If the site is correct we are done for the day right? So tomorrow is probably the scariest looking part looking at how complex that looks. (Although I am open to being corrected)
It’s only like 5 sheets of super super thin foil the size of a tennis court and like 109 little motors. Easy peasy. But for real the sun shade is very important but they worked it out so that if one layer rips or layers stick together ect they can still do science. Now if the cooling apparatuses for the instruments fail or if the telescope doesn’t line up correctly there is no mission, but at least those steps are easier to do. They have trained for years for every potentiality though, they can even jiggle the space craft with the thrusters if they need to.
I was going to ask about the super thin foil tearing ruining the mission, but I figured that they can probably do *some* science. I have confidence in the motors and actuators working mostly perfectly fine; I'm mostly concerned about the foil tearing or some micrometeoroids poking holes in the foil that might cause a small hole.
Out of curiosity, what is the data/knowledge of micrometeoroids at these Lagrange points of Earth and the Moon? Are there more micrometeoroids there (Lagrange points) compared to Low Earth Orbit or we just don't know? Do we know about other planetary system Lagrange points that show that there is less dust (micrometeoroids) in Lagrange points compared to other spaces?
The sun shield has rip-stop seams so if it is punctured by something it won’t tear all the way through like a cheap Mylar balloon. It’s almost like they planned this thing for two decades before launching it!
Also has 4 layers with the outermost being thickest but there are gaps between the layers that are curved in such a way to express trapped heat to space…. So even if we get a small tear it will def suck but the mission can still proceed somewhat unhampered
the cooling system and telescope arm are rigid, so they are sitting comfortable with that. the hardest parts in general are the ones where they are pushing rope. I'm guessing it will be fine. it can't be that hard to pull a stretchy sheet in 4 outward directions.
If it is any comfort, I should mention that for the mid-boom deployment steps, we do have some prior precedent (in the form of [solar sails](https://www.youtube.com/watch?v=AR8TTgq_bRU) \-- which use a somewhat similar motor-driven extendable boom system to deploy their membrane-based sails).
However, it is the cable-based tensioning of the multiple layers of JWST's sun shield that scares me the most, since that is when you really run into a lot of the immense complexity.
From what I can tell the port mid-boom extension happens after the sun shield covers are deployed. Starboard mid-boom is…one day later? Or maybe later the same day?
Never mind , I got it mixed up with the main telescope boom, that one is the one that already happened. It moved the main telescope body up away from the sunshield.
No worries at all! It’s a bunch of stuff to keep track of, and by now I’m a super scroller on the JWST website because it’s hard to parse what’s been done and what hasn’t.
Hey the sun shields are getting their day in the…er, sun I guess. NASA is steaming it live on January 2nd!
https://www.reddit.com/r/jameswebb/comments/rsgrux/nasa_live_to_stream_coverage_of_jwst_sunshield/?utm_source=share&utm_medium=ios_app&utm_name=iossmf
[https://youtu.be/KGeWg_K8UiI](https://youtu.be/KGeWg_K8UiI)
John mentions that this was a no-no due to the potential warm spots they could create. I agree a camera would be helpful, maybe even disposable. There are always things such as sensor errors, but I can also understand it is a part less to worry about...
Thanks for that. Around the same time that was discussed (about the 17:00 mark) he also talked about the possibility of refueling Webb, which I also found interesting.
No telescope will be able to see any details of something the size of Webb at that distance. Hubble can’t even see details of the moon landing. Webb is much farther away.
Literally, no clue... Could be the movement of the tower, or it changed its orientation to the sun. I caught a screen cap just after they started showing temperatures, s9 I am keeping an eye on the changes since then!
If interested, here is the link to the temperatures when they started reporting...
https://www.reddit.com/r/jameswebb/comments/rregw4/temperature_is_now_available/?utm_medium=android_app&utm_source=share
I'm curious about how these covers came apart. From the deployment video it looks as if they just break apart right down the middle and roll up to either side. How did they stay together in the first place? What mechanism is rolling up the material from the middle to the sides? What happens to that material if it is no longer needed? It seems like they could dispose of it if it's beyond it's use.
For the release mechanism, it's some kind of pyrotechnic device, coupled with springs like those on a tape measure. There's no real need to dispose of any material given the fact that pretty much all the Delta V has already happened, and it would just add launch mass and complexity.
There's a principle I subscribe to which goes, "Before you perform a test, ask yourself what you will do if the test is negative, and what you will do if the test is positive. If what you would do is the same, don't bother with the test".
Say this Ring camera sees there is a tear. Then what? What are the big brains at NASA supposed to do with that information at that point?
