The James Webb Space Telescope

In summary, the James Webb Space Telescope (JWST) is a highly advanced telescope that is set to launch in 2021. It is designed to study the universe in infrared light and will be able to see further and with more clarity than any other telescope before it. The JWST will be placed in orbit around the Sun, approximately 1.5 million kilometers from Earth, and will be able to observe objects dating back to the early universe. Its primary goals include studying the formation of galaxies, the birth of stars and planets, and potentially even finding signs of life on other planets. The JWST is expected to provide groundbreaking discoveries and revolutionize our understanding of the universe.
  • #71
Borg said:
The cruising speed yesterday was in excess of 2.5 miles/second. Today, it's down to less than 1.1. It's going to take a month to get to L2 at this rate. :oldwink:
1 last night and 0.83 this morning GMT.
29 days to reach L2. 26 to go!
 
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  • #72
417,000 km - it crossed the orbital distance of the Moon. Sunshield deployment should start in about half a day and take several days.
 
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  • #73
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  • #74
Jonathan Scott said:
it can't turn round without exposing sensitive components to the sun.
Just like the management, it's keeping its backside covered.
 
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  • #76
This link below gives distance traveled and a brief summary of what's happening:

Where is JWTS!
 
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  • #77
I just saw an announcement that temperature data from JWST is now available.

Does anyone have a link to get access to the real time data?
 
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  • #78
anorlunda said:
Does anyone have a link to get access to the real time data?
Different from the "Where is..." link above your post?

ADD -- The start of the info about the temperature data:

1640809698266.png
 
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  • #79
Sorry, I should have linked this.

 
  • #80
According to the official blog page, after the two initial mcc burns, there is enough remaining propellent to substantially exceed 10 years of service life!
 
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  • #81
4 days 8 hours after launch:

JWSTtemp.png


We already have a large difference between hot and cold side.

Next step is the deployable tower (edit: already in progress), increasing the separation between spacecraft and sunshield before the latter is expanded.
 
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  • #82
Webb telescope will be looking deep into the universe (back into earlier universe) so if someone is looking at the milky way from the farthest known galaxy would they think they were seeing an earlier universe?
 
  • #83
finney said:
Webb telescope will be looking deep into the universe (back into earlier universe) so if someone is looking at the milky way from the farthest known galaxy would they think they were seeing an earlier universe?
Yes, they would be seeing an earlier form of the Milky Way.
 
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  • #84
mfb said:
4 days 8 hours after launch:

View attachment 294873

We already have a large difference between hot and cold side.

Next step is the deployable tower, increasing the separation between spacecraft and sunshield before the latter is expanded.
Very cool (pun intended.) Where did you find that data?
 
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  • #85
On the where is Webb? page that has been linked multiple times.Deployable Tower Assembly is in progress.
 
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  • #86
I tried finding answers to the below questions on NASA's website and on Wikipedia, but was unable to:

1. How is JWST pointed? There does not appear to be any mechanism, as on a terrestrial telescope. Is the whole telescope with heat shield just rotated and tilted a limited number of degrees? I noticed that the heat shield is elongated, allowing it to be tilted up to 90 degrees and still being shielded from the sun. In the specs of JWST the minimum adjustment is 0.1 arc seconds.

2. I read that the JWST is orbiting the L2 Lagrange point. At what angles is that orbital plane relative to the line of centers of the sun and earth? Is the orbit perpendicular to that line of centers or some other angles?

3. What is the radius of that orbit?
 
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  • #88
Momentum flap deployed, sunshield cover removed. We are passing many of the single points of failure now.

The cold side has warmed up a bit since my last post, it's now -45 degrees at the mirror and -145 degrees at the instruments. I expect it to cool down again once the sunshield deployment starts.
KurtLudwig said:
1. How is JWST pointed?
The telescope part rotates/tilts, the sunshield part stays where it is because it needs to keep shielding the Sun. Reaction wheels take care of that.

An L2 halo orbit has to be perpendicular to the L2/Sun direction because only these two dimensions are an attractive potential. You can't orbit L2 along the L2/Sun direction. About 800,000 km, as you can find on the Wikipedia page.
 
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  • #89
This has to be nerve wracking for astronomers.
 
