Colonization of the outer Solar System
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| Space colonization |
Some of the moons of the outer planets of the solar system are large enough to be suitable places for colonization. Many of the larger moons contain water ice, liquid water, and organic compounds that might be useful for sustaining human life. Colonies in the outer solar system could also serve as centers for long term investigation of the planet and the other moons. In particular, robotic devices could be controlled by humans without the very long time delays needed to communicate with Earth. There have also been proposals to place robotic aerostats in the upper atmospheres of the gas giant planets for exploration and possibly mining of helium-3, which could have a very high value per unit mass as a thermonuclear fuel.[1][2]
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[edit] The Jovian system
The Jovian system in general poses particular disadvantages for colonizing because of its severe radiation environment and its particularly deep gravity well. Its radiation would deliver about 3,600 rems per day to unshielded colonists at Io and about 540 rems per day to unshielded colonists at Europa, while somewhere around 75 rems within only a few days is generally enough to cause radiation poisoning, and somewhere around 500 rems within only a few days is fatal.[3]
[edit] Jupiter
Jupiter could be the site of airborne colonies such as floating cities, assuming the radiation and gravity issues in traveling to and from the atmosphere are properly addressed. Jupiter has an atmospheric depth with the same pressure as Earth sea level, where there is also a blue sky, though it is colder than on Earth; further down, Jupiter has an atmospheric depth that is the same average temperature as the surface of the Earth, where the pressure is about five bars.
One significant challenge to overcome in colonizing Jupiter would be the intense radiation in the planet's magnetosphere.
[edit] Europa
The Artemis Project designed a plan to colonize Europa.[4][5] Scientists are to inhabit igloos and drill down into the Europan ice crust, exploring any sub-surface ocean. It also discusses use of air pockets for human inhabitation.
[edit] Ganymede
Ganymede is the largest moon in the Solar System, making it a possible target for colonization. Ganymede is also the only moon with a magnetosphere.
[edit] Callisto
NASA performed a study called HOPE (Revolutionary Concepts for Human Outer Planet Exploration) regarding the future exploration of the solar system.[6] The target chosen was Callisto. It could be possible to build a surface base that would produce fuel for further exploration of the solar system.
[edit] Trojan asteroids
The 2006 announcement by the Keck Observatory that the binary Trojan asteroid 617 Patroclus, and possibly large numbers of other Trojan objects in Jupiter's orbit, are likely composed of water ice, with a layer of dust, suggests that mining water and other volatiles in this region and transporting them elsewhere in the Solar system, perhaps via the proposed Interplanetary Transport Network, may be feasible in the not-so-distant future. This could make colonization of the Moon, Mercury and main-belt asteroids more practical.
[edit] The Saturnian system
Robert Zubrin identified Saturn, Uranus and Neptune as "the Persian Gulf of the solar system", as the largest sources of deuterium and helium-3 to drive the pending fusion economy, with Saturn the most important and most valuable of the three, because of its relative proximity, low radiation, and excellent system of moons.[7]
[edit] Titan
Robert Zubrin identified Titan as possessing an abundance of all the elements necessary to support life, making Titan perhaps the most advantageous locale in the outer Solar System for colonization, and saying "In certain ways, Titan is the most hospitable extraterrestrial world within our solar system for human colonization."[8] The surface of Titan is mostly uncratered and thus inferred to be very young and active, and probably composed of mostly water ice, and lakes of liquid hydrocarbons (methane/ethane) in its polar regions. While the temperature is cryogenic (95 K) it should be able to support a base, but more information regarding Titan's surface and the activities on it is necessary. The thick atmosphere and the weather, such as potential flash floods, are also factors to consider.
Incidentally, a widely published expert on terraforming, Christopher McKay, is also a co-investigator on the Huygens probe that landed on Titan in January 2005.
