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NASA Awards Aerospace Model Systems Fabrication Follow-On Contract
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By NASA
The NESC Mechanical Systems TDT provides broad support across NASA’s mission directorates. We are a diverse group representing a variety of sub-disciplines including bearings, gears, metrology, lubrication and tribology, mechanism design, analysis and testing, fastening systems, valve engineering, actuator engineering, pyrotechnics, mechatronics, and motor controls. In addition to providing technical support, the
TDT owns and maintains NASA-STD-5017, “Design and Development Requirements for Space Mechanisms.”
Mentoring the Next Generation
The NESC Mechanical Systems TDT actively participates in the Structures, Loads & Dynamics, Materials, and Mechanical Systems (SLAMS) Early Career Forum that mentors early-career engineers. The TDT sent three members to this year’s forum at WSTF, where early-career engineers networked with peers and NESC mentors, gave presentations on tasks they worked on at their home centers, and attended splinter sessions where they collaborated with mentors.
New NASA Valve Standard to Reduce Risk and Improve Design and Reliability
Valve issues have been encountered across NASA’s programs and continue to compromise mission performance and increase risk, in many cases because the valve hardware was not qualified in the environment as specified in NASA-STD-5017. To help address these issues, the Mechanical Systems TDT is developing a NASA standard for valves. The TDT assembled a team of subject matter experts from across the Agency representing several disciplines including mechanisms, propulsion, environmental control and life support systems, spacesuits, active thermal control systems, and materials and processes. The team has started their effort by reviewing lessons learned and best practices for valve design and hope to have a draft standard ready by the end of 2025.
Bearing Life Testing for Reaction Wheel Assemblies
The Mechanical Systems TDT just concluded a multiyear bearing life test on 40 motors, each containing a pair of all steel bearings of two different conformities or a pair of hybrid bearings containing silicon nitride balls. The testing confirmed that hybrid bearings outperformed their steel counterparts, and bearings with higher conformity (54%) outperformed bearings with lower conformity (52%). The team is disassembling and inspecting the bearings, and initial results have been surprising. The TDT was able to “recover” some of the bearings that failed during the life test and get them running as well as they did when testing began. Some bearings survived over five billion revolutions and appeared like new when they were disassembled and inspected. These results will be published once analysis is complete.
X-57 Design Assessment
The Mechanical Systems TDT was asked by the Aeronautics Mission Directorate to assess the design of the electric cruise motors installed on X-57. The team responded quickly to meet the Project’s schedule, making an onsite visit and attending numerous technical interchange meetings. After careful review of the design, the TDT identified areas for higher-level consideration and risk assessment and attended follow-on reviews to provide additional comments and advice.
CLARREO Pathfinder Inner Radial Bearing Anomaly
The Climate Absolute Radiance and Refractivity Observatory (CLARREO) Pathfinder was designed to take highly accurate measurements of reflected solar radiation to better-understand Earth’s climate. During payload functional testing, engineers detected a noise as the HySICS pointing system was rotated from its normal storage orientation. Mechanical Systems TDT members reviewed the design and inspection reports after disassembly of the inner bearing unit, noticing contact marks on the bore of the inner ring and the shaft that confirmed that the inner ring of the bearing was moving on the shaft with respect to the outer ring. Lubricant applied to this interface resolved the noise problem and allowed the project to maintain schedule without any additional costs.
JPL Wheel Drive Actuator Extended Life Test Independent Review Team
A consequence of changes to its mission on Mars will require the Perseverance Rover to travel farther than originally planned. Designed to drive 20 km, the rover will now need to drive ~91 km to rendezvous and support Mars sample tube transfer to the Sample Retrieval Lander. The wheel drive actuators with integral brakes had only been life tested to 40 km, so a review was scheduled to discuss an extended life test. The OCE Science Mission Directorate Chief Engineer assembled an independent review team (IRT) that included NESC Mechanical Systems TDT members. This IRT issued findings and guidance that questioned details of the JPL assumptions and plan. Several important recommendations were made that improved the life test plan and led to the identification of brake software issues that were reducing brake life. The life test has achieved 40 km of its 137 km goal and is ongoing. In addition, software updates were sent to the rover to improve brake life.
