Janus and Epimetheus are two small moons orbiting Saturn. They share a common orbit and have many common features. Many scientists argue that they can be remnants of a larger moon.
Basic Data[]
Janus has a diameter of 179 km, while Epimetheus has a diameter of 116 km. Both moons orbit Saturn at 151400 km in 0.695 Earth days. Their orbit lies between Mimas and the main rings. Both moons have a similar low density (0.6) and both share a similar albedo (0.71).
Their low density suggest they can be piles of rubble, small fragments kept together by their weak gravity. However, their surfaces are full with craters. A strong impact can disintegrate a pile of rubble. So, the fragments that compose them must be kept together by an additional force. There is a probability that during some impacts, part of the ice melted and glued the fragments.
Both moons are not spherical and might have a homogenous structure. With their low density and high albedo, we can conclude that they are made of water ice, with small amounts of impurities. Both moons must have high porosity and might have large caverns beneath the surface, a structure also suggested for Hyperion.
The most interesting aspect is that both are co-orbitals. They share the same orbit. Let's suppose that Janus orbits closer to Saturn then Epimetheus. At some point, Janus, moving faster, approaches Epimetheus. As this happens, their mutual gravity slows Epimetheus, forcing it to get closer to Saturn and to move faster. At the same time, Janus is accelerated and moves outwards, on an outer orbit, moving slower. As a result, Epimetheus will move closer to Saturn then Janus. With each orbit, Janus will remain behind, until the two moons will get close again. The same process will happen and the two moons will shift positions again. This happens every four Earth years, last shift occurred in 2018.
Both moons orbit in a faint dust ring, which appears to be too rarefied to affect passing ships and buildings on the surface.
Colonization[]
Because both moons are very small, terraforming is out of question. Both moons are made of water ice with small amounts of other materials, which implies that mining will also not bring much revenue, to stimulate colonization.
The low gravity allows space transport to be cheaper then on a large moon. This can be an advantage for industrial corporations that want their goods to be shipped at low costs.
There are many small moons orbiting close to Saturn. However, the inner moons (like Pan or Daphnis) orbit within rings. Other moons, co-orbitals and Trojans of larger moons (like Helene, Methone or Calypso) are very small and objects on their surface can escape into space. The outer moons are too far and too small (except Phoebe), many times retrograde.
Janus and Epimetheus have significant gravity, so that objects on their surface will not easily be lost into space. They are relatively close to the larger moons of Saturn, which allows transport to be done at lower costs. Even more, because both are co-orbitals, shipping goods between them will be very easy and cheap.
Industrial colonization seems the best alternative for Janus and Epimetheus.
Since both moons have many craters, it is clear that their surface is hard enough to support buildings. The suspected caverns that might lie beneath the surface can also be used for many purposes.
Constructions[]
Temperatures around Saturn are very low, about -140 C. The Solar Constant is also very low. Solar panels could be used, but will require to cover a very large surface. The use of nuclear generators should be a better alternative. Both moons will have large nuclear generators that will provide all colonies and industrial centers with energy and heat. The generators must be placed in an area protected from impacts, but not underground. since both satellites are made of water ice, too much heat can melt the water or at least make it sublimate.
The second thing that needs to be built is a spaceport, which will handle all space traffic. Interplanetary transport will probably be done from the larger base on Helene. Special ships will transit between Janus, Epimetheus and Helene. Other ships, with atmospheric shields, will ferry between Janus, Epimetheus and the large moons of Saturn, which can be terraformed. A third category of ships will transit between the two moons and outer moons like Phoebe, which might contain raw materials for the industrial facilities. Finally, there will be ships traveling only between Janus and Epimetheus, carrying goods and workers.
The colonies are places where people will stay. Each colony must provide living space (appartments) for workers. Some people will come for limited periods of time, while others will want to come with their families. The colonies should have some institutions, including schools and hospitals. People will require places to hangout too, varying from clubs to parks. It all depends on how many people will come and if they will come with their families.
Because terraforming is impossible, humans will live in a closed ecosystem. An air and water recycling system is vital. Also, the colony needs to have storage spaces for food, water and oxygen. These items can be stored easy in the low temperatures on the moons. Additional, human dejections, waste water and carbon dioxide can be stored in low temperature, to be reprocessed by plants and bacteria or to be shipped to terraformed moons.
Food and oxygen can be produced on the moons, in enclosed spaces. An alternative is to bring them from nearby terraformed moons, an option that will be costly.
It is possible that each colony and even each industrial corporation will have its own ecosystem. In the same time, it is possible that a large system of air, waste and water pipes will cross each moon, connecting a central recycling station with each colony and each industrial center. The second option is more expensive to build, but will be cheaper to maintain.
On and inside the moons, transport can be done by a metro system for passengers. The same rails can be used for cargo when not many passengers are traveling.
The industrial areas, located on the surface or inside the moons, will be places where people will work. given the conditions on the moons (low temperatures, low gravity and no atmosphere), it will be better to develop different technologies then on Earth. Manufacturing companies will build their items in low temperature, with machineries developed to work in such conditions. workers will most time stay in control rooms, watching the assembly lines. If something goes wrong, workers will have to take space suits before going out.
Low gravity significantly reduces production costs, because machineries don't need to support their own weight. Working in low temperatures also has many advantages, like the use of superconductors to save energy.
Long time effects[]
As Janus and Epimetheus will develop their economies, they will be economically connected. they will employ a significant working population and will have a significant economical effect on Saturn, when Saturn System will become an independent state.
On a long timescale, both moons will have a significant part of their surface and of their interiors transformed. Pollution will become a problem because, without an atmosphere, everything dumped on the surface will remain there forever.
After one or two generations, Future races will develop. The cosmic race, made of people with weak bones and not adapted to gravity, will represent a significant amount of the population.