Other players can instantly start mission in my Railjack?

[(PSN)Unstar]

I did my first successful mission in my Railjack today with a random group that was assigned to it.  After the mission the Railjack was brought back to my Dry Dock.  I got out to look at the loot I got and see what I could do with the upgrades.

Then all of a sudden, without warning, I was teleported back into the ship and it set out into a new mission.  I saw one of the other players in the team standing at the Navigation in my Railjack, and I assume they chose a new mission.

I didn't want to go on a new mission yet though.  And unlike a normal Warframe mission selection, it didn't ask me if I was ready or give me any sort of countdown.  That would have at least given me time to abandon ship.

But more than that, I'm not sure why others can start a mission in my Railjack.  I wish they couldn't do that; it's my ship, I put a good deal of work into making it, I feel like I should decide whether it (and by extension me) goes on a mission or not.  But at the very least, I'd like to have the option to not go on a mission if I don't want to.

Edited December 22, 2019 by (PS4)Unstar
clarified that those starting the mission were players, not NPC's