Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
sabenapilot
Posts: 3779
Joined: Sat Feb 26, 2000 6:18 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sat Dec 25, 2021 2:28 pm

ESA did it: succesful launch and separation from the carrier rocket!
During the ascend into outer space, Ariane 5 had to perfom a very unusual oscilating roll manoeuvre to protect Webb from the Sun’s radiation.
After 27 minutes the telescope was released and the upper stage boosted away....

https://www.esa.int/Science_Exploration ... e_Universe

FWIW: Ariane first launched in 1979, also on Xmas Eve.
 
tommy1808
Posts: 14893
Joined: Thu Nov 21, 2013 3:24 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sat Dec 25, 2021 2:51 pm

texl1649 wrote:
Nomadd wrote:
zuckie13 wrote:
Exactly - it's a point you can stay near by orbiting that allows the Earth to act as part of the observatories sun shielding all the time. It's the closest point to earth with that property.

You absolutely don't want the Earth to help shield the Webb. Part of the reason for the large orbit around the L2 point is to keep the scope from passing through the Earth's shadow. The thermal transitions would screw everything up.


I believe the JWST will stay in the earth’s shadow the whole time. Part of the reason for L2’s selection was just that, as it helps keep it so cool?


So ... the solar panel is just dead weight?

Best regards
Thomas
 
User avatar
bikerthai
Posts: 5363
Joined: Wed Apr 28, 2010 1:45 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sat Dec 25, 2021 4:26 pm

So what is the answer?

Is the Earth partially block the sun or does not block the sun at all? Thus the sun shield and solar panel?


bt
 
User avatar
Tugger
Topic Author
Posts: 11834
Joined: Tue Apr 18, 2006 8:38 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sat Dec 25, 2021 4:39 pm

bikerthai wrote:
So what is the answer?

Is the Earth partially block the sun or does not block the sun at all? Thus the sun shield and solar panel?


bt

No, JWST will not be in the Earth's shadow.

The Earth's shadow extends about 870,000 miles out, away from the Sun.

The JWST will stabilize its orbit at L2, which about 930,000 miles (1.5M km) from Earth. So it will be outside of the shadow.

Tugg
 
User avatar
Francoflier
Posts: 6172
Joined: Wed Oct 31, 2001 12:27 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sat Dec 25, 2021 4:57 pm

JWST will not be in the dark shadow of Earth while in orbit around L2. The Earth's umbra (darkest shadow) only extends to about 870,000 miles. L2 is 930,000 miles away. The telescope will be sitting in Earth's penumbra or antumbra, where there is some shadowing effect from Earth but sun rays from the periphery of the sun's disc still shine brightly.
I'm not sure how far off L2 it will be orbiting so not sure how much the Earth will block the sun's rays, if at all, but either way the sun will always be visible at least in part from where it is.

https://en.wikipedia.org/wiki/Umbra,_pe ... mbra#Umbra

The sunshade is there to shield it from those sun rays and radiate the heat away into space so it can stay cold.
It's also convenient to have the sun and Earth constantly in the same corner of space as you don't have to worry about any of them disrupting your observations as they regularly pass in front of the telescope.
One of the limitations of JWST will be how much it can tilt on either axis before the sun rays start hitting the mirror. Depending on which axis (except the vertical one), it can be as low as a handful of degrees I believe. This restricts its field of view somewhat, but whatever it can still observe would happily keep scientists busy for much longer than it will ever be operational.

Edit: sorry for repeating part of Tugger's reply who beat me to it.
 
User avatar
bikerthai
Posts: 5363
Joined: Wed Apr 28, 2010 1:45 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sat Dec 25, 2021 7:10 pm

Thanks I was going going to break out my trigonometry to figure the worst case scenario (with direct alignment). But I also found that the L2 point is not really a point but an orbit "zone" that is influenced by the non circular orbit of the earth and the other nearby celestial body.

bt
 
GDB
Posts: 14996
Joined: Wed May 23, 2001 6:25 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sat Dec 25, 2021 11:59 pm

A fantastic launch, much to do until JWST is deployed and operational, nonetheless a real feather in the cap for ESA today.
Being the most expensive, scientifically important arguably and certainly most high profile payload they've ever done.
 