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  • #91
This video is very enjoyable. It analyzes the apparent trajectory of JWST as seen from Earth. It's a good reminder of how inadequate our simple mental models of orbits, trajectories, and frames of reference are.

 
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  • #92
Ooooh, we're half way there.
Oooh-oh, living on a prayer!

No but really, all good vibes to JWST. Everything is going great.
 
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  • #93
mfb said:
Momentum flap deployed, sunshield cover removed. We are passing many of the single points of failure now.

The cold side has warmed up a bit since my last post, it's now -45 degrees at the mirror and -145 degrees at the instruments. I expect it to cool down again once the sunshield deployment starts.The telescope part rotates/tilts, the sunshield part stays where it is because it needs to keep shielding the Sun. Reaction wheels take care of that.

An L2 halo orbit has to be perpendicular to the L2/Sun direction because only these two dimensions are an attractive potential. You can't orbit L2 along the L2/Sun direction. About 800,000 km, as you can find on the Wikipedia page.
If the telescope rotates with respect to the sun-shield, then the secondary mirror will be in sunlight. Please explain in detail.
If the telescope tilts, it and the secondary mirror will still be shielded.
 
  • #94
The requirement to stay in the shadow limits the observable range in the sky. Here is a discussion and here are more technical details (PDF download). Within +-5 degrees of roll the sunshade can keep its 3D orientation, for more it has to rotate around the JWST/Sun axis. It keeps its orientation relative to the Sun independent of the pitch angle.

New blog updates:
Webb Ready for Sunshield Deployment and Cooldown
First of Two Sunshield Mid-Booms Deploys
With Webb’s Mid-Booms Extended, Sunshield Takes Shape

The sunshield is now fully extended. It's not under tension yet, but it's enough to cool down the telescope side significantly. Tensioning the five layers will take at least two days.

That's a massive chunk of single points of failures:
all 107 membrane release devices associated with the sunshield deployment — every single one of which had to work in order for the sunshield to deploy — have now successfully released.
 
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  • #95
mfb said:
The requirement to stay in the shadow limits the observable range in the sky. Here is a discussion and here are more technical details (PDF download). Within +-5 degrees of roll the sunshade can keep its 3D orientation, for more it has to rotate around the JWST/Sun axis. It keeps its orientation relative to the Sun independent of the pitch angle.

New blog updates:
Webb Ready for Sunshield Deployment and Cooldown
First of Two Sunshield Mid-Booms Deploys
With Webb’s Mid-Booms Extended, Sunshield Takes Shape

The sunshield is now fully extended. It's not under tension yet, but it's enough to cool down the telescope side significantly. Tensioning the five layers will take at least two days.

That's a massive chunk of single points of failures:
We are getting through all the scary parts, and it's going great!
 
  • #96
KurtLudwig said:
If the telescope rotates with respect to the sun-shield, then the secondary mirror will be in sunlight. Please explain in detail.
If the telescope tilts, it and the secondary mirror will still be shielded.
If I am picturing correctly, the flap corrects for pitch. But I don't really know. It is a very interesting concept if one thinks about it.
 
  • #97
Happy new year everyone!
 
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  • #98
valenumr said:
We are getting through all the scary parts, and it's going great!
I think it's all scary. Until data arrives at Earth with the expected quality, it ain't over.
 
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  • #102
KurtLudwig said:
If the telescope rotates with respect to the sun-shield, then the secondary mirror will be in sunlight. Please explain in detail.
Looking at this "top" view, my understanding is that the telescope tilts to get pointing in one axis (equivalent to altitude in an Earth-bound alt-az telescope), and that the entire telescope+sunscreen rotates around the axis pointing at the sun to get pointing in the other axis (equivalent to azimuth).
Webb_Top_View.png
 
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  • #103
pinball1970 said:
Is this an issue?
The opening sentence in the linked article says "Taking advantage of its flexible commissioning schedule" That doesn't sound like an issue to me.
 
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  • #104
anorlunda said:
The opening sentence in the linked article says "Taking advantage of its flexible commissioning schedule" That doesn't sound like an issue to me.
Where's Webb and links not working for me. A few things on YT mentioned the same thing but I prefer to get it from the horses mouth. At least from someone who understands the horse.
Not an issue, good.
 
  • #105
pinball1970 said:
Where's Webb and links not working for me.
I just checked, and it's working for me...
 

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