222 including the center conductor. Ensure the center conductor is an alloyed copper (higher strength)  and that the silver coating on the strands has a well controlled thickness (thicker likely is better based on the test observations).  3. Cold Welding happens with clean metal to metal contact. These lessons learned are applicable to  other Moving Mechanical Assembly (MMA) components where sliding or rolling interfaces are metal to metal. Testing should simulate flight like conditions, sequences, and profiles to the maximum extent possible on any MMA especially considering the entire variable set that could potentially affect performance.  

Acknowledgments 

(1) Lockheed Martin Space Systems (LMSSC) Data, Assessments from Team, and Findings:   a. Special credit goes to the RF Engineers for their extensive coax cable knowledge and  testing   b. Analysis Group for their analysis expertise in macro and micro structures, metal  stress/strain, fatigue and dynamic simulation work  c. Failure Analysis Lab for steady hands and patience dissecting tens and hundreds of  cable specimens (DPA work) and documenting it beautifully.   Additional acknowledgements on the LM Team in Denver: Quality Lab for scanning and rendering all the CT scan cable images, and many more folks on the team that put in countless hours and thought ensuring our results were something we could rely on. Thanks to the whole Lockheed Martin, LM Customer, Aerospace Corporation, and Subcontractor Team for providing their time, resources, test samples, and units from which we gathered a lot of data and knowledge.   (2) Also special mention of Bob/Robert Pan from Aerospace Corporation for being a facilitator of  information transfer ensuring the contractor / customer and Aerospace team were in constant communication and providing additional data with Aerospace Corporation support through repeating tests for confirmation, refinement, and interpretation of results.  

References  (3) 2D In-situ X-Ray Image (Figure 7) courtesy of The Aerospace Corporation, Dr. Eric C. Johnson,  Shant Kenderian, and Robert Pan, Space Material Laboratory.   Published Papers on Cold Welding:   (4) Coaxial Cable Failure in a Spacecraft Mechanism, by Michael Chiu, Proceedings of the 34th  Aerospace Mechanisms Symposium, Goddard Space Flight Center, May 10-12, 2000 where the solution for cold welding in cables was to replace design with a design that had a PTFE barrier between the wire braid and foil   (5) Material Property Effects on Coaxial Cable Mechanical Failure, by R. B. Pan, J.B. Chang, C.C.  Wan, Y. R. Takeuchi, R. McVey, and I. Chen Proceeding of the 36th Aerospace Mechanisms Symposium, Glenn Research Center, May 15-17, 2002 where it shows DPA results and postulates a failure mechanism that relates low yield strength associated with the low hardness values to the cold welding of similar material at the interface, rapid initiation of multiple crack sites and fast crack propagation.  (6) Assessment of Cold Welding Between Separable Contact Surfaces Due to Impact and Fretting  Under Vacuum; by A. Merstallinger, M. Sales, E. Semerad, Austrian Institute of Technology, and B.D. Dunn, ESA/ESTEC European Space Agency; STM-279, November 2009.