User avatar
Nomadd
Posts: 608
Joined: Sat Dec 09, 2017 3:26 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sun Dec 26, 2021 1:31 am

The Earth's umbra, or area of total eclipse falls short of L2, but the sun would still be almost blocked, with just a bright ring around the earth. They'll avoid even the penumbra since the orbit around L2 will be huge, as in a couple hundred thousand miles. It's actually a more stable orbit than trying to maintain the exact L2 spot.
 
zanl188
Posts: 3933
Joined: Sat Oct 21, 2006 9:05 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sun Dec 26, 2021 2:02 am

Regarding inflight serviceability of JWST. Provisions have been made to refuel the spacecraft...

https://youtu.be/AxO3Wm9uPq8?t=3390
 
User avatar
Tugger
Topic Author
Posts: 11834
Joined: Tue Apr 18, 2006 8:38 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sun Dec 26, 2021 7:31 am

MCC1a maneuver has been completed. This is the first of several key positioning maneuvers.
https://www.space.com/james-webb-space- ... ctory-burn

Rugg
 
User avatar
JetBuddy
Posts: 2802
Joined: Wed Dec 25, 2013 1:04 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sun Dec 26, 2021 9:08 am

James Webb Space Telescope is such a morale boost during these times.

I was very relieved when the Arianespace launch went perfectly. Now we're all hoping for a perfect journey to L2.

Thanks NASA, ESA, all the scientists who created this technological marvel, and all the taxpayers who funded it.

Go JWST!
 
User avatar
SeJoWa
Posts: 530
Joined: Thu May 18, 2006 6:11 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sun Dec 26, 2021 8:59 pm

zanl188 wrote:
Regarding inflight serviceability of JWST. Provisions have been made to refuel the spacecraft...


Thank you for the link, very interesting. I was wondering what accomodations for future missions had been designed-in. I guess that with the hopefully successful development of SpaceX's Starship, the Webb telescope's design constraints will soon belong to history. It should be far less costly than maybe anticipated to send a refueling pod out to L2 even with a Falcon 9.

Edit: In the meantime, fingers crossed!
 
tomcat
Posts: 983
Joined: Thu Sep 28, 2000 4:14 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Mon Dec 27, 2021 5:39 pm

tommy1808 wrote:
texl1649 wrote:
Nomadd wrote:
You absolutely don't want the Earth to help shield the Webb. Part of the reason for the large orbit around the L2 point is to keep the scope from passing through the Earth's shadow. The thermal transitions would screw everything up.


I believe the JWST will stay in the earth’s shadow the whole time. Part of the reason for L2’s selection was just that, as it helps keep it so cool?


So ... the solar panel is just dead weight?

Best regards
Thomas


Speaking about the solar panel, it deployed earlier than planned: at less than 30 minutes after lift-off instead of about 33 minutes after lift-off according to the planning. The deployment actually occurred less than 2 minutes after the separation from the upper stage. Luckily this early deployment didn't lead to a collision with the upper stage. I wonder what triggered this early deployment.
 
User avatar
zululima
Posts: 490
Joined: Sat Jul 14, 2007 10:21 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Mon Dec 27, 2021 6:53 pm

The deployment trigger was event-based, and not time-scheduled. Webb was put into a stable trajectory/configuration earlier than estimates, which were conservative. Another thumbs up to Ariane 5 I guess.
 
tomcat
Posts: 983
Joined: Thu Sep 28, 2000 4:14 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Mon Dec 27, 2021 7:45 pm

zululima wrote:
The deployment trigger was event-based, and not time-scheduled. Webb was put into a stable trajectory/configuration earlier than estimates, which were conservative. Another thumbs up to Ariane 5 I guess.


Thanks for the explanation.
 
User avatar
Tugger
Topic Author
Posts: 11834
Joined: Tue Apr 18, 2006 8:38 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Mon Dec 27, 2021 7:59 pm

The main antenna has successfully deployed!
https://www.space.com/james-webb-space- ... ys-antenna

Tugg
 
texl1649
Posts: 2136
Joined: Thu Aug 02, 2007 5:38 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Mon Dec 27, 2021 11:53 pm

Informative site with distance and other data listed live;

https://webb.nasa.gov/content/webbLaunc ... sWebb.html
 
User avatar
JetBuddy
Posts: 2802
Joined: Wed Dec 25, 2013 1:04 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Tue Dec 28, 2021 9:57 am

texl1649 wrote:
Informative site with distance and other data listed live;

https://webb.nasa.gov/content/webbLaunc ... sWebb.html


Good site!

It looks like JWST has now reached the distance of the Moon from Earth.

