人们把宇宙空间的角逐称为“第四战场”。随着空间技术的发展,世界各国特别是苏美两个超级大国用于军事目的的外层空间开发不断升级,宇宙空间经常出现一些神秘的“不速之客”,各种人造天体频繁地升空和回收。宇宙空间的角逐强烈地吸引着众多的业余爱好 People call the race in space a “fourth battlefield.” With the development of space technology, the development of outer space for military purposes by countries in the world, especially the two superpowers in the Soviet Union and the United States, has been constantly escalating. Some mysterious “uninvited guests” often appear in the universe, and various man-made celestial bodies are frequently launched and recovered . The competition in space strongly enthused many hobbies