Eris Simulation

This is a simulation of what one would expect to find on a terraformed Eris, using formulas from Math And Terraforming. Please note that not even the supercomputers at NASA can provide us with a perfect simulation. The information showed here is only an approximation.

Basic data[]

Distance from Sun:
- Aphelion: 97.651 AU or 14599 million km
- Semi-major axis: 67.781 AU or 10133 million km
- Perihelion: 37.911 AU or 5668 million km
Diameter: 2327 km
Solar Constant:
- Aphelion: 0.000208
- Semi-major axis: 0.000431
- Perihelion: 0.00138
Mass: 0.0028 Earths
Mean density: 2.52 kg/l
Year length: 558.04 Earth years
Day length: 25.9 hours (assumed)
Rotation axial tilt: 90 degrees (assumed)

Important! The solar constant of 0.002 is the lowest that can support plant life. Because of this, no celestial body beyond Neptune could be terraformed without an artificial source of light.

Temperature[]

Main article: Temperature.

Before everything, we must acknowledge that Eris has an elliptical orbit. Because of this, with the same amount of greenhouse gasses, it will be very hot in summer and very cold in winter. For humans, the best temperature appears to be +15 C. We will see if, with the use of greenhouse gasses, this is possible to maintain.

See Temperature for more details regarding formulas used for this simulation.

Void temperature is the temperature a celestial body, neutral grey in color, exposed to a source of light of a known Solar Constant (Ks).

Aphelion: Ks = 0.000208, void temperature = -236.20 C or 36.95 K.
Semi-major axis: Ks = 0.000431, void temperature = -228.81 C or 44.53 K.
Perihelion: Ks = 0.00138, void temperature = -213.84 C or 59.31 K.

By amplifying temperatures (adding greenhouse effects), we get the following values:

For 15 C at aphelion:

Semi-major axis: 74 C
Perihelion: 189 C

For 15 C at semi major axis:

Aphelion: -34 C
Perihelion: 110 C

For 15 C at perihelion:

Aphelion: -93 C
Semi major axis: -57 C.

As one can see, if we use only heat and light from the Sun, Eris will experience very hot summers and very cold winters, unless some technology will add or remove greenhouse gasses from time to time. There is no way to get a concentration of greenhouse gasses that will allow life to resist all along the orbital path of Eris.

For this, Eris will need Greenhouse Gases. The Greenhouse Calculator shows us that we will need 481 kg per square meter of sulfur hexafluoride in order to maintain a temperature of 15 C at semi-major axis. That is a huge amount. The atmosphere will consist of 4.81% sulfur hexafluoride, assuming a similar volume with Earth's.

However, plants will not survive on Eris with the dim light they receive from the Sun. They need an alternative source of light. The only possibility is to use an Artificial sun. There are a few different approaches to this subject (we will discuss about them in the next sections).

Let's pretend that the artificial sun will produce both visible and infrared light and together with the Sun, it will ensure a Solar Constant similar to Jupiter's orbit.

Artificial sun[]

Main article: Artificial sun.

Because plants cannot survive with the low luminosity available at Eris's orbit, it will be impossible to maintain life without an extra source of light.

There are several ways to do this.

Orbital Stations. Eris has one known large moon, Dysnomia, which we can presume is tidal locked. On the surface, on the hemisphere facing Eris, a massive power plant can be built. It will produce both light and heat that will be sent towards the planet. Because Dysnomia is made mostly of water ice, we must build an insulation, to avoid melting the moon with residual heat from the power plant. Two additional power plants can be built in a synchronous orbit with Dysnomia, at the Lagrangean points L4 and L5. This way, Eris will be always illuminated, except for the poles.

Dysnomia orbits at 0.037 million km from Eris and has a diameter of 700 km. Orbital period is of 15.8 Earth days. The orbital period of Eris is unknown, some scientists speculate it to be around 25 hours. If Dysnomia is not tidal locked, then the power plants will not always be above the same point above the surface of Eris. With other words, from the surface you will always see one and sometimes two power plants.

