In my world there exists a planet called Solara Prime. The planet orbits a large yellow star, healthy and capable of sustaining the system. There is one planet and 4 moons whose orbits are roughly perpendicular to the star.
The smallest moon is roughly 6000 miles in diameter and has a similarly sized counterpart on the far side of the system, both roughly 750,000 miles from the planet. The closest moons are roughly 12,000 miles in diameter and 250,000 miles from the planet. The planet itself is roughly 24,000 miles in diameter and 95 million miles from the sun. The planet and its moons rotation, axis, and orbits allow atmosphere and for human habitation on all 5 planets.
All of the moons are habited, organically; that is they didn't colonize from the planet. Each of the moons and the planet have thriving societies of one type or other. Additionally, they have all figured out there are people on the other moons and planet.
Here's the question: Knowing there are people in relatively close proximity on other worlds, how would space travel have developed relative to what has happended here on earth assuming current level of technology and the fact there are 3× as many people? That's very broad so here are some smaller questions to support it?
- How long would it take to create a craft that could safely traverse planet to moon, moon to moon, ?
- How long would it take to create a reusable craft capable of traversing the entire system?
- Which force would be the greatest driver - trade, war, unification?
I have my own ideas about these questions, but am struggling to adequately describe the priority and time frame involved in the history of the worlds leading up to where they are now — regular, though expensive, space travel for leisure, business, trade, etc.