A service availability simulation for the ATDRSS space segment

A Monte Carlo service availability simulation (SAS) model has been developed as a tool to support the architecture evaluation process for NASA´s Advanced Tracking and Data Relay Satellite System (ATDRSS). The key component of the simulation is the spacecraft (S/C) reliability model which utilizes data on S/C subsystems for component configuration, reliability, and redundancy for the faithful generation of random S/C failures. The SAS logic responds to these failures to simulate the appropriate NASA responses for the launch and deployment of new S/C. The outputs of the simulation include the probability that the system meets projected communications requirements over time, required space-ground link capacity, statistics of future S/C launch dates, and number of S/C required over the system life cycle. The SAS is capable of modeling a broad set of system architectures and S/C configurations. Sample applications are described