International space station leak localization using vent torque estimation

A new method is presented in this paper to localize air leaks on the International Space Station based on the spacecraft attitude and rate behavior produced by a mass expulsion force of the leaking air. Thrust arising from the leak generates a disturbance torque, which is estimated using an unscented filter with a dynamical model (including external disturbances such as aerodynamic drag and gravity-gradient). The leak location can be found by estimating the moment arm of the estimated disturbance torque, assuming that leak is caused by only one hole. Knowledge of the leak thrust magnitude and its resulting disturbance torque are needed to estimate the moment arm. The leak thrust direction is assumed to be perpendicular to the structure surface and its magnitude is determined using a Kalman filter with a nozzle dynamics model. There may be multiple leak locations for a given response, but the actual geometric structure of the space station eliminates many of the possible solutions. Numerical results show that the leak localization method is very efficient when used with the conventional sequential hatch closure or airflow induction sensor system. A user friendly computer code has been developed to find the leak location with the proposed method.