What is the effect of the pintle in the thrusters?
So what is a pintle, anyway? According to the OED, A pin or bolt, in various mechanical contrivances; esp. one on which some other part turns, as in a hinge. In our context, its the little thing inside the thrusters that controls the gas flow. Nothing turns on it except figuratively, but it moves back and forth to change the size of a vent hole through which the gas is exhausted. The thrust is roughly proportional to the position of the pintle, and the pintles are (we hope) the only moving parts on the satellite except for the masses themselves. The pintles weigh about ten grams, and when they move (as they must to control the thrust) the whole satellite moves in reaction, as much as a couple of hundred angstroms. Thats pretty big on the scales we are measuring, and it must be allowed for. For this reason the pintles motion must be modelled in the drag-free control algorithm.
