From version 0.2 to 0.3 no migration is provided due to an engine bug at the time of this writing. I can not guarantee safety any other way.
The number of people using it is relatively low, so I'm taking my chance on this while i can.

Adds an alternative system to rockets, but mods need to set it up themselves, provides no functionality on its own. I repeat, without other mods supporting it, it will not do anything.

This was originally a part of Dea Dia (above 0.4, got extracted so I can make some progress). I wanted to change up a few things.
This is designed for planets that are very tightly linked together, avoid deadlocks and softlocks, and also to not have a situation where you have several rocket part recipes to account for that specific planet. I also spent way too long looking for edge cases that may break it.

API docs are in the data.lua file of this mod. For visuals, if someone hooks me up with a space map line renderer I can add that, but for now you need to draw on the map. Do make it a red dotted line so it matches the tooltips.
The examples for that:
https://mods.factorio.com/mod/outer-rim
https://mods.factorio.com/mod/nautical_map

You also want to set up your local materials to accommodate this. Things you don't want to be transferred should have low stack sizes to throttle them, and things you want to transport should have high ones.
Local buildings may also want to have high stack sizes, when this is written Dea Dia has no good way to move buildings between planets and that compensates for it.

You may also not add the vanilla space connection to your planets when you included this, as it can replace space platforms.