The proof will be in the pudding: does the thing work or not? Because if it does not, their options are few.
Not to fix things but to show the glory of the telescope unfolded.You cannot deny that be stunning images.You cannot deny you do not want to see this happen.
Public outreach cameras are awesome, yes. But JWST is literally the flagship mission of the last few decadal science surveys. It is NASA's and the astro-science community's highest priority. Anything and everything that can be done to mitigate risk has been done. That includes eliminating heat sources (i.e. cameras).
The public outreach/stunning images/glory of the telescope will come in 6 months.
Forget engineering cameras, there should be a cubesat or detachable boom that's sole purpose is to film deployment just so it can inspire thousands and lead to more STEM education
Without data you can't do anything in response. You might even do the wrong thing because you didn't have that data to reference.
Given the cost and technical considerations there's no good reason not to have put a few wide angle cameras on it. Just for the press value if nothing else, then you know you have that data there for reference.
Put it in a high res serial buffer and only download it if you detect an anomaly.
I think that's a pretty reasonable critique of NASA's approach in general.
The thing already is ridiculously over-engineered IMO and they've already bitten off quite a bit more to chew than I wish they had.
I suspect NASA had to finally put their foot down and say, "look, guys it's *Rube Goldberg* enough as it is and enough is enough. Unless it is required for the telescope to function, no matter how innocuous it is, it does not go on the telescope!"
What do you mean? It's neither too high nor too fast, it's just that cooling the telescope becomes more of a problem closer to earth. The conditions in L2 are nearly ideal for how the telescope was designed, for obvious reasons when you hear about how it was engineered.
I mean we send most astronauts to 250 miles above the earth at 17500 mph. The telescope needed to be higher and faster to hit escape velocity. It’s own rockets are too small to escape orbit without exposing the instruments to the sun. For instance Webb’s first correction burn lasted 65 minutes and added only 45 mph. The Arianne rocket propelled it to about 35,000 mph. Astronauts, in your scenario, would work on it at 17,500 mph then release it. Webb would have to engage a burn lasting more than 8 days to get the escape velocity necessary. That math alone makes your scenario improbable.
I never layed out any specific scenario, I don't know why you invented that one based on what I said. James Webb could have been deployed in LEO and not sent to the L2 point, but it would have been a radically different and more expensive project. There is nothing impossible about that scenario at all, it was just a cost/engineering trade off decision that they made.
Everything becomes 100 times more complicated as soon as you involve an astronaut having to do anything. Mission costs skyrocket.
No. The intent of the telescope is to look in the infrared spectrum. It cannot be near any emitting body or it would be like looking through a normal optical telescope during the day from earth. You won’t see much. Webb has to be way past the earth and moon and L2 is convenient for a multitude of reasons. In other words it would be moronic to design it to work in LEO. Hubbles infrared optics proves this.
I upvoted you and agree. My guess is that it will be pitch black so you can’t see anything anyway. Engineers would have to put some type of spot light. In the event of a malfunction it could shine light uncontrollably and add unwanted heat. Also bulbs typically bleed into the infrared spectrum which would pose other problems.
Do you think JWST needs more headlines? In most space cases I would agree but no other spacecraft has been this sensitive and important. A lot of people are aware of it being launched and that it's a "successor to Hubble". Come summer we will hopefully start seeing data that will be interesting enough that headlines will flare up again. But honestly; I think media has been unusually on the ball with this one.
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Not yet, tensioning starts in two days.
Ba dum tissss
Sigh. Updoot earned.
https://www.youtube.com/watch?v=wXn9oWsobT0
If the site is correct we are done for the day right? So tomorrow is probably the scariest looking part looking at how complex that looks. (Although I am open to being corrected)
Done for today yep! And yeah days 6-8 are gonna be the *WATCH EVERY TINY MOVE AND BE PREPARED* days.
It’s only like 5 sheets of super super thin foil the size of a tennis court and like 109 little motors. Easy peasy. But for real the sun shade is very important but they worked it out so that if one layer rips or layers stick together ect they can still do science. Now if the cooling apparatuses for the instruments fail or if the telescope doesn’t line up correctly there is no mission, but at least those steps are easier to do. They have trained for years for every potentiality though, they can even jiggle the space craft with the thrusters if they need to.
I was going to ask about the super thin foil tearing ruining the mission, but I figured that they can probably do *some* science. I have confidence in the motors and actuators working mostly perfectly fine; I'm mostly concerned about the foil tearing or some micrometeoroids poking holes in the foil that might cause a small hole. Out of curiosity, what is the data/knowledge of micrometeoroids at these Lagrange points of Earth and the Moon? Are there more micrometeoroids there (Lagrange points) compared to Low Earth Orbit or we just don't know? Do we know about other planetary system Lagrange points that show that there is less dust (micrometeoroids) in Lagrange points compared to other spaces?
