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Experimental EHD film thickness results are presented for DMA bearings operation at simulated space flight conditions in high vacuum. Short-term and long-term tests were conducted to investigate the effects of oil viscosity and composition, and bearing race roughness and cage design. It was found that a continuous film separation at the ball-race contacts was maintained in bearings with an outer ring-riding cage design and a medium-viscosity oil (225 cs at 25 Cel) for over 12500 h without noticeable wear, pitting or torque increase. Use of a low-viscosity oil (54 cs at 25 Cel) and the same cage design caused two bearing seizures at about 4000 h. However, a ball-riding cage design gave no such failure with the same low-viscosity oil up to 4440 h of operation.