Abstract: Information security about the CCSDS(Consultative Committee for Space Data System)recommendations is addressed, and the protection of spacecraft emphasized. The generic space mission security threats is simply analyzed. On the basis of the charac teristics of different security implementation options, benefits and shortcomings of dif ferent security implementation are obtained through comparing the impact on the CCSDS data architectures and services. The conclusion is useful to solve information security problems when space data system standards of CCSDS are applied.