European Space Agency’s effort for providing a radiation tolerant microprocessor to be the heart of future European spacecraft computers has evolved and been demonstrated on the LEON microprocessor. The LEON architecture is based on the SPARC v8 architecture and is a continuation of the ERC32, which was based on the SPARC v7. The intention was to build an architecture that would provide similar performances to the US microprocessors, with an “open source” non-fault-tolerant version for the general European market and develop the LEON architecture for a fault-tolerant and a flight model version. The work activity would consist on the consolidation of the development environment for the LEON, to identify the weaknesses and to implement or propose future implementations to the referred development environment.