APOD: JWST on the Road to L2 (2021 Dec 31)

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APOD: JWST on the Road to L2 (2021 Dec 31)

Post by APOD Robot » Fri Dec 31, 2021 5:05 am

Image JWST on the Road to L2

Explanation: This timelapse gif tracks the James Webb Space Telescope as it streaks across the stars of Orion on its journey to a destination beyond the Moon. Recorded on December 28, 12 consecutive exposures each 10 minutes long were aligned and combined with a subsequent color image of the background stars to create the animation. About 2.5 days after its December 25 launch, JWST cruised past the altitude of the Moon's orbit as it climbed up the gravity ridge from Earth to reach a halo orbit around L2, an Earth-Sun Lagrange point. Lagrange points are convenient locations in space where the combined gravitational attraction of one massive body (Earth) orbiting another massive body (Sun) is in balance with the centripetal force needed to move along with them. So much smaller masses, like spacecraft, will tend to stay there. One of 5 Lagrange points, L2 is about 1.5 million kilometers from Earth directly along the Earth-Sun line. JWST will arrive at L2 on January 23, 29 days after launch. While relaxing in Earth's surface gravity you can follow the James Webb Space Telescope's progress and complicated deployment online.

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by Dmpalmer » Fri Dec 31, 2021 6:21 am

I see a lot of brightness variation in the sequence. I would expect JWST to be constant brightness because it is stabilized to keep the same orientation relative to the Sun. The second stage booster that it was released from is in nearly the same orbit, and is not stabilized so it will get brighter and dimmer as it tumbles.

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by Antony Rawlinson » Fri Dec 31, 2021 9:09 am

Can anyone explain whether space debris accumulates at the L-points and whether it could endanger the spacecraft? I originally understood the Webb to be targeted for an L-point along the line of the Earth's orbit, and thought in terms of Jupiter's "Trojan" and "Greek" asteroids - but I guess the equivalent points for the Earth are considerably further than 1.5 million km away.

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by orin stepanek » Fri Dec 31, 2021 2:06 pm

Fantastic! I hope APOD Keeps us posted on the progress of JWST! :D I'm hoping for some great views as soon as possible from this wonderful Christmas present!
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by neufer » Fri Dec 31, 2021 2:24 pm

Antony Rawlinson wrote: Fri Dec 31, 2021 9:09 am
Can anyone explain whether space debris accumulates at the L-points and whether it could endanger the spacecraft? I originally understood the Webb to be targeted for an L-point along the line of the Earth's orbit, and thought in terms of Jupiter's "Trojan" and "Greek" asteroids - but I guess the equivalent points for the Earth are considerably further than 1.5 million km away.
https://en.wikipedia.org/wiki/Lagrange_point#Stability wrote:

:arrow: <<A contour plot of the effective potential due to gravity and the centrifugal force of a two-body system in a rotating frame of reference. The arrows indicate the gradients of the potential around the five Lagrange points—downhill toward them (red) or away from them (blue). Counterintuitively, the L4 and L5 points are the high points of the potential. At the points themselves these forces are balanced.

The triangular points (L4 and L5) are stable equilibria, provided that the ratio of M1(Sun)/M2(Earth) is greater than 24.96. This is the case for the Sun–Earth system, the Sun–Jupiter system, and, by a smaller margin, the Earth–Moon system. When a body at these points is perturbed, it moves away from the point, but the factor opposite of that which is increased or decreased by the perturbation (either gravity or angular momentum-induced speed) will also increase or decrease, bending the object's path into a stable, kidney bean-shaped orbit around the point (as seen in the corotating frame of reference).


The points L1, L2, and L3 are positions of unstable equilibrium. Any object orbiting at L1, L2, or L3 will tend to fall out of orbit; it is therefore rare to find natural objects there, and spacecraft inhabiting these areas must employ station keeping in order to maintain their position.
>>
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by bls0326 » Fri Dec 31, 2021 2:32 pm

Edit - I see neufer just answered the question. I posted mine anyway.
Antony Rawlinson wrote: Fri Dec 31, 2021 9:09 am Can anyone explain whether space debris accumulates at the L-points and whether it could endanger the spacecraft? I originally understood the Webb to be targeted for an L-point along the line of the Earth's orbit, and thought in terms of Jupiter's "Trojan" and "Greek" asteroids - but I guess the equivalent points for the Earth are considerably further than 1.5 million km away.
A quote from this website https://webb.nasa.gov/content/about/orbit.html

"However, L1, L2, and L3 are metastable so objects around these points slowly drift away into their own orbits around the Sun unless they maintain their positions, for example by using small periodic rocket thrust. This is why L1, L2, and L3 don't "collect" objects like L4 and L5 do."

