Drive motors from maxon motor specified for Mars

Did you know the NASA rovers Spirit and Opportunity on the planet Mars are each fitted with 39 drives made by the Swiss manufacturer maxon motor?

The small drives boast a range of special features, including efficiency levels of at least 90%. maxon's RE 8 DC motor is 8mm in diameter, 16mm long and can deliver a nominal 0.5W. It also weighs less than 4g. The motor shaft diameter is as thin as a pencil lead at only 0.8mm and is made of high tech ceramic material. Its electrical insulating properties allow for a compact commutator design.