NASA’s Webb Telescope Reaches Major Milestone as Mirror Unfolds


This artist’s conception of the James Webb Space Telescope in space shows all its major elements fully deployed. The telescope was folded to fit into its launch vehicle, and then was slowly unfolded over the course of two weeks after launch. Credits: NASA GSFC/CIL/Adriana Manrique Gutierrez

NASA’s James Webb Space Telescope team fully deployed its 21-foot, gold-coated primary mirror, successfully completing the final stage of all major spacecraft deployments to prepare for science operations.

A joint effort with the European Space Agency (ESA) and Canadian Space Agency, the Webb mission will explore every phase of cosmic history – from within our solar system to the most distant observable galaxies in the early universe.

“Today, NASA achieved another engineering milestone decades in the making. While the journey is not complete, I join the Webb team in breathing a little easier and imagining the future breakthroughs bound to inspire the world,” said NASA Administrator Bill Nelson. “The James Webb Space Telescope is an unprecedented mission that is on the precipice of seeing the light from the first galaxies and discovering the mysteries of our universe. Each feat already achieved and future accomplishment is a testament to the thousands of innovators who poured their life’s passion into this mission.”

The two wings of Webb’s primary mirror had been folded to fit inside the nose cone of an Arianespace Ariane 5 rocket prior to launch. After more than a week of other critical spacecraft deployments, the Webb team began remotely unfolding the hexagonal segments of the primary mirror, the largest ever launched into space. This was a multi-day process, with the first side deployed Jan. 7 and the second Jan. 8.

Mission Operations Center ground control at the Space Telescope Science Institute in Baltimore began deploying the second side panel of the mirror at 8:53 a.m. EST. Once it extended and latched into position at 1:17 p.m. EST, the team declared all major deployments successfully completed.

The world’s largest and most complex space science telescope will now begin moving its 18 primary mirror segments to align the telescope optics. The ground team will command 126 actuators on the backsides of the segments to flex each mirror – an alignment that will take months to complete. Then the team will calibrate the science instruments prior to delivering Webb’s first images this summer.

“I am so proud of the team – spanning continents and decades – that delivered this first-of-its kind achievement,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate in NASA Headquarters in Washington. “Webb’s successful deployment exemplifies the best of what NASA has to offer: the willingness to attempt bold and challenging things in the name of discoveries still unknown.”

Soon, Webb will also undergo a third mid-course correction burn – one of three planned to place the telescope precisely in orbit around the second Lagrange point, commonly known as L2, nearly 1 million miles from Earth. This is Webb’s final orbital position, where its sunshield will protect it from light from the Sun, Earth, and Moon that could interfere with observations of infrared light. Webb is designed to peer back over 13.5 billion years to capture infrared light from celestial objects, with much higher resolution than ever before, and to study our own solar system as well as distant worlds.

“The successful completion of all of the Webb Space Telescope’s deployments is historic,” said Gregory L. Robinson, Webb program director at NASA Headquarters. “This is the first time a NASA-led mission has ever attempted to complete a complex sequence to unfold an observatory in space – a remarkable feat for our team, NASA, and the world.”

NASA’s Science Mission Directorate oversees the mission. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the project for the agency and oversees the Space Telescope Science Institute, Northrop Grumman, and other mission partners. In addition to Goddard, several NASA centers contributed to the project, including Johnson Space Center in Houston, the Jet Propulsion Laboratory in Pasadena, Marshall Space Flight Center in Huntsville, Alabama, Ames Research Center in Silicon Valley, and others.

For more information about the Webb mission, visit:


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January 9, 2022 2:38 am

I wonder what its albedo is.

Dudley Horscroft(@dudleyhorscroft)
Reply to  Philip Mulholland.
January 9, 2022 3:45 am

On the working side in way of the mirror, +1. Elsewhere probably about 0.5 so as to ensure afap that it is not distorted by heat from elsewhere.

Gordon A. Dressler
Reply to  Dudley Horscroft
January 9, 2022 11:07 am


There is a difference between albedo (the percentage of incoming EM energy that is reflected from a given surface = function (EM frequency)) and the emissivity of that same surface. Additionally, Kirchhoff’s law states that when in thermal equilibrium, the emissivity of a body equals its absorptivity (but note that this law does not address reflectivity).