Another alternative could be the use of orbital stations located at a lower or higher altitude. Eris can host geostationary satellites, but gravitational perturbations from Dysnomia will disturb them from orbit on a long time scale.

Atmospheric Balloons. In this scenario, many small power plants will be floating in the atmosphere with the help of large balloons. This technology is possible, could be cheaper, but has some major disadvantages. The first and most important is that, by concentrating too much light and heat on a too small surface, will create vertical currents that can disrupt the layer of greenhouse gasses. A hole in the greenhouse insulation will automatically allow heat to escape into cosmos, cooling the area very fast. The massive drop in temperature will create other currents, further disrupting the layer of greenhouse gasses, in a runaway domino effect.

Surface Stations. A third option will be the construction of many surface stations, that will produce light and heat. Above each station, there must be a balloon with its surface coated with highly reflective materials. This will only illuminate and heat the area surrounding each station. By adding a large number of stations, we could, at least theoretically, terraform Eris.

Energy required. On Earth, the Solar Constant is roughly 1.98 calories per minute. It can also be described as 1.361 kW/square meter or 1.361 GW/square km. Eris has a diameter of 2327 km or a surface of 4250000 square km. So, it will require 5.79 million GW to simulate solar radiation at Earth's orbit. This does not include energy losses. However, if we want to create similar luminosity like on Jupiter's moons, where the solar constant is 0.0371, we will need only 108000 GW/square km per second. If we also include energy losses, probably we will need 120000 GW.

As for 2017, on Earth, humans produce 7098 GW/s, so, about 17 times less then what we need. Each power plane will have to produce around 30000 GW/s or over four times more power then all what we produce now on earth.

1g of uranium produces 24 GW. So, we will need to burn 5 kg of uranium in every second or 432000 t every Earth day (assuming we get all the energy transformed). The Earth has (in 2014) 7641600 t of uranium deposits, but it mostly is U238. So, if all that uranium were to be used to heat Eris, with no energy losses, we will be able to heat the planet for only 17.7 Earth days. Eris is much smaller and ice-covered. Because of this, uranium deposits must be far smaller then on Earth. Maybe, they will be exhausted in less then a day! So, the only feasible solution to produce energy is by using hydrogen fusion. Since Eris has huge deposits of water ice, we have enough hydrogen available.

The Sun will bring a little contribution to the heat we need:

At aphelion the Sun will bring 0.56% of energy.
At semi-major axis, the Sun will bring 1.16% of energy.
At perihelion, the Sun will bring 3.72% of energy.

As one can see, energy contribution from the Sun is negligible.

Atmosphere[]

See Atmosphere Parameters

Eris is large enough to support an atmosphere. It is slightly more massive then Pluto. For this simulation, we use an atmosphere with surface pressure of 1 bar and we will test it for temperatures of 15 C (optimal value for human colonization), -100 C (expected value for the energy output by the artificial sun suggested above) and -230 C (expected for Sun illumination at semi-major axis).

Atmosphere stability for oxygen molecules:
- Earth's gravity (15 degrees C): 4.116
- Eris's gravity (15 degrees C): 33.23
- Eris's gravity (-100 degrees C): 19.98
- Eris's gravity (-230 degrees C): 4.977
Atmosphere stability for water molecules:
- Earth's gravity (15 degrees C): 7.320
- Eris's gravity (15 degrees C): 59.08
- Eris's gravity (-100 degrees C): 35.50
- Eris's gravity (-230 degrees C): 8.848
Atmosphere stability for hydrogen molecules:
- Earth's gravity (15 degrees C): 65.88
- Eris's gravity (15 degrees C): 531.8
- Eris's gravity (-100 degrees C): 319.6
- Eris's gravity (-230 degrees C): 79.64

notes: A value below 10 means stability for over a million years, a value between 10 and 100 means stability between 0.1 and 10 millions of years, while a value higher then 100 means stability for less then 10 thousand years.

This calculation does not include solar wind erosion.

