NESC Mechanical Systems TDT provides extensive support across NASA’s mission directories. We are a diverse group representing various sub-disciplines including bearings, gears, metrology, lubrication and tribology, mechanism design, analysis and testing, fastening systems, valve engineering, actuator engineering, pyrotechnics, mechatronics, motor control, etc. is. In addition to providing technical support,
TDT owns and maintains NASA-STD-5017, “Space Mechanism Design and Development Requirements.”
Mentoring the next generation
NESC Mechanical Systems TDT is an active participant in the Structures, Loading and Mechanics, Materials, and Mechanical Systems (SLAMS) Early Career Forum, which mentors early career engineers. TDT sent three members to this year’s WSTF forum. There, young engineers networked with colleagues and NESC mentors, gave presentations on tasks they were working on at the hardware store, and participated in split sessions where they collaborated with their mentors.
New NASA valve standard reduces risk, improves design and reliability
Valve problems have occurred across NASA programs and continue to impair mission performance and increase risk. This is often due to the valve hardware not being certified for the environment specified in NASA-STD-5017. To address these issues, Mechanical Systems TDT is developing NASA standards for valves. TDT assembled a team of subject matter experts from across the agency representing several areas including mechanics, propulsion, environmental control and life support systems, spacesuits, active thermal control systems, and materials and processes. The team has begun work by reviewing lessons learned and best practices in valve design, and hopes to have a draft standard completed by the end of 2025.
Bearing life test of reaction wheel assembly
Mechanical Systems TDT has completed multi-year bearing life testing on 40 motors, each containing pairs of all-steel bearings of two different compatibility or pairs of hybrid bearings containing silicon nitride balls. Tests confirmed that hybrid bearings performed better than steel bearings, with higher compatibility bearings (54%) outperforming lower compatibility bearings (52%). The team is disassembling the bearing and inspecting it, and the initial results are surprising. TDT was able to “recover” some of the bearings that failed during the life test and have them operating as they were at the start of the test. Some bearings withstood more than 5 billion revolutions and looked as good as new when taken apart and inspected. These results will be published once the analysis is complete.
X-57 design evaluation
Mechanical Systems TDT was asked by the Air Mission Directorate to evaluate the design of the electric cruise motor installed on the X-57. The team responded quickly to meet the project schedule, making site visits and attending numerous technical exchange meetings. After carefully reviewing the design, TDT identified areas that required higher level consideration and risk assessment, and participated in subsequent reviews to provide additional comments and advice.
CLARREO Pathfinder Inner radial bearing abnormality
The Climate Absolute Radiance and Refractivity Observatory (CLARREO) Pathfinder is designed to make high-precision measurements of reflected solar radiation to better understand Earth’s climate. During functional testing of the payload, engineers detected noise when the HySICS pointing system was rotated from its normal storage orientation. The TDT member of the mechanical system reviewed the design and inspection report after disassembly of the inner bearing unit and noticed contact marks on the inner ring bore and shaft, indicating that the inner ring of the bearing was moving on the shaft relative to the outside. I have confirmed that. ring. Lubricating this interface solved the noise problem and kept the project on schedule at no additional cost.
JPL Wheel Drive Actuator Life Extension Test Independent Review Team
As a result of the Mars mission changes, the Perseverance rover will have to travel farther than originally planned. The rover is designed to travel 20 km, but will need to travel up to 91 km to rendezvous to support the transfer of the Mars sample tube to the sample recovery lander. As wheel drive actuators with integrated brakes had only been life tested up to 40 km, a review was scheduled to consider life extension testing. The Chief Engineer of the OCE Science Mission Directorate assembled an Independent Review Team (IRT) that included NESC Mechanical Systems TDT members. This IRT issued findings and guidance that questioned the details of JPL’s assumptions and plans. Several key recommendations were made to improve the life test plan and identify brake software issues that reduce brake life. The life test has completed 40km out of the target of 137km and is still ongoing. Additionally, a software update was sent to the spacecraft to extend the life of the brakes.
Orion Crew Module Hydrazine Valve
When the hydrazine valve in Orion’s crew module failed to close, the production team turned to mechanical systems TDT for help. TDT members attended two meetings and then visited valve manufacturers. There, it was determined that this valve was a scaled-down version of the 12-inch SLS pre-valve that had been the subject of a previous NESC evaluation and shared similar issues. The Orion program requested support for NESC’s materials and mechanical systems. TDT members from Mechanical Systems then worked closely with Lockheed Martin (LM) mechanical fellows to review all detailed valve vendor drawings and assembly instructions and document any issues. A subsequent meeting was held in which both LM and the NASA Propulsion Technology Fellow were briefed on the recommendation for redesign and requalification. These recommendations have now been promoted to the LM Vice President for Mission Success and Orion’s LM Chief Engineer.
