One of the most common questions about Surviving Mars is "How do you connect domes to each other?". The answer is: You don't.
In a surprisingly obvious oversight in game design and gameplay mechanic, the team behind Surviving Mars decided to deny any way to connect domes, both literally and logistically. Not only there are no walkways, corridors, or tunnels to connect domes, colonists are completely incapable of leaving their dome and saultzing over to a neighbour's to get a necessity met -- if there is plenty of food in the dome outside their house but none in their own, they will damn well starve to death.
This not only severely limits creativity -- as every dome must always contains the exact same configuration every time -- but it also makes no sense; we're able to send a space rocket to Mars and terraform its atmosphere, but commuting 50 steps to another dome is an insurmountable endeavour.
Luckily, this is a guide, and while we can't teach you how to connect domes until Haemomint and Paradox actually adds it into the game, we can teach you how to make them at least somewhat inter-dependable.
Surviving Mars: Connecting Domes Guide
Again, you can't do it in the logical, ideal sense of the word, but you can sort of do it by careful placement of a few specific buildings.
Mines and factories are all located outside domes, allowing you to overlap their areas of influence to get colonists from both bubbles working in the same place.
Shuttles can also be used to transfer resources and colonists between domes far away, though it is more the equivalent of a courier service than a commute system -- colonists will not go far out to another dome to work, then return to the original one to sleep: They straight up live and work somewhere, or they don't.
Lastly, domes do get bigger as you progress in the game and unlocks them via research, allowing you to offset the small space restriction at the start of the game. It's not a connection solution, but it helps a bit.
We'll update this guide depending on what content updates the game gets, but unfortunately, until the developers properly add the ability for domes to interact with each other (and fix the terrible colonist management system), Surviving Mars may never achieve lift-off.