bernhold@qtp.ufl.edu (David E. Bernholdt) (06/29/90)
This is something I have been wondering about since the HST went up, and it seems particularly appropriate to ask it now... During the boost into orbit, the shuttle and presumably its contents (human and mechanical) endure a fair bit of jostling. Can anybody address the (possible) effects of the ascent on something so large and high precision as the HST mirrors? Are there special mountings (substantially different from those ground-based mirrors) on the HST mirror to prevent problems? Or perhaps in mounting the entire HST inside the cargo bay? The NPR report this evening had an interview with a master telescope builder of an instrument installed in Chile by a European consortium (neither the site nor the group were specifically named). Apparently their mirror suffered similar troubles, but the design included force actuators, which they used to tweak the mirror into focus. Obviously, HST either doesn't include such hardware, or the abberation is beyond the capability of the system. Can anyone say which? -- David Bernholdt bernhold@qtp.ufl.edu Quantum Theory Project bernhold@ufpine.bitnet University of Florida Gainesville, FL 32611 904/392 6365
henry@zoo.toronto.edu (Henry Spencer) (06/30/90)
In article <1062@orange19.qtp.ufl.edu> bernhold@qtp.ufl.edu (David E. Bernholdt) writes: >...the (possible) effects of the ascent on something so large and >high precision as the HST mirrors? Are there special mountings >(substantially different from those ground-based mirrors) on the HST >mirror to prevent problems? ... A great deal of care was taken on this, and concern about it was one reason why the original plans to bring the thing back down for servicing were changed. The aberration problem seems too symmetrical and smooth (it's practically "textbook perfect" spherical aberration) to be accounted for that way. >...their mirror suffered similar troubles, but the design included force >actuators, which they used to tweak the mirror into focus. Obviously, >HST either doesn't include such hardware, or the abberation is beyond >the capability of the system. Can anyone say which? HST has "tweaking" actuators, but they aren't sufficient to deal with it. They probably *could* deal with minor warping due to launch accelerations and the like, but they don't have enough authority to correct a mis-shaped mirror. -- "Either NFS must be scrapped or NFS | Henry Spencer at U of Toronto Zoology must be changed." -John K. Ousterhout | henry@zoo.toronto.edu utzoo!henry
ankleand@mit-caf.MIT.EDU (Andrew Karanicolas) (06/30/90)
In article <1062@orange19.qtp.ufl.edu> bernhold@qtp.ufl.edu (David E. Bernholdt) writes:
<stuff deleted concerning mirror distortion from rough ride up on shuttle>
I was reading in the New York Times (June 28) that the distortion they observed
was "perfectly symmetrical, textbook case". It sounds like the mirror design
itself is faulty.
Andy Karanicolas
MIT Microsystems Laboratory
ankleand@caf.mit.edufmgst@unix.cis.pitt.edu (Filip M Gieszczykiewicz) (06/30/90)
Greetings. A little note about how to fix the "Hobbled Spaced-out Telescope" :-) <The NPR report this evening had an interview with a master telescope <builder of an instrument installed in Chile by a European consortium <(neither the site nor the group were specifically named). Apparently <their mirror suffered similar troubles, but the design included force <actuators, which they used to tweak the mirror into focus. Obviously, ^^^^^^^^^ ^^^^^^^^^^^^^^^^ I read somewhere that they used fish scales (0-10lb). They glued hooks to the underside of the mirror and attached the scaled between the hooks and the wall under the mirror and that, they said, corrected the imperfection. Interesting! <HST either doesn't include such hardware, or the abberation is beyond <the capability of the system. Can anyone say which? < <David Bernholdt bernhold@qtp.ufl.edu <Quantum Theory Project bernhold@ufpine.bitnet <University of Florida Take care and have fun (in that order :-) -- _______________________________________________________________________________ "The Force will be with you, always." It _is_ with me and has been for 10 years Filip Gieszczykiewicz "A man without a dream is like a fish without water." FMGST@PITTVMS or fmgst@unix.cis.pitt.edu "My ideas. ALL MINE!!"