It is possible to generate oxygen from silica and water, which are the primary components of Titan. By introducing enough Oxygen, it may be possible to allow humans to breathe on Titan without much modification, besides adding an immense amount of heat through greenhouse gasses such as:SF6 . However, SF6 poses two main problems. Firstly, Fluorine, the main component of SF6, is relatively rare. Also, SF6 freezes at −64 °C, whilst the mean temperature of titan is -179.15 °C. That means that any SF6 added without warming Titan previously, would fall down as snow. Another possibility, is to add NF3 instead of SF6. It is somewhat easier to do, as the atmosphere of Titan is almost entirely composed of nitrogen. Any F2 released into the atmosphere would react with N2 and form NF3. However, that does not eliminate the need to search for fluorine. Unlike SF6, NF3 is not inert. Also, NF3 is liquid at -179.15 °C.
Titan’s crust is completely ice frozen to the point where it becomes similar to land. Underneath this is potentially a liquid ocean, and underneath that is an ice mantle. If the temperature raised to allow for liquid water on the surface, either floating platforms would have to be established, or potentially the establishment of artificial continents. The latter would be very difficult as you don’t get to silicon or any other similar substance till you get to the core (which itself is silicon oxide).
This would also rule out importing of all terrestrial lifeforms as well as the vast majority of aquatic ones which somehow rely on the sea floor (unless you build an artificial one).
- Surface temperature (mean): 134 K ± 11 K
- Escape velocity: 2.440 km/s
- Equatorial surface gravity: 1.235 m/s2 (0.126 g)
-Surface pressure: 7.5 pbar
The terraforming of Callisto would be very difficult with current technology. Nevertheless here’s one theory. The terraforming of Callisto would require vast amounts of nitrogen gas to be deposited or created as its buffer gas; bacteria can help add nitrogen by converting ammonia found on Callisto’s surface into nitrates, then nitrogen. After this, the entire Earth’s supply and reserves of a potent green house gas, say Sulfur Hexafluoride would have to be sent to Callisto. As Callisto has a relative abundance of water-ice, terraforming might not be as difficult as it seems. After the greenhouse gases begin heating Callisto, the water would melt to form oceans (The Oxygen part of the atmosphere could be created by electrolysis of some of this water). Another advantage with the moon is the low radiation levels it receives, making a magnetic field, or the move of its orbit, unnecessary to the terraforming process. Callisto’s day is over 16 times longer than Earth’s, so its atmosphere would have to be thick enough to distribute heat from the day to the night side.
The other theoretical plan, however, is more practical. Because Callisto is farther away from the sun than the Moon, it would be less problematic for Callisto to hold an atmosphere. The best way to create a stable atmosphere, is to fill it with heavy inert gases (Xenon, Krypton). However, those gasses only exist in trace amounts throughout the Solar System, so the only possible way to create them in great amounts, is via nuclear fusion. That, however, is beyond the current technology.
If we do create a stable atmosphere above the Armstrong’s Limit, our next challenge would be warming up the satellite. The strongest known greenhouse gas is Sulfur Hexafluoride. Sulphur is relatively common in the Solar System. It is abundant on Io, wich is also it the Jovian system. Fluorine, however, is quite rare and it makes up most atomic mass of SF6. For that reason, we cannot rely on SF6 alone.
It is theorized, that below the ice, Callisto holds “bubbles” of Oxygen and Hydrogen mixture. If those were reacted with carbon, than they would form CO2 and CH4 respectively. Both are greenhouse gases. It is also theorized that Callisto contains large amounts of Ammonia ice, which is both a source of nitrogen, and a powerful greenhouse gas at the same time. Oxygen, if needed, could be easily created by electrolysis of water.
If we bring the surface temperature above the melting point of water, then our next problem would be the lack of a solid surface; about half of the mass of Callisto is ice, and it is very reasonable to believe that having melted, it would cover the whole surface of Callisto with a global ocean. Constructing artificial continents is very impractical. It is much easier to build small floating bases.
Europa is an icy satellite of Jupiter. Terraforming Europa would be far easier than Io, Mercury and Venus, but much harder than Mars. This satellite would first need a new thick atmosphere. The atmospheric pressure would have to be around 7 bars. Most importantly, Europa is within a huge radiation belt from Jupiter. The building of radiation deflectors around Europa would currently be highly impractical. Europa would have to be heated so it can support liquid water on its surface. The problem is that if Europa reaches the shadow of Jupiter, it can freeze again. A few hundred tons of Sulfur Hexaflouride, the most powerful greenhouse gas could keep terraformed Europa warm. The new atmosphere of Europa would have to be composed of 70-79% nitrogen, 19-29% oxygen, and 1% of water, carbon dioxide, hydrogen, argon, methane, ammonia, and sulfur hexaflouride. After the ocean fully melts, Europa would most likely need artificial continents due to the fact the moon has vast amounts of water and a rocky surface would be deep within the ocean. From sunset to sunrise, a night on Europa is about 1.78 Earth-days, so during this time colonists may likely need to retreat underground until the return of day. Another method would be to move Europa’s orbit so the tidal heating is stronger and would melt the ice, the oceans and the atmosphere would retain the heat. You would have to add an atmosphere before the ocean is exposed to the vacuum of space and you would also need a magnetosphere, this would be made as a byproduct of the tidal heating as the flexing moon jostled about the magma creating an internal dynamo.