Mirror on the Move

Q.  How do you move a 9,000 pound mirror around?
A.  Very carefully.  Some pictures of the process of removing a 100 inch diameter telescope mirror for re-aluminizing and putting it back.

During the summer of 2001 I had the privilege of working with the staff of the Mount Wilson Observatory servicing the mirror of the 100 inch diameter Hooker telescope.  This instrument went into service in 1917 and has been in use since then.  Every one to two years the mirror surface has to be re-aluminized to maintain proper optical properties.  Even though it is very old this telescope has been kept up to date with modern additions including digital imaging and adaptive optics which compensates for atmospheric distortion.  These changes allow this telescope to acquire images approaching the quality of the Hubble space telescope.

Below are some pictures I took during the process.  These are thumbnails and clicking on them will show the full size image.

Protected mirror in it's cell moved away from telescope. Lifting fixture being lowered.
Adjusting fixture. Part way up.
Now above access port to lower level. Approaching lower level.
Edge of mirror. About 13 inches thick and 9,000 pounds weight. Freshly aluminized mirror just removed from vacuum chamber.
Bringing fixture in for lift back to upper deck. Positioning lifting fixture.
Working with one of small (about 20 inch diameter) secondary mirrors. Empty cell with support pads.
Freshly coated mirror on way down. The under side is not coated. Approaching the cell.
Coming in for a soft landing. Note the construction and design of lifting fixture. Final guidance.
Mirror in cell on transport fixture part way back under telescope. Protective cover removed for final positioning.
Getting close. Transport fixture has two fixed and two castered wheels.  Electric jack stands at each corner for lifting and lowering. And closer.
Close-up view of mirror surface. Final tightening of flange bolts.
Re-attached.  All that's left is removal of all the equipment and transport fixture.  The telescope was collimated and used that night. Where it all happened.
This picture is from the towercam operated by the UCLA Dept. of Astronomy from the top of the 150 ft. solar telescope tower.


Updated July 21, 2002

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