That website includes some nice graphics about the L2 orbit.

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by Chris Peterson » Fri Dec 31, 2021 3:32 pm

Dmpalmer wrote: Fri Dec 31, 2021 6:21 am I see a lot of brightness variation in the sequence. I would expect JWST to be constant brightness because it is stabilized to keep the same orientation relative to the Sun. The second stage booster that it was released from is in nearly the same orbit, and is not stabilized so it will get brighter and dimmer as it tumbles.
It could be as simple as atmospheric variations (like thin clouds or haze) over the two hours of exposure time.
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by neufer » Fri Dec 31, 2021 3:39 pm

https://www.youtube.com/watch?v=YtPLPdKHhe0 wrote:
Click to play embedded YouTube video.
James Webb Sunshield Deployment Livestream!

<<We're going live to cover the critical deployment of the James Webb Space Telescope's sunshield with special guest, Dr. Heidi B. Hammel! Join us to wait for the signal to come in and ask JWST Interdisciplinary Scientist Dr. Heidi Hammel your questions!>>
Art Neuendorffer

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by johnnydeep » Fri Dec 31, 2021 9:16 pm

neufer wrote:
https://www.youtube.com/watch?v=YtPLPdKHhe0 wrote:
Click to play embedded YouTube video.
James Webb Sunshield Deployment Livestream!

<<We're going live to cover the critical deployment of the James Webb Space Telescope's sunshield with special guest, Dr. Heidi B. Hammel! Join us to wait for the signal to come in and ask JWST Interdisciplinary Scientist Dr. Heidi Hammel your questions!>>
Thanks - I'm in at the T-4 minute mark!
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by FormerGoddardSFCemployee » Tue Jan 04, 2022 1:24 pm

The link on this page to "Where is Webb" leads to a Goddard Space Flight Center webpage.

The page has two potential trackers activated: cdnjs.cloudflare.com and fonts.gstatic.com .
Blocking the first tracker will disable the correct display of all numbers on the page (try e.g. the EFF privacy badger to verify).

Is it too much to ask of NASA/GSFC to avoid the use of trackers on such a harmless page simply serving astronomy-interested fans?
Or at least to keep the page functional when the trackers are blocked?

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by johnnydeep » Tue Jan 04, 2022 1:52 pm

FormerGoddardSFCemployee wrote: Tue Jan 04, 2022 1:24 pm The link on this page to "Where is Webb" leads to a Goddard Space Flight Center webpage.

The page has two potential trackers activated: cdnjs.cloudflare.com and fonts.gstatic.com .
Blocking the first tracker will disable the correct display of all numbers on the page (try e.g. the EFF privacy badger to verify).

Is it too much to ask of NASA/GSFC to avoid the use of trackers on such a harmless page simply serving astronomy-interested fans?
Or at least to keep the page functional when the trackers are blocked?
Are you referring to this site: https://jwst.nasa.gov/content/webbLaunc ... sWebb.html ? I had only been using Adblock Plus to block ads, but I hadn't been using any extension specifically to block "trackers". So, based on your comment, I installed the EFF Privacy Badger extension (from https://privacybadger.org), and it reports 4 trackers blocked on the whereIsWebb page:

Trackers blocked on WhereIsWeb page.JPG

But I don't see any difference in the information displayed on the page where I block all 4 trackers or not:

Where Is Webb Example Display.JPG

So, is this different from the behavior you're seeing? Hmm, I just tried again and it reports only two of trackers listed above now being blocked. Not sure what's going on...
You do not have the required permissions to view the files attached to this post.
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by Chris Peterson » Tue Jan 04, 2022 2:01 pm

FormerGoddardSFCemployee wrote: Tue Jan 04, 2022 1:24 pm The link on this page to "Where is Webb" leads to a Goddard Space Flight Center webpage.

The page has two potential trackers activated: cdnjs.cloudflare.com and fonts.gstatic.com .
Blocking the first tracker will disable the correct display of all numbers on the page (try e.g. the EFF privacy badger to verify).