“The Aft Deployable Instrument Radiator (ADIR) is a 4 foot (1.2 meters) by 8 foot (2.4 m) panel attached to the back of the observatory and connected by aluminum foil straps to Webb’s instruments. The radiator is covered in honeycomb cells with an ultra-black surface, allowing the mechanism to pull heat away from the observatory instruments and send it into space, according to NASA.”

The mention of ultra-black surface implies a surface emissivity close 1.0, and an albedo close to zero. It is also logical to assume that, since the “cold” side of JWST “sees” deep space at an average temperature of about 3 K yet has surface temperatures running around 40 K, all of the exposed surfaces on that side (in the shadow of the sun shield) would have been designed to have high surface emissivities (probably above 0.8) to maximize radiation of spacecraft-generated heat.

That means the hot side of the exposed sun shade’s surface has an albedo very close to 1.0 (as you stated), but the cold side of the spacecraft has an albedo that averages below 0.1 (consistent with “ultra-black” surfaces).  

Reply to  Gordon A. Dressler
January 9, 2022 12:18 pm

Having directly worked with the ADIR, as I have mentioned in previous posts perhaps, I may add some perspective. “Ultra-Black” surfaces is an understatement. These panels are so black that they seem to suck the nearby light from the room. Thy don’t look so much like panels as they do “holes in space”.

Reply to  Philip Mulholland.
January 10, 2022 9:27 pm

Doesn’t matter, it’ll be far from Earth 🌍 at L2. Won’t help global warming, oops, planet-killing climate crisis causing, evil death rays from the Sun. They did offer that in the budget proposal to Congress that got this thing approved, but they exaggerated… a bit.

Need I say it, sarc!

Reply to  PCman999
January 10, 2022 9:44 pm

Can you imagine the science that could be done by placing a whole array of various types of ‘telescopes’ in deep, constantly shaded craters on the Moon’s north pole, where it would be shielded from every kind of interference coming from everywhere except up.

Doug Huffman(@doughuffman)
January 9, 2022 4:21 am

I have enjoyed watching its speed drop as it coasts up the gravity ‘hill’ to drop into the swale on the other side. I might wish for some informative infographics to flesh out the rather sterile orbital mechanics numbers.

Matthew Schilling
Reply to  Doug Huffman
January 9, 2022 5:58 am

Me too. The first time I noticed, it was skimming along at just over one mile per second. It has since “slowed” to less than one mile every four seconds. That’s still a third faster than commercial air travel and a dozen times faster than my average highway speed.

If I only I could travel that “slowly” when my wife and I go to see our grandkids! (Whatever happened to “Over the river and through the woods TO Grandmother’s house WE go”?)

Reply to  Matthew Schilling
January 9, 2022 6:11 am

Whatever happened to “Are we there yet?”

Reply to  Doug Huffman
January 9, 2022 7:18 am

Since WMAP went to L2 in 2001, NASA published actual orbital measurements – animated gif, click to play :
WEBB is going there right now. Calculations and measurements may differ….

Reply to  bonbon
January 9, 2022 7:35 am

Here is the planned JWST orbit (from wiki) :
comment image

Reply to  bonbon
January 9, 2022 9:47 am

There are many ways to map an orbit and this one is interesting because it removes earth’s orbital sweep relative to the sun. This is how the path of the spacecraft would look to a person on earth. The “looped” section at the end is called the Halo Orbit. To someone observing from another position (from above the ecliptic) it would look very different. A very fun way to discover orbital mechanics to to play with a spirograph toy.

Reply to  bonbon
January 10, 2022 7:25 pm

wow orbital movement wrt earth is across nearly 60 deg of sky

the deployment cartoon de-emphasizes that considerably (looks more like 10 or 15 deg).

Reply to  bonbon
January 10, 2022 7:13 pm

So the halo orbit appeared to reverse from CW to CCW after 12 loops, interesting.

Intelligent Dasein
January 9, 2022 4:59 am

Can’t we just get the facts without all the breathless adulation, or are science articles written exclusively by female glue sniffers these days?

Matthew Schilling
Reply to  Intelligent Dasein
January 9, 2022 5:49 am

Can’t we try to inspire people and spark the imagination of young people without the “get off my yard” grumps whining about it?

Reply to  Intelligent Dasein
January 9, 2022 7:27 am

A bit too much smarmy Lollapalooza .
Just imagine the smarm when WEBB blows the Big Bang out of kilter!

Joseph Zorzin
Reply to  bonbon
January 9, 2022 8:56 am

not gonna happen

Flash Chemtrail
Reply to  bonbon
January 9, 2022 9:28 am

NASA will simply adjust the data by introducing a dark particle/energy/quantum field that cannot be detected or something similar. Big Bang miracle is saved again.

