Another Delay.

No earlier than the 24th of December.

IIRC, the UVA Charlottesville Astronomy Dept. & Green Bank collaborated on a 25th anniversary t-shirt
"President Jefferson Missed The Grand Tour of 1804, and All We Got Was This Lewis & Clarke Expedition T-Shirt"

The weather forecast at the launch site is for thunderstorms every day for the indefinite future. Launch is delayed at least another day.

Launch window opens at 1220 GMT, NASA TV coverage begins at 0800 GMT.

GO JWST!!!

Fingers crossed...

Nice daybreak in Kourou, when the birds began to sing!

2 mins...

HERE WE GO!!!

Textbook launch & separation, successful array deployment, spacecraft is power-positive.

All I wanted for Christmas this year.

Everything perfect throughout launch and 30 minutes into the flight. JWST has separated from the upper stage and has deployed its solar panels, all nominal. Now cruise to its destination continues.

A long journey is over, but another long one has just begun!
Cool tracking page here: https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html

Also cool that there are "amateurs" out there receiving and decoding telemetry from JWST. https://destevez.net/2021/12/decoding-james...pace-telescope/

The tracking page's numbers are derived from precalculated flight dynamics data. Means that the numbers are approximate & pre-computed prior to playback you see.

As it stands I understand the telescope's trajectory is spot-on. MCC-1a had the potential to last as long as 3 hours, but thanks to excellent launcher performance the burn only needed to be a paltry 65 minutes. This is a bonus. Means more fuel for stationkeeping.

Yes interesting that the burns can only speed up JWST due to its constrained orientation. The 2nd 9-minute course correction burn was completed an hour ago. Here are the most recent blog entries.

Forward and aft sun-shield pallets successfully deployed.
https://blogs.nasa.gov/webb/2021/12/28/forw...eld-deployment/

NASA is reporting that they have already used less fuel than anticipated, so a longer mission is now possible.

NASA Says Webb’s Excess Fuel Likely to Extend its Lifetime Expectations

The possibility of a longer lifetime is phenomenally good news. The observational demands of exoplanet atmosphere studies alone – to say nothing of all of the other competing priorities – is going to require years of observation, and one paper regarding the TRAPPIST-1 system alone determined that if astronomers could only plan on 6 years of JWST operation, they would need to coordinate as a community to get a baseline amount of observation completed in that time. (This is further constrained by the constraints of pointing away from the Sun and near-ecliptic targets like TRAPPIST-1 having a limited interval each year during which observation is possible.)

Even a substantial increase in lifetime will still leave many desirable observations unattainably expensive in terms of observation time. If we had 10 JWSTs with lifetimes of 20 years each, they'd each be booked for every second of their time. Time is going to be a precious, finite, and ultimately scarce resource for this mission.

As I recall, missions that run out of fuel usually do so many years after their nominal mission lifetimes. If NASA says there is no enough fuel for 10 years of operation, that would be based on conservative estimates of fuel during operations. These estimates do usually end up being conservative.

Let's all get together in 20 years and I'll bet there will be a new JWST image to share (assuming that fuel does end up being the limiting factor and nothing else critical fails).

IIRC, the was a recent test which involved a "reuse" engine was able to grab the engine bell of an existing satellite that was almost out of propellant, latch on, and provide another "X years" of service.

Positioned in the the second Lagrange Point JWST will not have to use much fuel to maintain position. In any case give the advances being made by SpaceX with "Starship" upgrade/refuelling of JWST may be a possibility within the next decade. Or perhaps an observatory on the far side of the moon?

Yes, this one:
https://en.wikipedia.org/wiki/Intelsat_901
Since engine bells are on practically every satellite, and they are usually of the same overall shape, they are the best way to hook onto something that was not designed to be serviced. Since JWST is in that (large!) category, I expect that a servicing mission would mostly do that (assuming the instruments are still good in 2035, or whenever).
And a photo of JWST fully deployed would be pretty awesome, of course

JWST's mirror and instruments will be in the dark, so there should never be a photo of them.

Project scientist John Mather said, "In-space refueling of #JWST? Logically possible but difficult." I would presume that this will not occur.

In the case of Intelsat, it was just attached and used its own thrusters to push the satellite where needed. No need to open anything up. Though I digress, this is is all strictly academic, and hopefully will remain so for a very long time to come!

Brrr... Winter is Coming!

Pretty sure I recall a NASA official saying they would not even think about a robotic refueling mission till the telescope was on-station and operational and proving its worth. Then they would begin work. Might have been Zurbuchen.

Whether it would be a robotic arm uncapping the gas tanks, or clip-on module, or something else, wasn't said. Since this is likely 10-15 years out, there's plenty of time to develop and refine the technicals.

Fun looking at this 16 years later...

... is there an engineering camera that can return "unfolding images" ... it seems that for $10,000,000,000 they could put one 1024x1024 camera on JWST --- and test out the radio and such -- You could always shut it down when unfolded...

I'm sure we would have seen those images. Good PR. I also remember them saying on the launch livestream that the solar panel deploy would be the last time anyone would ever lay eyes on JWST.

Of all the spacecraft we've launched, this is the one that would be the most satisfying to see after it fully deploys.

