Before We Leave

I would suggest saving this one till you have completed most of the game. You more than likely will not get this naturally unless you've played the game a fair amount and set up trade networks with multiple spaceships. I was still short by about 40 spaceships.

This achievement can be obtained by reloading a single game save multiple times.

I loaded a save from a game that had a well established island with more than 30 peeps. It already had one launch pad. I built 2 more launch pads. (You can build more if your island can support them.) I started construction for a trade spaceship at each of them. Set the priority for each to "high" so that workers will focus on working at your launch pads.

Monitor the construction of each ship. When a ship is nearing completion, pause construction on that ship. (The final phase of construction is to load 30 fuel.) When all ships are paused near completion, make a game save. Unpause all ships and let them compete loading the fuel and crew. Once you have been notified that all spaceships are ready, then reload your save. Rinse and repeat until the achievement unlocks.

You do not need to launch them. I was launching them all, but my achievement popped while they were still sitting on the launch pad.

Trade spaceships require 40 wood, 15 steel, 10 glass, 10 tools, and a source of power for phase one of their construction. Phase two requires 30 fuel and a crew of 10 peeps. You pause the construction for each individual launch pad by clicking on the pad, then at the top of the box that pops up is a green pause button. You prioritize buildings by clicking the up arrow just to the left of the green pause button.