Conclusion: At low altitude, where temperature is higher, the atmosphere seems to be less stable. However, at higher elevations, where temperature is similar to Jupiter's orbit, we find conditions similar to Earth's Moon (see Luna Simulation for details). Since solar winds are very weak at Eris's distance, the atmosphere will be stable for many thousands of years.

Surprisingly, if we switch off the artificial sun, the atmosphere becomes stable for oxygen and water vapors (however, they will freeze and fall to the surface) and metastable for hydrogen.

Hydrogen is produced by interactions between ionizing radiation and water molecules. This process will occur on a far smaller scale on Eris, so the hydrogen loss will be very small.

The atmosphere will look like this:

Ground average temperature: 15 degrees C

Surface pressure at sea level: 1
Atmosphere total mass (Earth = 1): 0.68
Atmosphere breathable height: 150 km
Atmosphere total height: 446 km

Ground average temperature: -100 degrees C

Surface pressure at sea level: 1
Atmosphere total mass (Earth = 1): 0.52
Atmosphere breathable height: 118 km
Atmosphere total height: 351 km

Ground average temperature: -230 degrees C

Surface pressure at sea level: 1
Atmosphere total mass (Earth = 1): 0.25
Atmosphere breathable height: 61 km
Atmosphere total height: 182 km

Combined values (surface 15 C, high layers -100 C)

Atmosphere total mass (Earth = 1): 0.6
Atmosphere breathable height: 140 km
Atmosphere total height: 400 km.

The atmosphere will be fluffy and divided in two layers. Below the greenhouse layer, it will be warmer, while above them, it will be cooler. Water molecules, if they pass above the greenhouse layer, will freeze and fall back down.

Climate Simulation[]

Main article: Climate.

The climate of Eris will be artificially maintained. At every moment, we can increase or decrease energy output from the artificial suns, changing ground temperature.

Simulation for semi-major axis, without the use of an artificial sun, only using greenhouse gasses:

At equinox:

poles: 15.0 C
75 deg: 15.2 C
60 deg: 15.2 C
45 deg: 15.3 C
30 deg: 15.3 C
15 deg: 15.3 C
equator: 15.4 C

At winter solstice (assuming Eris is tilted 90 degrees):

poles: 14.6 C
75 deg: 14.7 C
60 deg: 14.7 C
45 deg: 14.7 C
30 deg: 14.8 C
15 deg: 14.8 C
equator: 15.0 C

At summer solstice (assuming Eris is tilted 90 degrees):

poles: 15.4 C
75 deg: 15.3 C
60 deg: 15.3 C
45 deg: 15.3 C
30 deg: 15.2 C
15 deg: 15.2 C
equator: 15.0 C

Simulation with the use of an artificial sun (radiation from the Sun is considered negligible):

poles: 14.2 C
75 deg: 14.7 C
60 deg: 14.9 C
45 deg: 15.1 C
30 deg: 15.2 C
15 deg: 15.3 C
equator: 15.4 C

Assuming an axial tilt of 90 degrees, we can get seasonal variations as follows:

Day - night cycle variation:

Even in the most powerful telescope, Eris appears only as a bright dot. We have no idea what is on its surface. Its light curve shows no variations. Because of this, scientist concluded that it might be covered with an uniform layer of methane ice or it might have its axis oriented to the inner Solar System (thus assuming an axial tilt of 90 degrees). The rotation period was estimated based on light radial speed. However, there is room for large errors. So, we don't know clearly how long is the day on Eris. Still, assuming a day with the same length as Earth's day, we get the following values:

With no artificial sun:

Greenhouse gas concentration set for aphelion:
- Daily temperature variation: 0.0016 degrees C/24h
Greenhouse gas concentration set for semi-major axis:
- Daily temperature variation: 0.0033 degrees C/24h
Greenhouse gas concentration set for perihelion:
- Daily temperature variation: 0.0105 degrees C/24h.

With artificial sun:

Daily temperature variation: 0.555 degrees C/24h.