Joseph Zorzin
Reply to  Flash Chemtrail
January 9, 2022 12:59 pm

what’s your alternative to the BB?

Dan Kurt
Reply to  Joseph Zorzin
January 9, 2022 1:50 pm

@Joseph Zorzin “what’s your alternative to the BB?”

Steady State Hypothesis
See F. Hoyle & H. Arp. Read Seeing Red by Halton Arp. Check out Sky Scholar

Doug Huffman(@doughuffman)
Reply to  Joseph Zorzin
January 9, 2022 5:17 pm

Lee Smolin’s fundamental time, and emergent contingent space from big bang’s.

Time is eternal and infinite, space is not.

Flash Chemtrail
Reply to  Joseph Zorzin
January 9, 2022 6:02 pm

I need to provide an alternative theory before criticizing the consensus? I believe my credentials speaks for itself.

Reply to  Joseph Zorzin
January 10, 2022 6:02 am

The Big Bang Never Happened : See LPPFusion, Eric Lerner.
The BB Scorecard is highly embarrassing :
The Real Crisis in Cosmology – Getting It Right with No Big Bang

Quantitative thorough evaluation.

Last edited 15 days ago by bonbon
Joseph Zorzin
Reply to  bonbon
January 10, 2022 6:16 am

hmmm…. I’ll check it out- I don’t care which theory is true- don’t have a stake in it and I like to look at all perspectives- which is why I’m here and not like the other 99.99% of people in Taxachusetts who worship the green God- I do have a strong interest in cosmology- fantastic stuff, that is, the universe is fantastic whether we can understand it or not and full understanding is a long way off- especially making sense of dark energy and dark matter- no doubt Lerner has ideas on that- so I’ll see what he says- thanks for the reference

Gordon A. Dressler
Reply to  Intelligent Dasein
January 9, 2022 12:44 pm

Speaking of glue sniffing, choosing a pseudonym (pen name) that includes the word “intelligent” speaks volumes.

The Emperor's New Mask
January 9, 2022 5:00 am

“…to prepare for science operations.”

Sadly, I no longer associate NASA with science.

Joseph Zorzin
Reply to  The Emperor's New Mask
January 9, 2022 8:53 am

their engineering though is pretty good

Reply to  Joseph Zorzin
January 9, 2022 12:28 pm

Nope, with the exception of JPL they farm that out too. The last A in NASA stand for Administration. They propose missions, we propose engineering solutions
The do run and manage world class test facilities though. It allows other to do the science ad engineering.

Gordon A. Dressler
Reply to  Joseph Zorzin
January 9, 2022 1:40 pm

Uhhhhh . . . NASA did not perform the engineering of JWST.

In 2003, NASA selected the TRW (now part of Northrop Grumman) proposed design for JWST in a competitive bidding process. One of the prime reasons given for the selection of the TRW-NGC design over competing designs was the innovative 5-layer extendable sun shield design that enabled totally passive cooling of the spacecraft instruments down to the range of about 40 K. This offered the possibility of a JWST mission life far greater than that possible if an on-board dewer of liquid helium had to flown and used for active cooling to such low temperature.

Of course, NASA had review management authority over the spacecraft design as it subsequently was revised and matured over the following decade or so.

Moreover, TRW-NGC, as the prime contractor, was responsible for developing and building just the spacecraft element, which included the satellite bus, sunshield, Deployable Tower Assembly (DTA) and the Mid Boom Assembly (MBA). Ball Aerospace & Technologies was subcontracted to design,develop and build the Optical Telescope Element (OTE), including its critical mirror control actuators and electronics, and the structural housing for the Integrated Science Instrument Module (ISIM).

The four main scientific instruments contained in the ISIM were designed, developed, and fabricated by the following lead organizations:
— Near-Infrared Camera: the University of Arizona
— Near-Infrared Spectrograph: ESA, with components provided by NASA/GSFC.
— Mid-Infrared Instrument: the European Consortium with ESA, and by NASA/JPL
— Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph (used to point the telescope and detect atmospheric conditions on distant planets): the Canadian Space Agency.

Beyond this listing of primary subcontractors, there were undoubtedly additional dozens (if not hundreds) of sub- and sub-sub-contractrors that contributed critical design work to JWST.

Clearly, the design of JWST was a team effort, and NOT due solely to NASA.

