Friday, 1 June 2018

Human Colony on Titan

Titan is Saturn's largest moon (and the second largest in the Solar-System after Jupiter's moon, Ganymede). It is unique in many ways, most notably for its thick atmosphere, weather patterns, including rain, and its lakes and rivers. It is one of the best places in the Solar-System for a large human colony. It has the potential to support millions, in fact.

And there is, of course, the potential to discover a completely different form of life and biology to that of our own.

Saturn's largest moon, Titan. Left: a true colour image. Right: overlaid with an infra-red view of the surface.

Here's why Titan would be a promising place to build a colony:

  • Titan's thick atmosphere and air pressure, that's just above that of Earth's surface, would eliminate the requirement for bulky pressure suits. A suit would simply need to provide warmth and oxygen.
  • The hydrocarbon lakes would provide the materials to make plastics that could be used to make all the required structures for living and working.
  • The atmosphere would provide excellent protection from radiation and meteorites, and make any leaks or failures of habitats a problem rather than a lethal failure (the indoor and outdoor pressure would be the same and therefore any leaks very slow).
  • Drilling into the surface would provide all the water a colony could ever want. And from that could be extracted oxygen, and hydrogen for fuel.
  • The low gravity would make return to space relatively easy, and the thick atmosphere would make aircraft particularly easy and economical to fly. Human-powered flight is possible.
  • If there is any life on the surface of Titan it is likely to be methane-based, which should mean it would be unable to survive in a human environment. The danger of either life-form infecting the other would be minimal. It's very likely they could coexist without any problems.

There are significant challenges to overcome, but none are in any way insurmountable:

  • The surface temperature is extremely low at about -180 degrees Celsius. This is significantly colder than even the coldest locations on Earth. New types of clothing and insulation will need to be developed to cope with this.
  • It is currently unknown exactly how detrimental to health living in such a low gravity environment would be. Those born and raised on Titan may well be unable to leave the moon due to the weakness of their bodies. They would certainly never be able to visit Earth.
  • The journey time from Earth to Titan would be many years using conventional rocket technology. Unless the ship had a rotating section to generate artificial gravity, and effective radiation protection, the crew would suffer significant health issues. Nuclear propulsion would significantly reduce journey times (this has been researched heavily but never used).
  • There is a possibility of water-based life existing in the subsurface oceans. The water extracted for use by the colonists would need to be thoroughly studied and sterilised to prevent contamination and infection.

A view of Titan's surface from an altitude of 70 kilometres

Creating a Self-Sustaining Colony

Landing on airless moons is always problematic due to the need to rely solely on rockets to slow down enough for a safe landing. A large amount of fuel needs to be transported each time. No such problem exists at Titan. The thick atmosphere and low gravity of the moon makes it easy to take advantage of aerobraking techniques and relatively small parachutes (compared to the large parachutes that would be required in the thin atmosphere of Mars).

Because of this very large landing craft, carrying hundreds of tonnes of cargo, or even hundreds of colonists, should be able to land quite easily.

Before colonists arrive in large numbers a sizeable 'town' of habitats will be needed, with power generation and crop growing facilities to enable self-sufficiency. It needs to be well planned, with plenty of redundancy, factories (making use if the liquid hydrocarbons), and with roads and airstrips, and space launch facilities.  There will be no chance of rescue for a colony so far from Earth.

The initial habitats will have to be sent by unmanned missions. They will be built robotically. The first humans will then arrive to expand the facilities and establish what will become the first self-sustaining colony. It's likely that this initial stage would take two or three decades to complete. Essentially, the first generation of colonists would be living in a frontier town, with limited but slowly improving comforts.

A shuttle takes off for a journey to an orbiting station around Titan. Once the colony matures and fuel and manufacturing factories are established there will be regular trips to and from the moon's surface to other colonies in the Saturnian system.

The second and future generations would benefit from the growing colony, with spacious homes, more recreation time, and a growing system of orbital facilities to support life on the surface including communications, and transit to and from the surface and to other colonies that will no doubt have been established elsewhere in the Saturnian system and beyond.

At this point, when survival is routine rather than the main task of each colonist each day, research and scientific discovery can take priority. And it will no doubt focus on the indigenous life that is quite possibly abundant on the moon. Such life could well be complex, with the lakes especially teeming with larger creatures that are just impossible to detect without a surface presence.

A large methane-based complex life-form living in one of the hydrocarbon seas on Titan. The actual life on Titan is likely to be less extravagant than that shown in this image, but it still could have evolved into an array of sizeable creatures.  

Titan could have a diverse ecosystem, far removed from what we know here on Earth. It is the most exciting location in the Solar-System to look for life. There will be no shortage of scientists willing to live there when the time comes to send them.

Robotic Exploration

Before any human colonisation of Titan can start we need to know much more about the moon and its surface conditions. We must send surface exploration missions there at the earliest opportunity.

Some missions have been proposed since 2008, such as the Titan Saturn System Mission. It's an ambitious proposal consisting of an orbiter, a balloon to explore the atmosphere and photograph the surface, and a lander that would splash down in one of the methane lakes.

Another proposal is the Titan Mare Explorer. It's a relatively low cost mission that would put a lander on one of Titan's seas. Unfortunately it did not receive funding, but the lander could end up as the lander for the Titan Saturn System Mission if that ever gets off the ground.

Kraken Mare, Titan's largest sea, seen from a high altitude. NASA is researching the possibility of sending a submarine to explore the sea's depths. If it goes ahead it would be a remarkable mission, and one that has the potential to encounter what could be a complex ecosystem of methane-based life.

Flying in Titan's atmosphere is easy due to it's high density and the moon's low gravity. AVIATR proposes sending an aeroplane that would spend a year flying aound Titan, before attempting a landing. And there is ongoing research into a submarine that would explore Kraken Mare, the largest sea on Titan.

None of the above proposals are ever likely to launch. But there is a proposal that has a reasonable chance of getting full approval. Dragonfly, as it is known, would send a rotorcraft (similar to a quadcopter drone) to explore the moon. It would have the ability to fly at speeds up to 10 metres per second and reach altitudes of up to 4 kilometres. It would land and recharge from its radioisotopic generator during Titan's long nights. While landed it would sample the surface composition. It’s an ambitious and cost effective proposal.

The Dragonfly drone: an essential mission to Titan, and one that could be launched in the next decade

In July 2019 NASA will select either Dragonfly or CAESAR (a comet sample and return mission) for launch in the mid 2020s.

Titan's huge importance cannot be stressed enough, both to help ensure the future of our species by being one of the best places for a sustainable human colony, and by being the likely home of a completely new form of life.

Both of those reasons must ensure that Dragonfly is chosen.

They simply must.

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