"the astronauts walked in outer space without a tether"
"the first major milestone in space exploration was in 1957, when the USSR's Sputnik 1 orbited the Earth"
outer space的用法和样例:
例句
The space shuttle will orbit a weather satellite. 太空梭将把一个气象卫星送入运行轨道。
Living in space is not an impossible dream. 在外太空居住不是不可能实现的梦想。
Outer space is the common wealth of mankind. 外层空间是全人类的共同财富。
The two space vehicles docked in space and exchanged astronauts. 两个宇宙飞行器在外层空间对接并交换宇航员。