Thread: The Webb Space Telescope : Flight, deployment, and L2 destination.

The in-flight deployment of the various components of the Webb Space Telescope (WST) is going as planned. The extension of WST’s sunshield mid-booms and deployment of the shields themselves has now be achieved, which is the most complex aspect of the "self-assembly" sequence. This step ran longer than anticipated, so tensioning of the shields will be delayed 24 hours, until Sunday, 2 January. The full tensioning process will take two days.

As the sunshield deployment is the most problematic, its completion by tensioning means only relatively simple mechanics remain - assembly of the optics. Again, anyone wanting to follow WST's flight to its final destination at L2 should use the following link for real time data and deployment sequence information :


https://www.jwst.nasa.gov/content/we...ereIsWebb.html



Once the telescope gets to the L2 point, it will enter its orbit there. This is covered in another thread:


How Can the WebbTelescope Orbit L2?

"Tensioning"
That's ironic.

No pressure lads and lasses.

Originally Posted by geordief

"Tensioning"
That's ironic.

No pressure lads and lasses.

It is rather ironic. The tensioning step is ready to start, but delayed again.

No pressure at all right now for that team. Mission managers have decided to slow things down a bit for the next step. They are looking at the temperature of the drive motors, and just want to get a full appreciation of all subsystems. *

So no tensioning yet. But it has to be there for some of them. This next step of yanking on the five panels of the sunshield is probably like tuning 10 grand pianos by remote control. It will take a lot of effort to optimize the shielding, one would think. Probably a wise move to delay it, decided during the real mission rather than in a simulation.


"NASA delays tightening James Webb Space Telescope sunshield to study power system"

* https://www.space.com/james-webb-spa...-tension-delay

The tensioning of the sunshield has begun (1), after a review of all systems. It is expected to take 2-3 days. The first layer, the one closest to the Sun, has already finished (this afternoon). Four more to go.

One might say the tension is going up, and down, depending on perspective!

Found an interesting article from NASA on the Webb's four instruments for data acquisition. These are:

- Near Infrared Camera
- Mid Infrared Instrument
- Fine Guidance Sensor
- Two Near Infrared Spectrographs

Cooling these instruments is one of the steps that will take quite a while, since the coldest must reach less than 7 K (2). This article offers some remarkable insight into how these instruments will be so sensitive, and tease out various details of faint, distant objects.


"Webb Team Moving Forward With Sunshield Tensioning"

1. https://blogs.nasa.gov/webb/2022/01/...ld-tensioning/


"NASA’s Webb Telescope Will Have the Coolest Camera in Space "

2. https://www.nasa.gov/feature/jpl/nas...amera-in-space

JWST final unfolding seems to be the most anticipated event of the year 2022. Thanks for up to date news

Originally Posted by Double Helix

The tensioning of the sunshield has begun (1), after a review of all systems. It is expected to take 2-3 days. The first layer, the one closest to the Sun, has already finished (this afternoon). Four more to go.

One might say the tension is going up, and down, depending on perspective!

Found an interesting article from NASA on the Webb's four instruments for data acquisition. These are:

- Near Infrared Camera
- Mid Infrared Instrument
- Fine Guidance Sensor
- Two Near Infrared Spectrographs

Cooling these instruments is one of the steps that will take quite a while, since the coldest must reach less than 7 K (2). This article offers some remarkable insight into how these instruments will be so sensitive, and tease out various details of faint, distant objects.


"Webb Team Moving Forward With Sunshield Tensioning"

1. https://blogs.nasa.gov/webb/2022/01/...ld-tensioning/


"NASA’s Webb Telescope Will Have the Coolest Camera in Space "

2. https://www.nasa.gov/feature/jpl/nas...amera-in-space

It has been finally deployed!
https://www.bbc.com/news/science-environment-59873738

Originally Posted by Kevin_Hall

It has been finally deployed!
https://www.bbc.com/news/science-environment-59873738

Yes it has!!

