"广阔无垠的空间" can be translated into English as "vast expanse of space" or "boundless expanse of space".
Both expressions convey the idea of an extremely large and seemingly limitless area in space. Here are some examples of how these phrases might be used in a sentence:
The telescope allows us to peer into the vast expanse of space, revealing countless stars and galaxies.
Astronauts often describe the feeling of floating in the boundless expanse of space as both awe-inspiring and humbling.