Well, that's a compromise you make when you realize that launches to orbit cost IIRC, their weight in gold,
(while Mars / outer solar system cost their weight in diamonds)
Once somebody figures out how to do an integrated thin-film mylar solar array / 20 megapixel camera chip, we might get some interesting deployment videos.

Did anybody ELSE have a "WOW" moment when Breakthrough-Starshot mentioned that they were looking imprinting a hologram of a light stable sail onto a flat surface?

TANGENT - Could a James Webb v 2.0 "cheat" by imprinting a hologram of a 40m scope onto bigger mylar sail?

Once the sunshield is partially unfolded, the rest of JWST will be in the dark for the remainder of its mission and they don't want sunlight on it, even now. Any sunlight on the mechanisms now is just a delay before the long passive cooling process will complete.

If you want to picture JWST during its mission, picture the night side of an atmosphere-less world. That's what it's going to look like: black on black.

For reference, the operational temperature will be a little warmer than Triton but a little cooler than the satellites or Uranus. The effect of perpetual shade will be about like having it out at 25 AU.

Perhaps a low light camera can see the silhouette and/or use starlight (if it doesn't emit too much heat energy, or somehow get in the way of the deployment)?

As for refueling, IIRC the fuel tank may be accessible just in case.

The sunshield covers have now been released and rolled up!

https://blogs.nasa.gov/webb/2021/12/30/webb...nshield-covers/

Maybe they left out cameras to eliminate any unnecessary heat generating activities, especially on the cold mirror side.

Some suspense with a successful first side arm deployment of the sun shield:

https://blogs.nasa.gov/webb/2021/12/31/firs...-booms-deploys/

It looks like they're giving themselves some time after successfully extending both booms.

Tensioning will start tomorrow.

Webb Sunshield Tensioning To Begin Tomorrow

Edit -

Here it is, the next day. The JWST team has decided to take another day and proceed tomorrow.

Deployment Timeline Adjusted as Team Focuses on Observatory Operations

The spacecraft was originally scheduled to launch in 2007. I suspect that its design was set in stone before the the recent proliferation of high resolution engineering cameras in planetary missions became practical. I doubt that a proposal to add such cameras during the final years of testing and trouble-shooting would have been viewed with much enthusiasm, even if the cameras could have seen anything and wouldn’t be a risk to the operating temperature.

The first layer has been tensioned.

First Layer of Webb’s Sunshield Tightened

That was quick!

https://blogs.nasa.gov/webb/2022/01/03/seco...ully-tightened/

Sunshield fully tensioned!

https://www.nasa.gov/press-release/sunshiel...gship-telescope

Finding this part of the mission very engaging but at the same time very tense given the impossibility of fixing anything that goes wrong!

There's a lot of coverage on this but little detail - does anyone know of any documents with detailed arrangement of the wires and pulleys they keep talking about for the sunshield?
TIA

There have to be volumes. There was a 5-year period between "assembly complete" and launch that apparently included a test in which some part of the shield malfunctioned/tore. There's a wiki page for the shield alone with some links: https://en.wikipedia.org/wiki/James_Webb_Sp...scope_sunshield

Some live coverage here, secondary mirror already deployed and about to be latched:

https://www.youtube.com/watch?v=21X5lGlDOfg

You can now watch a recording of the full one and a half hours of "James Webb Space Telescope: Secondary Mirror Deployment - Mission Control Live"

https://www.youtube.com/watch?v=-EnlaXnFcGs

I spent some time looking at the NASA Tech Report Server but didn't really find anything that had a lot of detail about the sunshield (AKA sunshade). It may be that because it's a somewhat separate system designed largely by a subcontractor, the usual publication paths don't apply.

https://ntrs.nasa.gov/api/citations/2020000...20200001556.pdf is a very high-level discussion but has no satisfying details and there are no references to anything about the sunshade, though it mentions a 1/3-scale test model of it.

Secondary mirror deployed and latched.
https://blogs.nasa.gov/webb/2022/01/05/seco...ment-confirmed/

I didn't find much if anything about the mechanisms, motors, pulleys, or rigging arrangements either. I did find a paper that talks about the analysis of the behavior of the shield and gossamer structures. http://www.ryanfellini.com/publications/08SS_Fellini.pdf Perhaps more will turn up in time..

Also wondering about re-tensioning the membranes mid-mission, if that's something that can be done, if it needs to be done..? Watched a video, it's spring loaded and self-adjusting over the upcoming years.

Thanks, I couldn't find anything in detail - shame as it must have had a great deal of work on this contraption.

Another question which may be dumb
In the photos the secondary mirror looks convex but intuitively wouldn't you expect it to be concave to focus the light back onto the instrument?
e.g. Mirror Photo Link

This may help.
Click to view attachment

Very useful, thanks

Perhaps counterintuitive, but AFAIK all three-mirror anastigmats ( https://en.wikipedia.org/wiki/Three-mirror_anastigmat ) like JWST, and all Cassegrains for that matter, have convex secondaries. The Gregorian configuration has a concave secondary, though.
https://www.telescope-optics.net/two-mirror.htm

Thanks, it makes sense when you see the light cone diagrams. According to your linked document, the Cassegrain design dates from 1672 so there's a bit of catching up to do for a telescope novice like me!