Satellites in Earth orbit are subject to a potential impact of larger space debris objects as well as to a permanent small particle flux. For the prediction of the object flux onto a spacecraft as well as for the assessment of the future evolution of the particle environment causing that flux, a conception of the quality and quantity of the current object populations in orbit is required. However, only small fractions of the actual population can be observed, either directly or indirectly. The remaining significant gaps in the knowledge are closed by the application of space debris and meteoroid models like the European MASTER model. To this end, MASTER simulates the generation process for seven different space debris source terms in detail.In a first part of this work, the theory and implementation logic of the underlying generation models for all seven source terms is documented in detail, with a special emphasise on the two considered fragmentation models and the chosen Solid Rocket Motor (SRM) particle generation mechanism. The population generation process, which is for most sources built around the processing of single events from a dedicated database, is described. This database currently contains parameters of 170 explosions and collisions, 1033 solid rocket motor firings, 16 NaK coolant releases as well as 2 West-Ford needle incidents.