Colonization of Titan

Saturn's moon Titan in natural color.

Saturn’s orange moon Titan is one of several candidates for a possible future colonization of the outer solar system. There are many possible reasons for colonization, one of which is mining or collecting hydrocarbons which currently power much of Earth's machinery.

Natural resources

Lakes of Titan

According to Cassini data from 2008 Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth. These hydrocarbons rain from the sky and collect in vast deposits that form lakes and dunes.^[1] "Titan is just covered in carbon-bearing material—it’s a giant factory of organic chemicals," said Ralph Lorenz, who leads the study of Titan based on radar data from Cassini. “This vast carbon inventory is an important window into the geology and climate history of Titan.” Several hundred lakes and seas have been observed, with each of several dozen estimated to contain more hydrocarbon liquid than Earth's oil and gas reserves. The dark dunes that run along the equator contain a volume of organics several hundred times larger than Earth's coal reserves. ^[2]

Titan 'sea' (left) compared at scale to Lake Superior (right)

Radar images obtained on July 21, 2006 appear to show lakes of liquid hydrocarbon (such as methane and ethane) in Titan's northern latitudes. This is the first discovery of currently-existing lakes anywhere besides Earth. The lakes range in size from about a kilometer to one which is one hundred kilometers across.^[3]

On March 13, 2007, JPL announced that it found strong evidence of seas of methane and ethane in the northern hemisphere. At least one of these is larger than any of the Great Lakes in North America.^[4]

Suitability

The Jovian system is the least likely to be developed for collecting resources from a gas giant, because of its extraordinary radiation belt. The American aerospace engineer and author Robert Zubrin identified Saturn as the most important and most valuable of the three other gas giants, because of its relative proximity, low radiation, and excellent system of moons. He also named Titan as the most important moon on which to establish a base to develop the resources of the Saturn system. ^[5]

Habitability

Space colonization

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Robert Zubrin has pointed out that Titan possesses an abundance of all the elements necessary to support life, saying "In certain ways, Titan is the most hospitable extraterrestrial world within our solar system for human colonization." ^[6] The atmosphere contains plentiful nitrogen and methane, and strong evidence indicates that liquid methane is on the surface and, liquid water, and ammonia are present under the surface and are often delivered to the surface by volcanic activity. Water can easily be used to generate breathable oxygen. Nitrogen is ideal to add buffer gas partial pressure to breathable air; indeed, nitrogen forms about 78% of Earth's atmosphere.^[7] Nitrogen, methane and ammonia can all be used to produce fertilizer for growing food.

Atmosphere

Additionally, Titan has an atmospheric pressure one and a half times that of Earth. This means that the interior air pressure of landing craft and habitats could be set equal or close to the exterior pressure, reducing the difficulty and complexity of structural engineering for landing craft and habitats compared with low or zero pressure environments such as on the Moon, Mars, or the asteroids. The thick atmosphere would also make radiation a non-issue, unlike on the Moon, Mars, or the asteroids. While Titan's atmosphere contains trace amounts of hydrogen cyanide, in the event of pressure suit breach, the concentration would not inflict more than a slight headache.

Gravity

Titan has a surface gravity of 0.14 g, slightly less than that of the Moon. Managing long-term effects of low gravity on human health would therefore be a significant issue for long-term occupation of Titan, more so than on Mars. These effects are still an active field of study. They can include symptoms such as loss of bone density, loss of muscle density, and a weakened immune system. Astronauts in Earth orbit have remained in microgravity for up to a year and more at a time. Effective countermeasures for the negative effects of low gravity are well-established, particularly an aggressive regime of daily physical exercise or weighted clothing. The variation in the negative effects of low gravity as a function of different levels of low gravity are not known, since all research in this area is restricted to humans in zero gravity. The same goes for the potential effects of low gravity on fetal and pediatric development. It has been hypothesized that children born and raised in low gravity such as on Titan would not be well adapted for life under the higher gravity of Earth.^[8]

Temperature

The temperature on Titan is about 94 K (−179 °C, or −290.2 °F), so insulation and heat generation and management would be significant concerns. Although the air pressure at the surface is about 1.5 times that of Earth sea level, because of the colder temperature, the density of the air is about 4.5 times that of Earth sea level. This substantial density should moderate shifts in temperature over time and from one locale to another, to a fraction of the types of temperature changes familiar from the day/night cycle, the seasons, and weather on Earth. The corresponding narrow range of temperature variation further reduces the difficulties in structural engineering.

Relative thickness of the atmosphere combined with extreme cold makes additional troubles for human habitation. Unlike vacuum, the high atmospheric density makes thermoinsulation a significant engineering problem.

Flight on Titan

The very high ratio of atmospheric density to surface gravity also greatly reduces the wingspan needed for an aircraft to maintain lift, so much so that a human would be able to strap on wings and easily fly through the atmosphere.^[6]

References

1. ^ Findings from the study led by Ralph Lorenz, Cassini radar team member from the Johns Hopkins University Applied Physics Laboratory, USA, are reported in the 29 January 2008 issue of the Geophysical Research Letters.
2. ^ Titan’s surface organics surpass oil reserves on Earth. 13 February 2008 http://www.esa.int/esaSC/SEMCSUUHJCF_index_0.html
3. ^ Cassini-Huygens: News
4. ^ Cassini-Huygens: News
5. ^ Robert Zubrin, Entering Space: Creating a Spacefaring Civilization, section: The Persian Gulf of the solar system, pp. 161-163, Tarcher/Putnam, 1999, ISBN 978-1-58542-036-0
6. ^ ^{a b} Robert Zubrin, Entering Space: Creating a Spacefaring Civilization, section: Titan, pp. 163-166, Tarcher/Putnam, 1999, ISBN 978-1-58542-036-0
7. ^ Robert Zubrin, The Case for Mars: The Plan to Settle the Red Planet and Why We Must, p. 146, Simon & Schuster/Touchstone, 1996, ISBN 978-0-684-83550-1
8. ^ Robert Zubrin, "Colonizing the Outer Solar System", in Islands in the Sky: Bold New Ideas for Colonizing Space, pp. 85-94, Stanley Schmidt and Robert Zubrin, eds., Wiley, 1996, ISBN 978-0-471-13561-6

Further reading

• Stephen L. Gillett, "Titan as the Abode of Life," Analog, Vol. CXII No. 13, pp. 40–55 (1992)