Custom couplings and springs let rover explore Mars

The NASA rover Curiosity recently reached Mars and if all went well, the wheeled robot is relying on several custom components from the engineers at Helical Products Co. Inc., Santa Maria, Calif. For example, the subsystem mounted on the rover’s front-mounted arm that will dig up and retrieve soil samples makes use of a flexible coupling from Helical. The coupling lets soil samples be vibrated and sifted, so only powder is transferred inside Curiosity for further processing and analysis. The coupling is compliant in all directions (axial, angular, and parallel), so it can compensate for misalignments to the vibratory drive. The coupling also reduces bearing loads on the drive while reliably transmitting the torque needed to sift the samples.

 After five months of intensive design work, Helical manufactured the couplings out of 15-5PH stainless steel heat treated to H1025. This will give the device the strength, fatigue resistance, and ability to maintain these characteristics despite the frigid Martian temperatures (–160°F). Engineers at Helical also had to add NASA-specified connectors to the coupling.    

The rover also incorporates custom-machined springs from Helical. They are critical components in a locking mechanism that ensure the rocker-bridge joints in the rover’s six-wheeled suspension stay locked in place once unfolded and deployed on the surface of Mars. The lightweight titanium springs had to meet strict requirements for compression and lateral translation spring rates. And like the couplings the company made for the rover, the springs needed to have NASA-approved connectors.