Freeman Dyson Freeman John Dyson (15 December 1923 – 28 February 2020) was a British-American theoretical physics, theoretical physicist and mathematician known for his works in quantum field theory, astrophysics, random matrix, random matrices, math ...

proposed that

trans-Neptunian object A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU). ...

s, rather than

planet A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...

s, are the major potential habitat of life in space. Several hundred billion to trillion

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

-like ice-rich bodies exist outside the orbit of

Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...

, in the

Kuiper belt The Kuiper belt ( ) is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...

and Inner and Outer

Oort cloud The Oort cloud (pronounced or ), sometimes called the Öpik–Oort cloud, is scientific theory, theorized to be a cloud of billions of Volatile (astrogeology), icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 A ...

. These may contain all the ingredients for life (water ice, ammonia, and carbon-rich compounds), including significant amounts of

deuterium Deuterium (hydrogen-2, symbol H or D, also known as heavy hydrogen) is one of two stable isotopes of hydrogen; the other is protium, or hydrogen-1, H. The deuterium nucleus (deuteron) contains one proton and one neutron, whereas the far more c ...

and

helium-3 Helium-3 (3He see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and hydrogen-1 are the only stable nuclides with ...

. Since Dyson's proposal, the number of trans-Neptunian objects known has increased greatly. Colonists could live in the

dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, orbital dominance like the ...

's icy crust or mantle, using fusion or geothermal heat and mining the soft-ice or liquid inner

ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...

for

volatiles Volatility or volatile may refer to: Chemistry * Volatility (chemistry), a measuring tendency of a substance or liquid to vaporize easily ** Volatile organic compounds, organic or carbon compounds that can evaporate at normal temperature and pre ...

and

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

s. Given the light gravity and resulting lower pressure in the ice mantle or inner ocean, colonizing the rocky

core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber ...

's outer surface might give

colonists A settler or a colonist is a person who establishes or joins a permanent presence that is separate to existing communities. The entity that a settler establishes is a settlement. A settler is called a pioneer if they are among the first settli ...

the largest number of

and volatile resources as well as insulating them from cold. Surface habitats or

domes A dome () is an architectural element similar to the hollow upper half of a sphere. There is significant overlap with the term cupola, which may also refer to a dome or a structure on top of a dome. The precise definition of a dome has been a m ...

are another possibility, as background radiation levels are likely to be low. Colonists of such bodies could also build rotating habitats or live in dug-out spaces and light them with

fusion reactor Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices ...

s for thousands to millions of years before moving on. Dyson and

Carl Sagan Carl Edward Sagan (; ; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist and science communicator. His best known scientific contribution is his research on the possibility of extraterrestrial life, including e ...

envisioned that humanity could migrate to neighbouring star systems, which have similar clouds, by using natural objects as slow interstellar vessels with substantial natural resources; and that such interstellar colonies could also serve as way-stations for faster, smaller interstellar ships. Alternatively Richard Terra has proposed using the materials from the Oort-cloud objects to build vast starlight collecting arrays to power habitats, thus making an Oort-cloud community essentially independent of its central star and fusion fuel supplies.Richard P. Terra, "Islands in the Sky: Human Exploration and Settlement of the Oort Cloud", in ''Islands in the Sky: Bold New Ideas for Colonizing Space'', Stanley Schmidt and Robert Zubrin, eds. Wiley, 1996,

References

Bibliography

*Freeman Dyson, "The World, the Flesh, and the Devil", Third J.D. Bernal Lecture, May 1972, reprinted in Communication with Extraterrestrial Intelligence, Carl Sagan, ed., MIT Press, 1973, *Richard P. Terra, "Islands in the Sky: Human Exploration and Settlement of the Oort Cloud", in Islands in the Sky: Bold New Ideas for Colonizing Space, Stanley Schmidt and Robert Zubrin, eds. Wiley, 1996, *Ben R. Finney and Eric M. Jones, eds., Interstellar Migration and the Human Experience, University of California Press, 1986, *David G. Stephenson, "Comets and Interstellar Travel", in Journal of the British Interplanetary Society, 36, 1983, pp. 210–214. {{DEFAULTSORT:Colonization Of Trans-Neptunian Objects +Trans-Neptunian objects Freeman Dyson Trans-Neptunian objects