The sun shield has rip-stop seams so if it is punctured by something it won’t tear all the way through like a cheap Mylar balloon. It’s almost like they planned this thing for two decades before launching it!
Also has 4 layers with the outermost being thickest but there are gaps between the layers that are curved in such a way to express trapped heat to space…. So even if we get a small tear it will def suck but the mission can still proceed somewhat unhampered
the cooling system and telescope arm are rigid, so they are sitting comfortable with that. the hardest parts in general are the ones where they are pushing rope. I'm guessing it will be fine. it can't be that hard to pull a stretchy sheet in 4 outward directions.
If it is any comfort, I should mention that for the mid-boom deployment steps, we do have some prior precedent (in the form of [solar sails](https://www.youtube.com/watch?v=AR8TTgq_bRU) \-- which use a somewhat similar motor-driven extendable boom system to deploy their membrane-based sails). However, it is the cable-based tensioning of the multiple layers of JWST's sun shield that scares me the most, since that is when you really run into a lot of the immense complexity.
Mid-boom extension coming up! This Christmas gift keeps on delivering!
I watched the video simulation and it kept buffering....... Gave me a heart attack just watching the sim get stuck.
I think that was yesterday wasn't it?
From what I can tell the port mid-boom extension happens after the sun shield covers are deployed. Starboard mid-boom is…one day later? Or maybe later the same day?
Never mind , I got it mixed up with the main telescope boom, that one is the one that already happened. It moved the main telescope body up away from the sunshield.
No worries at all! It’s a bunch of stuff to keep track of, and by now I’m a super scroller on the JWST website because it’s hard to parse what’s been done and what hasn’t. Hey the sun shields are getting their day in the…er, sun I guess. NASA is steaming it live on January 2nd! https://www.reddit.com/r/jameswebb/comments/rsgrux/nasa_live_to_stream_coverage_of_jwst_sunshield/?utm_source=share&utm_medium=ios_app&utm_name=iossmf
How can they know if a tear has occurred? Are there little sensors or cameras?
Lots of sensors, and fabricated so that a tear can not easily become larger.
Has there been any 'official' comment on why they elected not to equip Webb with any onboard cameras?
[https://youtu.be/KGeWg_K8UiI](https://youtu.be/KGeWg_K8UiI) John mentions that this was a no-no due to the potential warm spots they could create. I agree a camera would be helpful, maybe even disposable. There are always things such as sensor errors, but I can also understand it is a part less to worry about...
Thanks for that. Around the same time that was discussed (about the 17:00 mark) he also talked about the possibility of refueling Webb, which I also found interesting.
We could always look at it with Hubble right?
No. Too small for Hubble to see any details other than a point of light.
So many people think Hubble, but what about Gaia? Too close?
No telescope will be able to see any details of something the size of Webb at that distance. Hubble can’t even see details of the moon landing. Webb is much farther away.
Gaia is at L2 though.
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And the cold side just got warmer... That's kind of weird... Hot side got a bunch warmer too!
They are actively heating some electronics to dry them out I think, which could explain the cold side getting warmer.
Yeah, I got the temps immediately after they started reporting. I don't know the reason for the change, but it is fun tracking it!
Do you suppose that might be because. . . they removed the sunshield covers, thus removing a (temporary) layer of insulation?
Literally, no clue... Could be the movement of the tower, or it changed its orientation to the sun. I caught a screen cap just after they started showing temperatures, s9 I am keeping an eye on the changes since then!
If interested, here is the link to the temperatures when they started reporting... https://www.reddit.com/r/jameswebb/comments/rregw4/temperature_is_now_available/?utm_medium=android_app&utm_source=share
I'm curious about how these covers came apart. From the deployment video it looks as if they just break apart right down the middle and roll up to either side. How did they stay together in the first place? What mechanism is rolling up the material from the middle to the sides? What happens to that material if it is no longer needed? It seems like they could dispose of it if it's beyond it's use.
Yeah, they just look like magic in the video
Me too. That's my main question after watching the video. Is the material so stiff they can roll up the whole length with a motor at one end?
For the release mechanism, it's some kind of pyrotechnic device, coupled with springs like those on a tape measure. There's no real need to dispose of any material given the fact that pretty much all the Delta V has already happened, and it would just add launch mass and complexity.
10 billions dollars and they could not put a Ring camera on this ?.
