An oceanic planet (or satellite) is a habitable body having all its surface covered by Water. Oceanic planets might already exist or they can be a result of terraforming.
Many celestial bodies can contain too high an amount of water. They will look like an endless ocean. Many scientists have theorized ocean planets to exist around stars. Terraforming processes can transform an ice-covered world into an oceanworld. Depending on what their parent star is, on their orbit and distance and on Geographic features, these worlds can be or not a good destination for future settlers.
Oceanic Earth Edit
Imagine a planet orbiting at the Comfort Zone, the best orbit in the Habitable Zone of a star. The main difference is that this planet, similar to Earth, has no piece of dry land. This is how Earth would look like if the oceans were 10 km higher then they are today. Mount Everest will be 1152 meters below sea level. In some places, water will be over 20 km deep.
Climate and life Edit
In such an environment, hurricanes will continuously form close to the equator and slowly migrate to the poles. The atmosphere will have a higher humidity coefficient. Even so, there will be many sunny days. Waves will move on forever, probably higher then they are on Earth oceans. Tides will also be higher because there is no land to stop their movement. On Earth, America is oriented North-South and blocks the tides to circle. A tsunami will also circle its waves over the ocean. But, since there is no land above the sea, there is no reason to worry about tides and tsunami forces. Close to the poles, ice will form, but it will be pushed away by global currents. Depending on how tilt is the rotation axis, winters will be harder and will create larger or smaller icebergs.
Oceanic plants will love this place and so will fish. But there will be a major problem. Without a bottom or a reef, the density of life will not reach very high levels. The largest amount of vegetation will be found around human buildings. Birds and mammals need some kind of land surface to rest and breed upon. Artificial islands can provide them with the needed shelter, while structures floating just below water will be useful for fish, corals and plankton.
At a low technological level, settlers will have to live all their lives floating on the ocean. Stronger waves and hurricanes will be a big problem for floating cities to form. However, at some depth (for example 30 meters), the sea is more peaceful. We can imagine settlers building their homes below sea level, in submarines anchored by the ocean floor and with permanent contact with the surface to provide them with fresh air. In this scenario, high mountains will be chosen for larger cities, since they are a better alternative to set anchor.
For sea lovers, this will be a paradise. They will live all their lives in or under water.
The economy of an oceanic planet will be different from what we have on Earth. Food is grown and harvested in water. We can conceive that the main source of food will be fish, probably combined with some algae. Sea birds will only live around human settlements because they need dry land to rest and breed. So do sea animals. Settlers will have to create artificial islands for wild life. Some islands must be considered reservations, while others will provide food. Industry will also be different. It will be easier to build structures under water than to use existing ships. Water can contain a lot of minerals and some of them may be extracted and used. Underwater mining is difficult at depths of over 1000 meters, so in many cases settlers will need to bring their raw materials from other planets. Also, pollution will be a problem. There will be no place to dump waste.
Every floating city will be exposed to waves and currents. So, a big structure must be flexible enough to survive. Will a huge city like New York survive? It will need many adaptations to do so. First, there will be no sky-scrappers, because they will have no foundations to be built upon. More than likely, buildings will grow downwards and not upwards. Every building must be anchored to the other ones and probably also to the ocean floor, in order to keep it in a fixed position. Waves and currents will move each structure. Some unused space is needed to avoid collisions. And because we are building below water, security is very important. On a sky-scrapper, a broken window will only allow wind to enter, but on an ocean-scrapper, it will generate a flood, possibly causing the whole structure to sink and taking also other buildings by their anchor cables. Another challenge is that we cannot protect the city from waves and rains. Building a dike will simply not work because water pressure is transmitted through the depths. Waves will simply move through below the dikes. Excess rain water will be a risk of sinking. It looks more logical to build structures that are not so high, so that water will just flow over them when this is needed.
In addition, free-floating towns could exist. Smaller, they can be driven by currents or they might have an engine, to move to chosen destinations or to keep them in place.
Transportation will also be a challenge. An oceanic city will face strong waves and will not be safe from hurricanes. First, it would look like boats will be the best way to move around, but when the weather turns bad, submarines are the best solution. They are unaffected by waves. Convertible boats, able to submerge, will be a good invention. Flying is also a good way to move around.
Commerce will be important and can be included into a global network. On Earth, the oceans are the major trade ways of goods. If the planet gets split into many states, an embargo will not affect people like on Earth. There will always remain a navigable route. The extreme deep waters are opened paths for submarines. More difficult will be to exchange cargo with the cosmos. A spaceport will be harder to construct because there is no ground foundation. Floating or submerged bases will need to be far larger then a transatlantic. Exposed to strong currents and waves, they will need to be extremely strong to resist. Another option is to build many bases that will become a spaceport. Because currents occur, position of each base will slightly change, so spaceships must adapt their trajectories.
