# 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:** 9
**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:** [January 5, 2022, 9:26am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/161 "2022-01-05T09:26:44Z")
If it starts singing “Daisy Bell” I’m gonna worry. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [January 5, 2022, 11:29am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/162 "2022-01-05T11:29:36Z")
I noticed something a bit puzzling about the [Where is Webb](https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html?units=english) page. That version has English units including Fahrenheit. Note that those temps are in whole degrees. Switch to metric and they’re converted to C with two decimal places. That is, of course, false precision. So where do the Fahrenheit temps come from? What scale and precision does the telemetry report in? I would not expect whole degrees F. Possibly whole degrees C or tenths of degrees C. I don’t think there’s any technical requirement for more exact measurement, but could easily be wrong. ---
**Author:** ![squeegee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/squeegee/32/14537_2.png) [@squeegee](https://boards.straightdope.com/u/squeegee)\ **Post date:** [January 5, 2022, 4:56pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/163 "2022-01-05T16:56:41Z")
> [@wolfpup](#): > > the upcoming deployment of the secondary mirror that is obviously absolutely crucial. Its function is to reflect the light gathered by the primary mirror back down to the instrument package at its base. Without the secondary mirror, the telescope is completely useless. Watching the NASA live feed, they’re saying the secondary mirror deployment is complete. 🎉 ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [January 5, 2022, 4:57pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/164 "2022-01-05T16:57:48Z")
They’ve been playing around with the format of the temperature display. Both F and C are now whole numbers. I think you just caught it in transition. I’m guessing from the original format that the raw data is Celsius to two decimal places. ---
**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:** [January 5, 2022, 5:00pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/165 "2022-01-05T17:00:47Z")
They updated it not all that long ago, as I saw it maybe an hour or so ago, looked at it specifically due to this thread. All the Celsius numbers ended with .22’s or .33’s or .67’s, almost like they were the result of dividing by 9 for some reason\*. \*and yes, I do know the reason that you’d get numbers ending in that fashion. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [January 5, 2022, 5:55pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/166 "2022-01-05T17:55:26Z")
> [@wolfpup](#): > > Both F and C are now whole numbers. I think you just caught it in transition. I No, it was like that a day or so ago too. Maybe they fixed it because someone read this thread. ---
**Author:** ![Fiendish\_Astronaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiendish_astronaut/32/3295_2.png) [@Fiendish\_Astronaut](https://boards.straightdope.com/u/Fiendish_Astronaut)\ **Post date:** [January 5, 2022, 6:17pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/167 "2022-01-05T18:17:56Z")
That site reminds me how odd it is that I’m used to using miles and celsius, rather than consistently using using either metric or imperial units. Anyway, great to hear the launch was so optimal that they have much more than 10 years of fuel for stationkeeping duties. ---
**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:** [January 5, 2022, 6:41pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/168 "2022-01-05T18:41:37Z")
> [@pjd](#): > > That ol’ sunshield structure is very hot - 134F / 56.67C !!! Now it’s getting cooler … 128F ! ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [January 5, 2022, 8:28pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/169 "2022-01-05T20:28:17Z")
> [@wolfpup](#): > > I’m guessing from the original format that the raw data is Celsius to two decimal places. I know bugger-all about space-based sensors, but wouldn’t the raw data be some kind of thermocouple voltage or similar? I mean not in F or C or anything so straightforward. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [January 5, 2022, 9:36pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/170 "2022-01-05T21:36:28Z")
> [@DPRK](#): > > wouldn’t the raw data be some kind of thermocouple voltage or similar? I’m sure that the telemetry is just digitized values of some such voltage levels. I was making a WAG about the probable accuracy of the readings, as opposed to what is posted on the public site (even my house thermostat reads tenths of a degree Celsius). Also, there are far more temperature sensors than just the four that are being reported. ------------------// As stated previously, the secondary mirror is now in place and latched! I had the impression that this was going to be a multi-day operation but the status page (linked several times above) confirms full deployment complete. **[Here is a link to a bunch of pictures](https://www.flickr.com/photos/nasawebbtelescope/albums/72157624546074858)** associated with the assembly of the secondary mirror and related components. Very impressive! It gives you an idea of what a massive and complex piece of equipment the JWST is: ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [January 5, 2022, 10:32pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/171 "2022-01-05T22:32:05Z")
