Long-Lived Lubrication for Spacecraft Equipment

Vacuum and radiation conditions in space are discussed, as these appear to cause the major limitations on lubrication for spacecraft equipment. While many lubricants suffer a drastic loss in lifetime as a result of these environments, experimental studies have demonstrated that certain oils and greases can lubricate lightly loaded ball bearings without replenishment for periods of two years and more under the following conditions of operation: speeds of 8000 rpm, temperatures of 160 to 200 F, and vacuum of 10⁻⁸ torr. Selected oils and greases have also lubricated satisfactorily to radiation doses of 10⁷ roentgens in vacuum, which is several times the internal dose that would be accumulated in a period of one year in space. Experimental evaluations of molybdenum disulfide and special retainer materials are also discussed.