Is it too much to ask of NASA/GSFC to avoid the use of trackers on such a harmless page simply serving astronomy-interested fans?
Or at least to keep the page functional when the trackers are blocked?
Neither are remotely a privacy risk, both offer valuable services that would be a pain for a website developer to have to offer some kind of alternative to. Both are ubiquitous on the web, and in most cases disabling them will break site functionality.

In any case, feel free to take it up with NASA. This site has no control over it.
Chris

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by johnnydeep » Tue Jan 04, 2022 9:52 pm

JWST imaged from Earth on 1/1/2022, when it was about 720,000 km away, using a Takahashi Epsilon 180ED Astrograph (a $5000 USD scope!):

Click to play embedded YouTube video.

So, could Hubble get a good image of the JWST?
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by neufer » Wed Jan 05, 2022 1:36 am

https://www.nasa.gov/press-release/sunshield-successfully-deploys-on-nasa-s-next-flagship-telescope wrote:
Sunshield Successfully Deploys on NASA’s Next Flagship Telescope

<<On Jan. 4, 2022, engineers successfully completed the deployment of the James Webb Space Telescope’s sunshield, seen here during its final deployment test on Earth in December 2020 at Northrop Grumman in Redondo Beach, California. The five-layer, tennis court-sized sunshield is essential for protecting the telescope from heat, allowing Webb’s instruments to cool down to the extremely low temperatures necessary to carry out its science goals.

The James Webb Space Telescope team has fully deployed the spacecraft’s 70-foot sunshield, a key milestone in preparing it for science operations.

The sunshield – about the size of a tennis court at full size – was folded to fit inside the payload area of an Arianespace Ariane 5 rocket’s nose cone prior to launch. The Webb team began remotely deploying the sunshield Dec. 28, 2021, three days after launch.

NASA will hold a media teleconference at 12:45 p.m. EST today, Tuesday, Jan. 4, to discuss the completion of this critical step. To participate by telephone, media must RSVP to Laura Betz at: laura.e.betz@nasa.gov. Audio of the teleconference will also stream on the agency’s website.

“This is the first time anyone has ever attempted to put a telescope this large into space,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at the agency’s headquarters in Washington. “Webb required not only careful assembly but also careful deployments. The success of its most challenging deployment – the sunshield – is an incredible testament to the human ingenuity and engineering skill that will enable Webb to accomplish its science goals.”

The five-layered sunshield will protect the telescope from the light and heat of the Sun, Earth, and Moon. Each plastic sheet is about as thin as a human hair and coated with reflective metal, providing protection on the order of more than SPF 1 million. Together, the five layers reduce exposure from the Sun from over 200 kilowatts of solar energy to a fraction of a watt.

This protection is crucial to keep Webb’s scientific instruments at temperatures of 40 kelvins, or under minus 380 degrees Fahrenheit – cold enough to see the faint infrared light that Webb seeks to observe.

“Unfolding Webb’s sunshield in space is an incredible milestone, crucial to the success of the mission,” said Gregory L. Robinson, Webb’s program director at NASA Headquarters. “Thousands of parts had to work with precision for this marvel of engineering to fully unfurl. The team has accomplished an audacious feat with the complexity of this deployment – one of the boldest undertakings yet for Webb.”

The unfolding occurred in the following order, over the course of eight days:
  • Two pallet structures – forward and aft – unfolded to bring the observatory to its full 70-foot length

    The Deployable Tower Assembly deployed to separate the telescope and instruments from the sunshield and the main body of the spacecraft, allowing room for the sunshield to fully deploy

    The aft momentum flap and membrane covers were released and deployed

    The mid-booms deployed, expanding perpendicular to the pallet structures and allowing the sunshield to extend to its full width of 47 feet

    Finally, at approximately 11:59 a.m. EST Tuesday, the sunshield was fully tensioned and secured into position, marking the completion of the sunshield deployment
The unfolding and tensioning of the sunshield involved 139 of Webb’s 178 release mechanisms, 70 hinge assemblies, eight deployment motors, roughly 400 pulleys, and 90 individual cables totaling roughly one quarter of a mile in length. The team also paused deployment operations for a day to work on optimizing Webb’s power systems and tensioning motors, to ensure Webb was in prime condition before beginning the major work of sunshield tensioning.

“The sunshield is remarkable as it will protect the telescope on this historic mission,” said Jim Flynn, sunshield manager at Northrop Grumman, NASA’s primary contractor for Webb. “This milestone represents the pioneering spirit of thousands of engineers, scientists, and technicians who spent significant portions of their careers developing, designing, manufacturing, and testing this first-of-its-kind space technology.”

