【正确答案】 Space trash refers to those useless artificial objects that orbit around the earth. The constant collision of these objects produces even more trash in space, which not only causes huge hidden troubles to the astronautic project but also pollutes the cosmic space, and eventually brings disaster to human beings. Currently, the major methods to remove space trash are natural removing and artificial removing, both of which are not ideal. The most effective way is to eradicate the possibility that satellites become space trash from the very beginning. Only by doing so can we guarantee the sustainable development of astronautic project.