Questions tagged [james-webb-telescope]

Launched in 2021, the James Webb Space Telescope (often called JWST) is a large, near infrared and visible space telescope with 18 mirror segments in Earth's L2 point. Use for questions about the telescope.

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How well is JWST doing on maintaining its Halo orbit?

I looked around a little bit online but did not find anything discussing how well JWST is doing with managing its orbit. I was wondering if there were any surprises or issues. It's been out there ...
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How does the James Webb space telescope measure wind shear?

NASA.gov has an image of the James Webb space telescope's nircam tracking a high speed belt near Jupiter's equator. They measured the speed by looking at wind shears in millibars. How does Webb do ...
psl's user avatar
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12 votes
3 answers
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Would electrically powered thrusters on JWST have made it last for decades longer?

Since the lifespan of the James Webb Space Telescope is determined by the amount of fuel it can carry for its thrusters, used to decelerate the reaction wheels used to orient the telescope, and since ...
Ryan Christiansen's user avatar
1 vote
2 answers
168 views

What is the advantage of optical astronomy over infrared astronomy in space telescopes?

The Habitable Worlds Observatory, the proposed successor to the James Webb has an identically sized 6.5 meter mirror but operates primarily in visible light. Infrared telescopes like Webb have the ...
Andykins 's user avatar
21 votes
1 answer
3k views

What was so hard about the washer nuts on the JWST?

In a YouTube "Short", Dr. Becky explains that a problem with ten washer nuts wound up adding 800 days and $800 million to the JWST. The problem is that they came loose in the shake test, and ...
Greg's user avatar
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10 votes
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How close can a spacecraft get to the Sun if it is limited solely by passive cooling?

The Parker Solar Probe’s trajectory will take it within 8.5 solar radii of the sun’s photosphere. Its instruments, hiding in the shadow of the alumina-coated composite sun shield, will bask in 29 °C ...
Woody's user avatar
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Are the 10 identical stars in this JWST image one of the same?

Consider: In this image you can see a cluster of 3 stars in the bottom left, one big star in the middle up and many more identical stars scattered throughout the image. Are they all the same star? ...
Afek Ben nachum's user avatar
14 votes
2 answers
4k views

Could the James Webb Resolve Earth?

Hypothetically, if one were to point the James Webb at Earth: Could it be focused in such a way that the entire Earth was in it's FOV, or is it too close? If this were possible, what would be the ...
ScottishTapWater's user avatar
1 vote
1 answer
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Rotation and orientation of James Webb's mirror from ground stations

There are definitely pre-determined plans in the agenda of the James Webb telescope to take images from the universe, but if there is a need for any reason (intentional or emergency) to change the ...
Merlin's user avatar
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9 votes
1 answer
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If James Webb goes "over the hill" is it gone for good?

James Webb is in a Halo orbit around Earth's L2 point. It is in a gravitational saddle: two directions are stable ("up-down" and "front-back"). The "in-out" direction is ...
Kevin Kostlan's user avatar
1 vote
0 answers
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How redshifted galaxies will JWST be able to detect? [closed]

I see that the MIRI camera/spectrograph on JWST has an operational wavelength span between 5 and 28 micrometers. Now visible not redshifted light has wavelengths between 400 and 700 nanometers. If ...
Agerhell's user avatar
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Can the JWST look at Earth? What would it see? [duplicate]

There's a few questions on the site about whether we can see the James Webb Space Telescope from Earth (i.e. here and here), but I'm wondering about the opposite - can we see Earth using the JWST? I ...
Dubukay's user avatar
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6 votes
1 answer
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Why does JWST make images of planets from solar system?

NASA has already made images of planets from the solar system before. So why is NASA/ESA making images of planets from the solar system by using the JWST instead of exploring unseen parts of universe?...
M. Pedro's user avatar
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2 votes
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Why was JWST cancelled in 2011?

I saw this table in this section: In the third column from the bottom, it says "Proposed cancel": Why so?
M. Pedro's user avatar
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Why is the hot part of Webb's MIRI cryocooler in the 300K area?

Longer wavelengths require cooler temperatures to detect efficiently. The MIRI detects all the way out to 25 μm and so needs to be cooled to 7 K. Webb can passively cool down to 40 K with its sun-...
Kevin Kostlan's user avatar
2 votes
2 answers
132 views

Gyros for long term attitude control

James Webb telescope is limited to a 10 year service life by its fuel, as I understand it. While propellant would be required to translate the craft for orbital maneuvering, could pure attitude ...
RC_23's user avatar
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Could any of the JWST instruments image the rings around 10199 Chariklo?