Tourism can be found on oceanic planets. In fact, on Earth, almost all tourism is done around the sea. However, tourists will not find paradise islands. Every island will be in fact floating on the sea. A resort station might have many floating islands, arranged each day into a different way. Tourist clubs might organize trips with their islands instead of boats. Below the sand and the palm trees found on surface, visitors will find exotic clubs, casinos and hotels awaiting them. And when they will look on the window, they will see fish.
Other models Edit
Despite the model shown above, many others might be created by terraformers:
Hot oceanic planet Edit
By taking the oceanic world closer to its sun, temperature will rise. Without a shield to protect from solar heat, oceans will warm. At the equator, temperatures can reach extreme values, but at the poles it will be similar to the Mediterranean Sea. If the planet has a very tilted axis, settlers will need to migrate between poles to keep at the right temperature.
There is a limit up to where an oceanic planet can exist, the point where water starts to boil at the equator. Beyond that point, water vapors will create a runaway greenhouse effect and will transform the planet into a new Venus.
Extreme climate on an oceanic planet Edit
In case of a Low - spinning planet or a planet with an Elliptical orbit, temperatures will change to extreme values. Water modulates heat better then land, making winters warmer and summers colder. However, if the day or the night lasts for too long, this is what will happen:
- If temperatures don't exceed too far away borders, during day, temperature can rise to above 40 degrees C. If the air is moisture, it can be unbreathable. Then, during night, temperatures will drop below freezing. When ice gets formed, it creates an insulation. So, the air receives no further heat from the ocean and cools faster. Then, ice reflects light and keeps the air cool. However, currents can bring new warm water or can take the ice to a warmer place. So, settlers will have to stay below the surface, where temperatures remain comfortable during the extreme weather.
- If temperatures get beyond limits, like in case of a Tidal Locked Planet, some extreme features will be seen. Temperature can reach too high values, so that water starts boiling, creating violent storms on its way. On the opposite side of the planet, temperatures drop to values like -150 C and below, making oxygen to freeze. This will generate very strong oceanic and atmospheric currents, trying to mix the air and water.
Please note that planet size is very important. For a small, low - spinning planet, its reduced size makes more easy for water to circle around.
Outer oceanic planet Edit
Settlers can use greenhouse gasses to increase temperature on an Outer Planet. This is probably the fate of many moons of Jupiter and the other gas giants. When temperature rises, the ices melt, creating a large planetary ocean.
What is different in this scenario is that the planet has a strong thermal shield. The sun brings only a tiny fraction of heat to the planet (in case of Jupiter, only 1% of what it brings to Earth). In night time, the greenhouse gasses keep extra heat blocked, so that the planet radiates the same amount of heat it received during day. If this equilibrium is not achieved, the planet will heat or cool. So, on a terraformed Earth located at the orbit of Jupiter, day-night temperature changes will be only of 1% (below 0.1 C). The difference between the hottest and coldest spot on the planet will also be very small (at maximum 3 C). Water also has a strong mixing effect on global temperatures. An oceanic planet will have basically the same temperature on all its surface.
Since there will be no significant temperature fluctuations, winds and water currents will also be very small, not affecting much the sea. This will be a very quiet sea, more like the water of a lake. Waves will probably never reach one meter high, except if they are created by underwater volcanism. On the other hand, the air will be saturated with water vapors, like a dense endless fog. At first, the ocean will share the same temperature with the air only down to a limited depth, but it will slowly, gradually heat.
Since currents and waves are so small, these planets can sustain endless cities and even floating continents. The material for these continents can be achieved from hydrocarbons found in the primary environment and must be seriously protected from fire. Other ways for building continents also exist, like using floating minerals, based on lithium.
Cold oceanic planet Edit
The moons of Jupiter, Saturn and Uranus, Triton and Pluto might be potential candidates for this category.
By using greenhouse gasses, temperatures can rise. Some settlers might consider that it is cheaper to still allow some ice to exist. Based on the amount, there can be 3 different models of terraformed worlds:
- Ice-covered planets have an inner ocean, covered by a layer of ice. Depending on what the settlers want to achieve, the ice can vary. It could be deep enough to support a sky-scrapper or only as thin as needed to keep it separated from air. Atmospheric temperatures will be kept below freezing, but not too low, to keep maintenance costs lower for the settlements. Below ice, water can be populated with Earth-like creatures.
- Partially ice-covered planets have both exposed oceans and ice. The ice is expected to be thinner and exposed to movements and cracks. However, it can provide a temporary ground for snow nomads.