With the sunshield now fully deployed, most of the very worrisome aspects of a major fault have just evaporated. The five layers of the shield are now separated and fully taught, providing an extremely effective barrier to solar radiation.

The link provided above by @Kevin_Hall has a great story on BBC News, and the first picture in this link shows the Webb Space Telescope as it looks right now, with the shield fully deployed, and the mirror components waiting for deployment.

The next two major steps are :

- mirror deployments over the next two weeks

- orbital insertion burn at L2 in ca. 19 days

We are very close to having a functional telescope!

Is it possible we are looking for more than just light from early star systems?

https://www.bbc.com/future/article/2...ing-for-are-ai

I feel sure Martin Rees the astronomer will have a lot of interest here.

https://mindmatters.ai/2021/11/astro...e-a-life-form/

If it was detected, would they inform us?

Originally Posted by ox

Is it possible we are looking for more than just light from early star systems?

Webb will also study exoplanets for chemical signatures of life.*

But if it is AI, one questions if this telescope is capable of detecting it, unless they are transmitting in IR.



"Other Worlds - James Webb Space Telescope"

* https://jwst.nasa.gov/content/science/origins.html

Originally Posted by Double Helix

Originally Posted by ox

Is it possible we are looking for more than just light from early star systems?

Webb will also study exoplanets for chemical signatures of life.*

But if it is AI, one questions if this telescope is capable of detecting it, unless they are transmitting in IR.



"Other Worlds - James Webb Space Telescope"

* https://jwst.nasa.gov/content/science/origins.html

How is JSWT capable of finding exoplanets to live on? What mechanism does it use?

Originally Posted by Kevin_Hall

How is JSWT capable of finding exoplanets to live on? What mechanism does it use?

Molecular oxygen, O2, is highly reactive. For it to persist in the atmosphere of an exoplanet, some astrobiologists believe life is required to continuously generate it.

However, since radiation from a parent star could generate O2 by photodissociation of water in an exoplanet's atmosphere, this is not certain. But the level of O2 in that atmosphere might give some hints, particularly in combination with other molecules, like CO2, methane, etc. It seems unlikely that any firm chemical biosignature will, by itself, tell us if life exists on another planet.

The article below* provides an idea of how this might help to identify a biosignature. Again, it would never be proof of life, but might provide some probabilities, depending on the concentration detected, etc.


"New Technique May Give NASA's Webb Telescope a Way to Quickly Identify Planets with Oxygen"

* https://exoplanets.nasa.gov/news/161...s-with-oxygen/


Webb's secondary mirror is now locked into place. The main mirror deployment coming up next!

Does anybody know anything about LUVOIR? Is there any info about it? I've already tried to look for it, but have found nothing.

The Webb Space Telescope is now fully deployed!

The next and last most critical step is orbital insertion at L2 in about two weeks.

There will also be a lot of optimizing the various instruments and optics, not the least of which is alignment of the secondary mirror.

From what I gather it will then take 6 months to cool down enough for its instruments to work effectively!

So no pictures till then.

Originally Posted by geordief

From what I gather it will then take 6 months to cool down enough for its instruments to work effectively!

So no pictures till then.

That is correct. There is also the alignment of each segment of the main mirror, and alignment of the secondary mirror. Also calibration of instruments will be required.

All of this is expected to be accomplished in this cool-down period.

I have a cooking/heating range that burns kerosene.

It must take more than 8 hours to cool down once I turn it off.

The concept of a 6 month cooling off period seems pretty extreme.

I have some news. To begin with, JWST has got the chances to last 20 years with its fuel left.
Unfortunately, there are risks of getting hit by space debris. Does anybody know any details about it?

https://www.space.com/james-webb-spa...-fuel-20-years
https://futurism.com/the-byte/nasa-s...pace-telescope

Originally Posted by Kevin_Hall

I have some news. To begin with, JWST has got the chances to last 20 years with its fuel left.
Unfortunately, there are risks of getting hit by space debris. Does anybody know any details about it?

https://www.space.com/james-webb-spa...-fuel-20-years
https://futurism.com/the-byte/nasa-s...pace-telescope

The telescope will certainly sustain plenty of microimpactors over years of operation. There is not a lot of data to draw any firm conclusions as to operational risk.

