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National Aeronautics and Space Administration

Goddard Space Flight Center

Astrophysics Science Division | Sciences and Exploration

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Invasive Surgery

Having problems with the circulator turbine again, the Cryo-Cooler was cut-open and reworked with repairs and improvements.
After the HOST testing mission, the NCS was returned to Goddard and was prepared for its target purpose - installation into Hubble.

During a spin test after the HOST mission, the circulator again failed to start. Investigation revealed substantial damage to the surfaces between the shaft and bearings. The damage was attributed to the effects of the frozen contaminants during prior ground tests.

In response, the circulator was removed from the NCS. New rotors and bearings were fabricated and installed, and the machine was re-welded into the assembly. The shaft and bearings of the circulator were replaced with a new design incorporating a diamond-like-coating to improve margin against wear from contaminants. Improved contamination control procedures were also implemented to reduce the potential for contaminants entering the loop.


More . . .
Dr. Anne Marie Russell explains why there was so much work left despite the fact that NCS tested so well in space during HOST.