- Diffuse ice planets are a different category. It is supposed that some celestial bodies, like Callisto, have their interiors not differentiated. This means that there is a mixture of water ice, rocks and other ices. It is known that ice has its greatest density at +4C and that ice is lighter then water. First, the melting process will create lakes, oceans and islands (maybe continents). As melting advances, it will reach new pockets of ice. Islands will start to submerge, slowly or violently. If a pocket of frozen gasses is reached, they will make their way to the atmosphere, slowly or very violent. Depending on their composition, they can have various effects to the climate. At the end, the planet will covered with a global ocean.
Complete oceanic planet Edit
If a planet has no (or almost no) rocky core and is made only of water, there will still be something solid beneath. At high pressure, water gets into an exotic solid phase. It is expected that in case of outer planets, where currents are extremely slow, the oceans will not be so deep, because cold water will go down and there will be almost no force to push it back up.
Toxic oceanic planet Edit
What if the water is not like Earth oceans and there is no cheap way to purify it on a planetary scale? For example, if the oceans are as salty as Dead Sea? It will be hard for humans to live in this environment. Genetically modified organisms will need to be added. Humans will face also a big problem. It is not only that the water cannot be drank, but its vapors can carry toxic salts to the air.
Low air density oceanic planet Edit
Some celestial bodies, like the moons of Uranus, are too small to hold an atmosphere, but have enough water for a planetary ocean. One model for terraforming implies creating a protective layer above surface. This global layer can be something with strong greenhouse effect, high viscosity and transparent, keeping some pressure above the ocean. Above, a tenuous atmosphere is still needed, to keep the layer from completely losing its flexibility.
Low depth oceanic planet Edit
We can imagine a smooth planet, like a plain, with its highest elevation of only 500 meters above its deepest hole. There will not be much water needed to cover all land features. If water is not too deep, creating an island will be possible. Also, some buildings can have their foundations fixed on the ground. Settlers can take advantage of this.
Where only water can support life Edit
Around B - type stars, ultraviolet and X radiations are very strong. Genetically modified plants would be able to survive on land, but Earth-like plants can exist only in waters. A layer of 10 meters of water is enough to block UV light. For settlers, life in daytime will be hard, unless they take cover underground or underwater.
Massive engineering projects Edit
There is no place like home we say often. And it's true. Terraforming means transforming an alien world into something that can be inhabited by us, after all. In case of an oceanic planet, there are a few things that might be done, at high costs.
Removing extra water Edit
This is a hard task. A space elevator, if long enough, can be used to do the job. If it extends twice the geostationary orbit, at its outer end the centrifugal force will be equal (but in opposite direction) then the gravity on surface. So, water can be pumped from surface to the geostationary orbit, then it can flow to the outer end, producing energy, to feed the pumps. However, the energy used by a space elevator comes in fact from rotation speed. Using of this technology will increase rotation period until the object becomes tidal locked.
Water can be removed by overheating the planet, so that it boils and gets lost in the cosmic environment. Another method would be to use impacts. A third way, with higher costs, is to use a giant fleet of spaceships, to transport water out from the planet.
Modifying altitudes Edit
There are a few ways to create islands on an oceanic planet. The most logical way is to increase altitude of submerged mountains. Creating islands from scrap will be a hard job. Even harder will be to activate and control geological mechanisms, like plaque tectonics or volcanos to do the job for us.
Another way is to create deeper holes. By excavating the ocean floor in certain deep places, we can create basins to store water. Land can be used to create islands.
Impacts can be used to create islands, to make excavations and even to bring some extra rocky material.
Chemical compounds Edit
It is not good to think that ocean planets have the same chemical composition like Earth oceans. We might find water to be very salty or not salty at all. Composition of salts can differ much from Earth oceans and be very toxic or it might not have the required minerals for life.
For sure, terraforming an ocean planet is a hard task, but not impossible. Salts can be turn into insoluble compounds (and sequestrated on ocean floor), extracted (moved into outer space) or transformed (into new, useful chemical compounds). If this process is too expensive, genetically modified organisms can be inserted.
Artificial continents Edit
Is it possible to create an artificial continent on an oceanic planet? In theory, yes. It must be floating and very solid. For this, two materials can be used: floating polymers made from hydrocarbons or inorganic rocks based on lithium. The first option has a major disadvantage that in case of a fire, entire continents might burn (and make the atmosphere unbreathable). The second option is also very hard to apply, because lithium is found in small amounts. A third option, using floating metal objects, is also possible.
Some people proposed that humans will adapt so much to the outer space, that they will become new species. According to this theory, on an oceanic planet, we might find our children living in water like fishes. We don't know if a new race will born. What do we know is that some of our children will live on an oceanic planet and will call it home. They will develop new technologies required for their new life style, creating a civilization that we now can only hardly imagine.