[edit] Enceladus
On March 9th, 2006, NASA's Cassini space probe found possible evidence of liquid water on Enceladus.[9] According to that article, "pockets of liquid water may be no more than tens of meters below the surface." If these findings are confirmed, it would mean liquid water could be collected much more easily on Enceladus than on, for instance, Europa (see above). Discovery of water, especially liquid water, generally improves a celestial body's consideration for colonization dramatically. An alternative model of Enceladus' activity is the decomposition of methane/water clathrates - a process requiring lower temperatures than liquid water eruptions. The relatively higher density of Enceladus indicates a larger than Saturnian average silicate core that should provide materials for base operations.
[edit] Uranus
Because Uranus has the lowest escape velocity of the four gas giants, it has been proposed as a mining site for helium-3.[2] If human supervision of the robotic activity proved necessary, one of Uranus' natural satellites might serve as a base. An alternative is to place floating cities in its atmosphere. By using balloons filled with hydrogen, large masses can be suspended[citation needed] underneath at roughly Earth gravity. Saturn and Neptune could be suitable as well, but Jupiter would likely not be, due to its high gravity, escape velocity, and radiation.
[edit] Neptune
Neptune and its satellites could also be used for colonization, but are farther away, and Neptune has a higher surface gravity than Uranus. Its satellites, especially Triton, could also be colonized. Triton's surface shows signs of extensive geological activity implying a sub-surface ocean, perhaps of ammonia/water[10]. Such geothermal energy would make colonising a cryogenic world like Triton feasible.
[edit] Kuiper Belt and Oort Cloud
The noted physicist Freeman Dyson identified comets, rather than planets, as the major potential habitat of life in space.[11]
[edit] Challenges
There are various difficulties in colonizing the outer solar system. They include:
- Distance from Earth: The outer planets are much further from Earth than inner planets, and would therefore be harder and more time-consuming to reach.
- Planetary conditions: The outer planets have no surface to land on, so any habitation would have to use floating colonies, increasing complexity and decreasing reliability. The moons/comets do not have this problem, although some have specific problems (ie., Europa is in Jupiter's intense radiation bands).
- Power: Solar power is generally considered unsuitable because of the large distance from the sun. Nuclear power is believed to be the only suitable power source for the colonies.
[edit] See also
[edit] References
- ^ Robert Zubrin, Entering Space: Creating a Spacefaring Civilization, section: Settling the Outer Solar System: The Sources of Power, pp. 158-160, Tarcher/Putnam, 1999, ISBN 1-58542-036-0
- ^ a b Jeffrey Van Cleve (Cornell University) et al., "Helium-3 Mining Aerostats in the Atmosphere of Uranus", Abstract for Space Resources Roundtable, accessed May 10, 2006
- ^ Robert Zubrin, Entering Space: Creating a Spacefaring Civilization, section: Colonizing the Jovian System, pp. 166-170, Tarcher/Putnam, 1999, ISBN 1-58542-036-0
- ^ Artemis Society International official website
- ^ Peter Kokh et al., "Europa II Workshop Report", Moon Miner's Manifesto #110, Nov. 1997
- ^ Patrick A. Troutman (NASA Langley Research Center) et al., Revolutionary Concepts for Human Outer Planet Exploration (HOPE), accessed May 10, 2006 (.doc format)
- ^ Robert Zubrin, Entering Space: Creating a Spacefaring Civilization, section: The Persian Gulf of the solar system, pp. 161-163, Tarcher/Putnam, 1999, ISBN 1-58542-036-0
- ^ Robert Zubrin, Entering Space: Creating a Spacefaring Civilization, section: Titan, pp. 163-166, Tarcher/Putnam, 1999, ISBN 1-58542-036-0
- ^ NASA - NASA's Cassini Discovers Potential Liquid Water on Enceladus
- ^ Ruiz, Javier (2003). "Heat flow and depth to a possible internal ocean on Triton". Icarus 166: 436. doi:.
- ^ 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, ISBN 0-262-69037-3