Joseph Zorzin
Reply to  Gordon A. Dressler
January 9, 2022 1:49 pm

OK, Gordon and Rocketscientist- so much to learn in this blog! So, my understanding is that the project is international- but apparently not the engineering, it’s the astronomy science that will be international. The rocket was French, but nothing special there- it was an existing rocket, not designed for this mission. (?)

Reply to  Joseph Zorzin
January 9, 2022 3:01 pm

Here’s a nice cut away of the various segments. The trans-orbital stage was no doubt tailored.
What NASA does is manage the funding and bureaucratic massaging (not a misspelling), an absolutely vital part of any political program.

Gordon A. Dressler
Reply to  Joseph Zorzin
January 9, 2022 3:10 pm

Well, there is quite a bit of JWST-specific engineering that went into the ESA contribution of the Near-Infrared Spectorgraph, and the European Consortium+ESA contribution of the Mid-Infrared Instrument, and Canada‘s contribution of the Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph.

ESA has 22 member states: Austria, Belgium, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Luxembourg, the Netherlands, Norway, Poland, Portugal, Romania, Spain, Sweden, Switzerland and the United Kingdom.

Therefore, I assert that a significant and critical amount of international engineering has been contributed to the JWST mission . . . and it’s not just the “astronomy science” output from JWST instruments that should be viewed as “international”.

Put in the simplest of terms: without its scientific instruments, JWST is just a hugely expensive, useless spacecraft (with a very fancy sunshade and very sophistical, deformable mirror assembly).

That is, you can’t get the desired science observations (i.e., data) if the associated instruments aren’t designed properly.

Rick C
Reply to  Gordon A. Dressler
January 9, 2022 5:57 pm

With so many entities involved it’s amazing that they managed to launch a space telescope and not a camel. One thing we know for sure is that engineering decisions were not based on opinions or politics. When it comes to serious engineering of things that have to work, every solution must be tested and proven. Hubble was lucky that the unrecognized design error could be corrected after deployment. No such options exist for JWST. I, for one, can’t wait to see what the first images reveal.

Reply to  The Emperor's New Mask
January 10, 2022 6:08 am

The telescope is named after James E. Webb, who was the administrator of NASA from 1961 to 1968 and played an integral role in the Apollo program.

This machine will help some serious science, once it passes tests in July….

John Bell
January 9, 2022 8:11 am

Merely to contemplate the TRILLIONS of galaxies already discovered, that alone is mind bending!

Joseph Zorzin
Reply to  John Bell
January 9, 2022 8:55 am

and that’s only in the visible universe which is only an infinitesimal part of the total

Doug Huffman(@doughuffman)
Reply to  Joseph Zorzin
January 9, 2022 5:19 pm

prove it! The visible universe is the only falsifiable universe.

Reply to  Doug Huffman
January 10, 2022 6:10 am

Visible in infra red, JWST’s forte, is a universe of a different color entirely.

Gordon A. Dressler
Reply to  Doug Huffman
January 10, 2022 4:57 pm

“The visible universe is the only falsifiable universe.”

Hmmm . . . what a strange thing to say, Doug, given that according to the best scientific data today astronomers and cosmologists have concluded that dark matter makes up about 27% of the universe and dark energy makes up an additional 68%. The term “dark” is used for both because we have been unable to detect either the mass or the energy across the EM spectrum, from 3K temperature thermal emissions all the way to beyond gamma ray energies.

Hence, the “visible universe” (your words) makes up only about 5% of what scientists theorize exists in our universe . . . making it kinda hard to claim the other 95% is not “falsifiable”.

Last edited 15 days ago by Gordon A. Dressler
January 9, 2022 9:03 am

Well done those engineers!
Now we need some expertise to develop a similar degree of development of Small Nuclear Reactors. Come on RR.

Reply to  StephenP
January 9, 2022 12:32 pm

They’ve been around for decades. I worked with a colleague who was the tech officer for just such a small nuclear generator on a submarine. Small nuclear systems run ships the size of cities (with airports and hospitals) and when parked off shore can power the port city as well.

Reply to  Rocketscientist
January 9, 2022 4:03 pm

They would then seem to be the obvious choice for reliable electricity generation in the future instead of wind generators and solar panels.
Two questions, how much do they cost compared to these other methods of generation in terms of ££ per actual electricity produced and how long is their service life?

Doug Huffman(@doughuffman)
Reply to  StephenP
January 9, 2022 5:24 pm

US Marine propulsion nuclear power plants use HEU, fantabulously expensive.

