James Webb Space Telescope (Technical Post ONLY !)

FighterJock said:
jeffb said:
https://twitter.com/x/status/1479838328895643648
View: https://twitter.com/ThePlanetaryGuy/status/1479838328895643648?t=B2EYMp3xzkayJUhoKjh5Gg&s=19
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Good news about the primary mirror being deployed without a hitch. I was worried that one of the segments would get stuck or not be deployed at all. :cool:
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I know but, as per Aonestudio's post, it's fully deployed now.

50 major deployments, complete. 178 pins, released. 20+ years of work, realized.
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Brilliant work by the engineering teams. All the unfolding worked just beautifully. Here's hoping we start getting some spectacular images soon.
 
jeffb said:
FighterJock said:
jeffb said:
https://twitter.com/x/status/1479838328895643648
View: https://twitter.com/ThePlanetaryGuy/status/1479838328895643648?t=B2EYMp3xzkayJUhoKjh5Gg&s=19
Click to expand...

Good news about the primary mirror being deployed without a hitch. I was worried that one of the segments would get stuck or not be deployed at all. :cool:
Click to expand...

I know but, as per Aonestudio's post, it's fully deployed now.

50 major deployments, complete. 178 pins, released. 20+ years of work, realized.
Click to expand...

Brilliant work by the engineering teams. All the unfolding worked just beautifully. Here's hoping we start getting some spectacular images soon.
Click to expand...

I certainly would not like to have been one of the engineers in the control room when the primary mirror was unfolding, not knowing if it would work as planned, hats off to them.
 
FighterJock said:
I certainly would not like to have been one of the engineers in the control room when the primary mirror was unfolding, not knowing if it would work as planned, hats off to them.
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One SVR agent working under cover in NASA handed me over this microfilm depicting the engineer responsible for the Main mirror design watching telemetry during its deployment.
480x270_0xac120003_19465500151585064533.gif
On a serious note, all the deployments, and even more the launch of the Ariane-5 carrying JWST, were nervous moments, even for me. JWST is too important for all Humanity and i can only imagine how nervous were its developers.
 
Timeline updated. Start Mirror Segment movements delayed 2 days.

Individual Mirror Segment Movements
Nominal Event Time: UPDATE: Launch + 17 days (Jan 11)
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jwst.nasa.gov

Where Is Webb? NASA/Webb

During Webb's launch, deployment and commissioning, 'WhereIsWebb' tracked Webb's 'flight' to L2 orbit, its state and progress during its deployment and commissioning process, and finally the release of its first images. This process is now complete. During this process, the page constantly...
jwst.nasa.gov
 

James Webb Space Telescope

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Following the Next Steps in Webb’s Journey

After two weeks of complex structural deployments, Webb has passed a major milestone and is now fully unfolded in space. For insight on what to expect in the months ahead and how to follow along, we hear from Alexandra Lockwood, project scientist for Webb science communications at the Space Telescope Science Institute:

“Words can’t describe the pride and excitement the Webb team is feeling right now. From engineers to scientists to IT staff to graphic designers to administrative personnel (and more!), we are all overjoyed with the incredible successes of the observatory to date. While we still have a long way to go before getting the science, the engineering feats that have been accomplished, on Earth and now in space, are awe-inspiring. They are a testament to the hard work and expertise of the international Webb team.

“Now that the action-packed deployment sequence is over, we are moving into a much slower, yet deliberate, phase of the commissioning process. In the next two weeks, we will move each of the 18 primary mirror segments, and the secondary mirror, out of their launch positions. Then five months of commissioning will include 1) further cooling of the entire observatory, and of the Mid-Infrared Instrument in particular, 2) checking and then aligning the secondary and 18 mirror segments into a single coherent optical system, first with the NIRCam instrument and then with all instruments individually and in parallel, and 3) calibrating of each of the four instruments and their many scientific modes. The novelty and variety of science that this observatory can produce requires thousands of things to be checked ahead of time. But rest assured that this summer will sizzle with the hot (nay cold?) observations we will soon be sharing!

