Abstract : In this thesis, we study the development and the validation of asynchronous real time systems. We choose to use the language AADL for its specificities issued from the avionic industry, and for the precise description of its execution model. This thesis is divided in two main parts. In the first part we study the use of AADL as a support for the development of satellite flight software. In a second part we present a reduced version of AADL and the formal definition of its execution model. The objective of the first part is to demonstrate that AADL can be integrated in an existing development process of the spatial industry. In this part, we have identified several patterns used in the conception of flight software In the second part we define a mini-AADL enough complete to express most of the current concepts of real time systems. The formalization part of the execution model is mandatory for the validation of dynamic properties. This formal description allow to describe the behavior of AADL models. This description can be used with a model checker to animate AADL models and validate dynamic properties.