According to universal law of gravitation each particle in the universe attracts other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. A satellite is orbiting a planet at a constant height in a circular orbit. If the mass of the planet is reduced to half, then the gravitational force between them is reduced by half of the initial gravitational force. Thus, leads to reduced gravitational pull and satellite will not move.