“The team is committed to keeping you informed – even through the often slow and meticulous parts of this commissioning process. This blog will be updated weekly, and sometimes more often. Please check back to hear more status updates, in-depth explanations of Webb’s science and technology, and even some fun team anecdotes!

“We’re excited to be on this journey to #UnfoldTheUniverse with you.”

—Alexandra Lockwood, project scientist for Webb science communications, Space Telescope Science Institute
 
Commissioning has resumed:

Webb Begins Its Months-Long Mirror Alignment

Webb has begun the detailed process of fine-tuning its individual optics into one huge, precise telescope.

Engineers first commanded actuators – 126 devices that will move and shape the primary mirror segments, and six devices that will position the secondary mirror – to verify that all are working as expected after launch. The team also commanded actuators that guide Webb’s fine steering mirror to make minor movements, confirming they are working as expected. The fine steering mirror is critical to the process of image stabilization.

Ground teams have now begun instructing the primary mirror segments and secondary mirror to move from their stowed-for-launch configuration, off of snubbers that kept them snug and safe from rattling from vibration. These movements will take at least ten days, after which engineers can begin the three-month process of aligning the segments to perform as a single mirror.

James Webb Space Telescope

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Mirror, Mirror…On Its Way!

With major deployments complete, Webb continues its journey to its final halo orbit around L2. In the meantime, there are several smaller deployments in the next couple of weeks, which constitute the beginning of a several-month phase of aligning the telescope’s optics. This week, we have started the process of moving the mirror segments (all primary plus secondary) out of their stowed launch positions. For more details, here is Marshall Perrin from the Space Telescope Science Institute, home of the Webb Mission Operations Center:

“To support the movable mirrors during the ride to space, each of them has on its back three rigid metal pegs which can nestle into matching holder sockets in the telescope structure. Before launch, the mirrors were all positioned with the pegs held snug in the sockets, providing extra support. (Imagine Webb holding its mirrors tucked up close to its telescope structure, keeping them extra safe during the vibrations and accelerations of launch.) Each mirror now needs to be deployed out by 12.5 millimeters (about half an inch) to get the pegs clear from the sockets. This will give the mirrors ‘room to roam’ and let them be readied in their starting positions for alignment.

“Getting there is going to take some patience: The computer-controlled mirror actuators are designed for extremely small motions measured in nanometers. Each of the mirrors can be moved with incredibly fine precision, with adjustments as small as 10 nanometers (or about 1/10,000th of the width of a human hair). Now we’re using those same actuators instead to move over a centimeter. So these initial deployments are by far the largest moves Webb’s mirror actuators will ever make in space.

“And we don’t do them all at once. The mirror control system is designed to operate only one actuator at a time. That way is both simpler (in terms of the complexity of the control electronics) and safer (since computers and sensors can closely monitor each individual actuator as it works). Furthermore, to limit the amount of heat put into Webb’s very cold mirrors from the actuator motors, each actuator can only be operated for a short period at a time. Thus, those big 12.5-millimeter moves for each segment are split up into many, many short moves that happen one actuator at a time. Scripts sent from the Mission Operations Center will direct this process under human supervision, slowly and steadily moving one actuator at a time, taking turns between segments. At full speed, it takes about a day to move all the segments by just 1 millimeter. It’s about the same speed at which grass grows!

“This may not be the most exciting period of Webb’s commissioning, but that’s OK. We can take the time. During the days that we’re slowly deploying the mirrors, those mirrors are also continuing to slowly cool off as they radiate heat away into the cold of space. The instruments are cooling, too, in a gradual and carefully controlled manner, and Webb is also continuing to gently coast outwards toward L2. Slow and steady does it, for all these gradual processes that get us every day a little bit closer to our ultimate goal of mirror alignment.”

