5 ms·

This was an absurdly teeth-clenching deployment. And no back-up, even if the Ariane launch failed. No back-up. Congrats to everyone across the board for gett

This was an absurdly teeth-clenching deployment. And no back-up, even if the Ariane launch failed. No back-up. Congrats to everyone across the board for getting this amazing telescope right where it needs to be. Now all we need is the mirror alignment and we're in for some seriously incredible science.

mabbo 5y ago
Mirror alignment was done in the days leading up to insertion, wasn't it? Afaik, all that's left is testing and cooling- the cold side is still around 63K and needs to get down to 50K (-223C).
- entrep 5y ago
  Mirror deployment was done before insertion, moving the 18 mirrors up from their locked position by 12.5 mm. Now, 3 months of mirror alignment will follow. They will align with a reference star having to first move one mirror a little bit to identify how the mirror affects the alignment, then calculate the alignment and move the mirror. Each mirror's position can be controlled at 10 nm resolution.
  - jacquesm 5y ago
    It's not only position, also deformation by pulling or pushing on the center of the mirror changing it's curvature.
    - entrep 5y ago
      Correct. And since the beryllium mirrors are 8 times harder than steel, it's probably a tough job.
      - jacquesm 5y ago
        Not really. They are quite thin and the deformation is minute, on the order of less than a micron at the largest point.
        jacquesm 5y ago
        Edit: that should have been 10 micron.
    - dimator 5y ago
      I can't fathom how they have a servo, a linear actuator, or anything else, that can apply pressure to the mirror and keep it there, for years, in the most extreme environments. Every component of this thing is mind bending.
      - jacquesm 5y ago
        Electromagnet with a constant current running through it would do the job nicely I would think? Keep in mind that with the sun always shining where Webb is that power is not really their first constraint.
      - schiffern 5y ago
        "Cryogenic Nano-Actuator for JWST" https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden.pdf https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden....
      - ridgeguy 5y ago
        Here's a good paper on the mirror actuators [1]. Skimming, they look like hexapod rotary stepper architecture that would not need power to hold a position, only to change position. [1] https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden.pdf https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden....
        jacquesm 5y ago
        Steppers make good sense for that application, what a beautiful design. 7 nm step size with a repeat accuracy of 1 nm is insane precision.
        ridgeguy 5y ago
        It is a beautiful design, isn't it? I'll speculate that the engineers who designed this and other ground-breaking aspects of JWST feel the same euphoria that Beethoven might have felt on completing his 9th symphony. I think beauty wears many masks, but she's in every human effort to bring something new into the world.
s5300 5y ago
It’s really sad to think about how well NASA works when you consider how little funding they get and how hard they have to fight for it. It’s honestly quite ridiculous. I know a lot of military industrial complex boils down to being nationwide jobs programs, e.g. everything to do with the F-35. But NASA? I don’t think they’re anywhere near as close to being a “jobs program” Off the top of my head, I really can’t think of many things NASA as a whole has fucked up. Challenger & Columbia. Challenger wasn’t a NASA problem, it was a Politicians & Bureaucracy problem. As I earlier mentioned… the people responsible for my initial statement of “how well NASA works” knew that disaster was highly likely with Challenger launch. But bureaucracy didn’t care. Haven’t read into Columbia so won’t comment. So why the hell do they get so little funding… it’s depressing to think about. My cynicism doesn’t think James Webb success is going to bring in much more funding. SpaceX, understandably, is likely going to take more & more space related contracts. I still think NASA deserves much, much better treatment.
- dmd 5y ago
  I saw a study a few years ago where people were asked how much funding various agencies get, and the majority of people thought NASA was more than 10% of the federal budget; some even went as high as 25%. (It's less than half of 1%.)
- neatze 5y ago
  What are you talking about Webb was build by contracting defense contractors, like for example Northrop Grumman (primary contractor if not mistaken) and Lockheed Martin who also build F-35, there is YouTube video where Lockheed does presentation about Webb telescope project complexity.
  - mturmon 5y ago
    It’s true that Northrop Grumman was the prime contractor. You don’t want to keep all the skills to build this, and all the manufacturing steps, in-house. But the project leadership and key pieces of the design were at GSFC and JPL. Full list: https://webb.nasa.gov/content/meetTheTeam/team.html https://webb.nasa.gov/content/meetTheTeam/team.html

mabbo 5y ago

Mirror alignment was done in the days leading up to insertion, wasn't it? Afaik, all that's left is testing and cooling- the cold side is still around 63K and needs to get down to 50K (-223C).

