ADCS: The Attitude Determination and Control System (ADCS) board determines the satellite's orientation and controls it.  It uses a rate gyro to measure the satellite's "tumble" (angular rotation) and a magnetometer to measure the Earth's magnetic field.  It does not have an accelerometer -- Jagsat-1 is in free fall and the acceleration is always zero! The board has provisions for sun sensors but Jagsat-1 did not use them.  The board can control four "magnetorquers", which are coils of wire (on the solar panel boards) that emit a magnetic field.  The magnetorquer's magnetic field and the Earth's magnetic field interact to produce a torque, and the torque can be used to "detumble" the satellite (stop all rotation). To control the magnetorquer, special GNC (guidance, navigation, and control) software was written to measure magnetic field and tumble rate and then calculate how much current to send to each magnetorquer.