—Marshall Perrin, deputy telescope scientist, Space Telescope Science Institute
 
I know NASA is often the least cost effective organization in many ways, and one can definitely point to SLS as being over priced and redundant. But then again when they pull off crazy shit like dropping a rover from a hovering wire harness on another planet or self assembling an erector set in the L2 point, you kinda have to acknowledge that they do just pull of shit no one else in industry or the world can pull off.
 

Webb Mirror Segment Deployments Complete – James Webb Space Telescope

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Last week, the Webb team began moving the observatory’s individual mirror segments out of their launch positions. Today, we hear from Erin Wolf, Webb program manager at Ball Aerospace, about the completion of that process:

“Today, the James Webb Space Telescope team completed the mirror segment deployments. As part of this effort, the motors made over a million revolutions this week, controlled through 20 cryogenic electronics boxes on the telescope. The mirror deployment team incrementally moved all 132 actuators located on the back of the primary mirror segments and secondary mirror. 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, we 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.”

—Erin Wolf, James Webb Space Telescope Program Manager, Ball Aerospace
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Webb Mirror Segment Deployments Complete

Last week, the Webb team began moving the observatory’s individual mirror segments out of their launch positions. Today, we hear from Erin Wolf, Webb program manager at Ball Aerospace, about the completion of that process:

“Today, the James Webb Space Telescope team completed the mirror segment deployments. As part of this effort, the motors made over a million revolutions this week, controlled through 20 cryogenic electronics boxes on the telescope. The mirror deployment team incrementally moved all 132 actuators located on the back of the primary mirror segments and secondary mirror. 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, we 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.”

—Erin Wolf, James Webb Space Telescope Program Manager, Ball Aerospace
 
Orbital Insertion Burn a Success, Webb Arrives at L2

Today, at 2 p.m. EST, Webb fired its onboard thrusters for nearly five minutes (297 seconds) to complete the final postlaunch course correction to Webb’s trajectory. This mid-course correction burn inserted Webb toward its final orbit around the second Sun-Earth Lagrange point, or L2, nearly 1 million miles away from the Earth.

The final mid-course burn added only about 3.6 miles per hour (1.6 meters per second) – a mere walking pace – to Webb’s speed, which was all that was needed to send it to its preferred “halo” orbit around the L2 point.

“Webb, welcome home!” said NASA Administrator Bill Nelson. “Congratulations to the team for all of their hard work ensuring Webb’s safe arrival at L2 today. We’re one step closer to uncovering the mysteries of the universe. And I can’t wait to see Webb’s first new views of the universe this summer!”


Webb’s orbit will allow it a wide view of the cosmos at any given moment, as well as the opportunity for its telescope optics and scientific instruments to get cold enough to function and perform optimal science. Webb has used as little propellant as possible for course corrections while it travels out to the realm of L2, to leave as much remaining propellant as possible for Webb’s ordinary operations over its lifetime: station-keeping (small adjustments to keep Webb in its desired orbit) and momentum unloading (to counteract the effects of solar radiation pressure on the huge sunshield).

“During the past month, JWST has achieved amazing success and is a tribute to all the folks who spent many years and even decades to ensure mission success,” said Bill Ochs, Webb project manager at NASA’s Goddard Space Flight Center. “We are now on the verge of aligning the mirrors, instrument activation and commissioning, and the start of wondrous and astonishing discoveries.”

Now that Webb’s primary mirror segments and secondary mirror have been deployed from their launch positions, engineers will begin the sophisticated three-month process of aligning the telescope’s optics to nearly nanometer precision.

Watch a special episode of NASA Science Live at 3 p.m. EST today to learn more about what’s next for the James Webb Space Telescope.