The asteroid 10199 Chariklo orbits between Saturn and Uranus. It has two rings with radii 386 and 400 km and widths of about 6.9 km and 0.12 km respectively. It is currently 15.94 AU from Earth. Do ...
Dave Gremlin's user avatar
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2 votes
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JWST Gravitational lensing

In the JWST deep field image we see gravitational lensing but it is not there in stefans quintent image of much more massive galaxy cluster. What are the criteria for seeing magnified images of ...
Bhushan Timilsina's user avatar
2 votes
0 answers
73 views

Visualizing halo orbits

I'd like to visualize JWST's orbit (or any halo orbit that resembles it) preferably in Python. Does anyone have any code or resource I could read? Thanks in advance!
Alvaro's user avatar
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1 answer
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If JWST can look into 13 billion years past then why it cannot check sun formation which happened only 4.603 billion years ago?

If JWST can look into past then why it cannot find how the sun formed 4.603 billion years back? I heard that JWST will process infrared light waves to make them more clear to the human eye but not it ...
user2225190's user avatar
1 vote
0 answers
51 views

Is it practically possible to replace deformed mirror segments after impact in a service mission? [duplicate]

After reading the first articles about Webb being hit by micrometeorites/ dust and that this was more than expected, I was wondering whether it would be possible to have a service mission to replace ...
Torsten Knodt's user avatar
2 votes
1 answer
552 views

How did the JWST take a selfie?

During the alignment of JWST primary mirrors, this selfie was taken: (source: NASA) I think we're seeing here the primary mirrors, with the secondary in the center and the reflection of the support ...
Ludo's user avatar
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4 votes
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What kind of hardware and software does the James Webb space telescope computer use?

What kind of software, operating system, database, processor, architecture, antenna used for communication back to Earth, basically what computer does it use.
Kalai Selvan's user avatar
23 votes
8 answers
4k views

Why didn't JWST include any sensors capable of blue and green visible wavelengths

JWST wavelength sensing starts at 600nm, corresponding to red/orange visible light, and then into the IR. It seems there is no sensor or filter included below 600nm meaning that green and blue light ...
TopCat's user avatar
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15 votes
2 answers
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What will now happen with Hubble?

The James Webb Telescope just started it’s scientific work. The amazing pictures and information is definitely better than Hubbles. What will now happen with Hubble?
The Rocket fan's user avatar
10 votes
2 answers
1k views

Interesting diffraction pattern on JWST composite false-color image released today (July 11) at Biden preview - how does this arise?

There was an earlier question on the diffraction pattern in the Mar 16 test image that was mainly explained by the hexagonal shape of the individual mirror segments. Today's image has similar ...
Roger Wood's user avatar
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1 vote
1 answer
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Why did NASA release JWST image of SMACS 0723 one day before the scheduled time?

A few hours ago, NASA released JWST image of galaxy cluster SMACS 0723 one day before the scheduled time: President Joe Biden unveiled this image of galaxy cluster SMACS 0723, known as Webb’s First ...
M. Pedro's user avatar
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2 votes
1 answer
306 views

Hubble vs JWST telescope

Can you quantify how much better JWST is compared to Hubble? For instance, from what distance can each "see" (differentiate) a sun-like star? Maybe there are other measures.
user2679290's user avatar
24 votes
3 answers
8k views

What is that black thing in center of every star in this JWST image?

I circled that black thing in this image with blue color: The image above, which NASA released on Wednesday (July 6, 2022), represents 32 hours of observing time from JWST's Fine Guidance Sensor.
M. Pedro's user avatar
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Are first official science images of JWST are most far distant images ever taken by space telescope?

In JWST, it says: NASA has scheduled the first official science images release event for Tuesday, 12 July 2022 at 10:30 am EDT/usa. Are first official science images of JWST are most far distant ...
M. Pedro's user avatar
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0 votes
1 answer
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Are these latest anticipated images of JWST released to public?

I came across this line from here: These latest anticipated images (around 10-20 predicted) however are said to be so beautiful that Associate Administrator for NASA’s Science Mission Directorate, ...
M. Pedro's user avatar
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3 votes
0 answers
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How long does NASA take to post process JWST images?

My question came from this comment. How long does NASA take to post process JWST images?
M. Pedro's user avatar
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2 votes
1 answer
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Does NASA already have James Webb Space Telescope's 1st science photos with them?

From this link, it clearly says: The main image release event will take place on July 12 at 10:30 a.m. EDT (1430 GMT). Does NASA already have James Webb Space Telescope's 1st science photos with ...
M. Pedro's user avatar
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18 votes
7 answers
4k views

Is there something inherently more difficult about servicing satellites in the 2nd Sun-Earth Lagrangian point?

There are several questions already asked on here about the potential for servicing the James Webb Space Telescope. This question asks what happens if the JWST needs repair. Basically, there are no ...
Curious Layman's user avatar
3 votes
0 answers
126 views

Where and when will the first images from James Webb be published?

