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A comment on James Webb telescope reaches its final destination in space, million miles away. Parent comment

Re:James Webb telescope reaches its final destination in spa... by dimator on Tuesday January 25, 2022 @03:33PM (#30077647)
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.

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Re:James Webb telescope reaches its final destination in spa... by ridgeguy on Tuesday January 25, 2022 @06:01PM (#30079362)
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....

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Re:James Webb telescope reaches its final destination in spa... by jacquesm on Wednesday January 26, 2022 @02:55AM (#30082947)
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.
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Re:James Webb telescope reaches its final destination in spa... by ridgeguy on Saturday January 29, 2022 @10:24PM (#30133603)
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.

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Re:James Webb telescope reaches its final destination in spa... by schiffern on Tuesday January 25, 2022 @05:55PM (#30079302)
"Cryogenic Nano-Actuator for JWST" https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden....
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Re:James Webb telescope reaches its final destination in spa... by jacquesm on Tuesday January 25, 2022 @04:36PM (#30078436)
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.
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