The world’s largest and most complex space science observatory has another 5 1/2 months of setup still to come, including deployment of the secondary mirror and primary mirror wings, alignment of the telescope optics, and calibration of the science instruments. After that, Webb will deliver its first images.>>
Art Neuendorffer

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by FormerGoddardSFCemployee » Wed Jan 05, 2022 6:34 am

Thank you, for your comments on the tracker issue with the whereisWebb link, johnnydeep and Chris Peterson, much appreciated.

Here is my humble view reading your comments:
Tracking is a form of spying on user activities which are not related to the current page. It is not forbidden, but luckily there are ways to block it.
I use the full block of all trackers when surfing.
johnnydeep, that is why you still got the functionality on Webb's way to L2, you were blocking cdnjs.cloudflare.com cookies=yellow, but not the domain=red, otherwise the numbers are off.

Chris, you wrote:
Neither are remotely a privacy risk, both offer valuable services that would be a pain for a website developer to have to offer some kind of alternative to. Both are ubiquitous on the web, and in most cases disabling them will break site functionality.
These are very general statements, and certainly not true for my daily experience. With full blocking activated I do not encounter problems with functionality of websites, they all work just fine without the tracking, even news channels. So seemingly there are ways for developers to provide the functionality of their content without them, but they add trackers for those who do not care.

And the story with the link on the APOD page is more detailed. The page was working well with all trackers blocked for me since the start of Webb.
Then, a few days after APOD included the link on 31 Dec which is another boost in prominence for this link, they changed the page including its tracking functionality. And I find that poor for any harmless astronomy link of NASA, and I did enough webpages to know that the simple functionality of this nice whereisWebb page can be done without relying on the cloudflare CDN.

I hope this is not too long to read...

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by johnnydeep » Wed Jan 05, 2022 1:18 pm

neufer wrote: Wed Jan 05, 2022 1:36 am
https://www.nasa.gov/press-release/sunshield-successfully-deploys-on-nasa-s-next-flagship-telescope wrote:
Sunshield Successfully Deploys on NASA’s Next Flagship Telescope

<<On Jan. 4, 2022, engineers successfully completed the deployment of the James Webb Space Telescope’s sunshield, seen here during its final deployment test on Earth in December 2020 at Northrop Grumman in Redondo Beach, California. The five-layer, tennis court-sized sunshield is essential for protecting the telescope from heat, allowing Webb’s instruments to cool down to the extremely low temperatures necessary to carry out its science goals.
...

The five-layered sunshield will protect the telescope from the light and heat of the Sun, Earth, and Moon. Each plastic sheet is about as thin as a human hair and coated with reflective metal, providing protection on the order of more than SPF 1 million. Together, the five layers reduce exposure from the Sun from over 200 kilowatts of solar energy to a fraction of a watt.
...>>
Two million sunblock would have been better:

Click to play embedded YouTube video.
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by Chris Peterson » Wed Jan 05, 2022 2:31 pm

FormerGoddardSFCemployee wrote: Wed Jan 05, 2022 6:34 am Thank you, for your comments on the tracker issue with the whereisWebb link, johnnydeep and Chris Peterson, much appreciated.

Here is my humble view reading your comments:
Tracking is a form of spying on user activities which are not related to the current page. It is not forbidden, but luckily there are ways to block it.
I use the full block of all trackers when surfing.
johnnydeep, that is why you still got the functionality on Webb's way to L2, you were blocking cdnjs.cloudflare.com cookies=yellow, but not the domain=red, otherwise the numbers are off.

Chris, you wrote:
Neither are remotely a privacy risk, both offer valuable services that would be a pain for a website developer to have to offer some kind of alternative to. Both are ubiquitous on the web, and in most cases disabling them will break site functionality.
These are very general statements, and certainly not true for my daily experience. With full blocking activated I do not encounter problems with functionality of websites, they all work just fine without the tracking, even news channels. So seemingly there are ways for developers to provide the functionality of their content without them, but they add trackers for those who do not care.

And the story with the link on the APOD page is more detailed. The page was working well with all trackers blocked for me since the start of Webb.
Then, a few days after APOD included the link on 31 Dec which is another boost in prominence for this link, they changed the page including its tracking functionality. And I find that poor for any harmless astronomy link of NASA, and I did enough webpages to know that the simple functionality of this nice whereisWebb page can be done without relying on the cloudflare CDN.