Hope this question is not out of place here. So, do you have an exact URL where JWST first pictures will be released, and do we know the exact time that will be happening, or we just assume it will be ...
Nonamed's user avatar
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2 votes
1 answer
185 views

Is JWST the first telescope to release test images before its first light?

On February 11 2022, James Webb Space Telescope released this image to test its mirrors: Is JWST the first telescope to release test images before its first light?
M. Pedro's user avatar
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6 votes
2 answers
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Can JWST come in for a pit stop? Is the fuel supply on JWST adequate for a transfer to an Earth Moon libration point to allow repairs?

The James Webb Space Telescope is generally considered to be in an unserviceable location at SEL2. If servicing becomes necessary, is it possible for the JWST to use a low energy heteroclinic transfer ...
Woody's user avatar
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0 votes
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How could Webb's lifetime be extended? [duplicate]

This article says why the lifetime of the Webb telescope is limited by the fuel it carries. Why NASA’s James Webb Space Telescope Will Never Live As Long As Hubble In short, Webb must stay near the ...
mmesser314's user avatar
5 votes
4 answers
358 views

Would it be practical to position a telescope like JWST at Sun-Earth L4 or L5?

During a discussion of Lagrange points I was asked why we didn't put JWST at SE L4 or L5 since they are less unstable than L2. I thought a bit and came to think that the Earth gravity driven Halo ...
BradV's user avatar
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2 votes
1 answer
443 views

What type of actuator mechanism(s) used to move the Fine Steering Mirror on JWST?

JWST’s Primary Mirror has gotten the lion’s share of attention, and rightly so. But recently I’ve been trying to find out how the FSM is moved. I’ve found what appears to be photos of the FSM lab ...
BradV's user avatar
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13 votes
2 answers
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What caused the JWST Instrument Radiator temperature to start cooling faster on day 34?

As shown on the temperature plots, the D-Instrument Radiator temperature was slowly dropping after sunshield deployment. Around day 34, however, the temperature started to decrease faster than before....
Nate Lowry's user avatar
0 votes
1 answer
146 views

Is JWST's weak link the Cryocooler for the MIRI instrument?

While most of JWST uses passive cooling to get instruments to low operating temperature the MIRI requires active measures to get to 7K. I've been reading about the complex system developed to cool ...
BradV's user avatar
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12 votes
2 answers
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How does the JWST change focus when it goes from looking at a near subject to looking at a far subject? (Does it even change focus?)

After following the extensive steps in the process of aligning and phasing the optics and instruments of JWST... I now wonder if further focus adjustments would be made based on distance to subject. ...
BradV's user avatar
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-5 votes
1 answer
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how much cheaper would the J Web Telescope be per unit if economies of scale were applied in the creation of a complete industrial complex on Luna? [closed]

very few items are manufactured as expensively as space based hardware for a lot of good reasons, yet one of those reasons can be fixed. if standard industrial practices such as, intermodal shipping, ...
Stellar Nomad's user avatar
2 votes
2 answers
845 views

JWST - batteries?

I am interested in how batteries might be used on the JWST. A few questions come to mind: Does the JWST have onboard batteries? If so, What kind of batteries are they? Are they rechargeable? If ...
Bruce Simonson's user avatar
8 votes
1 answer
766 views

Are JWST displayed temperatures equilibrated to stable?

The JWST vehicle temperature displayed on the Where is Webb site seem to have stabilised. They have not noted a change in several days. Is the current temperature, the stable equilibrated values with ...
tckosvic's user avatar
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8 votes
1 answer
446 views

JWST - pick-off mirrors?

In the documentation that I’ve been looking through recently, I occasionally come across references and diagrams to “pick-off” mirrors. For example, from this JWST user documentation article, there is ...
Bruce Simonson's user avatar
12 votes
1 answer
2k views

JWST - image acquisition - what is a dither pattern?

While perusing one of the sample science programs for the JWST (NIRCam WFSS Deep Galaxy Observations), I came across Step 5, “Decide on dither pattern.” Instead of guessing — or worse, assuming — what ...
Bruce Simonson's user avatar
3 votes
1 answer
399 views

JWST - image stabilization?

I am curious about how the JWST accomplishes image stabilization. This paper from 2005 addresses this, but a more general high-level description of the processes would be helpful, from someone with ...
Bruce Simonson's user avatar
25 votes
3 answers
4k views

Diffraction artifact on the March 16, 2022 JWST aligned test image

On March 16, 2022 we were treated to the first image from the JWST of a star, where all 18 segments were aligned and in common focus. What a wonderful photo: (Source: Webb Twitter. Full 18 MP ...
Bruce Simonson's user avatar

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