# James Webb Space Telescope general discussion thread **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Tags:** science-math\ **Created:** [December 25, 2021, 1:18pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624 "2021-12-25T13:18:56Z")\ **Posts on this page:** 20\ **Page:** 24
**Author:** ![k9bfriender](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/k9bfriender/32/3283_2.png) [@k9bfriender](https://boards.straightdope.com/u/k9bfriender)\ **Post date:** [February 11, 2022, 3:59pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/461 "2022-02-11T15:59:34Z")
My god! It’s full of stars! ---
**Author:** ![Cardigan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardigan/32/187_2.png) [@Cardigan](https://boards.straightdope.com/u/Cardigan)\ **Post date:** [February 11, 2022, 4:01pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/462 "2022-02-11T16:01:08Z")
First light in this instance is kinda…weird. ---
**Author:** ![Folly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/folly/32/3219_2.png) [@Folly](https://boards.straightdope.com/u/Folly)\ **Post date:** [February 11, 2022, 4:03pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/463 "2022-02-11T16:03:05Z")
\*old man in the back of the theater shaking his cane\* Focus!! ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [February 11, 2022, 8:38pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/464 "2022-02-11T20:38:12Z")
There’s a short youtube video here - although it was disappointing that they didn’t put little cameras to show us any live pics of the telescope, there is a lens on one of the main cameras that takes a selfie of the mirror array. [![](https://img.youtube.com/vi/oTQvKuvdcmM/maxresdefault.jpg "James Webb Space Telescope beams back mirror selfie & first star imagery") ](https://www.youtube.com/watch?v=oTQvKuvdcmM) ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [February 12, 2022, 6:49am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/465 "2022-02-12T06:49:17Z")
> [@kwintenstraler](#): > > The first images captured by Webb will be released today at 10:30 a.m. EST (1530 GMT) via NASA’s James Webb Space Telescope blog. [Dr. Becky](https://www.youtube.com/watch?v=6v72L_1L4lQ) geeked out about it. It’s not quite as intense as her launch video but her enthusiasm is infectious. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [February 12, 2022, 7:44am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/466 "2022-02-12T07:44:16Z")
> [@TroutMan](#): > > The CERN styleguide, for example, specifies that [the plural is never used.](https://writing-guidelines.web.cern.ch/entries/kelvin.html) The JWST blog uses kelvins in the plural. Examples: > [@](#): > > 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](https://www.jpl.nasa.gov/news/nasas-webb-telescope-will-have-the-coolest-camera-in-space). 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). ---
**Author:** ![kwintenstraler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kwintenstraler/32/10698_2.png) [@kwintenstraler](https://boards.straightdope.com/u/kwintenstraler)\ **Post date:** [February 12, 2022, 11:46am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/467 "2022-02-12T11:46:44Z")
Yeah I saw that too. Love her videos ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [February 13, 2022, 8:36am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/468 "2022-02-13T08:36:06Z")
> [@Dr.Strangelove](#): > > But it also has a kind of clutch system to disengage the ball screw, essentially switching it from coarse to fine adjustments. I was wrong about this; the real solution is even more elegant and clever. There’s a video here: [![](https://img.youtube.com/vi/5MxH1sfJLBQ/maxresdefault.jpg "The clever engineering of James Webb's mirror actuators") ](https://www.youtube.com/watch?v=5MxH1sfJLBQ) Instead of a clutch, there are two disks that can each have a pin along their circumference and can only transmit force when the pins are in contact. Essentially, it’s designed to have almost a full revolution of backlash. When you want a coarse adjustment, you just keep going until the pins come in contact and engage the ball screw drive. Then, for the fine adjustment, you back up, and then only the cam that drives the compound flexure is active (until you hit the pin from the other direction). Thus, they can conditionally drive either coarse+fine or fine-only with a single stepper motor and no other control inputs. Requires some software work to track the various positions, but software has no mass, and doesn’t break once you write it. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [February 13, 2022, 8:40am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/469 "2022-02-13T08:40:28Z")
> [@Dr.Strangelove](#): > > but software has no mass, and doesn’t break once you write it. In my career, writing some software and using much more other software, I seems to me I’ve seen plenty of counter-examples to both these assertions. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [February 13, 2022, 9:00am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/470 "2022-02-13T09:00:36Z")