But did find one article which offers some information*.

No doubt they knew there would be these risks, but clearly could not enclose such a large telescope in a housing capable of protecting it from damage.

We can only hope nothing substantial knocks it out. One has to believe the risks of a knock out must be rather low, or they would never have built it.

Look at all the satellites, etc. in orbit, and the orbital debris which they have to survive. Very few get knocked out, even over many years of service.

Webb is in a much cleaner place than NEO, so the risk of serious impacts has to be lower, likely by orders of magnitude.


"Micrometeoroid Impact Risk Assessment for Interplanetary Missions"

* https://www.hou.usra.edu/meetings/or...r/pdf/6070.pdf

JWST has begun the alignment of its 18 golden hexagons. It will take 3 months, to set them up in order them to become a single focusing tool.
https://www.space.com/james-webb-spa...rror-alignment

Originally Posted by Kevin_Hall

JWST has begun the alignment of its 18 golden hexagons. It will take 3 months, to set them up in order them to become a single focusing tool.
https://www.space.com/james-webb-spa...rror-alignment

This is a remarkable process considering the number of mirrors, and actuators which are required - and without failure. All this activity is operating at temperatures now below 75 K, and getting colder all the time. The precision of the process must be astronomical, to be certain!

Quoting from the "Where is Webb" NASA site* :

" The 18 primary mirror segments and secondary mirror are adjustable via six actuators that are attached to the back of each mirror. The primary mirror segments also have an additional actuator at its center that adjusts its curvature. The telescope's tertiary mirror remains stationary. The primary and secondary mirror segments will move a total of 12.5mm, in small increments, over the course of ~10 days to complete each segment's deployment.

After all individual mirror segment deployments are completed, the detailed optical mirror alignment process begins which is about a 3 month process. In parallel, as temperatures cool enough, instrument teams will turn on their instruments and begin each instrument's commissioning process."

end quote

There are a lot of very clever people working on this.


* https://www.jwst.nasa.gov/content/we...l?units=metric

The primary mirror segment deployments have been completed. This is a major step in preparing this mirror for fine tuning to obtain optimal performance from all 18 segments - to begin working as a single mirror. The complexity of this next step, and accuracy required for this process is truly amazing.

Quoting from NASA's Webb site :

"The primary mirror segments were driven 12.5 millimeters away from the telescope structure. Using six motors that deploy each segment approximately half the length of a paper clip, these actuators clear the mirrors from their launch restraints and give each segment enough space to later be adjusted in other directions to the optical starting position for the upcoming wavefront alignment process. The 18 radius of curvature (ROC) actuators were moved from their launch position as well. Even against beryllium’s strength, which is six times greater than that of steel, these ROC actuators individually shape the curvature of each mirror segment to set the initial parabolic shape of the primary mirror.

Next up in the wavefront process will be moving mirrors in the micron and nanometer ranges to reach the final optical positions for an aligned telescope. The process of telescope alignment will take approximately three months."

end quote

Adjusting these beryllium plates down to the nanometer range is more than impressive, to say the least!

For an extensive review of these mirrors, the details of the actuators, and assembly of the 18 segments into their final structure, visit the NASA link below:


"Webb's Mirrors "

https://webb.nasa.gov/content/observ...ors/index.html

The telescope has successfully completed its insertion burn, and is now in orbit at L2 (1).

Now we wait another few months or so while the optics and instruments are optimized before data acquisition will begin.

The second NASA link below describes some of the first objects that Webb will be looking at (2).


Orbital Insertion Burn a Success, Webb Arrives at L2

1. https://blogs.nasa.gov/webb/2022/01/...arrives-at-l2/


Back to the Beginning: Probing the First Galaxies with Webb

2. https://www.nasa.gov/feature/goddard...xies-with-webb

Could it zoom in on this?

https://news.sky.com/story/milky-way...efore-12526377

Originally Posted by ox

Could it zoom in on this?

https://news.sky.com/story/milky-way...efore-12526377

Seems like it would have to emit a significant and distinct IR signal, distinguishing it from background IR, to be picked up by the WST.