Next up is Mid Course Correction Burn 1b, and then Sunshield deployment. I'm a bit nervous about that last one.
 
User avatar
DIRECTFLT
Posts: 2909
Joined: Sat Jan 02, 2010 3:00 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Sat Jan 08, 2022 6:36 pm

James Webb Space telescope’s ‘golden eye’ opens, last major hurdle

https://apnews.com/article/space-launch ... 84bd009ce3
 
FGITD
Posts: 2016
Joined: Wed Jun 15, 2016 1:44 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Mon Jan 10, 2022 12:20 am

Read on a tweet from spaceflight now that the Webb mission systems engineer team is confirming that the Ariane 5 did its job exactly as perfectly as possible, and the estimated fuel lifespan for Webb is now estimated to be about 20 years. This was originally one of the most conservative estimates, now a reality.

Gotta say, in the grand scheme of the project, the launch might only seem like a blip, but Ariane really did everyone proud.
 
ZaphodHarkonnen
Posts: 1225
Joined: Sun Jan 04, 2015 10:20 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Mon Jan 10, 2022 12:43 am

FGITD wrote:
Read on a tweet from spaceflight now that the Webb mission systems engineer team is confirming that the Ariane 5 did its job exactly as perfectly as possible, and the estimated fuel lifespan for Webb is now estimated to be about 20 years. This was originally one of the most conservative estimates, now a reality.

Gotta say, in the grand scheme of the project, the launch might only seem like a blip, but Ariane really did everyone proud.


Everyone involved in the delivery and operations for JWST have been smashing it out of the park right now. Telescope is fully unfolded, delivery was so spot on it would make Tory Bruno of ULA proud for Arianespace. Other than being disgustingly over budget and late, it is going well so far. Here's hoping in another 15 years we'll be able to use that docking port to extend its operating life another 20 years.
 
TheSonntag
Posts: 4679
Joined: Wed Jun 15, 2005 7:23 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Tue Jan 18, 2022 1:00 pm

Cannot wait to see the pictures. This is going to be a very interesting time for astronomy.
 
tomcat
Posts: 983
Joined: Thu Sep 28, 2000 4:14 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Tue Jan 25, 2022 11:21 pm

Webb has completed its final Mid Course Correction Burn and is now in L2 orbit! The next five months will be dedicated to the cooldown and the commissioning of the beast.

https://webb.nasa.gov/content/webbLaunch/deploymentExplorer.html
 
ZaphodHarkonnen
Posts: 1225
Joined: Sun Jan 04, 2015 10:20 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Wed Jan 26, 2022 12:33 am

O_O

A dozen years late and astoundingly over budget. But they did it! <3
 
AngMoh
Posts: 1192
Joined: Fri Nov 04, 2011 5:03 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Wed Jan 26, 2022 10:23 am

ZaphodHarkonnen wrote:
O_O

A dozen years late and astoundingly over budget. But they did it! <3


It might be well over budget, but I think $10B is a bargain for what they have done compared with a lot of military projects. It is an amazing technical feat and I have been looking at the "where is Webb" site almost daily to track the progress. Compared with that, Bloomberg just reported that Microsoft has spent $22B on glasses (ok it is the "Integrated Visual Augmentation System") and it does not work yet. Compared with these glasses, Webb is an absolute bargain.
 
User avatar
Tugger
Topic Author
Posts: 11834
Joined: Tue Apr 18, 2006 8:38 am

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Wed Jan 26, 2022 4:08 pm

Yes a big congrats on everything so far. I kept watching it but was afraid to say anything with all the known single point failure tasks still to go.

It seems though that everyone is letting out a big sigh of relief and is confident that everything is working as it should. It is wonderful to see (and it is being watched, it is now a thing to spot in the night for fun) and I look forward to the first images and many more after that.

Tugg
 
zanl188
Posts: 3933
Joined: Sat Oct 21, 2006 9:05 pm

Re: James Webb Space Telescope has a launch date: Dec 18 2021

Fri Jan 28, 2022 12:51 pm

ZaphodHarkonnen wrote:

Everyone involved in the delivery and operations for JWST have been smashing it out of the park right now. Telescope is fully unfolded, delivery was so spot on it would make Tory Bruno of ULA proud for Arianespace. Other than being disgustingly over budget and late, it is going well so far.


That’s the effect PAO is going for by intentionally under promising and over delivering. Just like that everything is wonderful. Some PA person is worth their weight in gold right now.

Who is online

Users browsing this forum: No registered users and 17 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos