3 ms·
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
by 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 agoIt's not only position, also deformation by pulling or pushing on the center of the mirror changing it's curvature.
- entrep 5y agoCorrect. And since the beryllium mirrors are 8 times harder than steel, it's probably a tough job.
- dimator 5y agoI 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 agoElectromagnet 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 agoHere'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 agoSteppers 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 agoIt 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.