Author Alise Fisher
Posted onJanuary 24, 2022
CategoriesJames Webb Space Telescope
Webb’s Journey to L2
 
First image in from JWST:

webbtelescopefirstimage-600x338.jpg
 

Photons Incoming: Webb Team Begins Aligning the Telescope – James Webb Space Telescope

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With deployment of the mirror segments now complete, and the instruments turned on, the team has begun the numerous steps required to prepare and calibrate the telescope to do its job. The telescope commissioning process will take much longer than previous space telescopes because Webb’s primary mirror consists of 18 individual mirror segments that need to work together as a single high-precision optical surface. The steps in the commissioning process include:
  1. Segment Image Identification
  2. Segment Alignment
  3. Image Stacking
  4. Coarse Phasing
  5. Fine Phasing
  6. Telescope Alignment Over Instrument Fields of View
  7. Iterate Alignment for Final Correction
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Over time will space debris slowly degrade the quality of the images? Sorry if this is a dumb question. I know ISS suffers from small strikes of debris and the solar panels have degraded since.

Edit: I had to reword my question.
 
Low Earth orbit has a lot more debris than the area around L2: in LEO, there's manmade debris. Around L2, you just get natural debris - and because JWST's orbit is unstable, debris doesn't tend to hang around.

On average, JWST is expected to encounter micrograms of dust per year. So there'll be some degradation, but a lot less than in LEO.
 
Hobbes said:
Low Earth orbit has a lot more debris than the area around L2: in LEO, there's manmade debris. Around L2, you just get natural debris - and because JWST's orbit is unstable, debris doesn't tend to hang around.

On average, JWST is expected to encounter micrograms of dust per year. So there'll be some degradation, but a lot less than in LEO.
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I believe it’s the sun shield that will degrade before the mirror does but that should still last many years.
 

Webb Is Chilling Out​


While we have started the long process of aligning the telescope mirrors, almost all of the components on Webb’s cold side are still continuing to cool.
Webb’s giant sunshield keeps the telescope and cameras out of both direct sunlight and sunlight that is reflected from Earth and the Moon. Everything on the cold side of the sunshield is passively cooling, radiating heat into deep space. That will continue until the telescope and the three near-infrared (NIR) instruments reach a steady-state temperature, where the milliwatts of energy that get through the sunshield, plus heat generated by the instruments’ own electronics, exactly balances the loss of heat into space. We expect that the primary mirror will cool to below 50 kelvins (about -370 degrees Fahrenheit, or -223 degrees Celsius), and the NIR instruments will reach about 40 kelvins (about -388 degrees Fahrenheit, or -233 degrees Celsius).
Webb’s Mid-Infrared Instrument (MIRI) needs to be even colder. In addition to passive cooling, MIRI will be cooled by a closed-cycle gaseous-helium cryocooler, or refrigerator, down to a temperature below 7 kelvins (-447 degrees Fahrenheit, or -266 kdegrees Celsius). Unlike some previous cryogenic missions, which were cooled by boiling off liquid helium and venting it into space, MIRI’s cooler reuses its helium, just like the refrigerator in your kitchen continuously recycles its own coolant. The Webb team turned on the first stage of the MIRI cryocooler this week.

More on the link below.

Webb Is Chilling Out – James Webb Space Telescope

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Photons Received: Webb Sees Its First Star – 18 Times – James Webb Space Telescope

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Photons Received: Webb Sees Its First Star – 18 Times

The James Webb Space Telescope is nearing completion of the first phase of the months-long process of aligning the observatory’s primary mirror using the Near Infrared Camera (NIRCam) instrument.

The team’s challenge was twofold: confirm that NIRCam was ready to collect light from celestial objects, and then identify starlight from the same star in each of the 18 primary mirror segments. The result is an image mosaic of 18 randomly organized dots of starlight, the product of Webb’s unaligned mirror segments all reflecting light from the same star back at Webb’s secondary mirror and into NIRCam’s detectors.

What looks like a simple image of blurry starlight now becomes the foundation to align and focus the telescope in order for Webb to deliver unprecedented views of the universe this summer. Over the next month or so, the team will gradually adjust the mirror segments until the 18 images become a single star.

