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The Hubble Team is flying significantly more Crew Aids and Tools (CATS) for this mission than ever before. Every servicing mission continues to advance the technology, developing more complex tools that enable the astronauts to accomplish increasingly more difficult tasks, of which the Advanced Camera for Surveys (ACS) and Space Telescope Imaging Spectrograph (STIS) repairs are prime examples.
Two of the 116 specialized tools developed for SM4 are the Mini Power Tool (MPT) and the Fastener Capture Plate (FCP).
 The MPT (left) is a small, high speed, low torque power driver that astronauts will use on all the cover plate fasteners requiring removal in the ACS and STIS repair tasks. The tool's low torque is an advantage, because higher torque risks breaking a fastener. The high speed is also essential. "Speed is very crucial for getting the [repair] tasks in the box in the time frame that we're allocated", explains EVA Tool Engineer Justin Cassidy. "So, in this case faster is better."
The FCP is a transparent plate that will capture the many tiny fasteners (111 for STIS) as they are removed from the instruments' cover. With openings large enough for the drill bit but smaller than the fasteners being removed, this ingenious plate will prevent the fasteners from floating away, and it will also preclude the need for astronauts to handle very small fasteners with bulky EVA gloves. Both the STIS and ACS FCPs are numbered to indicate the exact order in which the fasteners are to be removed.
| In addition to the quantity of fasteners that must be removed for the STIS repair, three different size fasteners were used on the cover plate, requiring different drill bits for extraction. Engineers color-coded the FCP for the STIS repair (right) for this reason. |
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The ACS repair is a more difficult and extensive effort due to the location of the electronics box, but some of the tools developed for the STIS repair have been modified to perform similar tasks for the ACS repair. The FCP developed for ACS (left) only has to contend with 26 fasteners, all of which are the same size. |
The astronauts performing the instrument repair tasks have practiced extensively in the use of these new tools, both in the Cleanroom at the Goddard Space Flight Center and in the Neutral Bouyancy Lab at Johnson Space Center.
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(left) Astronaut Mike Massimino, wearing space gloves, practices the STIS repair using the MPT and FCP tools |
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