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An artificial planet could potentially be created by an advanced civilization. Even if our current technology is unable to create such a thing, we can foresee the benefits of it.

Principles[edit | edit source]

By using various future technologies, it is possible to create a large cosmic object like a planet or a large satellite. There are two methods:

Dust Accretion[edit | edit source]

This involves concentrating dust from a large cloud, such as a protoplanetary disk. Current technology is unable to change the orbits of many small-sized particles and space rocks, but some possible methods are:

  • A giant trawl collects dust and compacts it into larger boulders, which are then carried by spaceships.
  • Using light. The effect of light on dust is known from comet tails. However, the energy needed to push all the dust needed for a planet is simply too much. It may be cheaper to collect and move the dust.
  • Moving a larger object, like an asteroid, through a dust cloud, so that its gravity can collect all the matter.
  • Artificial gravity, though this is a highly speculative technology

Asteroid Belts and Rings[edit | edit source]

Could we create a planet from the Asteroid Belt? Unfortunately, the mass of all asteroids is only 4% of that of the Moon ([1]). Other stars might have a larger asteroid belt, massive enough to create a planet. Engineers will have to slowly divert the orbits of all asteroids, so that they can be set on a collision course. The impacts must not be violent because, at their low gravity, asteroids might tear apart instead of creating a larger body. The process will take tens of years but the result will be a larger body, with enough gravity to support an atmosphere.

In the case of planetary rings (such as Saturn's), the problem is different. Rings occur inside the Roche limit, within which any large body will be torn apart by tidal forces. So, even if somehow we collide the particles in a planetary ring together, the newly formed object will not stay in one piece. In order to create a new moon, the matter in the rings must be moved away from the planet.

Collisions of Larger Objects[edit | edit source]

In many places, there are asteroids, dwarf planets or complex moon systems. These objects might be too small to support an atmosphere on their own. However, if we somehow make them collide, we could create a larger body. For the Solar System, by slowly pushing the moons of gas giants and ice giants, we could create the following (they are my own calculations):

Jupiter

  • By colliding the four Galilean Moons (minor moons excluded), we could create an object with a diameter of 7000 km.
  • By colliding the four Galilean Moons (minor moons included), the resulting object will have a diameter of 8000 km.

Saturn

  • By colliding all moons (Titan excluded), we could create an object with a diameter of 2500 km.
  • By colliding all moons of Saturn (Titan included), the resulting object will have a diameter of 5500 km (not much more than Titan itself).

Uranus

  • By colliding all moons of Uranus, we could create an object with a diameter close to 2000 km.
  • By colliding the dwarf planets from the Kuiper Belt, we might be able to create something the size of Earth's moon.

Neptune

  • By colliding all moons of Neptune (Triton excluded), we could create an object with a diameter close to 1000 km.
  • By colliding all moons of Neptune (Triton included), the resulting object will have a diameter of 1500 km (not much more than Triton itself).

The New Planet[edit | edit source]

Assuming a composition similar to Earth, the newly created object will initially be a ball of molten lava. Settlers will have to wait millennia for it to cool down, unless technology is used to accelerate the process. If the bodies involved in collision contain too much water ice (like the moons of gas giants and ice giants), this water may be lost during impact (via the impact itself or via evaporation because of the resulting heat).

When temperatures will drop enough, the crust will be thin and fragile. Quakes and volcanos will be frequent. The extreme volcanism will affect the atmosphere and all ecosystems. Terraforming an extremely volcanic planet may be difficult.

The Lack of Matter[edit | edit source]

Small-sized objects are light. Sometimes, their combined mass is too small to create a large enough body. For example, the combined mass of the Asteroid Belt is only 4% the mass of Earth's Moon. The combined mass of all other moons of Saturn is only 8.5% the mass of Titan and the combined mass of the moons of Uranus is less than the mass of Saturn's moon Rhea. The combined mass of the entire Kuiper Belt is estimated to have between 1 and 10% the mass of Earth. Because of this, in a majority of cases, there might not be enough matter to create an artificial planet.

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