TDT owns and maintains NASA-STD-5017, “Design and Development Requirements for Space Mechanisms”.
Mentoring the next generation
NESC Mechanical Systems TDT actively participates in the Structures, Loads and Dynamics, Materials, and Mechanical Systems (SLAMS) Early Career Forum that mentors early career engineers. TDT sent three members to this year’s forum at WSTF, where early-career engineers networked with peers and NESC mentors, gave presentations about the work they do at their home centers, and participated in breakout sessions. where he cooperated with the guardians.
New NASA valve standard to reduce risk and improve design and reliability
Valve problems have been encountered in all NASA programs and continue to compromise mission performance and increase risk, in many cases because the valve hardware was not qualified in an environment such as NASA-STD-5017. is described in To help address these issues, Mechanical Systems is developing a NASA standard for TDT valves. TDT brought together a team of subject matter experts from across the agency, including mechanisms, propulsion, environmental control and life support systems, spacesuits, active thermal control systems, and materials and processes. The team has begun its effort by reviewing lessons learned and best practices for valve design and hopes to have a draft standard ready by the end of 2025.
Bearing Life Testing for Reaction Wheel Assemblies
Mechanical Systems TDT has just concluded a multi-year bearing life test on 40 motors, each with a pair of two different compatibility all-steel bearings or a pair of hybrid bearings containing silicon nitride balls. Testing confirmed that the hybrid bearings outperformed their steel counterparts, with high compatibility bearings (54%) outperforming low compatibility (52%) bearings. The team has been disassembling and inspecting the bearings, and the initial results have been surprising. TDT was able to “recover” some of the bearings that had failed during the life test and had them running as well when testing began. Some bearings survived more than five billion revolutions and appeared as good as new when disassembled and inspected. The results will be published after the analysis is complete.
X-57 Design Evaluation
Mechanical Systems TDT was asked by the Aeronautics Mission Directorate to review the design of the electric cruise motors installed on the X-57. The team responded quickly, conducted onsite visits and participated in numerous technical exchange meetings to meet the project schedule. After carefully reviewing the design, TDT identified areas for high-level consideration and risk assessment and participated in follow-on reviews to provide additional comments and advice.
CLARREO Pathfinder Internal Radial Bearing Irregularity
The Climate Absolute Radiance and Refractivity Observatory (CLARREO) pathfinder was designed to make highly accurate measurements of reflected solar radiation to better understand Earth’s climate. During payload functional testing, engineers detected noise as the HySICS pointing system was rotated from its normal storage orientation. Mechanical Systems TDT members reviewed the design and inspection reports after disassembling the inner bearing unit, observed contact marks on the inner ring and shaft bore, which confirmed that the bearing’s inner ring was in contact with the outer. It was moving on the shaft. A lubricant applied to this ring interface solved the noise problem and allowed the project to stay on schedule without incurring additional costs.
JPL Wheel Drive Actuator Extended Life Test Independent Review Team
Changes to its mission to Mars will require the Perseverance rover to travel further than originally planned. Designed to drive 20 km, the rover will now need to travel 91 km and help transfer the Mars sample tube to the sample recovery lander. Wheel drive actuators with integral brakes were only life tested for 40 km, so a review was scheduled to discuss an extended life test. 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 JPL assumptions and plan details. Several key recommendations were made that improved the life test plan and identified brake software issues that were reducing brake life. Life Test has achieved 40 km of its 137 km target and is ongoing. In addition, Rover received a software update to improve brake life.
Orion Crew Module Hydrazine Valve
When the Orion crew module hydrazine valve failed to close, the production team sought assistance from Mechanical Systems TDT. A TDT member attended two meetings and then met with the valve manufacturer, where it was determined that the valve was a smaller version of the 12-inch SLS prevalve that was the subject of a previous NESC evaluation and similar. Shared problems. The Orion program requested NESC material and mechanical systems support. The Mechanical Systems TDT member then worked closely with the Lockheed Martin (LM) Fellow for Mechanisms to review all of the valve vendor’s detailed drawings and assembly procedures and document any issues. A follow-on meeting was held to brief both the LM and NASA’s Technical Fellows for Propulsion that a redesign and capability was recommended. These recommendations are now relayed to the LM Vice President for Mission Success and the LM Chief Engineer for Orion.