Custom voice-coil actuator heads to asteroid Bennu

BEI Kimco, a brand of Sensata Technologies, is a part of NASA’s first asteroid sampling mission that could revolutionize understanding of the early solar system. BEI Kimco designed a customized moving magnet voice coil actuator (VCA) to meet the harsh requirements for a spectrometer moving mirror application on the Origins-Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-Rex) spacecraft. The OSIRIS-Rex launched on Sept 8, 2016 from Cape Canaveral Air Force Station, in its mission to rendezvous with the Asteroid Bennu in 2018 and return samples to Earth in 2023.

For this space mission, a customized BEI Kimco moving magnet VCA was attached to, and will position the moving mirror assembly of the OSIRIS-Rex Thermal Emission Spectrometer (OTES). As the spacecraft approaches Bennu, the spectrometer will scan the surface so that the material can be analyzed for different parameters. OSIRIS-REx will spend two years surveying the asteroid in unprecedented detail. Then, in a robotic first, the spacecraft will reach out its mechanical arm and take a sample from the asteroid. Though the sample will be small – only a couple of pounds at most – it will be a time capsule of sorts recording our solar system’s creation. With the sample stored safely, the spacecraft will speed away from the asteroid on a path back to Earth.

The VCA was manufactured to custom requirements for high reliability and fail-safe operation. Redundant technology, low-outgassing and high precision for exact motion control positioning were all key requirements of the actuator design. It was also critical to stay within the specific size, weight and power limits. This was achieved in a housing measuring approximately 2 in. in diameter by 3 in. long. To meet the requirements for near-zero emissions, BEI Kimco developed the actuator minimizing the use of adhesives or inks and using only approved materials. This design primarily uses mechanical assembly methods within a clean manufacturing process, thereby eliminating substances that could cause outgassing. High-energy Neodymium Iron Boron (NeFeB) magnets were incorporated to provide superior operating efficiencies.

“The Astroid Bennu sampling mission was another exciting opportunity for us to meet unique customer demands,” says Jim McNamara, Senior Applications Engineer at BEI Kimco. “In this case, a customized low outgassing design with high reliability, built-in redundancies, strict quality control, and cleanliness were all needed. It will be interesting to see the results of the mission in 2023 when the samples are brought to earth.”