This January two new NASA rovers — Spirit and Opportunity — will reach Mars and examine rocks for signs of water and ancient life. Many rover functions depend on one of 78 motors aboard that come from Maxon Precision Motors, Burlingame, Calif. The rovers are bigger than previous Martian explorers such as the Sojourner which was about 2 ft long and weighed about 22 lb. The two new rovers are 4.9-ft high X 7.5-ft wide X 5.2-ft long, and each weighs 384 lb.