I hope this is not too long to read...
Well, like I said, neither are trackers. And both are useful, and making many sites functional with them disabled would require extra work. I use one on my own site, and I am not interested in providing workarounds for people who choose to block it. Not worth my effort.

You will have to decide for yourself what level of privacy you desire. But in any case, like I said, this is hardly the place to complain. Nobody here has any say about how NASA operates their websites.
Chris

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by johnnydeep » Wed Jan 05, 2022 5:41 pm

Chris Peterson wrote: Wed Jan 05, 2022 2:31 pm
FormerGoddardSFCemployee wrote: Wed Jan 05, 2022 6:34 am Thank you, for your comments on the tracker issue with the whereisWebb link, johnnydeep and Chris Peterson, much appreciated.

Here is my humble view reading your comments:
Tracking is a form of spying on user activities which are not related to the current page. It is not forbidden, but luckily there are ways to block it.
I use the full block of all trackers when surfing.
johnnydeep, that is why you still got the functionality on Webb's way to L2, you were blocking cdnjs.cloudflare.com cookies=yellow, but not the domain=red, otherwise the numbers are off.

Chris, you wrote:
Neither are remotely a privacy risk, both offer valuable services that would be a pain for a website developer to have to offer some kind of alternative to. Both are ubiquitous on the web, and in most cases disabling them will break site functionality.
These are very general statements, and certainly not true for my daily experience. With full blocking activated I do not encounter problems with functionality of websites, they all work just fine without the tracking, even news channels. So seemingly there are ways for developers to provide the functionality of their content without them, but they add trackers for those who do not care.

And the story with the link on the APOD page is more detailed. The page was working well with all trackers blocked for me since the start of Webb.
Then, a few days after APOD included the link on 31 Dec which is another boost in prominence for this link, they changed the page including its tracking functionality. And I find that poor for any harmless astronomy link of NASA, and I did enough webpages to know that the simple functionality of this nice whereisWebb page can be done without relying on the cloudflare CDN.

I hope this is not too long to read...
Well, like I said, neither are trackers. And both are useful, and making many sites functional with them disabled would require extra work. I use one on my own site, and I am not interested in providing workarounds for people who choose to block it. Not worth my effort.

You will have to decide for yourself what level of privacy you desire. But in any case, like I said, this is hardly the place to complain. Nobody here has any say about how NASA operates their websites.
FormerGoddardSFCemployee:
As Chris said, only NASA would be able to address your concern. And, with your observation that it is necessary to disable the trackers completely to see the bad behavior, I was able to duplicate the issue: namely, that all the numbers show as unset:

whereiswebbtrackerblocksinfo.JPG

And, ultimately, I agree with you that it would be good for the page to work properly even with the trackers blocked, and it should be easy enough for the site programmer to do. Also, since you say the behavior changed quite recently, you might actually get the issue corrected if you contact NASA. The main page advertises this contact email to use for website issues: GSFC-NASAWebb@mail.nasa.gov
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by neufer » Wed Jan 05, 2022 6:57 pm

https://www.youtube.com/watch?v=-EnlaXnFcGs wrote:
Click to play embedded YouTube video.

<<Webb's secondary mirror is fully deployed. Webb's secondary mirror had to deploy in microgravity, and in extremely cold temperatures, and it ultimately had to work the first time without error. It also had to deploy, position, and lock itself into place to a tolerance of about one and a half millimeters, and then it has to stay extremely stable while the telescope points to different places in the sky – and that’s all for a secondary mirror support structure that is over 7 meters in length. Webb's secondary mirror is at the end of the Secondary Mirror Support Structure (SMSS). The secondary mirror plays an important role in reflecting the light from the primary mirror to where the instruments sit, behind the primary mirror.>>
Art Neuendorffer

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by johnnydeep » Wed Jan 05, 2022 9:20 pm

neufer wrote: Wed Jan 05, 2022 6:57 pm
https://www.youtube.com/watch?v=-EnlaXnFcGs wrote:
Click to play embedded YouTube video.

