Press Release

Bal Seal Springs Aid Astronauts in Hubble Repair

By SpaceRef Editor
July 13, 2009
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When astronauts embarked on the latest mission to repair the Hubble Space Telescope, Bal Seal Engineering’s canted-coil(TM) springs went along for the ride in a set of special tools designed to make the job easier and more efficient.

Bal Seal’s small, precision-engineered springs played an important role in several of the major repair operations conducted during “Servicing Mission 4,” NASA’s final voyage from the Kennedy Space Center in Cape Canaveral, Florida, to the famous orbiting telescope. Over the course of five history-making spacewalks, the crew of the STS-125 Atlantis relied on the simplicity and unique physical properties of the springs to help their tools work in an environment where failure definitely wasn’t an option.

One of the more important tools employing Bal Seal springs for grounding functions during repairs was a “fastener capture plate,” designed by engineers at Goddard Space Center for NASA. This plate, which was fitted precisely over a panel covering a failed electronics card, enabled astronauts to remove and retain 111 tiny screws 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.

Another critical piece of hardware on the Hubble repair mission was a Cardlok Manipulation Tool, or “CMT,” designed for Goddard and NASA by Alliant Techsystems (NYSE: ATK – News). Inside the CMT, a low-speed hand tool resembling a long Allen wrench, a beryllium-copper Bal Seal spring was used to provide electrical grounding and ensure smooth rotary motion.

Hans Raven, an ATK engineer who worked with a team to design the CMT and more than 100 other tools for the final Hubble repair mission, said he selected a Bal Seal spring after observing its use in other tool applications.

“I was looking for a way to allow the CMT to rotate while efficiently grounding the rotating portion to the shaft.” Raven said. “I didn’t want to overcomplicate things by using a ball bearing, and when I saw the [Bal Seal] spring, a light bulb went off. The multi-point coil contact provided exceptional grounding – zero resistance across the path. It was the ideal solution for this tool.” 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 Space Telescope Imaging Spectrograph (STIS). They also installed two new instruments: the Cosmic Origins Spectrograph (COS) and the Wide Field Camera 3 (WFC3).

With repairs and upgrades complete, NASA expects the Hubble Space Telescope will be capable of taking pictures of the universe until at least 2014.

About Bal Seal Engineering, Inc.

Bal Seal Engineering, Inc. is a global provider of custom-engineered sealing, conducting, connecting and shielding solutions for aerospace applications. Products include Bal Seal(TM), Bal Shield(TM) and Bal Contact(TM) solutions, all of which employ unique canted-coil(TM) spring technology for enhanced equipment performance and reliability. For the latest news and information about Bal Seal, visit or call 800-366-1006.

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SpaceRef staff editor.