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  • 1
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    The International Space Station Solar Alpha Rotary Joint Anomaly Investigation (2010)
    In:  CASI
    Details
    Publication Date: 2018-06-11
    Description: The Solar Alpha Rotary Joint (SARJ) is a single-axis pointing mechanism used to orient the solar power generating arrays relative to the sun for the International Space Station (ISS). Approximately 83 days after its on-orbit installation, one of the two SARJ mechanisms aboard the ISS began to exhibit high drive motor current draw. Increased structural vibrations near the joint were also observed. Subsequent inspections via Extravehicular Activity (EVA) discovered that the nitrided case-hardened steel bearing race on the outboard side of the joint had extensive damage to one of its three rolling surfaces. A farreaching investigation of the anomaly was undertaken. The investigation included metallurgical inspections, coupon tests, traction kinematics tests, detailed bearing measurements, and thermal and structural analyses. The results of the investigation showed that the anomaly had most probably been caused by high bearing edge stresses that resulted from inadequate lubrication of the rolling contact. The profile of the roller bearings and the metallurgical properties of the race ring were also found to be significant contributing factors. To mitigate the impact of the damage, astronauts cleaned and lubricated the race ring surface with grease. This corrective action led to significantly improved performance of the mechanism both in terms of drive motor current and induced structural vibration.
    Keywords: Space Sciences (General)
    Type: Proceedings of the 40th Aerospace Mechanisms Symposium; 187-206; NASA/CP-2010-216272
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    NASA Docking System Block 1: NASA's New Direct Electric Docking System Supporting ISS and Future Human Space Exploration (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA Docking System (NDS) Block 1 is a key component of NASA's vision for space exploration. It is designed to provide capability for visiting vehicles to dock to the International Space Station's recently-installed International Docking Adapter ports. It is the first docking system to be developed by NASA since the Apollo-Soyuz Test Project of the 1970's. The NDS Block 1 includes provisions for capture, structural attachment, power/data transfer, and undocking. It uses a direct-drive electromechanical Stewart Platform capture system architecture, along with an innovative automated control scheme, to achieve an unprecedented level of performance and simplicity. Its design implements the new International Docking System Standard, which will be a key enabler of diverse and flexible exploration missions in future iterations. NDS qualification was completed in 2017 to support a planned first flight in 2018 on the Boeing CST-100 Starliner.
    Keywords: Mechanical Engineering
    Type: JSC-E-DAA-TN51081 , Aerospace Mechanisms Symposium; May 16, 2018 - May 18, 2018; Cleveland, OH; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Space Station Solar Array Joint Repair (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Space Sciences (General)
    Type: JSC-CN-33199 , 2015 ASTM International Rolling Element Bearings; Apr 29, 2015 - Apr 30, 2015; Anaheim, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Root Cause Investigation of the Starboard Solar Alpha Rotary Joint Anomaly on the International Space Station (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Solar Alpha Rotary Joint (SARJ) is a single-axis pointing mechanism used to orient the solar power generating arrays relative to the sun for the International Space Station (ISS). Approximately 83 days after its on-orbit installation, one of the two SARJ mechanisms aboard the ISS began to exhibit high current draw. Later inspections via Extravehicular Activity (EVA) discovered that the case hardened steel race ring on the outboard side of the joint had extensive damage to one of its three rolling surfaces. A far-reaching investigation of the anomaly was undertaken, comprising metallurgical inspections, coupon tests, traction kinematics tests, detailed bearing measurements, and thermal and structural analyses. The investigation found that the race ring damage had been caused by high bearing edge stresses that resulted from inadequate lubrication of the rolling contact. The profile of the roller bearings and the metallurgical properties of the race ring were also found to be significant contributing factors.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-CN-18874 , 40th Aerospace Mechanisms Symposium; May 12, 2010 - May 15, 2010; Cocoa Beach, Fl; United States
    Format: application/pdf
    Location Call Number Expected Availability
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    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    The International Space Station Solar Alpha Rotary Joint Anomaly Investigation (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Solar Alpha Rotary Joint (SARJ) is a single-axis pointing mechanism used to orient the solar power generating arrays relative to the sun for the International Space Station (ISS). Approximately 83 days after its on-orbit installation, one of the two SARJ mechanisms aboard the ISS began to exhibit high drive motor current draw. Increased structural vibrations near the joint were also observed. Subsequent inspections via Extravehicular Activity (EVA) discovered that the nitrided case hardened steel bearing race on the outboard side of the joint had extensive damage to one of its three rolling surfaces. A far-reaching investigation of the anomaly was undertaken. The investigation included metallurgical inspections, coupon tests, traction kinematics tests, detailed bearing measurements, and thermal and structural analyses. The results of the investigation showed that anomaly had most probably been caused by high bearing edge stresses that resulted from inadequate lubrication of the rolling contact. The profile of the roller bearings and the metallurgical properties of the race ring were also found to be significant contributing factors. To mitigate the impact of the damage astronauts cleaned and lubricated the race ring surface with grease. This corrective action led to significantly improved performance of the mechanism both in terms of drive motor current and induced structural vibration.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-CN-19606 , 40th Aerospace Mechanisms Symposium; May 12, 2010 - May 14, 2010; Cocoa Beach, FL; United States
    Format: application/pdf
    Location Call Number Expected Availability
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    NASA TECHNICAL REPORTS
  • 6
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    Unknown
    Space Station Solar Array Joint Repair (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In Oct 2007 the International Space Station (ISS) crew noticed a vibrating camera in the vicinity of Starboard Solar Alpha Rotary Joint (SARJ). It had less than 5 months of run time when the anomaly was observed. This approximately 3.2 meter diameter bearing joint supports solar arrays that power the station critical to its operation. The crew performed an EVA to identify what was causing the vibration. It was discovered that one of the 3 bearing tracks of this unconventional bearing had significant spalling damage. This paper discusses the SARJ's unique bearing design and the vulnerability in its design leading to the observed anomaly. The design of a SARJ vacuum test rig is also described along with the results of a life test that validated the proposed repair should extend the life of the SARJ a minimum of 18 years on-orbit.
    Keywords: Spacecraft Design, Testing and Performance; Astronautics (General); Mechanical Engineering
    Type: JSC-CN-33444 , 2015 ASTM International Rolling Element Bearings Conference; Apr 29, 2015 - Apr 30, 2015; Anaheim, CA; United States
    Format: application/pdf
    Location Call Number Expected Availability
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    NASA TECHNICAL REPORTS
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