Design ‘service life’ is 30 years at full power.

Doug Huffman(@doughuffman)
Reply to  Rocketscientist
January 9, 2022 5:21 pm

There is no “tech officer”. There is the ships Third Officer Engineer, like Rod Adams of Adams’ Atomic Insights.

January 9, 2022 9:12 am

Why don’t we just send up a larger reflector and block 10% of the sun’s rays. Then Al Gore and Mann can just turn the dial every morning depending on what their plans are for the day.

Reply to  FlaMArk
January 9, 2022 12:33 pm

Simpsons did it.

Joseph Zorzin
Reply to  Rocketscientist
January 9, 2022 1:03 pm

Isn’t Homer a nuclear power plant safety officer?

Reply to  Joseph Zorzin
January 9, 2022 3:03 pm

Which is why they are designed to run themselves.

Doug Huffman(@doughuffman)
Reply to  Joseph Zorzin
January 9, 2022 5:24 pm

Homer Simpson is a cartoon

Joseph Zorzin
Reply to  Doug Huffman
January 10, 2022 2:28 am

yes of course and a funny one- it’s very funny that a bumbling idiot would be the safety guy on a nuclear reactor

Gordon A. Dressler
January 9, 2022 10:26 am

Not mentioned in the above article, but to be noted when recognizing the difficulties overcome in achieving the current status of JWST is this fact:
“As part of the deployment process, there were 344 actions where a single-point failure could scuttle the telescope.” (my underling emphasis added)

In simple terms, the usual aerospace engineering practice of using redundancy to insure reliable flight operations had to be sacrificed to a significant amount for JWST to meet its design packaging volume and mass constraints.

That this string of operations was done without a single major anomaly is just remarkable.

Last edited 16 days ago by Gordon A. Dressler
Reply to  Gordon A. Dressler
January 9, 2022 12:38 pm

What it corresponded to was an astronomic level of reliability for any particular mechanism or system. (pun intended)

Reply to  Gordon A. Dressler
January 9, 2022 2:59 pm

Dang; that there sounds just like my motor car.
Just one bit fails, like an electric sensor bit, and the whole thing needs to be towed.
Once upon a time they could be dismantled on a roadside; the broken bit found and fixed with a bit of baling wire and a popsicle stick……….until the next bit broke.

Reply to  Walnutter
January 10, 2022 6:17 am

Had a cam sensor fail recently. Got so darned p*ssed off that I repaired it myself. Towing costs got me once. Sensor cost $30. There are 6 of them in a Nissan, and a Merc has up to 19 computer modules – so forget repair. As for a Tesla do not open the engine.

Last edited 15 days ago by bonbon
Mike Dubrasich
January 9, 2022 10:47 am

Fine tuning/adjusting the mirror segments is the most difficult part. It may take six months, and if not successful will seriously handicap Webb. It’s a bold undertaking; I wish them luck.

Reply to  Mike Dubrasich
January 9, 2022 10:55 am

At least they didn’t leave the lens cap on.

Reply to  Chaswarnertoo
January 9, 2022 12:43 pm

That Reddit meme was one of the first images a friend sent me. It may be laughable but I’ve seen a test vehicle (cruise missile) fail for just such checklist omissions.

Reply to  Rocketscientist
January 9, 2022 5:46 pm

I worked in the development area for cutting edge jet engines (the company shall remain nameless) years ago. This particular engine had been meticulously assembled and was set in the test cell ready to go. The engine started spooling up, everything was green until the wrench left by someone in the intake got sucked into the forward compressor.

Reply to  rbabcock
January 9, 2022 9:50 pm

Tell us the rest of the story!

Reply to  noaaprogrammer
January 10, 2022 6:18 am

He is here to tell the story!

Matthew Schilling
Reply to  Chaswarnertoo
January 10, 2022 11:14 am

The Brit Navy recently lost a fighter jet off its carrier because someone forgot to remove a cover.

Tom Abbott
January 9, 2022 12:10 pm

Great news! I’m looking forward to some nice pictures.

michael hart
January 9, 2022 1:11 pm

Pleased that it’s working out so far. I read a few commentaries putting the mission’s chances at only 50/50 when everything is considered.

Doug Huffman(@doughuffman)
Reply to  michael hart
January 9, 2022 5:27 pm

All ‘missions’ chances are 50/50, fun or fail, with no alternative, no exceptions.

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