Spacecraft Contamination Analysis-A Possible Application Of Modern TOF-SIMS

The problems of spacecraft contamination cause greatly the worldwideattention with the request for long lifetime and high reliability on spacecraftincreasingly. To decrease or even prevent spacecraft contamination, it needsto know causes of contamination, such contamination components, mechanismof contamination, materials causing contamination and so on, in whichdetecting the spacecraft contamination components is an important one. It isobserved that Time of Flight-Secondary Ion Mass Spectroscopy (TOF-SIMS)is developing quickly these years. It has powerful analytical ability, and iswidely applied in many fields. Combing the problems of spacecraftcontamination in our country, TOF-SIMS is tried to study it, analyze thespacecraft contamination components, and provide the reliable scientificevidences for concluding contamination sources.Three typical samples of spacecraft contamination, which collectedcontamination from Chinese space simulation system on ground, were used tostudy spacecraft contamination components. It was studied at three aspects inthis paper: by practical analysis experiments, the analytical ability of severalanalysis techniques was studied on tiny amount of spacecraft contaminationcomponents;by interpretation of mass spectra for contamination of elementsand compounds, the analytical ability of spacecraft contamination componentswas investigated by TOF-SIMS;by interrelation of positive and negative ionimages of components, surface distribution of spacecraft contaminationcomponents and their possible delamination information were researched byTOF-SIMS.By experimental study in this paper, the results show: because modernTOF-SIMS possesses the high sensitivity and the ability of parallel massdetection and it does not need any pretreatment, it can effectively detect tinyamount of surface contamination components;because it possesses high massresolution and high mass accuracy and it can analyze all kinds of elements,isotopes and compounds, it can fingerprint spacecraft contamination by whichtheir possible sources can be concluded;because it possesses high lateralresolution, surface distribution and possible delamination of all kinds ofcontamination can be obtained to reveal the possible formation process forparts of contamination. Therefore, TOF-SIMS is a powerful analyticaltechnique detecting the components of spacecraft contamination. Nevertheless,there are also some faults: because of its high sensitivity, the device speciallysampling and preserving samples is needed;on account of the universality ofmaterials concerning spacecrafts, special database of mass spectra is needed;for the study is rough, the depth profiling mode of TOF-SIMS is needed toprove analytical results of surface imaging.This paper was fulfilled under the program, "discussion on analyzingspacecraft contamination components by modern mass spectra technique,"supported by Chinese Aerospace Innovation Fund. The established target wasachieved under cooperation with Beijing Institute of Spacecraft EnvironmentEngineering, China Academy of Space Technology.