Very few critical things left to do. Aft radiator deploy, foldout of the two mirror wings, and the orbital insertion burn. Speaking of that final burn, the Russian Angara-A5 heavy-lift rocket stage that apparently has just entered the atmosphere in an uncontrolled re-entry, probably somewhere over the South Pacific, was actually supposed to be safely parked in a high-altitude orbit. What went wrong? The rocket failed to re-ignite! 😲 ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [January 6, 2022, 7:07am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/172 "2022-01-06T07:07:32Z")
I thought the final L2 insertion was going to be done with the RCS thrusters? ---
**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:** [January 6, 2022, 9:00am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/173 "2022-01-06T09:00:44Z")
> [@k9bfriender](#): > > All the Celsius numbers ended with .22’s or .33’s or .67’s, almost like they were the result of dividing by 9 for some reason\*. An excellent observation. The [data source](https://jwst.nasa.gov/content/webbLaunch/flightCurrentState2.0.json) the page uses also (seemingly) only reports whole numbers divided by 9 (currently, I see 10.555, -156.667, and -198.333). Although the numbers are in C, it certainly looks like they were originally whole numbers in F and converted. > [@DPRK](#): > > I know bugger-all about space-based sensors, but wouldn’t the raw data be some kind of thermocouple voltage or similar? I mean not in F or C or anything so straightforward. It could be almost anything, really. Some sensors will just output a converted value directly. In other cases, it might (as you guess) be a raw voltage value from a thermocouple as measured by some microcontroller. My inclination is that they’d send the raw voltages over telemetry to give themselves the best possible information, but for something as simple as a temperature, maybe not. ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [January 6, 2022, 12:35pm UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/174 "2022-01-06T12:35:10Z")
> [@Fiendish\_Astronaut](#): > > That site reminds me how odd it is that I’m used to using miles and celsius Ha — I use km and Fahrenheit. If one of us dies, the universe will be out of balance! ---
**Author:** ![Bootb](https://avatars.discourse-cdn.com/v4/letter/b/e19b73/32.png) [@Bootb](https://boards.straightdope.com/u/Bootb)\ **Post date:** [January 7, 2022, 12:35am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/175 "2022-01-07T00:35:05Z")
It appears that NASA has been hiding something from us. > **[Sunshield](https://xkcd.com/2564/)** > > RIP the surface of Mars ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [January 7, 2022, 1:09am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/176 "2022-01-07T01:09:14Z")
It doesn’t happen as often as it used to but, with this science and engineering marvel, I’m proud to be an American. ---
**Author:** ![Euphonious\_Polemic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/euphonious_polemic/32/3002_2.png) [@Euphonious\_Polemic](https://boards.straightdope.com/u/Euphonious_Polemic)\ **Post date:** [January 7, 2022, 2:08am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/177 "2022-01-07T02:08:40Z")
Here’s a list of people and organizations to thank. Yes, many from USA, and also many from Canada and Europe, as this is a collaboration. We can also thank the launch facility in French Guiana. > **[Institutional Partners Webb/NASA](https://webb.nasa.gov/content/meetTheTeam/team.html#fullTextListingOfContributors)** > > James Webb Space Telescope ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [January 7, 2022, 3:46am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/178 "2022-01-07T03:46:11Z")
Is the sunshield vulnerable to micrometeorite impacts? It seems like it would be, and there could be random space dust between the telescope and its orbital point. If that’s the case, doesn’t it seem like you’d want to delay deploying the sunshield until it’s on station so there’s no chance it will get impacted during transit? Or would delaying the sunshield deployment damage some critical component? Presumably not since the telescope travelled a few days without any sun shield. ---
**Author:** ![Euphonious\_Polemic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/euphonious_polemic/32/3002_2.png) [@Euphonious\_Polemic](https://boards.straightdope.com/u/Euphonious_Polemic)\ **Post date:** [January 7, 2022, 4:35am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/179 "2022-01-07T04:35:22Z")
I may be wrong, but perhaps the components need to be shielded as they are deployed en route? And the whole thing requires some months to cool down to operational temperatures. ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [January 7, 2022, 4:36am UTC](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624/180 "2022-01-07T04:36:33Z")
Ah, good point, I didn’t think about how slow it is to cool things down in space. Maybe it takes weeks or months to get the instruments down to operating temperature. [Previous page](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624.md?page=8) [Next page](https://boards.straightdope.com/t/james-webb-space-telescope-general-discussion-thread/956624.md?page=10)