After Creating An Atmosphere, the second step in terraforming is adjusting temperature. This process does not stop until the planet or moon is completely terraformed. Depending on conditions, temperature is adjusted using different methods and different timetables.
Outer planets Edit
On an Outer Planet without a significant atmosphere, many gases are trapped in the icy crust. If we melt the ice (partially or entirely), we can create an atmosphere. However, majority of Greenhouse Gases freeze at -100 C. In order to terraform the moons of Jupiter, Saturn, Uranus, Neptune and Kuiper Belt dwarf planets, we need to work in a different way.
The first step is to divert a comet and impact the planet. The comet will be vaporized and many gases at the impact site will boil. This will create a tenuous atmosphere like the one around Mars. Before it freezes, we have to deploy large amounts of greenhouse gases. It is better if these gases are prepared and stored on the planet before the impact. To see how much we would need, see Greenhouse Calculator.
As temperature increases, more gases will escape from the crust. In the end, water ice will also start to melt, but before this happens, we will see many gas plumes erupting from the surface.
If the planet already has an atmosphere, an impact would still be needed to increase temperature to the point where greenhouse gases don't freeze. Above that point, we can deploy large amounts of these gases to increase temperature.
To melt, water needs 333.55 kJ/kg, while the Sun, at Earth's orbit, gives 81.65 kJ/m2/min. However, given Earth's rotation and reflected radiation, only about 35 kJ can be used. Still, this is enough to melt a layer of 1 mm ice in a minute. By doing the math, one can see that in an Earth day solar radiation can melt a layer of 1.4 meters and in an Earth year a layer of 511 meters.
Things will not be the same for all planets and moons. The further we are from the Sun, the lesser will be the energy received:
- Mars: 62 cm melt daily and 220 meters melt in an Earth year.
- Ceres: 18 cm melt daily and 66 meters melt in an Earth year.
- Jupiter: 5.2 cm melt daily and 19 meters melt in an Earth year.
- Saturn: 1.5 cm melt daily and 5.6 meters melt in an Earth year.
- Uranus: 3.9 mm melt daily and 1.38 meters melt in an Earth year.
- Neptune: 1.6 mm melt daily and 56 cm melt in an Earth year.
In addition to all this, before melting the ice, we have to wait a long time for the ice to heat up to zero C.
One can see how long will this process will take. For Europa, assuming a crust of 10 km thick of ice, it will take 526 years to melt it. The same crust, at the orbit of Neptune, will require 18000 years to melt. But if the crust is over 100 km thick and the subsurface ocean is completely frozen, heating it up with solar energy is simply not feasible.
Another problem is that, as melts, water is heavier then ice. It will tend to infiltrate through cracks into the surface. The first water will simply vanish. And given the low rate of melting on an icy moon, the water will melt the ice below and will create a moulin, or a vertical cave reaching in the end to the subsurface ocean.
Making an oceanic planet Edit
It will take millennia to heat up and melt all the ice of an outer planet. However, we can use alternate methods to bring heat:
- Impact the planet with diverted asteroids
- Use of atomics or other artificial technologies to heat-up the planet
- Stimulate volcanism by bombarding the sub-ocean rocky crust.
Using part of the crust Edit
The use of ground insulation is a good solution if we want to save time. The idea is to build a planetary scale thermal insulation and to cover the crust with it. Above the insulation, we can place soil and ice to melt, while below it, the ice will remain frozen for a long time.
Later adjustments Edit
As the atmosphere is changed and plants cover the planet, greenhouse effect will be lower. We will need to add greenhouse gases again.
Fire flood and Noah flood scenarios Edit
Some planets like Venus are in a runaway greenhouse effect. Other planets will enter the same phase once we divert comets and icy moons to replenish their atmospheres and oceans. As we do this, temperature rises to high values, where all water is a gas or a hyperfluid. In this scenario, temperatures reach above 450 C and stay high for a while. If the runaway greenhouse effect is artificial, we call this a Fire Flood
Then, at one point, we add micro helium balloons to cool them down. Temperature drops and the water starts condensing. This is a Noah Flood. The process is violent and is followed by a sharp decrease of greenhouse effect. The planet would end up in an ice age unless we remove part or all balloons. This can be achieved easily if we make them to have a short half-life. With other words, balloons will disintegrate just when they should.
Later, as we do Ameliorating The Atmosphere, carbon dioxide will be transformed into oxygen and Atomic Carbon, lowering the greenhouse effect. Also, when we insert plant life, temperatures will continue to drop. To counter these events, we need to increase the greenhouse effect by removing Micro Helium Balloons or adding Greenhouse Gases.
Other scenarios Edit
Small celestial bodies like Luna cannot support a fire flood. Their low gravity will make a significant part of the hot atmosphere, saturated with water vapors, to escape into space. There, we have to adjust the temperature carefully. adding water and gases will be done gently, without causing a runaway greenhouse effect. And again, in the last phases, when carbon dioxide is transformed into oxygen and plant life is inserted, we have to add a mild greenhouse effect to maintain an optimal temperature.
Maintaining the best temperature is critical in all terraforming scenarios. No other process can be done without this.