So far the data is radio waves, with no certainty as to what is generating it.

Originally Posted by ox

Could it zoom in on this?

https://news.sky.com/story/milky-way...efore-12526377

If as suggested it is an ultra-long-period magnetar (1), it is likely emitting IR. A different group (from the above discovery) has already submitted a proposal to study another magnetar using the Webb Telescope since this compact object has significant emission in the IR (2).


"A radio transient with unusually slow periodic emission"

1. https://www.nature.com/articles/s41586-021-04272-x


"Infrared emission from the magnetar 4U 0142+61: A dusty fallback disk?"

2. https://www.stsci.edu/jwst/phase2-public/2635.pdf


So you might have a target for the Webb, ox. But there is a pretty long waiting line. Wouldn't expect to get any data soon, especially with all the time required for the telescope's commissioning.

This process is going to take quite a while. It appears another five months will be required for cool down, instrument calibration and optical alignment. The optics cannot be fully aligned until the instrument calibration is complete.

For more on what is going on with the telescope at L2, see the link below :


" About Webb Orbit "

https://jwst.nasa.gov/content/about/orbit.html

During the first cycle of work, the telescope will study near-Earth objects, large asteroids, planets of the solar system, comets, trans-Neptunian objects, exoplanets - a total of 2,100 observations are expected to be made.
Since, as a rule, scientists from different countries participate in astronomical research, the objects of observation were grouped by topics. In total, there were several dozen of them, and it is not possible to list them all, so I will name only a few. James Webb will study the three largest low-albedo asteroids, Trojan asteroids (including the targets of the future NASA Lucy mission), trans-Neptunian objects, Kuiper belt objects, red and brown dwarfs. The telescope will examine the Great Red Spot of Jupiter, the vortex at the south pole of Neptune, the satellites of Saturn, the atmosphere of the planet itself, Uranus and Titan. As well as exoplanets, including the recently discovered TRAPPIST-1 e, protostars, protoplanets, supernovae, comets, quasars, and distant galaxies.

Is this post a direct cut and paste from here?
If so, why is it not credited?

Segment Alignment and Image Stacking of the 18 mirrors making up the telescope's primary mirror is proceeding smoothly. They have now transitioned from 18 different images of the calibration star at the detector to one image.

To get a better appreciation for this process, see the NASA link below:


"Webb Mirror Alignment Continues Successfully"

https://blogs.nasa.gov/webb/2022/02/...-successfully/

Good to hear.

Originally Posted by geordief

Good to hear.

Now there is more that's good to hear, and great to see!

"Fine Phasing" of the telescope has been accomplished, and now tack-sharp images are being observed*. While still undergoing optimization, it appears that the the Webb Space Telescope has resolution on the order of Hubble at this point. One can even spot distant galaxies in the background of the "calibration" star.

Quoting from the link below :

"We now have achieved what's called 'diffraction limited alignment' of the telescope: The images are focused together as finely as the laws of physics allow," said Marshall Perrin who works on Webb at the Space Telescope Science Institute in Baltimore, Maryland."

and :

"The engineering images that we see today are as sharp and as crisp as the images that Hubble can take, but are at a wavelength of light that is totally invisible to Hubble," said Jane Rigby from Nasa's Goddard Space Flight Center in Greenbelt, Maryland."

end quotes


At least there is some good news to read about. This has got to make a lot of astronomers very happy.



"James Webb: 'Fully focused' telescope beats expectations"

* https://www.bbc.com/news/science-environment-60771210

Yes,I saw that too.I wonder what "The images are focused together as finely as the laws of physics allow" actually means.

Great picture to be going on with.

