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Structures and Materials Division Research and Technology Directorate NASA Glenn Research Center

Tribology and mechanical Components Branch
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Aero Drive Systems - Advanced Gear Systems
Research Objectives
Develop the main interface seal for the Low Impact Docking System (LIDS) which NASA is developing as the new docking system for future missions to the International Space Station, the Moon, and Mars.

LIDS main interface seal and CEV docking with ISS
LIDS model (top) and location on CEV (below) as it prepares to dock to the International Space Station.
Technical Challenges
  • Large diameter (58 in.) seals must:
    • Exhibit extremely low-leakage of less than 0.0025 lbm/day (0.001kg/day)
    • Meet extremely high reliability requirements for man-rated vehicles
    • Accommodate off-nominal conditions including gapping and axial misalignment
    • Exhibit low sealing compression and adhesion forces
    • Withstand long term exposure to the following space environments without excessive damage or loss of sealing ability:
      • Atomic oxygen (AO)
      • Ultraviolet (UV) radiation
      • Ionizing radiation
      • Micro-meteoroid and orbital debris (MMOD)
      • Vacuum conditions
      • Thermal cycling
    • Operate at temperatures from -50 C to +50 C including thermal gradients
    • Endure long mating periods (~7 months) and repeated docking

Current Research

The NASA GRC Structural Seals Team is supporting NASA JSC by developing the main interface seal for LIDS. Main activities in this effort currently include:

  • Leakage testing of seals for JSC’s 54-in. diameter Engineering Demonstration Unit (EDU 54)
  • Installation and assembly of a new test rig to evaluate full-scale seal leak rates as well as compression and adhesion loads during simulated docking and undocking
  • Fabrication of seals for JSC’s 58-in. diameter Engineering Demonstration Unit (EDU 58)
  • Seal bond integrity evaluations
  • Sub-scale seal leakage, compression, adhesion, and vibration testing
  • Long-term (e.g., 7 month) seal compression testing under vacuum
  • Impact testing of candidate seal materials to evaluate risk of MMOD strikes
54 inch diameter seal
Above: Close-up of 54 inch diameter seal
Simulated MMOD impact in candidate seal elastomer material
Above: Simulated MMOD impact in candidate seal elastomer material

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Pat Dunlap
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NASA Seals and Secondary Flows Symposium

November 19, 2013 - Postponed to Nov. 2014 due to Government Shutdown in October. Watch for new date.

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Last Updated: May 5, 2009