The Astrobotic Technology lunar rover will be powered by two motors mounted inside the body, powering chain drives to each side's wheels. The video below shows an initial test of one motor under load -- raising and lowering a 25-kg weight hanging from a pulley. Thermocouples taped to the motor and gear boxes measured how the heat generated during the test flowed down to the base plate during a two-hour run. To operate throughout the lunar day, the chief challenge is to cool the motors and electronics inside the rover. The motors must stay below 100 C. During this test, the temperatures did not exceed 60 C. Subsequent tests will actively cool the base plate, and will operate the apparatus inside a vacuum chamber.