宇宙空間

1. Origins, structure, and basic meaning

• Structure: 宇宙空間 is read as うちゅうくうかん and is a compound noun for outer space beyond the terrestrial environment.
• Basic usage: It is used to contrast motion in space with motion on Earth or to name the expanse through which a spacecraft travels.

2. Common pitfalls and similar expressions

• Setting with では
  • 宇宙空間では establishes space as the setting and contrasts it with Earth.
• Route with を
  • In 宇宙空間を進む, を marks the spatial route traversed by the spacecraft rather than an ordinary direct object.