Orion Crew Module Hydrazine Valve
When an Orion crew module hydrazine valve failed to close, the production team asked the Mechanical Systems TDT for help. A TDT member attended two meetings and then visited the valve manufacturer, where it was determined this valve was a scaled-down version of the 12-inch SLS prevalve that was the subject of a previous NESC assessment and shared similar issues. The Orion Program requested NESC materials and mechanical systems support. The Mechanical Systems TDT member then worked closely with a Lockheed Martin (LM) Fellow for Mechanisms to review all 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 Technical Fellows for Propulsion that a redesign and requalification was recommended. These recommendations have now been elevated to the LM Vice President for Mission Success and the LM Chief Engineer for Orion.
NASA’s Perseverance Mars rover selfie taken in July 2024.
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By NASA
NASA has selected multiple companies to expand the agency’s Near Space Network’s commercial direct-to-Earth capabilities services, which is a mission-critical communication capability that allows spacecraft to transmit data directly to ground stations on Earth.
The work will be awarded under new Near Space Network services contracts that are firm-fixed-price, indefinite-delivery/indefinite-quantity contracts. Project timelines span from February 2025 to September 2029, with an additional five-year option period that could extend a contract through Sept. 30, 2034. The cumulative maximum value of all Near Space Network Services contracts is $4.82 billion.
Some companies received multiple task orders for subcategories identified in their contracts. Awards are as follows:
Intuitive Machines of Houston will receive two task order awards on its contract for Subcategory 1.2 GEO to Cislunar Direct to Earth (DTE) Services and Subcategory 1.3 xCislunar DTE Services to support NASA’s Lunar Exploration Ground Segment, providing additional capacity to alleviate demand on the Deep Space Network and to meet the mission requirements for unique, highly elliptical orbits. The company also previously received a task order award for Subcategory 2.2 GEO to Cislunar Relay Services. Kongsberg Satellite Services of Tromsø, Norway, will receive two task order awards on its contract for Subcategory 1.1 Earth Proximity DTE and Subcategory 1.2 to support science missions in low Earth orbit and NASA’s Lunar Exploration Ground Segment, providing additional capacity to alleviate demand on the Deep Space Network. SSC Space U.S. Inc. of Horsham, Pennsylvania, will receive two task order awards on its contract for Subcategories 1.1 and 1.3 to support science missions in low Earth orbit and to meet the mission requirements for unique, highly elliptical orbits. Viasat, Inc. of Duluth, Georgia, will be awarded a task order on its contract for Subcategory 1.1 to support science missions in low Earth orbit. The Near Space Network’s direct-to-Earth capability supports many of NASA’s missions ranging from climate studies on Earth to research on celestial objects. It also will play a role in NASA’s Artemis campaign, which calls for long-term exploration of the Moon.
NASA’s goal is to provide users with communication and navigation services that are secure, reliable, and affordable, so that all NASA users receive the services required by their mission within their latency, accuracy, and availability requirements.
These awards demonstrate NASA’s ongoing commitment to fostering strong partnerships with the commercial space sector, which plays an essential role in delivering the communications infrastructure critical to the agency’s science and exploration missions.
As part of the agency’s SCaN (Space Communications and Navigation) Program, teams at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, will carry out the work of the Near Space Network. The Near Space Network provides missions out to 1.2 million miles (2 million kilometers) with communications and navigation services, enabling spacecraft to exchange critical data with mission operators on Earth. Using space relays in geosynchronous orbit and a global system of government and commercial direct-to-Earth antennas on Earth, the network brings down terabytes of data each day.
