The concepts of transient fault handling in the MARS architecture are discussed. After an overview of the MARS architecture, the mechanisms for the detection of transient faults are discussed in detail. In addition to extensive checks in the hardware and in the operating system, time-redundant execution of application tasks is proposed for the detection of transient faults. The time difference between the effective and the maximum execution time of an application task is used for this purpose. Whenever a transient fault has been detected, the affected component is turned off and reintegrated immediately by retrieving the uncorrupted state of the actively redundant partner component. In order to reduce the probability of spare exhaustion (in the case of permanent faults) 'shadow components' are introduced. The reliability improvement, which can be realized by these techniques, is calculated by detailed reliability models of the architecture, where the parameters are based on experimental results measured on the present MARS prototype implementation. >