion of such a lens is usable and the astronomical lenses shows say a galaxy but the rest is too diffused to be any good. All you have to do to prove that is to see the Einstein rings where a galaxy is spread out in a circular path completely destroying any idea of visualizing say individual stars in that mashup.
Only if it is perfectly aimed will you see anything worthwhile.
I studied gravitational lensing as it appears here in our solar system and for one thing, even with the mass of the entire sun, the FIRST focus is near 100 billion km out in space and that focus line extends only as far as the distance to the star producing the light, so if we were to see the focus of light coming from Alpha Centauri, it will produce a focus beam of about 4 light years and then no more focus so Sirius, an 8 lightyear beam. I envision using such focused light for solar sails, free energy in space if the beam is aiming at the place you want to probe otherwise you don't get any advantage from that free energy unless you can pick another beam in mid-travel.

If I could command a big scope, I would aim directly opposite the light from some star and see if that resultant beam hits a distant rogue planet or some such, which would probably be a short term burst of reflected light where that light came from a star on the opposite side of the sun but all stars move so the beam would be like a flashlight illuminating a room where you might move the beam around to see what is in the room, same thing would happen to such focused beams, it would impinge on some asteroid or other, and for our solar system there would be ZERO in the way of such beams in a sphere 200 odd billion LY across because the focus doesn't even START till you are out around 100 billion Km from Sol so such energy would be totally worthless inside our solar system.

@sonhouse
Here is a list from NASA as to first extrasolar targets:

https://phys.org/news/2022-07-nasa-reveals-webb-telescope-cosmic.html

@jimm619 said
https://www.npr.org/2021/12/17/1064724045/this-new-space-telescope-should-reveal-what-the-universe-looked-like-as-a-baby?utm_source=pocket-newtab

https://news.yahoo.com/nasa-james-webb-space-telescope-first-targets-images-data-172517196.html

See the deepest view into the universe ever taken…

https://webb.nasa.gov/content/webbLaunch/whereIsWebb.html

We are really in for a treat tomorrow. All systems go. This image is taken from a slice of sky of the approximate size of someone on Earth holding a grain of sand at arms length. Look at all those stars! Look at all those galaxies!

@Liljo
I notice in that image a gravitational lensing affair going on there too. That seems to go out quite a ways in that photo, I see some curved galaxy images way out from the big curved ones closer to center so those galaxies are WAY WAY away, and there will be a lot more of that sort of thing when they get fully rolling. I hope they can find a spot of sky without local stars, they muck up the image with those spikes.
I wonder if they can photoshop the spikes out, they probably have software for that a lot better than photoshop though.