Titan (giant moon)
This article is about how advanced atomically precise technology could be used to research and colonize Saturn's giant moon Titan.
Contents
Basic facts
Size
Titan is by far the largest moon of planet Saturn. With almost the size of planet mercury he has a size sufficient to clear his orbit from other objects of similar mass. This criterion just with the sun instead of a planet as main body is used for the relatively new distinction between planets (like e.g. mercury) and dwarf planets (like e.g. pluto). It seems only natural that moons with a property akin to what discerns a planet from a dwarf planet deserve a special title too. So I'll refer to these moons as giant moons complementary to the title dwarf planet. (The titles dwarf planet and giant moon are not mutually exclusive. Plutos companion Charon e.g. takes both.) There are several other giant moons in our solar system but they alle
Atmosphere
Titan is the only moon in the solar system with a true atmosphere. In fact the atmosphere has even a slightly higher pressure than what is pressure at Earth's sea level. About 1.5 atm. A pressure very comfy for humans. The temperature is very low though ~95K or about minus 280°C (numbers rounded for easy memorization). Note that this is not much higher than the evaporation point of nitrogen 77K. So the atmosphere is just a dozen and view degrees above the point of freezing out. The low temperature probably plays a big role that Titan can hold his atmosphere despite his small gravity.
Due to the fact that the temperature is about three times lower than on earth in absolute terms the density of the air very roughly three times bigger than the density air on earth has when compressed to 1.5 bar titan pressure. That makes about ~4.5kg per cubic meter as opposed to ~1kg per cubic meter on earth. There will be significant deviations due to the nearness to the condensation point. (TODO: calculate Titans atmospheric density)
Resources
Titan is rich in hydrocarbons much of them are in the form of methane. This is pretty much an ideal form for processing in an avanced nanofactory. The methane lakes are basically seas of building material just like the atmosphere of Venus is.
In the outer solar system water is the most prevalent substance since oxygen and hydrogen are two of the most common elements in the universe and it is not hot enough that it evaporates into space. Water though does not make an ideal building material. It gets harder at very low temperatures but it still holds together just by weak hydrogen bonds. It's constituent atoms hydrogen and oxygen on their own can't be reconfigured into a stronger substance.
Transport
The ground might be soft moist and maybe even gunky at places.
Combined with the low gravity normal walking and driving might prove to be difficult.
For fast transport diamondoid gem gum rails may be installed.
Low gravity (0.14g) and high "air" density makes flying very easy. Normal air isn't a lifting gas like on Venus though.
Airmeshes form an intermediate between rail systems and flying.
Habitation
Most important is good thermal isolation.
For that some reversibly crushable atomically precise metamaterial is ideal.
Just like on earth vacuum balloons can be made. See: Robust metamaterial balloons
On titan space suits do not need do be overpressure-suits but with advanced gem gum suits that can provide normal levels of mobility even for over-pressure suits this doesn't matter much.
Water and oxygen can be taken from the environment just as organic material for food (bio-processing is not APM!).
For gravity keeping eyesight and bones healthy decently massive stable centrifuges are needed. Given sufficient energy advanced APM has the capacity to produce those quickly.
Energy
Solar
Titan receives very little light at Saturns distance from the sun. Then there is a haze layer high up in the atmosphere that filters even more from that light.
Autonomous solar energy collecting airships in high numbers could collect some energy for small initial colonies. While individually very low energy and slow combined they can provide useful levels of energy. This won't work for global scale colonization though.
Space solar energy import may be an option. Either locally with very big collectors of far from the inner solar system like e.g. excess energy reflected away from Venus. Quickly switchable planetary scale energy sources might cause difficult/dangerous situations though political and on political level and technical failure risk level.
Cemical
There's no free oxygen on Titan so conventional combustion engines on titan would work in reverse with oxygen that needs to be pre-produced. Instead of a combustion engine with advanced atomically precise technology one will do something different but for the sake of it let's look at how a combustion engine would work there. You'd need to carry around liquid oxygen (which does not need much chilling/pressurization at the present ambient temperatures) and burn it with the there omnipresent methane (the equivalent to air humidity on earth). The exhaust would ultimately produce a lot of snow and ice (water sand and gravel).
Some energy might have accumulated in the organic dunes of Titan from the high molecular weight organic compounds raining down from the upper atmosphere. There incoming UV light activates/splits methane & co which then can recombine in higher energetic forms. If this is enough to be usable it could provide energy for a while.
Wind
Some slight winds might concentrate the little solar energy that falls on Titan. Airmeshes could be of use.
Nuclear
Since energy is rather scarce on titan using nuclear energy sources is very tempting. But this is probably a rather bad choice. Titan has the excellent benefit of a thick atmosphere that shields perfectly against the harsh radiation of space. Combined with the fact that the ground mainly consists of light and thus predominantly non-radioactive elements Titan might have lower radiation levels than the natural levels on earth.
With Titans very active weather system radioactive spills will quickly spread on a global scale and thwart that unique benefit titan has to provide too us. Especially tritium seems bad. Liquid methane probably does not dissolve cesium and iodine very well which is good but tritium (radioactive hydrogen) when it doesn't fly around freely gets built in both the water and the hydrocarbons that is everywhere. Titan is rare of heavy elements so fuel for nuclear fission needs to be imported from somewhere. Possibly earth or later from metal asteroids of the main asteroid belt between mars and Jupiter. One option is to produce energy with immature and unsafe nuclear technology safely in space and then import it down to titans surface chemically via (many) space elevators.
Titan has lots of water and possibly also lithium (since it's a light element less prone to sink to the giants moon core) so nuclear fusion seems a natural choice. If the AP technology is at a level that makes 100% tritium tight fusion reactors possible then this should be fine.
Geothermal
There is enough tidal heating on titan that a global subsurface ocean is suspected. Maybe ~0°C water "hot springs" can be tapped.
Fun / Sports
On titan with low gravity 0.14g and high density atmosphere 4.5kg/m^3 it should be possible for humans to fly just with muscle force. Going too high up and taking a dive might be dangerous though.
