Imagine you are floating in a cube in space.
Port and starboard work well with marine vessels and aircraft who often deal with such orientation issues.
I presume space personnel use similar terms to aircraft folks.
Port and starboard unambiguously refer to the left and right side of the vessel, not the observer.
Why is port-starboard terminology used in aviation?.
port/starboard, fore/aft, top/below
"You can go (left) until you hit the cube's port sideportside."