Again, it is highly visible that Eris, by only using heat from the Sun, will have very little temperature variations. However, if we use an artificial sun that will mimic Sun's luminosity at the orbit of Jupiter, a slight variation in temperature becomes relevant.

Seasons:

Without the effect of an artificial sun, depending only on greenhouse gasses, Eris will experience no significant temperature variations caused by seasons. The highest difference will occur at the poles during polar nights and it will be of only 0.8 degrees C.

If we use an artificial sun, things are different. It all depends on what angle is the orbit of the sun tilted and on what we want to have. To create a winter, we have to decrease the energy output, while to create a summer, we have to increase it.

If the artificial sun orbits around the equator, then no light will reach the poles. The sun will be visible up to very close to the poles. However, if the artificial sun has a tilted orbit, its light will reach the poles.

Surprisingly, it is impossible to create polar days. If the artificial sun will have its orbit tilted by 90 degrees and will pass above the poles during each rotation, then, we will see equatorial nights occurring on the points of the equator that are further away from the orbit plain.

Eris is very far away from the Sun. Seasons are very long, lasting a century. However, by using an artificial sun, we can create our own seasons.

Altitude variations:

Eris will have a fluffy atmosphere and will not experience significant temperature variations with altitude. To experience the same climate change one will see on Earth on a mountain 1 km high, on Eris you will have to get around 20 km high.

Atmosphere Cooling Events:

An outer planet that orbits too far from a source of heat, will experience atmosphere cooling events. Basically, gasses in the outer atmosphere, not protected by a greenhouse insulation, freeze and fall down. As they reach lower altitudes, they sublimate, cooling the lower layers of the atmosphere. This forces the atmosphere to lose its moisture, creating rains. After the atmosphere cools down, the sky becomes blue and the air starts heating again. As this happens, humidity rises back to values close to 100%.

Without an artificial sun, using only greenhouse gasses, the atmosphere has a very low capacity to gain heat:

Aphelion: 0.0016 degrees C/24h or 1 degree C in 625 Earth days
Semi-major axis: 0.0033 degrees C/24h or 1 degree C in 303 Earth days
Perihelion: 0.0105 degrees C/24h or 1 degree C in 95 Earth days.

With an artificial sun, the heating capability is much higher:

Artificial sun simulation: 0.555 degrees C/24h or 10 degrees C in 18 Earth days.

Simulation without an artificial sun reveals something endangering. Without an artificial source of heat, the atmosphere will need sometimes more then an Earth year to heat itself with one degree C. In such conditions, it is questionable if Eris will be able to maintain its surface temperature at all.

However, the simulation using an artificial sun reveals that we can create our own cooling episodes.

Conclusion.

The simulation reveals that Eris will behave like an Outer Planet. The climate pattern will be Monoclime.

Without an artificial source of light, Eris will not be able to support plant life. However, even if greenhouse gasses can support Earth-like temperatures, without an extra source of heat, the planet will be unable to recover from atmosphere cooling events.

With a temperature of 15 degrees C and small variations, the air will get quickly filled with moisture up to 100%, filled with clouds and hazes. It will not be a healthy, nor pleasant place to live in.

However, with the use of an artificial sun, we can overpass this problem. We can turn the sun down (or almost entirely down, letting only little light so we can see), cooling the planet and removing moisture as rainfall. Then, we can increase energy output above average, to heat the planet. For a while, we will have blue skies until the atmosphere will get saturated with moisture. A good climate scheme will be like this one:

20 days of 10% energy output will decrease temperature from 20 to 10 C, forcing rain to occur.
20 days of 145% energy output, rising temperature from 10 to 20 C, as the sky will be mostly blue and the atmosphere will absorb moisture.
Additional 10 days with 100% energy output will ensure the atmosphere gets 100% moisture to feed a rain cycle.

Geography[]

The Sky[]

The Sun will appear as a very bright star in the sky. Its light will be enough for the human eye to see light and colors.

