Abstract: A solution to the electromagnetic position/orientation tracking problem is presented in an environment wherein strong electromagnetic distortion may be present includes at least one source of an AC electromagnetic field, at least one witness sensor measuring components of the electromagnetic induction vector at known spatial points close to, or within the volume of interest, at least one wireless probe sensor placed on the object being tracked, and a control and processing unit. The wireless sensor has a known response or distortion to the electromagnetic field generated by the primary source. The control/processing unit uses data from the witness sensor(s) to locate the probe sensor, treating the probe sensor as a secondary source of the AC electromagnetic field; that is, as a transponder with initially known magnetic parameters.

Abstract: A propulsion thruster (10) includes a solid-fuel, liquid-oxidizer main rocket engine (11), a tank (22) of liquid oxygen, and a turbine (32)-driven pump (30) for pumping liquid oxygen to the main engine. A solid-fuel, liquid-oxidizer auxiliary engine (40) has its oxidizer input port (50) coupled to the output (30b) of the turbopump, for generating drive fluids for the turbine (32) of the turbopump. The temperature of the turbine drive fluids is reduced to prevent damage to the turbine, and the mass flow rate is increased, by injecting water from a tank (60) into the drive fluids at the output (48) of the auxiliary engine (40). Starting is enhanced by preventing cooling of the solid fuel by the liquid oxidizer, which is accomplished by applying gaseous oxygen from a tank (90) to the oxidizer input port (50) of the auxiliary engine (40).