“The entire Webb team is ecstatic at how well the first steps of taking images and aligning the telescope are proceeding. We were so happy to see that light makes its way into NIRCam,” said Marcia Rieke, principal investigator for the NIRCam instrument and regents professor of astronomy, University of Arizona.

[Firts picture here]

This image mosaic was created by pointing the telescope at a bright, isolated star in the constellation Ursa Major known as HD 84406. This star was chosen specifically because it is easily identifiable and not crowded by other stars of similar brightness, which helps to reduce background confusion. Each dot within the mosaic is labeled by the corresponding primary mirror segment that captured it. These initial results closely match expectations and simulations. Credit: NASA


During the image capturing process that began Feb. 2, Webb was repointed to 156 different positions around the predicted location of the star and generated 1,560 images using NIRCam’s 10 detectors, amounting to 54 gigabytes of raw data. The entire process lasted nearly 25 hours, but notedly the observatory was able to locate the target star in each of its mirror segments within the first six hours and 16 exposures. These images were then stitched together to produce a single, large mosaic that captures the signature of each primary mirror segment in one frame. The images shown here are only a center portion of that larger mosaic, a huge image with over 2 billion pixels.

“This initial search covered an area about the size of the full Moon because the segment dots could potentially have been that spread out on the sky,” said Marshall Perrin, deputy telescope scientist for Webb and astronomer at the Space Telescope Science Institute. “Taking so much data right on the first day required all of Webb’s science operations and data processing systems here on Earth working smoothly with the observatory in space right from the start. And we found light from all 18 segments very near the center early in that search! This is a great starting point for mirror alignment.”

[Video here]
View: https://youtu.be/QlwatKpla8s


Lee Feinberg, Webb optical telescope element manager at NASA’s Goddard Space Flight Center, explains the early stages of the mirror alignment process.


Lee Feinberg, Webb optical telescope element manager at NASA’s Goddard Space Flight Center, explains the early stages of the mirror alignment process.
Each unique dot visible in the image mosaic is the same star as imaged by each of Webb’s 18 primary mirror segments, a treasure trove of detail that optics experts and engineers will use to align the entire telescope. This activity determined the post-deployment alignment positions of every mirror segment, which is the critical first step in bringing the entire observatory into a functional alignment for scientific operations.

NIRCam is the observatory’s wavefront sensor and a key imager. It was intentionally selected to be used for Webb’s initial alignment steps because it has a wide field of view and the unique capability to safely operate at higher temperatures than the other instruments. It is also packed with customized components that were designed to specifically aid in the process. NIRCam will be used throughout nearly the entire alignment of the telescope’s mirrors. It is, however, important to note that NIRCam is operating far above its ideal temperature while capturing these initial engineering images, and visual artifacts can be seen in the mosaic. The impact of these artifacts will lessen significantly as Webb draws closer to its ideal cryogenic operating temperatures.

“Launching Webb to space was of course an exciting event, but for scientists and optical engineers, this is a pinnacle moment, when light from a star is successfully making its way through the system down onto a detector,” said Michael McElwain, Webb observatory project scientist, NASA’s Goddard Space Flight Center.

[second Picture here]

This “selfie” was created using a specialized pupil imaging lens inside of the NIRCam instrument that was designed to take images of the primary mirror segments instead of images of space. This configuration is not used during scientific operations and is used strictly for engineering and alignment purposes. In this case, the bright segment was pointed at a bright star, while the others aren’t currently in the same alignment. This image gave an early indication of the primary mirror alignment to the instrument. Credit: NASA


Moving forward, Webb’s images will only become clearer, more detail-laden, and more intricate as its other three instruments arrive at their intended cryogenic operating temperatures and begin capturing data. The first scientific images are expected to be delivered to the world in the summer. Though this is a big moment, confirming that Webb is a functional telescope, there is much ahead to be done in the coming months to prepare the observatory for full scientific operations using all four of its instruments.
 
 

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