Hiya Frances - well done for posting, I think this is fascinating
I don't know what spaceships are supposed to represent in dreams and medis - but it's interesting that in the dreams you are gradually mastering the craft. You are one of team and your progress is steady and positive. Have you recently started developing holistically in an area that you once thought too difficult, challenging or even a "out of this world"! If so the dreams/medis could just be encouragement for you to continue with it - that the attainable is becoming attainable if you work in accordance with others. Maybe? Just my thoughts.
Now for the wacky interpretation....
Like Mulder, I believe.

I've read a few writers over the years also who are starting to come around to the point of view that our previous soul existences could just as easily been on a another planet as from an earlier historical period on Earth. I find this interesting. I aslo met a guy in our first few months here who believes he has had abduction expriences from an early age - he is now late middle aged. He's a down to earth man with an ordinary job. Some of these experiences have been validated and shared by others. He pointed out to me that a lot of "abductees" have seemingly developed healing or psychic abilities since their experiences.... he for example now sees auras and can immediately tell if a person has had a similar experience to his own - he sees a particular light in their aura. His wife has developed a sort of medical clairvoyance and can see ailments in the body.
Coming to no particular conclusion as yet, I find this fascinating.
I'm not saying I think you are reliving an abuduction exprience - so please don't get me wrong. But I do think there is a correlation between the psychic frequency (if such a thing can be quantified) and "out of this world" experience. Perhaps during our dream time, our vibration is raised to the point where we tune in to other planetary frequencies? Perhaps, if we have had other worldly pastlives, our Higher Selves allow us to remember these when it helps with an issue/experience in this life.
An old Spiritualist trance-medium teacher of mine used to claim he channelled aliens at times. They used to find being in a human body so strange apparently that they couldn't communicate - just make him laugh - hysterically

Not sure about that one!
But anyway - now my true colours are showing - quite liberating really

Thank you for helping me let the cat out of the bag. I'd love to hear how your experiences develop.
Take care