In one science-fiction novel, there was described an alternative to terraforming icy planets and moons. The idea is that during terraforming process, only a limited amount of ice will be melt, the remaining ice will be protected from melting by an artificial layer that will insulate it. This model can be sometimes a better alternative then the use of Artificial Continents.
Major problems while terraforming icy planets Edit
Icy planets and icy moons contain a huge amount of water. They are covered by a thick layer of ice, that might sometime cover a subsurface ocean. By heating the ice, you will get an Oceanic Planet.
It is known that in many cases the ocean below ice might be toxic for Earth - type life. For example, Titan has a subsurface ocean that might be as salty as the Dead Sea . Also, data from Cassini reveals that the underground ocean of Enceladus is alkaline and thus not friendly for Earth life. If we melt the ice, salts from the ocean will reach up to the surface and will threaten our new ecosystems.
On an icy world, like the moons of all gas giants, the amount of energy received from the Sun is small. With the help of greenhouse gasses we can prevent heat from escaping, but since the incoming radiation is small, it will take much time until we get the ice melted. Nobody might want to wait for millennia for the ice to melt.
A look inside an ice planet Edit
As far, we have studied all major icy moons orbiting the four known gas giants and also Pluto. We have learned a few interesting things:
The ice that covers them is not just water. It is in fact dirty water, like the snow on Earth around a city. The dominant component is water, but there are many other things: solids (silicon, salts and other solid compounds, carbon dioxide and other solidified gasses, organics).
The vast majority of icy bodies appear to be differentiated. So, they have a solid icy crust, followed by a subsurface liquid water ocean. Below the ocean, there is a core of solid rock and beneath it, there might be an inner core with heated, liquid materials. In some cases, the core might have cooled enough and is entirely solid. Also the ocean might have cooled and is completely frozen.
NASA's Dawn spacecraft discovered that Ceres is partially differentiated . This means that Ceres's interior is not completely separated, its inner core was never heated enough to be liquid and its mantle did not separate completely. Instead of a subsurface ocean. Ceres actually had a salty muddy mixture with water.
Also, there are experts that say an icy body can exist without being differentiated. It is speculated that Calisto has an undifferentiated interior . It is strange how a large body like Calisto could have formed without producing enough heat to separate its water into an ocean. If this moon really is a mixture of rocks and ices, then we have to re-consider many of our theories and acknowledge that we might be wrong.
The terraforming of an icy body with the use of ground insulation would require the following steps:
The first phase should be heating the planet (or moon). In this step, the use of greenhouse gasses should gradually increase temperature up to a level where ices start to melt. Gasses that are frozen or trapped in the ice will start to evaporate and form an atmosphere. Water ice will also melt and create the future oceans.
As the process goes on, solid particles will accumulate on the bottom of the future ocean. If they are in enough quantities, they can become future continents.
As the process keeps going, liquid water will accumulate on the surface. Since water is heavier then ice, ice fragments will crack and reach the surface. As the process goes on, another thing will happen. It is seen in Greenland that in summer, melting water on the ice caps form lakes that are getting deep very fast, until they reach the bottom of the glacier. Also, icebergs from below will climb to the surface. This is the point where the insulation layer will be needed. If not, water will gradually find its way down to the subsurface ocean or to the core of the planet.
Ground insulation Edit
To limit the melting process, at some point, an artificial layer must cover the ice and separate it from the above ocean. But what material can do that and on a planetary scale? It is known that many icy planets have organic molecules and many ingredients needed for life. Maybe some genetically modified bacteria might be just what we need. In the same way corals on Earth create the huge coral reefs, this artificial bacteria might be enough to build a global insulation layer. The layer must be thick enough to prevent deeper ices from melting for a lengthy period of time (at least 1000 years) and soft enough to accommodate with long-lasting tectonic movements.
If the planet is not differentiated, then it consists of a mixture of ices and rocks. In this case, the existing solid rocks can be used as a natural barrier, therefore reducing the surface that needs to be insulated.
If the planet is differentiated, then on the surface and melted ice there will be a limited amount of solid rocks. In order to create continents, we can do two things: we can divert some of the newly melted water towards the subsurface ocean or we can send it into the outer space. The first technique might be cheaper, but can result into quakes and volcanoes. The second option is more expensive and might create a ring of icy debris in orbit.
Once the insulation layer is in place, terraforming can be continued.
After terraforming Edit
The insulation layer is not 100% proof. There are many threads to its integrity:
- At the beginning, it might be elastic, but over time, it can become rigid and might crack.
- Planetary seismic and tectonic activity might break the insulation layer.
- It is impossible to check the integrity of the entire layer. Some pores might exist even during its formation.
- Corrosive substances can affect the layer over years. These can be man-made chemicals, natural occurring substances (like carbonic acid) or something in the ices below.
A maintenance team will always be needed to survey the insulation layer.
However, after some time, heat from the ocean will eventually reach through the insulation layer. If the insulation is prefect, over time, heat from the planet's interior will slowly melt the ice.
After some time, as heat from the surface reaches the ice, first will the gasses evaporate and create bubbles that in the end will escape through the layer. Then, slowly, water pockets will accumulate. They will slowly migrate downwards, creating deep cracks into the ice layer. Finally, at some point, the insulation layer will be damaged up to a point where repairing is too expensive. The planet will be a Short Lived Earth, but it might be just enough to give us a new environment for a few centuries or millennia.