Threads get a grip on shock, vibration

Unconventional fasteners seal interplanetary probe When the Cassini-Huygens spacecraft goes into orbit around Saturn next July, it will have endured not only the vibration, shock, and temperature extremes of a Titan IV rocket launch, but also the seven-year, 750 million mile journey from Earth. Later, the Huygens probe will dive into the murky atmosphere of Titan, Saturn's largest moon, measuring atmospheric composition all the way down to the frigid surface. Despite the harsh conditions, several hundred fasteners must maintain a vacuum-tight seal or else the mission is doomed. To meet this challenge, NASA engineers turned to an unconventional internal thread design that has helped manufacturers combat thread loosening and stripping in a wide array of tough earthbound applications. A thread form developed by addresses loosening and stripping caused by vibration, shock, and temperature change. It differs from that of conventional fasteners in that a 30° "wedge" ramp is cut