Scientists working on the Mars Path- finder at the NASA Jet Propulsion Laboratory in Pasadena, Calif., needed a motor with low-arcing and long brush life that could operate the Sojourner rover on Mars. They chose the REO16DC motor from Maxon Precision Motors Inc. in Burlingame, Calif.
The Maxon motor was the only device NASA engineers could find that extended long life through arc reduction and low inductance, says Howard Eisen, subsystem leader for the Mars Pathfinder Team at JPL.
Of 11 DC miniature motors located in one of each of the six drive wheels of the rover, four are used to steer the vehicle, and one to deploy scientific instruments.
JPL designers performed some modifications so that the motors could function on the Mars terrain.
Each Maxon motor weighs 38 grams, measures 16 millimeters in diameter by 41 millimeters in length, and has an ironless rotor to ensure smooth rotation, even at the slow 3.3-foot-per-minute travel speed of the sojourner. Its low inertia and linear speed-torque constants enable it to handle grades as high as 26 degrees.
Rated at 3.2 watts output power and 86 percent efficiency, the Maxon motors are designed to withstand temperatures down to -100 degrees Celsius. In addition they use the Maxon Capacitor Long Life technology which cuts arcing in metal-brush motors to maximize brush life. Maxon`s moving-coil rotor, which cuts inductance to a bare minimum, also contributes to the long brush and commutator life. - J.M.
For more information on Maxon Precision Motors, contact Jack Rice by phone at 415-697-9614, by fax at 415-697-2887, by mail at Maxon Precision Motors Inc., 838 Mitten Road, Burlingame, Calif., 94010, or on the World Wide Web at http://www.mpm.maxonmotor.com/.