James Webb Information Thread!

[Funkworks]

Who’s doing level 3?
Five levels



🛰🛰🛰🛰🛰

In other news, a Lego fan made a model of the telescope and Lego is looking at whether they can make it into a new set.
https://ideas.lego.com/projects/3decd220-889e-4eb3-b938-96aa3f788f0a/updates#content_nav_tabs
Featured on space.com and universetoday.com:
https://www.space.com/lego-james-webb-space-telescope-ideahttps://www.universetoday.com/152160/want-a-lego-james-webb-space-telescope-it-even-folds-up/

 

[alexzogh]

Was sent an interesting link from Nasa yesterday - lets you follow the JWST through the solar system in real time


https://eyes.nasa.gov/apps/orrery/#/sc_jwst

 

[kuririn]

Crucial motor burn today, around 2 PM EST.
JWST arrives at its' station , burn to insert it into L2 orbit.
No live broadcast from mission control.
Currently less than 1880 miles from destination (less than Honolulu to LA!), 99.79% distance complete and cruising at 450 mph.

 

[Marc_G]

Any idea how long the burn is? I'm assuming "a few minutes" but maybe it's even shorter?

 

[kuririn]

Any idea how long the burn is? I'm assuming "a few minutes" but maybe it's even shorter?

No idea.
How long does it take to go from 450 mph to zero?
And are the engineers going to do it gradually or full throttle?

 

[Marc_G]

My guess is the engine intentionally is capable of relatively gently push ; don't want to stress the optics and such.

 

[Peartree]

I wonder how fast it is *already* decelerating. If it's current speed is 450 mph, what will it be by this afternoon when they have to do the insertion burn? Obviously, the calculated launch speed was intended to get it there at the "optimum" speed and, since it's supposed to orbit L2, it's final speed isn't zero, so I'm curious how much they'll need to *slow* its speed, and how much they're just changing direction to move into orbit. Then again, I'm not sure I would be able to follow the orbital mechanics math.

 

[kuririn]

My understanding is that it will be "drifting" back and forth at it's final station.
So if not zero then close to it.

 

[dhbarr]

I wonder how fast it is *already* decelerating. If it's current speed is 450 mph, what will it be by this afternoon when they have to do the insertion burn? Obviously, the calculated launch speed was intended to get it there at the "optimum" speed and, since it's supposed to orbit L2, it's final speed isn't zero, so I'm curious how much they'll need to *slow* its speed, and how much they're just changing direction to move into orbit. Then again, I'm not sure I would be able to follow the orbital mechanics math.

I was idly musing about where the insertion burn exhaust particles will end up. I know it's hydrazine (N2H4) and dinitrogen tetroxide (N2O4) so I guess there will be mostly water and nitrogen plus a bit of unreacted fuel/oxidizer and maybe some loose nitrogen and hydrogen.

BUT! Then I remembered that all the thrusters are pointed at the sun, so essentially we give the throttle a tiny blip every so often to Sisyphus it back up almost to the top of the hill.

 

[KennB]

An interesting graphic and video about the JWST orbit:
https://jwst.nasa.gov/content/about/orbit.html
And a live Q&A from NASA at 3 PM EST 24 January 2022:
https://www.nasa.gov/nasascienceliveIt will be archived for future viewing.

If you want to submit a questions, use #UnfoldtheUniverse on social media.

 

[user 35280]

L2 Insertion Burn, Mid Course Correction Burn (MCC2) - L2 Orbit Insertion. Status: Ongoing

 

[kuririn]

I think the "Where is Webb" page uses planned, not real time parameters.
Shows L2 point reached but cruising speed hasn't changed.
Wonder if the burn has started?

 

[Marc_G]

I think the "Where is Webb" page uses planned, not real time parameters.
Shows L2 point reached but cruising speed hasn't changed.
Wonder if the burn has started?

Just tried; couldn't get to the page just now. Sort of a space geek/nerd DDOS attack going on.

 

[cvanc]

It's in orbit at L2, burn is complete!

 

[kuririn]

Orbital Insertion Burn a Success, Webb Arrives at L2 – James Webb Space Telescope (nasa.gov)

 

[kuririn]

It was a 297 second burn that added 2.6 mph to Webb's speed.

 

[kuririn]

Now we wait for six months while they align and fine tune the segments.

 

[Marc_G]

Now we wait for six months while they align and fine tune the segments.

Would be cool if they posted interim pictures along the way showing various test images of well characterized targets.

 

[kuririn]

I was curious as to how wide the "halo orbit" was.
Where is Webb says cruising speed is 450 mph (.1255 mi/sec)
An article said the telescope completes an orbit once every 30 days.
So the circumference of the orbit is 450 x 24 x 30, or 324,000 miles.
C = 2pi x r, or pi x d.
So d = C/pi.
Anyhoo, I come out with a 103,000 miles diameter orbit.
However.....
I'm sure orbital mechanics is far more complex than that and the orbit is probably not a circle.

 

[dhbarr]

I think it's elliptical, roughly perpendicular to the ecliptic?

 

[Funkworks]

Here's a graph from NASA via CBS:

Number are in kilometers because the article says:

"For the rest of its operational life, Webb will circle L2 at distances between 155,000 and 517,000 miles, taking six months to complete one orbit. Because the orbit around L2 is not perfectly stable, small thruster firings will be carried out every three weeks or so to maintain the telescope's trajectory.

Asked to provide a layman's view of a Lagrange point, Jane Rigby, Webb project scientist at the Goddard Space Flight Center, told reporters "the way I see it in my head is like a Pringles potato chip."

The Lagrange zone's gravitational field "is a saddle point," she said. "So it's the middle of the Pringles potato chip. It is a semi-stable point in our solar system."

https://www.cbsnews.com/news/james-webb-space-telescope-nasa-orbit-destination/

 

[boomtube-mk2]

Would be cool if they posted interim pictures along the way showing various test images of well characterized targets.

The Webb just sent this one back.

 

[Marc_G]

View attachment 501552
The Webb just sent this one back.

Actually it sent back text from a tiny line at the bottom "Printed in the USA, all rights reserved, copyright Acme Chart Corporation"

 

[kuririn]

Actual picture of JWST in orbit around L2 a million miles away!


Ho hum.

 

[boomtube-mk2]

NASA just got back the first image from the James Webb, taken at the very edge of the known universe.



This would be funny if you had ever read John DeChancie's Skyway trilogy?

 

[Huxter]

I hear there's a good restaurant there as well?

 

[user 35280]

Actual picture of JWST in orbit around L2 a million miles away!
View attachment 501640

Ho hum.

it’s way past time for them to show us the real picture of our JWST with our HST!

 

[Marc_G]

it’s way past time for them to show us the real picture of our JWST with our HST!

I've often wondered what the Hubble's near focus capabilities are like. Sure, it is usually pointed at galaxies far, far away but does it have the ability to focus on nearby stuff like the moon or a satellite? I imagine the issues involved would include focusing ability as well as motion tracking ability for objects nearby that are moving at high relative angular speed.

 

[kuririn]

I've often wondered what the Hubble's near focus capabilities are like. Sure, it is usually pointed at galaxies far, far away but does it have the ability to focus on nearby stuff like the moon or a satellite? I imagine the issues involved would include focusing ability as well as motion tracking ability for objects nearby that are moving at high relative angular speed.

Not to mention allocating valuable time and resources to appeasing the general public's curiosity.
Zero scientific value.

 

[Marc_G]

I looked it up. Hubble indeed can and has imaged the moon.