This particular blog entry is going to be a throwback to some of the control systems work I did in my college days. Essentially, control systems engineering involves the design and analysis of the motion of a given system, in this case, an idealized rigid spacecraft. For any given system, or body, there is a set of equations of motion that can describe that system. Usually this involves things like translational velocity, angular velocity, translational accelerations, angular accelerations, and so on. Once the equations of motion of a body are understood, the state of the body, meaning the attitude and motion of it, can be controlled via commands to controlling devices. The process of studying these equations of motion, simulating them, and employing those simulations to develop computer code and hardware specifications is known as control systems engineering.