Hi everyone. I know about the equations of gravitation but something is still bothering me. The equation for total energy of a satellite in an orbit is -GMm/2r However, when the satellite suddenly lose control and heads to the Earth, why does the total energy in the system change according to r? Excluding air resistance of course... I always thought in a closed system, total energy remains constant? Im quite blur and my teacher just asked us to memorize the eqns. Thanks.