No planets will be visible from Eris at all (see Magnitude for details).

The moon, Dysnomia, will be visible as 19 units (see Angular Size for details). To see how it would look like, draw a circle 19 mm in diameter and look at it from a distance of 1m. It will be about twice larger then Earth's Moon.

The artificial suns will ensure light all day long. So, probably no stars will be visible. They will slowly move on the sky, so that, sometimes you could see two of them at the same time. The Sun will also be visible together with them.

Human Colonies[]

If we use an artificial sun:

Population limit: 6.01 million people
Land population feeding capacity: 11 people per square km
Largest city supported by environment: 15 000 people

Without an artificial sun:

Population limit: 36 000 people
Land population feeding capacity: plants cannot survive
Largest city supported by environment: 144 people.

Assuming it will have similar types of terrain Earth will have, Pluto can support a Population Limit of 110 000 people.

Eris will be highly dependent on its artificial suns. This will create some financial problems (see Maintaining a terrafomed world). There will be many costs that settlers will have to support:

fuel the artificial suns
Maintain the artificial suns
Maintain the ground insulation
Replenish atmosphere losses.

Industry[]

We don't know what resources are on Eris, but we know that maintaining the artificial suns will require some costs. The economy must be very powerful in order to support all this.

Shipping goods from somewhere else to Eris will be costly. Shipping goods from Eris to the inner Solar System will require much time.

In order to secure enough money for the artificial suns, the government of Eris might like to create a fiscal paradise, to encourage companies to come here. Then, we might see factories making everything, from toys and home products, to medicine and vehicles. The economy of Eris will probably look similar to how the economy of China behaves now.

Agriculture[]

Main article: Plants on new worlds.

Plants cannot survive with a solar constant below 0.002. Without an artificial sun, Agriculture outside illuminated domes is impossible. However, with an artificial sun, settlers can produce the food they need.

Transportation[]

Unfortunately, we know nothing about the Geography of Eris. We don't know if ground transportation (roads and railways) can cover a global network or if water transport can be used as a global system. Air transportation will certainly be an option, but it is costly for cargo.

Eris will probably use the three artificial space stations (one located on Dysnomia and one on Dysnomia's Lagrangean points L4 and L5) not only as artificial suns, but also as powerful communication satellites.

In addition, Dysnomia can be used as a space station for cargo and passengers. Smaller ships will transit between Dysnomia and the surface of Eris. Still, because Dysnomia is a large moon, the biggest ships might not be able to land there. They can use the other two stations, which will be artificial satellites.

Tourism[]

Triton and Pluto (see Triton Simulation and Pluto Simulation) will be considered places at the end of the world, since they are the furthest places where terraforming can be done only using light and heat from the Sun.

Eris is something different. As shown above, plants cannot survive on Eris without an extra source of light. In addition, when Eris is at aphelion, atmospheric cooling effects are too powerful and we will not be able to keep a stable climate.

Eris will be the first celestial body located beyond the end, beyond the outer limit where life is possible only using power from the Sun. This will be a fascinating place to visit. Many tourists will come to see with their own eyes the technological wonder that made Eris from a dead world a new paradise for humans.

Wild Life[]

Without an artificial sun, Eris will not be able to sustain plant life. There is not enough light.

With the use of an artificial sun, it will be possible. As shown in this simulation, Eris will have an interesting climate pattern, with temperatures oscillating between +10 and +20 degrees C, with periods of rain and periods of clear sky.

This kind of climate is suitable for most temperate plants and animals. Eris will have forests, pastures and ocean life.

Conclusion[]

The climate simulation of Eris proved that beyond a certain point we cannot rely on the Sun as the only source of light and heat. In this simulation, we chosen to use artificial suns in orbit. The Sun contributes with less then 5% of the energy output needed.

The lessons humans will learn while terraforming and living on Eris are very important, because principles and technologies used here can as well be used on a Rogue planet. The only major advantage that Eris has is its proximity to Earth, compared to planets that are free-floating in interstellar space.