Answer:
Orbit
Microgravity
Step-by-step explanation:
A word is said to be domain specific if such vocabulary is directly related or inclined very closely to a certain subject or knowledge domain. Each subject or field of knowledge has it's own domain specific vocabulary which are only used often when speaking within the specific field of study. The passage above speaks within the context of boundaries of teh physical universe called space. Space related vocabularies include words associated with the universe and planetary bodies including cosmos, galaxy, Microgravity, orbit, the planets and so on.
The words elevator and accelerating aren't domain specific as they are widely used in other domains including physics, engineering and other fields.