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Bearing good news for Mars landing
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10/10/2008
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The Pheonix Mars Lander uses Kaydon ‘Reali-Slim’ thin section bearings to position its robotic arm for digging in the permafrost there. This is the second Mars mission for these products, which are also in use on the two 2004 Mars Exploration Rovers, both of which are still functioning.
The robotic arm is designed to trench the surface, pick up soil and ice samples, and deposit them in instrumentation for testing and analysis. The arm is attached to the deck of the Lander, with a garden-sized trowel on its opposing end. The arm has four types of motion: up and down, side to side, backwards and forwards, and rotation. Three of the joints use Reali-Slim bearings. Up to 44 kg of force is needed to break through the ice, in order to reach a depth of about 50 cm. The bearings are made from heat-treated, 440C stainless steel and are mechanically honed to achieve a superior finish and torque. To enable them to operate in extreme cold, down to -108°C, the bearings are heated and use a low outgassing lubricant that neither gets too viscous in the cold, nor evaporates in the thin atmosphere.
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Author
Tom Shelley
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