【摘要】 <正> 航天事业在20世纪已取得显著进展和辉煌成就。21世纪即将来临。在21世纪,世界航天如何发展、将取得哪些重大成就,是人们关注的话题。为此,笔者根据有关材料汇编了这份材料,以供参考。共4讲,第一、二讲已刊登在本刊1998年第4期,下面为第三、四讲。更多还原

【Abstract】 Space cause has been rapidly developed and has achieved obvious successes in the 20th century . Now , it is a striking subject how to develop space cause and how many successes will achieve in the next century. This space lecture will give you an answer. The lecture is divided into four lessons. The first half which includes lesson one and lesson two was published in the last isue of 《Spacecraft Recovery and Remote Sensing of 1998》.Here is Lesson Three and Lesson Four.更多还原