Naiad is a small satellite of Neptune. It is the closest known moon orbiting Neptune and nearly the only know moon to orbit within the Roche limit.
Basic data[]
Naiad was never imaged with a high resolution enough to allow us to see surface details. It was discovered by Voyager 2 during Neptune flyby.
Naiad orbits Neptune at 48227 km, in 0.294 Earth days. It's estimated size is 96×60×52 km. At this size, estimated density is 1.3 kg/l, with a significant uncertainty.
Lack of stability[]
Naiad orbits deep within Neptune's Roche limit. So, on Naiad's surface, gravity from Neptune is stronger then moon's own gravity. A rock on the surface of Naiad, not fixed to the ground, will enter Neptune's orbit. Also, Naiad orbits faster then Neptune, which on a long timescale forces the moon to deorbit, getting closer and closer to the planet, until it will fall in Neptune's atmosphere or it will break apart into a ring.
The inner moons of Neptune are believed to be fragments from previous moons, that were destroyed when Neptune captured Triton into orbit. Some of them, like Larissa and Proteus, could be piles of rubble, loosely kept together by their weak gravities. However, if Naiad is made this way, it cannot resist Neptune's gravity and will break apart into a ring.
Internal structure[]
The fact that Naiad is still in one piece suggests that it is a single, large fragment of rock or ice. Another possibility is that Naiad has a much higher density, being made mostly of rock instead of ice.
Colonization[]
Because Naiad is very small, terraforming is out of question. The moon is suitable for Paraterraforming, mainly for Internal paraterraforming. Even that is risky, because the moon might break apart if we build large caverns inside.
If Naiad is made of rocks and not of ices, it can be a good destination for Industrial colonization. Materials that can be mined here can then be shipped away to other small moons (like Proteus), to be refined and to be used by local industrial centers.
A base on Naiad will experience major problems. Any ship needs to be well anchored to the surface, to make sure it will not end-up as a new satellite of Neptune. Settlers will live in an environment of almost zero-G, with center of gravity changing frequently between a direction and another. Any construction will need to be well fixed to the ground and the ground itself needs to be first inspected, not to break apart.
Reason for colonization[]
If Naiad has a greater mass, it might contain heavier chemical elements, which can be mined, powering-up a local economy. Naiad lies close to Neptune, making a ship require enough Delta-v to travel between Naiad and other moons. The fact that the main moon of Neptune, Triton, is retrograde, automatically implies that transport will be costly. But, it still will be much cheaper to send minerals from Naiad to Triton then it will be to send goods from the Inner Solar System.
If Naiad is just a huge block of ice and mining is not feasible, then the only reason why a colony would be feasible is to build a research facility to study Neptune. Naiad is close enough to allow detailed observations of Neptune.
Naiad could not had formed where it is now. If it is a fragment from a former moon that Neptune once had, it can tell us many things about how was the Neptunian System before Triton capture and how former moons were destroyed.