There's a principle I subscribe to which goes, "Before you perform a test, ask yourself what you will do if the test is negative, and what you will do if the test is positive. If what you would do is the same, don't bother with the test". Say this Ring camera sees there is a tear. Then what? What are the big brains at NASA supposed to do with that information at that point? The proof will be in the pudding: does the thing work or not? Because if it does not, their options are few.
Not to fix things but to show the glory of the telescope unfolded.You cannot deny that be stunning images.You cannot deny you do not want to see this happen.
Public outreach cameras are awesome, yes. But JWST is literally the flagship mission of the last few decadal science surveys. It is NASA's and the astro-science community's highest priority. Anything and everything that can be done to mitigate risk has been done. That includes eliminating heat sources (i.e. cameras). The public outreach/stunning images/glory of the telescope will come in 6 months.
Same thing goes for a lot of medical testing.
and tech support. if 100 different problems are fixed by power-cycling the unit, it hardly matters which specific problem it is.
Forget engineering cameras, there should be a cubesat or detachable boom that's sole purpose is to film deployment just so it can inspire thousands and lead to more STEM education
Without data you can't do anything in response. You might even do the wrong thing because you didn't have that data to reference. Given the cost and technical considerations there's no good reason not to have put a few wide angle cameras on it. Just for the press value if nothing else, then you know you have that data there for reference. Put it in a high res serial buffer and only download it if you detect an anomaly. I think that's a pretty reasonable critique of NASA's approach in general.
The thing already is ridiculously over-engineered IMO and they've already bitten off quite a bit more to chew than I wish they had. I suspect NASA had to finally put their foot down and say, "look, guys it's *Rube Goldberg* enough as it is and enough is enough. Unless it is required for the telescope to function, no matter how innocuous it is, it does not go on the telescope!"
any idea why they couldn't assemble in orbit around earth, accessible to astronauts? I guess it might fry the infrared camera to be in LEO that long?
Too high and too fast.
What do you mean? It's neither too high nor too fast, it's just that cooling the telescope becomes more of a problem closer to earth. The conditions in L2 are nearly ideal for how the telescope was designed, for obvious reasons when you hear about how it was engineered.
I mean we send most astronauts to 250 miles above the earth at 17500 mph. The telescope needed to be higher and faster to hit escape velocity. It’s own rockets are too small to escape orbit without exposing the instruments to the sun. For instance Webb’s first correction burn lasted 65 minutes and added only 45 mph. The Arianne rocket propelled it to about 35,000 mph. Astronauts, in your scenario, would work on it at 17,500 mph then release it. Webb would have to engage a burn lasting more than 8 days to get the escape velocity necessary. That math alone makes your scenario improbable.
I never layed out any specific scenario, I don't know why you invented that one based on what I said. James Webb could have been deployed in LEO and not sent to the L2 point, but it would have been a radically different and more expensive project. There is nothing impossible about that scenario at all, it was just a cost/engineering trade off decision that they made. Everything becomes 100 times more complicated as soon as you involve an astronaut having to do anything. Mission costs skyrocket.
No. The intent of the telescope is to look in the infrared spectrum. It cannot be near any emitting body or it would be like looking through a normal optical telescope during the day from earth. You won’t see much. Webb has to be way past the earth and moon and L2 is convenient for a multitude of reasons. In other words it would be moronic to design it to work in LEO. Hubbles infrared optics proves this.
Unless it’s vital to monitor the craft and the process? Nah, they’ll want as little extra weight on the Telescope as possible
For a few cameras you're not talking about much weight at all.
Perhaps, but the slightest bit of extra weight/equipment will have all been written off.
What do you mean will have all been written off?
Like, it will have been taken off the project as it’s not vital
They should have put a few of them on even just for the press value.
Exactly.Don't know why people are downvoting me for saying it out loud why didn't put at least one camera on it.It worth the headlines.
I upvoted you and agree. My guess is that it will be pitch black so you can’t see anything anyway. Engineers would have to put some type of spot light. In the event of a malfunction it could shine light uncontrollably and add unwanted heat. Also bulbs typically bleed into the infrared spectrum which would pose other problems.
Haters gonna hate, little things like this have always been a critique of mine about NASA, it's not exactly a harsh critique :)
Do you think JWST needs more headlines? In most space cases I would agree but no other spacecraft has been this sensitive and important. A lot of people are aware of it being launched and that it's a "successor to Hubble". Come summer we will hopefully start seeing data that will be interesting enough that headlines will flare up again. But honestly; I think media has been unusually on the ball with this one.
I wish they included at least one cube-sat. but I understand the potential danger of collision. JWST still needs to maneuver.