Well, I'm gonna come right out and say this: Serenity/Firefly has some BAD science, particularly with respect to terraforming and how many habitable planets/moons one solar system can contain.
For any given star, there is a "life zone" consisting of a specific range of distances from the star, where a planet within that zone could maintain an Earthlike atmosphere... too hot, and the atmosphere boils off... too cold, and it freezes out. In our solar system, the life zone would extend as far inward as Venus (which has its own problems with too much CO2 in the atmosphere) and as far outward as Mars (which is COLD, but not so cold that an Earthlike atmosphere isn't possible). There is also the possibility of some narrow life zones around gas giants.
The problem with Serenity is that it seems like EVERY planet and moon in the system is not only within the life zone (a practical impossibility), but also has Earthlike gravity... which would imply that the worlds are all roughly the same size, including the Earthlike moons of gas giants.
Whedon should have made sure from the get-go that the limit on terraformable worlds per system is a maximum of about 3... there SHOULD be interstellar/FTL travel in Serenity. Even the Firefly series itself was very hazy on this in the opening narrations (e.g., "a whole galaxy of Earths [implies many systems]", "found a new system [singular]", etc.).
For any given star, there is a "life zone" consisting of a specific range of distances from the star, where a planet within that zone could maintain an Earthlike atmosphere... too hot, and the atmosphere boils off... too cold, and it freezes out. In our solar system, the life zone would extend as far inward as Venus (which has its own problems with too much CO2 in the atmosphere) and as far outward as Mars (which is COLD, but not so cold that an Earthlike atmosphere isn't possible). There is also the possibility of some narrow life zones around gas giants.
The problem with Serenity is that it seems like EVERY planet and moon in the system is not only within the life zone (a practical impossibility), but also has Earthlike gravity... which would imply that the worlds are all roughly the same size, including the Earthlike moons of gas giants.
Whedon should have made sure from the get-go that the limit on terraformable worlds per system is a maximum of about 3... there SHOULD be interstellar/FTL travel in Serenity. Even the Firefly series itself was very hazy on this in the opening narrations (e.g., "a whole galaxy of Earths [implies many systems]", "found a new system [singular]", etc.).