Tool Coil Springs Aid in Hubble Repairs

Canted-Coil™ springs
Bal Seal Engineering
Foothill Ranch, CA
949-460-2100
www.balseal.com

When astronauts embarked on the latest mission to repair the Hubble Space Telescope, Bal Seal Engineering’s Canted-Coil™ springs went along for the ride in a set of special tools. The springs were incorporated in several major repair operations.

One of the tools employing the springs for grounding functions during repairs was the Fastener Capture Plate (FCP) designed by engineers at Goddard Space Flight Center. This transparent plate, which was fitted precisely over a panel covering a failed electronics card, enabled astronauts to remove and retain 111 tiny screws as they are removed from the instruments’ cover without losing them or allowing them to float into the telescope where they could have caused serious and costly damage. Springs in the plate connection points grounded the unit to the Hubble. With openings large enough for the drill bit but smaller than the fasteners being removed, this 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.

The FCPs are numbered to indicate the exact order in which the fasteners are to be removed. In addition to the quantity of fasteners that had to be removed for the Space Telescope Imaging System (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 for this reason.

Another critical piece of hardware on the Hubble repair mission was the Cardlok Manipulation Tool (CMT) designed for Goddard by Alliant Techsystems. Inside the CMT — a lowspeed hand tool resembling a long Allen wrench — a berylliumcopper spring was used to provide electrical grounding and ensure smooth rotary motion.

Working on the orbiting Hubble in shifts lasting more than six hours each, Atlantis astronauts used their collection of specialized tools to repair the telescope’s existing Advance Camera for Surveys (ACS) and STIS.

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