Still a few months of calibration of other instruments to go before operation proper begins it seems.(and the main instrument may even need to be less finely tuned to accommodate them,as I read it)

Originally Posted by geordief

I wonder what "The images are focused together as finely as the laws of physics allow" actually means.

Quoting from Where's Webb site:

"Although Image Stacking puts all the light in one place on the detector, the segments are still acting as 18 small telescopes rather than one big one. The segments need to be lined up with each other with an accuracy smaller than the wavelength of the light."

According to the BBC article posted above, the wavelength in this case is 2 microns - IR.

Not being an expert in optics, would guess this means that accuracy of the final adjustments must be smaller than 2 microns, which is pretty small considering the mirror's diameter is ca. 6.5 meters!

The laws of physics in this case probably means that a greater accuracy would not provide higher resolution.

For a higher resolution image of the first Webb image at maximum resolution, visit the NASA link below*.

If you are using a PC, you should get a plus sign on your cursor which by clicking allows you to blow up the image to see more objects.

There are a lot of galaxies in the background. This telescope should offer incredible performance!


* https://www.nasa.gov/sites/default/f...ge_labeled.png

No I don't see any "zoom in" facility.

I am using a small android phone with Chrome so maybe that is why.

I will have a go on the PC when I get a chance.

Originally Posted by geordief

No I don't see any "zoom in" facility.

I am using a small android phone with Chrome so maybe that is why.

I will have a go on the PC when I get a chance.

That is why I don't use those fool things. You can only get squinty-eyed pictures off them.

A nice big screen with a tower PC is the only way to use these images, etc.

The telescope has finished its step 6 "Telescope Alignment Over All Instrument Fields of View".

The Mid-Infrared Instrument (MIRI) is in the last phase of its cooldown, prior to its final mirror alignment (step 7).

To read more about these critical steps to push the internal instruments down to as low as 7 K, see the link below.

The long process of commissioning is approaching its end point.


"Webb’s Mid-Infrared Instrument Cooldown Continues"

* https://blogs.nasa.gov/webb/2022/04/...own-continues/

https://www.bbc.com/news/science-environment-61086170

Seems cooling has been achieved and there are a couple of months of calibration before observations start .

Originally Posted by geordief

https://www.bbc.com/news/science-environment-61086170

Seems cooling has been achieved and there are a couple of months of calibration before observations start .

Thanks for posting that link. Might not have read it since have looked at so many about this. It is the only one that explains why the Mid-Infrared Instrument (MIRI) has to be cooled to < 7 K. Almost all articles indicate down to 7 K, but this apparently is not quite good enough to eliminate dark currents (1).

As noted in the link below, dark currents occur in materials used for:

"photosensitive devices such as a photomultiplier tube, photodiode, or charge-coupled device even when no photons are entering the device; it consists of the charges generated in the detector when no outside radiation is entering the detector."

end quote

So the MIRI needs to get down to < 7 K or the signal will get swamped by dark currents. Quite a remarkable instrument to be sure.

The primary mirror is still at 42 K, and needs to get below 40 K for optimal performance. This is seen in the "Where is Webb" site (2), and is component c in the diagram. This will likely happen in the next week or so. Since it is the largest element on the "cold side" of the telescope, it is taking longer than all other components.



1. https://en.wikipedia.org/wiki/Dark_current_(physics)


2. https://www.jwst.nasa.gov/content/we...ereIsWebb.html

Think the focusing is complete,but there is still plenty to do before the proper work starts.

Seems some of the teams' work is complete now.

https://blogs.nasa.gov/webb/2022/04/...commissioning/

Originally Posted by geordief

Think the focusing is complete,but there is still plenty to do before the proper work starts.

The "image sharpness check" panels, blown up from the link are spectacular.

The MIRI image is of particular interest. as this is the mid-IR light (1,2).

The instrument appears ready to rock!



!. Mid-Infrared Instrument (MIRI)

https://webb.nasa.gov/content/observatory/instruments/miri.html


"Webb’s coolest instrument captures first star"

2. https://www.ukri.org/news/webbs-cool...es-first-star/