<<Webb's secondary mirror is fully deployed. Webb's secondary mirror had to deploy in microgravity, and in extremely cold temperatures, and it ultimately had to work the first time without error. It also had to deploy, position, and lock itself into place to a tolerance of about one and a half millimeters, and then it has to stay extremely stable while the telescope points to different places in the sky – and that’s all for a secondary mirror support structure that is over 7 meters in length. Webb's secondary mirror is at the end of the Secondary Mirror Support Structure (SMSS). The secondary mirror plays an important role in reflecting the light from the primary mirror to where the instruments sit, behind the primary mirror.>>
That really is some truly impressive engineering! I am ecstatic it has been going so well so far.
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by Fred the Cat » Wed Jan 05, 2022 9:31 pm

Would it be fair or correct to describe Webb as the most sensitive thermometer ever launched? Designed to observe in IR by collecting photons emitted of a thermal origin, it makes me think of it as a temperature measuring device.

Albeit one that might be able to block out a hot sun to see where ET could be sunbathing. :wink:
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by johnnydeep » Wed Jan 05, 2022 9:45 pm

Fred the Cat wrote: Wed Jan 05, 2022 9:31 pm Would it be fair or correct to describe Webb as the most sensitive thermometer ever launched? Designed to observe in IR by collecting photons emitted of a thermal origin, it makes me think of it as a temperature measuring device.

Albeit one that might be able to block out a hot sun to see where ET could be sunbathing. :wink:
Maybe. Most thermometers I know are measuring how much kinetic energy is added to the molecules they are made of. An IR telescope is merely capturing photons. Hmm, how do those remote thermometers - where you just point it at something - work? I suppose they must be measuring photons as well. And I guess the same goes for infrared goggles.

PS - I commend you on your posts, which are always concise and to the point but usually also include very interesting links!
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by Fred the Cat » Thu Jan 06, 2022 3:28 am

johnnydeep wrote: Wed Jan 05, 2022 9:45 pm
Fred the Cat wrote: Wed Jan 05, 2022 9:31 pm Would it be fair or correct to describe Webb as the most sensitive thermometer ever launched? Designed to observe in IR by collecting photons emitted of a thermal origin, it makes me think of it as a temperature measuring device.

Albeit one that might be able to block out a hot sun to see where ET could be sunbathing. :wink:
Maybe. Most thermometers I know are measuring how much kinetic energy is added to the molecules they are made of. An IR telescope is merely capturing photons. Hmm, how do those remote thermometers - where you just point it at something - work? I suppose they must be measuring photons as well. And I guess the same goes for infrared goggles.

PS - I commend you on your posts, which are always concise and to the point but usually also include very interesting links!
Finding evidence of Earth-like planets with telescopes will always be worthwhile; especially if the traffic there is light. :thumb_up:
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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by neufer » Fri Jan 07, 2022 2:37 pm

https://www.nasa.gov/press-release/nasa-to-host-coverage-briefing-for-webb-telescope-s-final-unfolding wrote:
Click to play embedded YouTube video.
<<NASA will provide live coverage and host a media briefing Saturday, Jan. 8, for the conclusion of the James Webb Space Telescope’s major spacecraft deployments. Beginning no earlier than 9 a.m. EST, NASA will air live coverage of the final hours of Webb’s major deployments. After the live broadcast concludes, at approximately 1:30 p.m., NASA will hold a media briefing. Both the broadcast and media briefing will air live on NASA TV, the NASA app, and the agency’s website. As the final step in the observatory’s major deployments, the Webb team plans to unfold the second of two primary mirror wings. When this step is complete, Webb will have finished its unprecedented process of unfolding in space to prepare for science operations.

Webb, an international partnership with the ESA (European Space Agency) and the Canadian Space Agency, launched Dec. 25 from Europe’s Spaceport in Kourou, French Guiana. Webb is now in the process of unfolding into its final configuration in space, a human-controlled process that provides the team with the flexibility to pause and adjust as needed. As a result of this process, the timing of these milestones may change. NASA provides regular updates on the Webb telescope blog. The public can also follow Webb’s deployments online via a “Where is Webb?” interactive tracker and a Deployments Explorer webpage.>>
Art Neuendorffer

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Re: APOD: JWST on the Road to L2 (2021 Dec 31)

Post by johnnydeep » Fri Jan 07, 2022 4:32 pm

I was wondering about something: if either or both of the two "wings" of the main mirror failed to unfold into position, could the telescope still do some imaging and provide useful data? After all, there would still be at least 12 of the 18 total hexagonal mirror segments in place. I would think there would only be a loss of resolution and light gathering power.
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