It can certainly seem otherwise at times… we do joke about “bit rot”. But seriously, bit rot only happens when the environment or assumptions change. There are a few small parts of our codebase that I wrote 20 years ago and are identical today. They’re pieces that make minimal assumptions about their inputs and have no dependencies at all. It’s rare that you can get away with that. On other hand, there are some automation scripts I wrote which were immensely reliable for a few years… until recently, when they all fell apart. The data they were processing grew in size, slowly but inexorably, until they exceeded some indirect thresholds I’d put in the script. Then the whole thing collapsed. In any case, I expect the driver for these actuators to really be a write-once thing. They have deterministic action and can limit the range of acceptable input. Though things could get interesting if they have to deal with a mechanical failure of some kind. Sometimes software can save the day on these sorts of issues. ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [February 14, 2022, 7:42pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/471 "2022-02-14T19:42:18Z")
I see they’ve added some more deployment details on the “where’s Webb” site … Currently on Segment Image Identification !! ---
**Author:** ![kwintenstraler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kwintenstraler/32/10698_2.png) [@kwintenstraler](https://boards.straightdope.com/u/kwintenstraler)\ **Post date:** [February 19, 2022, 5:29pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/472 "2022-02-19T17:29:30Z")
A new picture available from Webb on the blog : [Webb Team Brings 18 Dots of Starlight Into Hexagonal Formation – James Webb Space Telescope](https://blogs.nasa.gov/webb/2022/02/18/webb-team-brings-18-dots-of-starlight-into-hexagonal-formation/) ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [February 20, 2022, 12:24am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/473 "2022-02-20T00:24:40Z")
Maybe “Jus’ Chillin’” could be their current motto. ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [February 21, 2022, 7:24pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/474 "2022-02-21T19:24:26Z")
Why would someone do this - misinformation or plain ignorance ? [![]( " - YouTube") ](https://www.youtube.com/watch?v=p1P91Js-MD4) ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [February 21, 2022, 7:40pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/475 "2022-02-21T19:40:55Z")
Clicks. it’s not ignorance, they aren’t trying to push some alternate reality. But they know people are searching for JWST and will click on this. ---
**Author:** ![Cardigan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardigan/32/187_2.png) [@Cardigan](https://boards.straightdope.com/u/Cardigan)\ **Post date:** [February 21, 2022, 7:52pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/476 "2022-02-21T19:52:32Z")
I saw that same video this weekend and posed that very question. I notice on our YouTube feed there are lots of suggestions for videos like “The unsettling alien discovery JWST just revealed”. When you click on it, there’s no mention of any images or aliens. Just the usual discussions about mirror alignment and cold temperatures. ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [February 21, 2022, 7:52pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/477 "2022-02-21T19:52:49Z")
Then they are bastards. ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [February 21, 2022, 7:57pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/478 "2022-02-21T19:57:36Z")
Amen. There is a reason they have comments disabled. ---
**Author:** ![N9IWP](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/n9iwp/32/3154_2.png) [@N9IWP](https://boards.straightdope.com/u/N9IWP)\ **Post date:** [February 26, 2022, 1:01am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/479 "2022-02-26T01:01:25Z")
Images from mirrors now stacked into a single image. Still lots of adjustments to do. [https://blogs.nasa.gov/webb/2022/02/25/webb-mirror-alignment-continues-successfully/](https://blogs.nasa.gov/webb/2022/02/25/webb-mirror-alignment-continues-successfully/) Brian ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [February 26, 2022, 3:05am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/480 "2022-02-26T03:05:28Z")
> [@N9IWP](#): > > Images from mirrors now stacked into a single image. Still lots of adjustments to do. From the “Where Is Webb” site today: > [@](#): > > 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. That’s impressive that they will be able to line them all up with greater resolution than one wave length. I guess it helps that they are looking at infra-red and not ultraviolet. [Previous page](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624.md?page=23) [Next page](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624.md?page=25)