Learn more about NASA’s Near Space Network:
https://www.nasa.gov/near-space-network
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Joshua Finch
Headquarters, Washington
202-358-1100
joshua.a.finch@nasa.gov
Jeremy Eggers
Goddard Space Flight Center, Greenbelt, Maryland
757-824-2958
jeremy.l.eggers@nasa.gov
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By NASA
Download PDF: Contact Dynamics Predictions Utilizing theNESC Parameterless Contact Model
Modeling the capture of the Mars Sample Return (MSR) Orbiting Sample (OS) involves understanding complex dynamic behavior, which includes the OS making contact against the interior of the capture enclosure. The MSR Program required numerical verification of the contact dynamics’ predictions produced using their commercial software tools. This commercial software used “free” parameters to set up the contact modeling. Free parameters (also known as free variables) are not based on contact physics. The commercial contact model used by MSR
required seven free parameters including a Hertzian contact stiffness, surface penetration, stiffening exponent, penetration velocity, contact damping, maximum penetration depth for the contact damping value, and a smoothing function. An example of a parameter that is not free is coefficient of friction, which is a physics-based parameter. Consider the free parameter, contact stiffness. Contact stiffness is already present in the finite element model’s (FEM) stiffness matrix where the bodies come into contact, and surface penetration is disallowed in a physically realizable contact model, as FEM meshes should not penetrate one another during contact (i.e., the zero-contact limit penetration constraint condition).
As such, with each set of selected free parameters generating a different contact force signature, additional numerical verification is required to guide setting these parameters. Contact modeling is nonlinear. This means that the stiffness matrices of contacting bodies are continuously updated as the bodies come into contact, potentially recontact (due to vibrations), and disengage. The modal properties of contacting bodies continuously change with state transitions (e.g., stick-to-slip). Some contact models have been proposed and incorporated in commercial finite element analysis solvers, and most involve static loading. A relatively smaller number involve dynamics, which has historically proven challenging.
In 2005, NASA conducted a study testing several commercial contact solvers in predicting contact forces in transient dynamic environments. This was necessitated by the Space Shuttle Program (SSP)—after the February 2003 Columbia accident— deciding to include contact dynamics in the Space Shuttle transient coupled loads analysis (CLA) to capture the impact of contact nonlinearities. This rendered the entire CLA nonlinear. The study found major difficulties executing nonlinear CLAs in commercial software. A nonlinear solver developed by the NESC and Applied Structural Dynamics (ASD) that was able to produce physically realizable results was numerically verified by NASA and later experimentally validated as well. This nonlinear solver was subsequently utilized to execute all NASA SSP CLAs (i.e., crewed space flights) from 2005 to the final flight in 2011, as well as currently supporting the SLS Program.
The objective of the MSR contact verification work was to provide data that could be used by the MSR team to help define the free parameters listed above for the commercial tool contact model. The NESC/ASD solver was used to model contact between simple cantilever and free beams, deriving contact forces and relative displacements. These resulting data can be used to determine parameter values for more complex structures. Two of the modeled configurations, one for axial contact (Figure 1) and the other for stick/friction (Figure 2), and sample results from the NESC nonlinear dynamic analyses are presented in Figures 1 and 2.
For information, contact:
Dr. Dexter Johnson dexter.johnson@nasa.gov
Dr. Arya Majed arya.majed@nasa.gov
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By NASA
Credit: NASA NASA has selected FedSync-BFS, LLC of Alexandria, Virginia, to provide administrative services for multiple NASA centers.
The Multi-Center Administrative Support Services Contract is a firm-fixed-price and indefinite-delivery/indefinite-quantity contract with a value not to exceed $200 million during a five-year ordering period. The performance period begins April 1, 2025.
Contracted work will take place in six NASA centers and facilities, including Johnson Space Center in Houston, Kennedy Space Center in Florida, Marshall Space Flight Center in Huntsville, Alabama, the Michoud Assembly Facility in New Orleans, Stennis Space Center near Bay St. Louis, Mississippi, and the White Sands Test Facility in Las Cruces, New Mexico.
The contract will provide administrative support including, but not limited to, general office services, data management services, travel coordination, time and labor collection, property coordination, move coordination, training coordination, information services coordination, customer service, special events coordination, and miscellaneous activities.
For information about NASA and other agency programs, visit:
https://www.nasa.gov
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Tiernan Doyle
Headquarters, Washington
202-358-1600
tiernan.doyle@nasa.gov
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Last Updated Dec 13, 2024 LocationNASA Headquarters Related Terms
Johnson Space Center Kennedy Space Center Marshall Space Flight Center Michoud Assembly Facility NASA Centers & Facilities Stennis Space Center White Sands Test Facility View the full article
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