The threat of space debris on spacecraft has increased our attention to the survivability enhancement design of spacecraft. This paper studies the survivability assessment method, which has mainly two parts, namely susceptibility assessment and vulnerability assessment. Our emphasis focuses on how to assess the vulnerability of spacecraft to space debris. The basic vulnerability assessment process includes： （1） the analyses of the threat environment of space debris; （2） the process of identification of critical components of spacecraft, in which a DMECA （damage mode, effects, and criticality analysis） is introduced and an expert system is proposed to get the damage ratio of each component; （3） the spacecraft geometrical description method, in which ＂ shot line scanning method＂ is described to calculate the projected/overlapping area of components and determine the masking/shielding relationship among components; （4） the calculation of spacecraft kill probability and vulnerable area. At last, the authors conclude that the proposed assessment method is systemic and feasible, and it can give a quantitative assessment result of survivability/vulnerability in the spacecraft conceptual design. The theory contained in this paper is useful to develop computerized tool for spacecraft survivability analysis.
