Phoenix Mars Lander that began scooping up samples of Martian soil on June 4 has Reali-Slim thin-section bearings to position its robotic arm for digging in the permafrost.
This is the second Mars mission for the Reali-Slim thin-section bearings, manufactured by Kaydon Corporation Bearings Division of Muskegon, Mich.
The Reali-Slim thin-section bearings were also used in the two 2004 Mars Exploration Rovers, which are still sending geologic findings back to Earth, some 171 million miles away.
The robotic arm was built by Alliance Spacesystems of Pasadena, California for NASA's Jet Propulsion Laboratory. It is designed to trench the surface, pick up soil and ice samples, and deposit them in the Lander's instruments for testing (electrochemistry, conductivity and thermal analysis).
The 7-foot, 7-inch arm is attached to the deck of the Lander, with a garden-sized trowel on the end and a camera mounted above it that sends colour photographs of the samples to scientists on Earth.
The arm has four types of motion: up-and-down, side-to-side, back-and-forth and rotating. Three of the joints that accomplish these movements feature sets of custom-engineered Reali-Slim thin-section bearings from Kaydon. According to Richard Fleischner, mechanical engineering group supervisor at Alliance, they were specified for several reasons.
He says that the Kaydon bearings give them plenty of load capacity, even though they are lightweight and small enough to fit in the tight space and that they also have a full complement of balls to withstand the force and vibration of the launch. He added that they get good engineering support and a reasonable lead time from Kaydon.
Richard Fleischner said the Reali-Slim thin-section bearings take a heavy load during digging, as up to 100 pounds or more of force is needed to break through the ice and dig down about 20 inches.
The Reali-Slim thin-section bearings are made of heat-treated 440C stainless steel and mechanically honed to achieve a fine finish and improve torque.
The Reali-Slim thin-section bearings are heated to operate in extreme cold (the joints are designed to survive in -108°C) and use a low-outgassing lubricant that neither gets too viscous in extreme cold nor evaporates in the thin atmosphere.
The Phoenix Lander is expected to be on the job for three months, digging for evidence that Mars could sustain life.
The Reali-Slim thin-section bearings are available from CGB Precision Products .