entrep 5y ago
Mirror deployment was done before insertion, moving the 18 mirrors up from their locked position by 12.5 mm. Now, 3 months of mirror alignment will follow. They will align with a reference star having to first move one mirror a little bit to identify how the mirror affects the alignment, then calculate the alignment and move the mirror. Each mirror's position can be controlled at 10 nm resolution.
- jacquesm 5y ago
  It's not only position, also deformation by pulling or pushing on the center of the mirror changing it's curvature.
  - entrep 5y ago
    Correct. And since the beryllium mirrors are 8 times harder than steel, it's probably a tough job.
    - jacquesm 5y ago
      Not really. They are quite thin and the deformation is minute, on the order of less than a micron at the largest point.
      - jacquesm 5y ago
        Edit: that should have been 10 micron.
  - dimator 5y ago
    I can't fathom how they have a servo, a linear actuator, or anything else, that can apply pressure to the mirror and keep it there, for years, in the most extreme environments. Every component of this thing is mind bending.
    - jacquesm 5y ago
      Electromagnet with a constant current running through it would do the job nicely I would think? Keep in mind that with the sun always shining where Webb is that power is not really their first constraint.
    - schiffern 5y ago
      "Cryogenic Nano-Actuator for JWST" https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden.pdf https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden....
    - ridgeguy 5y ago
      Here's a good paper on the mirror actuators [1]. Skimming, they look like hexapod rotary stepper architecture that would not need power to hold a position, only to change position. [1] https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden.pdf https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden....
      - jacquesm 5y ago
        Steppers make good sense for that application, what a beautiful design. 7 nm step size with a repeat accuracy of 1 nm is insane precision.
        ridgeguy 5y ago
        It is a beautiful design, isn't it? I'll speculate that the engineers who designed this and other ground-breaking aspects of JWST feel the same euphoria that Beethoven might have felt on completing his 9th symphony. I think beauty wears many masks, but she's in every human effort to bring something new into the world.

s5300 5y ago

It’s really sad to think about how well NASA works when you consider how little funding they get and how hard they have to fight for it. It’s honestly quite ridiculous. I know a lot of military industrial complex boils down to being nationwide jobs programs, e.g. everything to do with the F-35. But NASA? I don’t think they’re anywhere near as close to being a “jobs program” Off the top of my head, I really can’t think of many things NASA as a whole has fucked up. Challenger & Columbia. Challenger wasn’t a NASA problem, it was a Politicians & Bureaucracy problem. As I earlier mentioned… the people responsible for my initial statement of “how well NASA works” knew that disaster was highly likely with Challenger launch. But bureaucracy didn’t care. Haven’t read into Columbia so won’t comment. So why the hell do they get so little funding… it’s depressing to think about. My cynicism doesn’t think James Webb success is going to bring in much more funding. SpaceX, understandably, is likely going to take more & more space related contracts. I still think NASA deserves much, much better treatment.

dmd 5y ago
I saw a study a few years ago where people were asked how much funding various agencies get, and the majority of people thought NASA was more than 10% of the federal budget; some even went as high as 25%. (It's less than half of 1%.)
neatze 5y ago
What are you talking about Webb was build by contracting defense contractors, like for example Northrop Grumman (primary contractor if not mistaken) and Lockheed Martin who also build F-35, there is YouTube video where Lockheed does presentation about Webb telescope project complexity.
- mturmon 5y ago
  It’s true that Northrop Grumman was the prime contractor. You don’t want to keep all the skills to build this, and all the manufacturing steps, in-house. But the project leadership and key pieces of the design were at GSFC and JPL. Full list: https://webb.nasa.gov/content/meetTheTeam/team.html https://webb.nasa.gov/content/meetTheTeam/team.html